%!PS-Adobe-3.0 %%BoundingBox: 75 0 595 747 %%Title: Enscript Output %%For: Magnus Thoang %%Creator: GNU enscript 1.6.1 %%CreationDate: Fri Oct 31 13:35:14 2003 %%Orientation: Portrait %%Pages: 15 0 %%DocumentMedia: A4 595 842 0 () () %%DocumentNeededResources: (atend) %%EndComments %%BeginProlog %%BeginProcSet: PStoPS 1 15 userdict begin [/showpage/erasepage/copypage]{dup where{pop dup load type/operatortype eq{1 array cvx dup 0 3 index cvx put bind def}{pop}ifelse}{pop}ifelse}forall [/letter/legal/executivepage/a4/a4small/b5/com10envelope /monarchenvelope/c5envelope/dlenvelope/lettersmall/note /folio/quarto/a5]{dup where{dup wcheck{exch{}put} {pop{}def}ifelse}{pop}ifelse}forall /setpagedevice {pop}bind 1 index where{dup wcheck{3 1 roll put} {pop def}ifelse}{def}ifelse /PStoPSmatrix matrix currentmatrix def /PStoPSxform matrix def/PStoPSclip{clippath}def /defaultmatrix{PStoPSmatrix exch PStoPSxform exch concatmatrix}bind def /initmatrix{matrix defaultmatrix setmatrix}bind def /initclip[{matrix currentmatrix PStoPSmatrix setmatrix [{currentpoint}stopped{$error/newerror false put{newpath}} {/newpath cvx 3 1 roll/moveto cvx 4 array astore cvx}ifelse] {[/newpath cvx{/moveto cvx}{/lineto cvx} {/curveto cvx}{/closepath cvx}pathforall]cvx exch pop} stopped{$error/errorname get/invalidaccess eq{cleartomark $error/newerror false put cvx exec}{stop}ifelse}if}bind aload pop /initclip dup load dup type dup/operatortype eq{pop exch pop} {dup/arraytype eq exch/packedarraytype eq or {dup xcheck{exch pop aload pop}{pop cvx}ifelse} {pop cvx}ifelse}ifelse {newpath PStoPSclip clip newpath exec setmatrix} bind aload pop]cvx def /initgraphics{initmatrix newpath initclip 1 setlinewidth 0 setlinecap 0 setlinejoin []0 setdash 0 setgray 10 setmiterlimit}bind def end %%EndProcSet %%BeginResource: procset Enscript-Prolog 1.6 1 % % Procedures. % /_S { % save current state /_s save def } def /_R { % restore from saved state _s restore } def /S { % showpage protecting gstate gsave 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where { pop languagelevel 1 ne { false setstrokeadjust false setoverprint } if } if } bind def /EndEPSF { count op_count sub { pos } repeat % Clean up stacks countdictstack dict_count sub { end } repeat b4_Inc_state restore } bind def % Check PostScript language level. /languagelevel where { pop /gs_languagelevel languagelevel def } { /gs_languagelevel 1 def } ifelse %%EndResource %%BeginResource: procset Enscript-Encoding-88591 1.6 1 /encoding_vector [ /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /.notdef /space /exclam /quotedbl /numbersign /dollar /percent /ampersand /quoteright /parenleft /parenright /asterisk /plus /comma /hyphen /period /slash /zero /one /two /three /four /five /six /seven /eight /nine /colon /semicolon /less /equal /greater 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/Ecircumflex /Edieresis /Igrave /Iacute /Icircumflex /Idieresis /Eth /Ntilde /Ograve /Oacute /Ocircumflex /Otilde /Odieresis /multiply /Oslash /Ugrave /Uacute /Ucircumflex /Udieresis /Yacute /Thorn /germandbls /agrave /aacute /acircumflex /atilde /adieresis /aring /ae /ccedilla /egrave /eacute /ecircumflex /edieresis /igrave /iacute /icircumflex /idieresis /eth /ntilde /ograve /oacute /ocircumflex /otilde /odieresis /divide /oslash /ugrave /uacute /ucircumflex /udieresis /yacute /thorn /ydieresis ] def %%EndResource %%EndProlog %%BeginSetup %%IncludeResource: font Courier-Bold %%IncludeResource: font Courier /HFpt_w 10 def /HFpt_h 10 def /Courier-Bold /HF-gs-font MF /HF /HF-gs-font findfont [HFpt_w 0 0 HFpt_h 0 0] makefont def /Courier /F-gs-font MF /F-gs-font 10 10 SF /#copies 1 def /d_page_w 520 def /d_page_h 747 def /d_header_x 0 def /d_header_y 747 def /d_header_w 520 def /d_header_h 0 def /d_footer_x 0 def /d_footer_y 0 def /d_footer_w 520 def /d_footer_h 0 def /d_output_w 520 def /d_output_h 747 def /cols 1 def userdict/PStoPSxform PStoPSmatrix matrix currentmatrix matrix invertmatrix matrix concatmatrix matrix invertmatrix put %%EndSetup %%Page: (0,1) 1 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 1 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 701 M (Network Working Group T. Ylonen) s 5 690 M (Internet-Draft SSH Communications Security Corp) s 5 679 M (Expires: March 31, 2004 D. Moffat, Editor, Ed.) s 5 668 M ( Sun Microsystems, Inc) s 5 657 M ( Oct 2003) s 5 624 M ( SSH Transport Layer Protocol) s 5 613 M ( draft-ietf-secsh-transport-17.txt) s 5 591 M (Status of this Memo) s 5 569 M ( This document is an Internet-Draft and is in full conformance with) s 5 558 M ( all provisions of Section 10 of RFC2026.) s 5 536 M ( Internet-Drafts are working documents of the Internet Engineering) s 5 525 M ( Task Force \(IETF\), its areas, and its working groups. Note that other) s 5 514 M ( groups may also distribute working documents as Internet-Drafts.) s 5 492 M ( Internet-Drafts are draft documents valid for a maximum of six months) s 5 481 M ( and may be updated, replaced, or obsoleted by other documents at any) s 5 470 M ( time. It is inappropriate to use Internet-Drafts as reference) s 5 459 M ( material or to cite them other than as "work in progress.") s 5 437 M ( The list of current Internet-Drafts can be accessed at http://) s 5 426 M ( www.ietf.org/ietf/1id-abstracts.txt.) s 5 404 M ( The list of Internet-Draft Shadow Directories can be accessed at) s 5 393 M ( http://www.ietf.org/shadow.html.) s 5 371 M ( This Internet-Draft will expire on March 31, 2004.) s 5 349 M (Copyright Notice) s 5 327 M ( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s 5 305 M (Abstract) s 5 283 M ( SSH is a protocol for secure remote login and other secure network) s 5 272 M ( services over an insecure network.) s 5 250 M ( This document describes the SSH transport layer protocol which) s 5 239 M ( typically runs on top of TCP/IP. The protocol can be used as a basis) s 5 228 M ( for a number of secure network services. It provides strong) s 5 217 M ( encryption, server authentication, and integrity protection. It may) s 5 206 M ( also provide compression.) s 5 184 M ( Key exchange method, public key algorithm, symmetric encryption) s 5 173 M ( algorithm, message authentication algorithm, and hash algorithm are) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 1]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 2 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( all negotiated.) s 5 668 M ( This document also describes the Diffie-Hellman key exchange method) s 5 657 M ( and the minimal set of algorithms that are needed to implement the) s 5 646 M ( SSH transport layer protocol.) s 5 624 M (Table of Contents) s 5 602 M ( 1. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 3) s 5 591 M ( 2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3) s 5 580 M ( 3. Conventions Used in This Document . . . . . . . . . . . . . 3) s 5 569 M ( 4. Connection Setup . . . . . . . . . . . . . . . . . . . . . . 3) s 5 558 M ( 4.1 Use over TCP/IP . . . . . . . . . . . . . . . . . . . . . . 4) s 5 547 M ( 4.2 Protocol Version Exchange . . . . . . . . . . . . . . . . . 4) s 5 536 M ( 4.3 Compatibility With Old SSH Versions . . . . . . . . . . . . 4) s 5 525 M ( 4.3.1 Old Client, New Server . . . . . . . . . . . . . . . . . . . 5) s 5 514 M ( 4.3.2 New Client, Old Server . . . . . . . . . . . . . . . . . . . 5) s 5 503 M ( 5. Binary Packet Protocol . . . . . . . . . . . . . . . . . . . 5) s 5 492 M ( 5.1 Maximum Packet Length . . . . . . . . . . . . . . . . . . . 6) s 5 481 M ( 5.2 Compression . . . . . . . . . . . . . . . . . . . . . . . . 7) s 5 470 M ( 5.3 Encryption . . . . . . . . . . . . . . . . . . . . . . . . . 7) s 5 459 M ( 5.4 Data Integrity . . . . . . . . . . . . . . . . . . . . . . . 9) s 5 448 M ( 5.5 Key Exchange Methods . . . . . . . . . . . . . . . . . . . . 10) s 5 437 M ( 5.6 Public Key Algorithms . . . . . . . . . . . . . . . . . . . 11) s 5 426 M ( 6. Key Exchange . . . . . . . . . . . . . . . . . . . . . . . . 13) s 5 415 M ( 6.1 Algorithm Negotiation . . . . . . . . . . . . . . . . . . . 13) s 5 404 M ( 6.2 Output from Key Exchange . . . . . . . . . . . . . . . . . . 16) s 5 393 M ( 6.3 Taking Keys Into Use . . . . . . . . . . . . . . . . . . . . 17) s 5 382 M ( 7. Diffie-Hellman Key Exchange . . . . . . . . . . . . . . . . 18) s 5 371 M ( 7.1 diffie-hellman-group1-sha1 . . . . . . . . . . . . . . . . . 19) s 5 360 M ( 8. Key Re-Exchange . . . . . . . . . . . . . . . . . . . . . . 20) s 5 349 M ( 9. Service Request . . . . . . . . . . . . . . . . . . . . . . 21) s 5 338 M ( 10. Additional Messages . . . . . . . . . . . . . . . . . . . . 21) s 5 327 M ( 10.1 Disconnection Message . . . . . . . . . . . . . . . . . . . 22) s 5 316 M ( 10.2 Ignored Data Message . . . . . . . . . . . . . . . . . . . . 22) s 5 305 M ( 10.3 Debug Message . . . . . . . . . . . . . . . . . . . . . . . 23) s 5 294 M ( 10.4 Reserved Messages . . . . . . . . . . . . . . . . . . . . . 23) s 5 283 M ( 11. Summary of Message Numbers . . . . . . . . . . . . . . . . . 23) s 5 272 M ( 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . 24) s 5 261 M ( 13. Security Considerations . . . . . . . . . . . . . . . . . . 24) s 5 250 M ( 14. Intellectual Property . . . . . . . . . . . . . . . . . . . 24) s 5 239 M ( 15. Additional Information . . . . . . . . . . . . . . . . . . . 24) s 5 228 M ( Authors' Addresses . . . . . . . . . . . . . . . . . . . . . 26) s 5 217 M ( Normative . . . . . . . . . . . . . . . . . . . . . . . . . 25) s 5 206 M ( Informative . . . . . . . . . . . . . . . . . . . . . . . . 25) s 5 195 M ( A. Contibutors . . . . . . . . . . . . . . . . . . . . . . . . 27) s 5 184 M ( Intellectual Property and Copyright Statements . . . . . . . 28) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 2]) s _R S PStoPSsaved restore %%Page: (2,3) 2 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 3 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (1. Contributors) s 5 668 M ( The major original contributors of this document were: Tatu Ylonen,) s 5 657 M ( Tero Kivinen, Timo J. Rinne, Sami Lehtinen \(all of SSH Communications) s 5 646 M ( Security Corp\), and Markku-Juhani O. Saarinen \(University of) s 5 635 M ( Jyvaskyla\)) s 5 613 M ( The document editor is: Darren.Moffat@Sun.COM. Comments on this) s 5 602 M ( internet draft should be sent to the IETF SECSH working group,) s 5 591 M ( details at: http://ietf.org/html.charters/secsh-charter.html) s 5 569 M (2. Introduction) s 5 547 M ( The SSH transport layer is a secure low level transport protocol. It) s 5 536 M ( provides strong encryption, cryptographic host authentication, and) s 5 525 M ( integrity protection.) s 5 503 M ( Authentication in this protocol level is host-based; this protocol) s 5 492 M ( does not perform user authentication. A higher level protocol for) s 5 481 M ( user authentication can be designed on top of this protocol.) s 5 459 M ( The protocol has been designed to be simple, flexible, to allow) s 5 448 M ( parameter negotiation, and to minimize the number of round-trips.) s 5 437 M ( Key exchange method, public key algorithm, symmetric encryption) s 5 426 M ( algorithm, message authentication algorithm, and hash algorithm are) s 5 415 M ( all negotiated. It is expected that in most environments, only 2) s 5 404 M ( round-trips will be needed for full key exchange, server) s 5 393 M ( authentication, service request, and acceptance notification of) s 5 382 M ( service request. The worst case is 3 round-trips.) s 5 360 M (3. Conventions Used in This Document) s 5 338 M ( The keywords "MUST", "MUST NOT", "REQUIRED", "SHOULD", "SHOULD NOT",) s 5 327 M ( and "MAY" that appear in this document are to be interpreted as) s 5 316 M ( described in [RFC2119].) s 5 294 M ( The used data types and terminology are specified in the architecture) s 5 283 M ( document [SSH-ARCH].) s 5 261 M ( The architecture document also discusses the algorithm naming) s 5 250 M ( conventions that MUST be used with the SSH protocols.) s 5 228 M (4. Connection Setup) s 5 206 M ( SSH works over any 8-bit clean, binary-transparent transport. The) s 5 195 M ( underlying transport SHOULD protect against transmission errors as) s 5 184 M ( such errors cause the SSH connection to terminate.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 3]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 4 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( The client initiates the connection.) s 5 668 M (4.1 Use over TCP/IP) s 5 646 M ( When used over TCP/IP, the server normally listens for connections on) s 5 635 M ( port 22. This port number has been registered with the IANA, and has) s 5 624 M ( been officially assigned for SSH.) s 5 602 M (4.2 Protocol Version Exchange) s 5 580 M ( When the connection has been established, both sides MUST send an) s 5 569 M ( identification string of the form "SSH-protoversion-softwareversion) s 5 558 M ( comments", followed by carriage return and newline characters \(ASCII) s 5 547 M ( 13 and 10, respectively\). Both sides MUST be able to process) s 5 536 M ( identification strings without carriage return character. No null) s 5 525 M ( character is sent. The maximum length of the string is 255) s 5 514 M ( characters, including the carriage return and newline.) s 5 492 M ( The part of the identification string preceding carriage return and) s 5 481 M ( newline is used in the Diffie-Hellman key exchange \(see Section) s 5 470 M ( Section 7\).) s 5 448 M ( The server MAY send other lines of data before sending the version) s 5 437 M ( string. Each line SHOULD be terminated by a carriage return and) s 5 426 M ( newline. Such lines MUST NOT begin with "SSH-", and SHOULD be) s 5 415 M ( encoded in ISO-10646 UTF-8 [RFC2279] \(language is not specified\).) s 5 404 M ( Clients MUST be able to process such lines; they MAY be silently) s 5 393 M ( ignored, or MAY be displayed to the client user; if they are) s 5 382 M ( displayed, control character filtering discussed in [SSH-ARCH] SHOULD) s 5 371 M ( be used. The primary use of this feature is to allow TCP-wrappers to) s 5 360 M ( display an error message before disconnecting.) s 5 338 M ( Version strings MUST consist of printable US-ASCII characters, not) s 5 327 M ( including whitespaces or a minus sign \(-\). The version string is) s 5 316 M ( primarily used to trigger compatibility extensions and to indicate) s 5 305 M ( the capabilities of an implementation. The comment string should) s 5 294 M ( contain additional information that might be useful in solving user) s 5 283 M ( problems.) s 5 261 M ( The protocol version described in this document is 2.0.) s 5 239 M ( Key exchange will begin immediately after sending this identifier.) s 5 228 M ( All packets following the identification string SHALL use the binary) s 5 217 M ( packet protocol, to be described below.) s 5 195 M (4.3 Compatibility With Old SSH Versions) s 5 173 M ( During the transition period, it is important to be able to work in a) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 4]) s _R S PStoPSsaved restore %%Page: (4,5) 3 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 5 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( way that is compatible with the installed SSH clients and servers) s 5 679 M ( that use an older version of the protocol. Information in this) s 5 668 M ( section is only relevant for implementations supporting compatibility) s 5 657 M ( with SSH versions 1.x. There is no standards track or informational) s 5 646 M ( draft available that defines the SSH 1.x protocol. The only known) s 5 635 M ( documentation of the 1.x protocol is contained in README files that) s 5 624 M ( are shipped along with the source code.) s 5 602 M (4.3.1 Old Client, New Server) s 5 580 M ( Server implementations MAY support a configurable "compatibility") s 5 569 M ( flag that enables compatibility with old versions. When this flag is) s 5 558 M ( on, the server SHOULD identify its protocol version as "1.99".) s 5 547 M ( Clients using protocol 2.0 MUST be able to identify this as identical) s 5 536 M ( to "2.0". In this mode the server SHOULD NOT send the carriage) s 5 525 M ( return character \(ASCII 13\) after the version identification string.) s 5 503 M ( In the compatibility mode the server SHOULD NOT send any further data) s 5 492 M ( after its initialization string until it has received an) s 5 481 M ( identification string from the client. The server can then determine) s 5 470 M ( whether the client is using an old protocol, and can revert to the) s 5 459 M ( old protocol if required. In the compatibility mode, the server MUST) s 5 448 M ( NOT send additional data before the version string.) s 5 426 M ( When compatibility with old clients is not needed, the server MAY) s 5 415 M ( send its initial key exchange data immediately after the) s 5 404 M ( identification string.) s 5 382 M (4.3.2 New Client, Old Server) s 5 360 M ( Since the new client MAY immediately send additional data after its) s 5 349 M ( identification string \(before receiving server's identification\), the) s 5 338 M ( old protocol may already have been corrupted when the client learns) s 5 327 M ( that the server is old. When this happens, the client SHOULD close) s 5 316 M ( the connection to the server, and reconnect using the old protocol.) s 5 294 M (5. Binary Packet Protocol) s 5 272 M ( Each packet is in the following format:) s 5 250 M ( uint32 packet_length) s 5 239 M ( byte padding_length) s 5 228 M ( byte[n1] payload; n1 = packet_length - padding_length - 1) s 5 217 M ( byte[n2] random padding; n2 = padding_length) s 5 206 M ( byte[m] mac \(message authentication code\); m = mac_length) s 5 184 M ( packet_length) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 5]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 6 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( The length of the packet \(bytes\), not including MAC or the) s 5 679 M ( packet_length field itself.) s 5 657 M ( padding_length) s 5 646 M ( Length of padding \(bytes\).) s 5 624 M ( payload) s 5 613 M ( The useful contents of the packet. If compression has been) s 5 602 M ( negotiated, this field is compressed. Initially, compression) s 5 591 M ( MUST be "none".) s 5 569 M ( random padding) s 5 558 M ( Arbitrary-length padding, such that the total length of) s 5 547 M ( \(packet_length || padding_length || payload || padding\) is a) s 5 536 M ( multiple of the cipher block size or 8, whichever is larger.) s 5 525 M ( There MUST be at least four bytes of padding. The padding) s 5 514 M ( SHOULD consist of random bytes. The maximum amount of padding) s 5 503 M ( is 255 bytes.) s 5 481 M ( mac) s 5 470 M ( Message authentication code. If message authentication has) s 5 459 M ( been negotiated, this field contains the MAC bytes. Initially,) s 5 448 M ( the MAC algorithm MUST be "none".) s 5 415 M ( Note that length of the concatenation of packet length, padding) s 5 404 M ( length, payload, and padding MUST be a multiple of the cipher block) s 5 393 M ( size or 8, whichever is larger. This constraint MUST be enforced) s 5 382 M ( even when using stream ciphers. Note that the packet length field is) s 5 371 M ( also encrypted, and processing it requires special care when sending) s 5 360 M ( or receiving packets.) s 5 338 M ( The minimum size of a packet is 16 \(or the cipher block size,) s 5 327 M ( whichever is larger\) bytes \(plus MAC\); implementations SHOULD decrypt) s 5 316 M ( the length after receiving the first 8 \(or cipher block size,) s 5 305 M ( whichever is larger\) bytes of a packet.) s 5 283 M (5.1 Maximum Packet Length) s 5 261 M ( All implementations MUST be able to process packets with uncompressed) s 5 250 M ( payload length of 32768 bytes or less and total packet size of 35000) s 5 239 M ( bytes or less \(including length, padding length, payload, padding,) s 5 228 M ( and MAC.\). The maximum of 35000 bytes is an arbitrary chosen value) s 5 217 M ( larger than uncompressed size. Implementations SHOULD support longer) s 5 206 M ( packets, where they might be needed, e.g. if an implementation wants) s 5 195 M ( to send a very large number of certificates. Such packets MAY be) s 5 184 M ( sent if the version string indicates that the other party is able to) s 5 173 M ( process them. However, implementations SHOULD check that the packet) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 6]) s _R S PStoPSsaved restore %%Page: (6,7) 4 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 7 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( length is reasonable for the implementation to avoid) s 5 679 M ( denial-of-service and/or buffer overflow attacks.) s 5 657 M (5.2 Compression) s 5 635 M ( If compression has been negotiated, the payload field \(and only it\)) s 5 624 M ( will be compressed using the negotiated algorithm. The length field) s 5 613 M ( and MAC will be computed from the compressed payload. Encryption will) s 5 602 M ( be done after compression.) s 5 580 M ( Compression MAY be stateful, depending on the method. Compression) s 5 569 M ( MUST be independent for each direction, and implementations MUST) s 5 558 M ( allow independently choosing the algorithm for each direction.) s 5 536 M ( The following compression methods are currently defined:) s 5 514 M ( none REQUIRED no compression) s 5 503 M ( zlib OPTIONAL ZLIB \(LZ77\) compression) s 5 481 M ( The "zlib" compression is described in [RFC1950] and in [RFC1951].) s 5 470 M ( The compression context is initialized after each key exchange, and) s 5 459 M ( is passed from one packet to the next with only a partial flush being) s 5 448 M ( performed at the end of each packet. A partial flush means that the) s 5 437 M ( current compressed block is ended and all data will be output. If the) s 5 426 M ( current block is not a stored block, one or more empty blocks are) s 5 415 M ( added after the current block to ensure that there are at least 8) s 5 404 M ( bits counting from the start of the end-of-block code of the current) s 5 393 M ( block to the end of the packet payload.) s 5 371 M ( Additional methods may be defined as specified in [SSH-ARCH].) s 5 349 M (5.3 Encryption) s 5 327 M ( An encryption algorithm and a key will be negotiated during the key) s 5 316 M ( exchange. When encryption is in effect, the packet length, padding) s 5 305 M ( length, payload and padding fields of each packet MUST be encrypted) s 5 294 M ( with the given algorithm.) s 5 272 M ( The encrypted data in all packets sent in one direction SHOULD be) s 5 261 M ( considered a single data stream. For example, initialization vectors) s 5 250 M ( SHOULD be passed from the end of one packet to the beginning of the) s 5 239 M ( next packet. All ciphers SHOULD use keys with an effective key length) s 5 228 M ( of 128 bits or more.) s 5 206 M ( The ciphers in each direction MUST run independently of each other,) s 5 195 M ( and implementations MUST allow independently choosing the algorithm) s 5 184 M ( for each direction \(if multiple algorithms are allowed by local) s 5 173 M ( policy\).) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 7]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 8 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( The following ciphers are currently defined:) s 5 668 M ( 3des-cbc REQUIRED three-key 3DES in CBC mode) s 5 657 M ( blowfish-cbc OPTIONALi Blowfish in CBC mode) s 5 646 M ( twofish256-cbc OPTIONAL Twofish in CBC mode,) s 5 635 M ( with 256-bit key) s 5 624 M ( twofish-cbc OPTIONAL alias for "twofish256-cbc" \(this) s 5 613 M ( is being retained for) s 5 602 M ( historical reasons\)) s 5 591 M ( twofish192-cbc OPTIONAL Twofish with 192-bit key) s 5 580 M ( twofish128-cbc OPTIONAL Twofish with 128-bit key) s 5 569 M ( aes256-cbc OPTIONAL AES \(Rijndael\) in CBC mode,) s 5 558 M ( with 256-bit key) s 5 547 M ( aes192-cbc OPTIONAL AES with 192-bit key) s 5 536 M ( aes128-cbc RECOMMENDED AES with 128-bit key) s 5 525 M ( serpent256-cbc OPTIONAL Serpent in CBC mode, with) s 5 514 M ( 256-bit key) s 5 503 M ( serpent192-cbc OPTIONAL Serpent with 192-bit key) s 5 492 M ( serpent128-cbc OPTIONAL Serpent with 128-bit key) s 5 481 M ( arcfour OPTIONAL the ARCFOUR stream cipher) s 5 470 M ( idea-cbc OPTIONAL IDEA in CBC mode) s 5 459 M ( cast128-cbc OPTIONAL CAST-128 in CBC mode) s 5 448 M ( none OPTIONAL no encryption; NOT RECOMMENDED) s 5 426 M ( The "3des-cbc" cipher is three-key triple-DES) s 5 415 M ( \(encrypt-decrypt-encrypt\), where the first 8 bytes of the key are) s 5 404 M ( used for the first encryption, the next 8 bytes for the decryption,) s 5 393 M ( and the following 8 bytes for the final encryption. This requires 24) s 5 382 M ( bytes of key data \(of which 168 bits are actually used\). To) s 5 371 M ( implement CBC mode, outer chaining MUST be used \(i.e., there is only) s 5 360 M ( one initialization vector\). This is a block cipher with 8 byte) s 5 349 M ( blocks. This algorithm is defined in [FIPS-46-3]) s 5 327 M ( The "blowfish-cbc" cipher is Blowfish in CBC mode, with 128 bit keys) s 5 316 M ( [SCHNEIER]. This is a block cipher with 8 byte blocks.) s 5 294 M ( The "twofish-cbc" or "twofish256-cbc" cipher is Twofish in CBC mode,) s 5 283 M ( with 256 bit keys as described [TWOFISH]. This is a block cipher with) s 5 272 M ( 16 byte blocks.) s 5 250 M ( The "twofish192-cbc" cipher. Same as above but with 192-bit key.) s 5 228 M ( The "twofish128-cbc" cipher. Same as above but with 128-bit key.) s 5 206 M ( The "aes256-cbc" cipher is AES \(Advanced Encryption Standard\)) s 5 195 M ( [FIPS-197], formerly Rijndael, in CBC mode. This version uses 256-bit) s 5 184 M ( key.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 8]) s _R S PStoPSsaved restore %%Page: (8,9) 5 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 9 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( The "aes192-cbc" cipher. Same as above but with 192-bit key.) s 5 668 M ( The "aes128-cbc" cipher. Same as above but with 128-bit key.) s 5 646 M ( The "serpent256-cbc" cipher in CBC mode, with 256-bit key as) s 5 635 M ( described in the Serpent AES submission.) s 5 613 M ( The "serpent192-cbc" cipher. Same as above but with 192-bit key.) s 5 591 M ( The "serpent128-cbc" cipher. Same as above but with 128-bit key.) s 5 569 M ( The "arcfour" is the Arcfour stream cipher with 128 bit keys. The) s 5 558 M ( Arcfour cipher is believed to be compatible with the RC4 cipher) s 5 547 M ( [SCHNEIER]. RC4 is a registered trademark of RSA Data Security Inc.) s 5 536 M ( Arcfour \(and RC4\) has problems with weak keys, and should be used) s 5 525 M ( with caution.) s 5 503 M ( The "idea-cbc" cipher is the IDEA cipher in CBC mode [SCHNEIER].) s 5 481 M ( The "cast128-cbc" cipher is the CAST-128 cipher in CBC mode) s 5 470 M ( [RFC2144].) s 5 448 M ( The "none" algorithm specifies that no encryption is to be done.) s 5 437 M ( Note that this method provides no confidentiality protection, and it) s 5 426 M ( is not recommended. Some functionality \(e.g. password) s 5 415 M ( authentication\) may be disabled for security reasons if this cipher) s 5 404 M ( is chosen.) s 5 382 M ( Additional methods may be defined as specified in [SSH-ARCH].) s 5 360 M (5.4 Data Integrity) s 5 338 M ( Data integrity is protected by including with each packet a message) s 5 327 M ( authentication code \(MAC\) that is computed from a shared secret,) s 5 316 M ( packet sequence number, and the contents of the packet.) s 5 294 M ( The message authentication algorithm and key are negotiated during) s 5 283 M ( key exchange. Initially, no MAC will be in effect, and its length) s 5 272 M ( MUST be zero. After key exchange, the selected MAC will be computed) s 5 261 M ( before encryption from the concatenation of packet data:) s 5 239 M ( mac = MAC\(key, sequence_number || unencrypted_packet\)) s 5 217 M ( where unencrypted_packet is the entire packet without MAC \(the length) s 5 206 M ( fields, payload and padding\), and sequence_number is an implicit) s 5 195 M ( packet sequence number represented as uint32. The sequence number is) s 5 184 M ( initialized to zero for the first packet, and is incremented after) s 5 173 M ( every packet \(regardless of whether encryption or MAC is in use\). It) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 9]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 10 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( is never reset, even if keys/algorithms are renegotiated later. It) s 5 679 M ( wraps around to zero after every 2^32 packets. The packet sequence) s 5 668 M ( number itself is not included in the packet sent over the wire.) s 5 646 M ( The MAC algorithms for each direction MUST run independently, and) s 5 635 M ( implementations MUST allow choosing the algorithm independently for) s 5 624 M ( both directions.) s 5 602 M ( The MAC bytes resulting from the MAC algorithm MUST be transmitted) s 5 591 M ( without encryption as the last part of the packet. The number of MAC) s 5 580 M ( bytes depends on the algorithm chosen.) s 5 558 M ( The following MAC algorithms are currently defined:) s 5 536 M ( hmac-sha1 REQUIRED HMAC-SHA1 \(digest length = key) s 5 525 M ( length = 20\)) s 5 514 M ( hmac-sha1-96 RECOMMENDED first 96 bits of HMAC-SHA1 \(digest) s 5 503 M ( length = 12, key length = 20\)) s 5 492 M ( hmac-md5 OPTIONAL HMAC-MD5 \(digest length = key) s 5 481 M ( length = 16\)) s 5 470 M ( hmac-md5-96 OPTIONAL first 96 bits of HMAC-MD5 \(digest) s 5 459 M ( length = 12, key length = 16\)) s 5 448 M ( none OPTIONAL no MAC; NOT RECOMMENDED) s 5 426 M ( Figure 1) s 5 404 M ( The "hmac-*" algorithms are described in [RFC2104] The "*-n" MACs use) s 5 393 M ( only the first n bits of the resulting value.) s 5 371 M ( The hash algorithms are described in [SCHNEIER].) s 5 349 M ( Additional methods may be defined as specified in [SSH-ARCH].) s 5 327 M (5.5 Key Exchange Methods) s 5 305 M ( The key exchange method specifies how one-time session keys are) s 5 294 M ( generated for encryption and for authentication, and how the server) s 5 283 M ( authentication is done.) s 5 261 M ( Only one REQUIRED key exchange method has been defined:) s 5 239 M ( diffie-hellman-group1-sha1 REQUIRED) s 5 217 M ( This method is described later in this document.) s 5 195 M ( Additional methods may be defined as specified in [SSH-ARCH].) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 10]) s _R S PStoPSsaved restore %%Page: (10,11) 6 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 11 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (5.6 Public Key Algorithms) s 5 668 M ( This protocol has been designed to be able to operate with almost any) s 5 657 M ( public key format, encoding, and algorithm \(signature and/or) s 5 646 M ( encryption\).) s 5 624 M ( There are several aspects that define a public key type:) s 5 613 M ( o Key format: how is the key encoded and how are certificates) s 5 602 M ( represented. The key blobs in this protocol MAY contain) s 5 591 M ( certificates in addition to keys.) s 5 580 M ( o Signature and/or encryption algorithms. Some key types may not) s 5 569 M ( support both signing and encryption. Key usage may also be) s 5 558 M ( restricted by policy statements in e.g. certificates. In this) s 5 547 M ( case, different key types SHOULD be defined for the different) s 5 536 M ( policy alternatives.) s 5 525 M ( o Encoding of signatures and/or encrypted data. This includes but is) s 5 514 M ( not limited to padding, byte order, and data formats.) s 5 492 M ( The following public key and/or certificate formats are currently defined:) s 5 470 M ( ssh-dss REQUIRED sign Raw DSS Key) s 5 459 M ( ssh-rsa RECOMMENDED sign Raw RSA Key) s 5 448 M ( x509v3-sign-rsa OPTIONAL sign X.509 certificates \(RSA key\)) s 5 437 M ( x509v3-sign-dss OPTIONAL sign X.509 certificates \(DSS key\)) s 5 426 M ( spki-sign-rsa OPTIONAL sign SPKI certificates \(RSA key\)) s 5 415 M ( spki-sign-dss OPTIONAL sign SPKI certificates \(DSS key\)) s 5 404 M ( pgp-sign-rsa OPTIONAL sign OpenPGP certificates \(RSA key\)) s 5 393 M ( pgp-sign-dss OPTIONAL sign OpenPGP certificates \(DSS key\)) s 5 371 M ( Additional key types may be defined as specified in [SSH-ARCH].) s 5 349 M ( The key type MUST always be explicitly known \(from algorithm) s 5 338 M ( negotiation or some other source\). It is not normally included in) s 5 327 M ( the key blob.) s 5 305 M ( Certificates and public keys are encoded as follows:) s 5 283 M ( string certificate or public key format identifier) s 5 272 M ( byte[n] key/certificate data) s 5 250 M ( The certificate part may have be a zero length string, but a public) s 5 239 M ( key is required. This is the public key that will be used for) s 5 228 M ( authentication; the certificate sequence contained in the certificate) s 5 217 M ( blob can be used to provide authorization.) s 5 195 M ( Public key / certifcate formats that do not explicitly specify a) s 5 184 M ( signature format identifier MUST use the public key / certificate) s 5 173 M ( format identifier as the signature identifier.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 11]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 12 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( Signatures are encoded as follows:) s 5 679 M ( string signature format identifier \(as specified by the) s 5 668 M ( public key / cert format\)) s 5 657 M ( byte[n] signature blob in format specific encoding.) s 5 624 M ( The "ssh-dss" key format has the following specific encoding:) s 5 602 M ( string "ssh-dss") s 5 591 M ( mpint p) s 5 580 M ( mpint q) s 5 569 M ( mpint g) s 5 558 M ( mpint y) s 5 536 M ( Here the p, q, g, and y parameters form the signature key blob.) s 5 514 M ( Signing and verifying using this key format is done according to the) s 5 503 M ( Digital Signature Standard [FIPS-186] using the SHA-1 hash. A) s 5 492 M ( description can also be found in [SCHNEIER].) s 5 470 M ( The resulting signature is encoded as follows:) s 5 448 M ( string "ssh-dss") s 5 437 M ( string dss_signature_blob) s 5 415 M ( dss_signature_blob is encoded as a string containing r followed by s) s 5 404 M ( \(which are 160 bits long integers, without lengths or padding,) s 5 393 M ( unsigned and in network byte order\).) s 5 371 M ( The "ssh-rsa" key format has the following specific encoding:) s 5 349 M ( string "ssh-rsa") s 5 338 M ( mpint e) s 5 327 M ( mpint n) s 5 305 M ( Here the e and n parameters form the signature key blob.) s 5 283 M ( Signing and verifying using this key format is done according to) s 5 272 M ( [SCHNEIER] and [PKCS1] using the SHA-1 hash.) s 5 250 M ( The resulting signature is encoded as follows:) s 5 228 M ( string "ssh-rsa") s 5 217 M ( string rsa_signature_blob) s 5 195 M ( rsa_signature_blob is encoded as a string containing s \(which is an) s 5 184 M ( integer, without lengths or padding, unsigned and in network byte) s 5 173 M ( order\).) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 12]) s _R S PStoPSsaved restore %%Page: (12,13) 7 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 13 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( The "spki-sign-rsa" method indicates that the certificate blob) s 5 679 M ( contains a sequence of SPKI certificates. The format of SPKI) s 5 668 M ( certificates is described in [RFC2693]. This method indicates that) s 5 657 M ( the key \(or one of the keys in the certificate\) is an RSA-key.) s 5 635 M ( The "spki-sign-dss". As above, but indicates that the key \(or one of) s 5 624 M ( the keys in the certificate\) is a DSS-key.) s 5 602 M ( The "pgp-sign-rsa" method indicates the certificates, the public key,) s 5 591 M ( and the signature are in OpenPGP compatible binary format) s 5 580 M ( \([RFC2440]\). This method indicates that the key is an RSA-key.) s 5 558 M ( The "pgp-sign-dss". As above, but indicates that the key is a) s 5 547 M ( DSS-key.) s 5 525 M (6. Key Exchange) s 5 503 M ( Key exchange begins by each side sending lists of supported) s 5 492 M ( algorithms. Each side has a preferred algorithm in each category, and) s 5 481 M ( it is assumed that most implementations at any given time will use) s 5 470 M ( the same preferred algorithm. Each side MAY guess which algorithm) s 5 459 M ( the other side is using, and MAY send an initial key exchange packet) s 5 448 M ( according to the algorithm if appropriate for the preferred method.) s 5 426 M ( Guess is considered wrong, if:) s 5 415 M ( o the kex algorithm and/or the host key algorithm is guessed wrong) s 5 404 M ( \(server and client have different preferred algorithm\), or) s 5 393 M ( o if any of the other algorithms cannot be agreed upon \(the) s 5 382 M ( procedure is defined below in Section Section 6.1\).) s 5 360 M ( Otherwise, the guess is considered to be right and the optimistically) s 5 349 M ( sent packet MUST be handled as the first key exchange packet.) s 5 327 M ( However, if the guess was wrong, and a packet was optimistically sent) s 5 316 M ( by one or both parties, such packets MUST be ignored \(even if the) s 5 305 M ( error in the guess would not affect the contents of the initial) s 5 294 M ( packet\(s\)\), and the appropriate side MUST send the correct initial) s 5 283 M ( packet.) s 5 261 M ( Server authentication in the key exchange MAY be implicit. After a) s 5 250 M ( key exchange with implicit server authentication, the client MUST) s 5 239 M ( wait for response to its service request message before sending any) s 5 228 M ( further data.) s 5 206 M (6.1 Algorithm Negotiation) s 5 184 M ( Key exchange begins by each side sending the following packet:) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 13]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 14 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( byte SSH_MSG_KEXINIT) s 5 679 M ( byte[16] cookie \(random bytes\)) s 5 668 M ( string kex_algorithms) s 5 657 M ( string server_host_key_algorithms) s 5 646 M ( string encryption_algorithms_client_to_server) s 5 635 M ( string encryption_algorithms_server_to_client) s 5 624 M ( string mac_algorithms_client_to_server) s 5 613 M ( string mac_algorithms_server_to_client) s 5 602 M ( string compression_algorithms_client_to_server) s 5 591 M ( string compression_algorithms_server_to_client) s 5 580 M ( string languages_client_to_server) s 5 569 M ( string languages_server_to_client) s 5 558 M ( boolean first_kex_packet_follows) s 5 547 M ( uint32 0 \(reserved for future extension\)) s 5 525 M ( Each of the algorithm strings MUST be a comma-separated list of) s 5 514 M ( algorithm names \(see ''Algorithm Naming'' in [SSH-ARCH]\). Each) s 5 503 M ( supported \(allowed\) algorithm MUST be listed in order of preference.) s 5 481 M ( The first algorithm in each list MUST be the preferred \(guessed\)) s 5 470 M ( algorithm. Each string MUST contain at least one algorithm name.) s 5 437 M ( cookie) s 5 426 M ( The cookie MUST be a random value generated by the sender. Its) s 5 415 M ( purpose is to make it impossible for either side to fully) s 5 404 M ( determine the keys and the session identifier.) s 5 382 M ( kex_algorithms) s 5 371 M ( Key exchange algorithms were defined above. The first) s 5 360 M ( algorithm MUST be the preferred \(and guessed\) algorithm. If) s 5 349 M ( both sides make the same guess, that algorithm MUST be used.) s 5 338 M ( Otherwise, the following algorithm MUST be used to choose a key) s 5 327 M ( exchange method: iterate over client's kex algorithms, one at a) s 5 316 M ( time. Choose the first algorithm that satisfies the following) s 5 305 M ( conditions:) s 5 294 M ( + the server also supports the algorithm,) s 5 283 M ( + if the algorithm requires an encryption-capable host key,) s 5 272 M ( there is an encryption-capable algorithm on the server's) s 5 261 M ( server_host_key_algorithms that is also supported by the) s 5 250 M ( client, and) s 5 239 M ( + if the algorithm requires a signature-capable host key,) s 5 228 M ( there is a signature-capable algorithm on the server's) s 5 217 M ( server_host_key_algorithms that is also supported by the) s 5 206 M ( client.) s 5 195 M ( + If no algorithm satisfying all these conditions can be) s 5 184 M ( found, the connection fails, and both sides MUST disconnect.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 14]) s _R S PStoPSsaved restore %%Page: (14,15) 8 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 15 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( server_host_key_algorithms) s 5 679 M ( List of the algorithms supported for the server host key. The) s 5 668 M ( server lists the algorithms for which it has host keys; the) s 5 657 M ( client lists the algorithms that it is willing to accept.) s 5 646 M ( \(There MAY be multiple host keys for a host, possibly with) s 5 635 M ( different algorithms.\)) s 5 613 M ( Some host keys may not support both signatures and encryption) s 5 602 M ( \(this can be determined from the algorithm\), and thus not all) s 5 591 M ( host keys are valid for all key exchange methods.) s 5 569 M ( Algorithm selection depends on whether the chosen key exchange) s 5 558 M ( algorithm requires a signature or encryption capable host key.) s 5 547 M ( It MUST be possible to determine this from the public key) s 5 536 M ( algorithm name. The first algorithm on the client's list that) s 5 525 M ( satisfies the requirements and is also supported by the server) s 5 514 M ( MUST be chosen. If there is no such algorithm, both sides MUST) s 5 503 M ( disconnect.) s 5 481 M ( encryption_algorithms) s 5 470 M ( Lists the acceptable symmetric encryption algorithms in order) s 5 459 M ( of preference. The chosen encryption algorithm to each) s 5 448 M ( direction MUST be the first algorithm on the client's list) s 5 437 M ( that is also on the server's list. If there is no such) s 5 426 M ( algorithm, both sides MUST disconnect.) s 5 404 M ( Note that "none" must be explicitly listed if it is to be) s 5 393 M ( acceptable. The defined algorithm names are listed in Section) s 5 382 M ( Section 5.3.) s 5 360 M ( mac_algorithms) s 5 349 M ( Lists the acceptable MAC algorithms in order of preference.) s 5 338 M ( The chosen MAC algorithm MUST be the first algorithm on the) s 5 327 M ( client's list that is also on the server's list. If there is) s 5 316 M ( no such algorithm, both sides MUST disconnect.) s 5 294 M ( Note that "none" must be explicitly listed if it is to be) s 5 283 M ( acceptable. The MAC algorithm names are listed in Section) s 5 272 M ( Figure 1.) s 5 250 M ( compression_algorithms) s 5 239 M ( Lists the acceptable compression algorithms in order of) s 5 228 M ( preference. The chosen compression algorithm MUST be the first) s 5 217 M ( algorithm on the client's list that is also on the server's) s 5 206 M ( list. If there is no such algorithm, both sides MUST) s 5 195 M ( disconnect.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 15]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 16 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( Note that "none" must be explicitly listed if it is to be) s 5 679 M ( acceptable. The compression algorithm names are listed in) s 5 668 M ( Section Section 5.2.) s 5 646 M ( languages) s 5 635 M ( This is a comma-separated list of language tags in order of) s 5 624 M ( preference [RFC3066]. Both parties MAY ignore this list. If) s 5 613 M ( there are no language preferences, this list SHOULD be empty.) s 5 602 M ( Language tags SHOULD NOT be present unless they are known to be) s 5 591 M ( needed by the sending party.) s 5 569 M ( first_kex_packet_follows) s 5 558 M ( Indicates whether a guessed key exchange packet follows. If a) s 5 547 M ( guessed packet will be sent, this MUST be TRUE. If no guessed) s 5 536 M ( packet will be sent, this MUST be FALSE.) s 5 514 M ( After receiving the SSH_MSG_KEXINIT packet from the other side,) s 5 503 M ( each party will know whether their guess was right. If the) s 5 492 M ( other party's guess was wrong, and this field was TRUE, the) s 5 481 M ( next packet MUST be silently ignored, and both sides MUST then) s 5 470 M ( act as determined by the negotiated key exchange method. If) s 5 459 M ( the guess was right, key exchange MUST continue using the) s 5 448 M ( guessed packet.) s 5 426 M ( After the KEXINIT packet exchange, the key exchange algorithm is run.) s 5 415 M ( It may involve several packet exchanges, as specified by the key) s 5 404 M ( exchange method.) s 5 382 M (6.2 Output from Key Exchange) s 5 360 M ( The key exchange produces two values: a shared secret K, and an) s 5 349 M ( exchange hash H. Encryption and authentication keys are derived from) s 5 338 M ( these. The exchange hash H from the first key exchange is) s 5 327 M ( additionally used as the session identifier, which is a unique) s 5 316 M ( identifier for this connection. It is used by authentication methods) s 5 305 M ( as a part of the data that is signed as a proof of possession of a) s 5 294 M ( private key. Once computed, the session identifier is not changed,) s 5 283 M ( even if keys are later re-exchanged.) s 5 250 M ( Each key exchange method specifies a hash function that is used in) s 5 239 M ( the key exchange. The same hash algorithm MUST be used in key) s 5 228 M ( derivation. Here, we'll call it HASH.) s 5 195 M ( Encryption keys MUST be computed as HASH of a known value and K as) s 5 184 M ( follows:) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 16]) s _R S PStoPSsaved restore %%Page: (16,17) 9 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 17 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( o Initial IV client to server: HASH\(K || H || "A" || session_id\)) s 5 679 M ( \(Here K is encoded as mpint and "A" as byte and session_id as raw) s 5 668 M ( data."A" means the single character A, ASCII 65\).) s 5 657 M ( o Initial IV server to client: HASH\(K || H || "B" || session_id\)) s 5 646 M ( o Encryption key client to server: HASH\(K || H || "C" || session_id\)) s 5 635 M ( o Encryption key server to client: HASH\(K || H || "D" || session_id\)) s 5 624 M ( o Integrity key client to server: HASH\(K || H || "E" || session_id\)) s 5 613 M ( o Integrity key server to client: HASH\(K || H || "F" || session_id\)) s 5 591 M ( Key data MUST be taken from the beginning of the hash output. 128) s 5 580 M ( bits \(16 bytes\) MUST be used for algorithms with variable-length) s 5 569 M ( keys. The only variable key length algorithm defined in this document) s 5 558 M ( is arcfour\). For other algorithms, as many bytes as are needed are) s 5 547 M ( taken from the beginning of the hash value. If the key length needed) s 5 536 M ( is longer than the output of the HASH, the key is extended by) s 5 525 M ( computing HASH of the concatenation of K and H and the entire key so) s 5 514 M ( far, and appending the resulting bytes \(as many as HASH generates\) to) s 5 503 M ( the key. This process is repeated until enough key material is) s 5 492 M ( available; the key is taken from the beginning of this value. In) s 5 481 M ( other words:) s 5 459 M ( K1 = HASH\(K || H || X || session_id\) \(X is e.g. "A"\)) s 5 448 M ( K2 = HASH\(K || H || K1\)) s 5 437 M ( K3 = HASH\(K || H || K1 || K2\)) s 5 426 M ( ...) s 5 415 M ( key = K1 || K2 || K3 || ...) s 5 393 M ( This process will lose entropy if the amount of entropy in K is) s 5 382 M ( larger than the internal state size of HASH.) s 5 360 M (6.3 Taking Keys Into Use) s 5 338 M ( Key exchange ends by each side sending an SSH_MSG_NEWKEYS message.) s 5 327 M ( This message is sent with the old keys and algorithms. All messages) s 5 316 M ( sent after this message MUST use the new keys and algorithms.) s 5 283 M ( When this message is received, the new keys and algorithms MUST be) s 5 272 M ( taken into use for receiving.) s 5 239 M ( This message is the only valid message after key exchange, in) s 5 228 M ( addition to SSH_MSG_DEBUG, SSH_MSG_DISCONNECT and SSH_MSG_IGNORE) s 5 217 M ( messages. The purpose of this message is to ensure that a party is) s 5 206 M ( able to respond with a disconnect message that the other party can) s 5 195 M ( understand if something goes wrong with the key exchange.) s 5 184 M ( Implementations MUST NOT accept any other messages after key exchange) s 5 173 M ( before receiving SSH_MSG_NEWKEYS.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 17]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 18 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( byte SSH_MSG_NEWKEYS) s 5 657 M (7. Diffie-Hellman Key Exchange) s 5 635 M ( The Diffie-Hellman key exchange provides a shared secret that can not) s 5 624 M ( be determined by either party alone. The key exchange is combined) s 5 613 M ( with a signature with the host key to provide host authentication.) s 5 580 M ( In the following description \(C is the client, S is the server; p is) s 5 569 M ( a large safe prime, g is a generator for a subgroup of GF\(p\), and q) s 5 558 M ( is the order of the subgroup; V_S is S's version string; V_C is C's) s 5 547 M ( version string; K_S is S's public host key; I_C is C's KEXINIT) s 5 536 M ( message and I_S S's KEXINIT message which have been exchanged before) s 5 525 M ( this part begins\):) s 5 492 M ( 1. C generates a random number x \(1 < x < q\) and computes e = g^x) s 5 481 M ( mod p. C sends "e" to S.) s 5 459 M ( 2. S generates a random number y \(0 < y < q\) and computes f = g^y) s 5 448 M ( mod p. S receives "e". It computes K = e^y mod p, H = hash\(V_C) s 5 437 M ( || V_S || I_C || I_S || K_S || e || f || K\) \(these elements are) s 5 426 M ( encoded according to their types; see below\), and signature s on) s 5 415 M ( H with its private host key. S sends "K_S || f || s" to C. The) s 5 404 M ( signing operation may involve a second hashing operation.) s 5 382 M ( 3. C verifies that K_S really is the host key for S \(e.g. using) s 5 371 M ( certificates or a local database\). C is also allowed to accept) s 5 360 M ( the key without verification; however, doing so will render the) s 5 349 M ( protocol insecure against active attacks \(but may be desirable) s 5 338 M ( for practical reasons in the short term in many environments\). C) s 5 327 M ( then computes K = f^x mod p, H = hash\(V_C || V_S || I_C || I_S ||) s 5 316 M ( K_S || e || f || K\), and verifies the signature s on H.) s 5 294 M ( Either side MUST NOT send or accept e or f values that are not in the) s 5 283 M ( range [1, p-1]. If this condition is violated, the key exchange) s 5 272 M ( fails.) s 5 239 M ( This is implemented with the following messages. The hash algorithm) s 5 228 M ( for computing the exchange hash is defined by the method name, and is) s 5 217 M ( called HASH. The public key algorithm for signing is negotiated with) s 5 206 M ( the KEXINIT messages.) s 5 184 M ( First, the client sends the following:) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 18]) s _R S PStoPSsaved restore %%Page: (18,19) 10 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 19 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( byte SSH_MSG_KEXDH_INIT) s 5 679 M ( mpint e) s 5 646 M ( The server responds with the following:) s 5 624 M ( byte SSH_MSG_KEXDH_REPLY) s 5 613 M ( string server public host key and certificates \(K_S\)) s 5 602 M ( mpint f) s 5 591 M ( string signature of H) s 5 569 M ( The hash H is computed as the HASH hash of the concatenation of the) s 5 558 M ( following:) s 5 536 M ( string V_C, the client's version string \(CR and NL excluded\)) s 5 525 M ( string V_S, the server's version string \(CR and NL excluded\)) s 5 514 M ( string I_C, the payload of the client's SSH_MSG_KEXINIT) s 5 503 M ( string I_S, the payload of the server's SSH_MSG_KEXINIT) s 5 492 M ( string K_S, the host key) s 5 481 M ( mpint e, exchange value sent by the client) s 5 470 M ( mpint f, exchange value sent by the server) s 5 459 M ( mpint K, the shared secret) s 5 437 M ( This value is called the exchange hash, and it is used to) s 5 426 M ( authenticate the key exchange. The exchange hash SHOULD be kept) s 5 415 M ( secret.) s 5 382 M ( The signature algorithm MUST be applied over H, not the original) s 5 371 M ( data. Most signature algorithms include hashing and additional) s 5 360 M ( padding. For example, "ssh-dss" specifies SHA-1 hashing; in that) s 5 349 M ( case, the data is first hashed with HASH to compute H, and H is then) s 5 338 M ( hashed with SHA-1 as part of the signing operation.) s 5 316 M (7.1 diffie-hellman-group1-sha1) s 5 294 M ( The "diffie-hellman-group1-sha1" method specifies Diffie-Hellman key) s 5 283 M ( exchange with SHA-1 as HASH, and Oakley group 14 [RFC3526] \(2048-bit) s 5 272 M ( MODP Group\). It is included below in hexadecimal and decimal.) s 5 250 M ( The prime p is equal to 2^1024 - 2^960 - 1 + 2^64 * floor\( 2^894 Pi +) s 5 239 M ( 129093 \). Its hexadecimal value is:) s 5 217 M ( FFFFFFFF FFFFFFFF C90FDAA2 2168C234 C4C6628B 80DC1CD1) s 5 206 M ( 29024E08 8A67CC74 020BBEA6 3B139B22 514A0879 8E3404DD) s 5 195 M ( EF9519B3 CD3A431B 302B0A6D F25F1437 4FE1356D 6D51C245) s 5 184 M ( E485B576 625E7EC6 F44C42E9 A637ED6B 0BFF5CB6 F406B7ED) s 5 173 M ( EE386BFB 5A899FA5 AE9F2411 7C4B1FE6 49286651 ECE65381) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 19]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 20 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( FFFFFFFF FFFFFFFF.) s 5 668 M ( In decimal, this value is:) s 5 646 M ( 179769313486231590770839156793787453197860296048756011706444) s 5 635 M ( 423684197180216158519368947833795864925541502180565485980503) s 5 624 M ( 646440548199239100050792877003355816639229553136239076508735) s 5 613 M ( 759914822574862575007425302077447712589550957937778424442426) s 5 602 M ( 617334727629299387668709205606050270810842907692932019128194) s 5 591 M ( 467627007.) s 5 569 M ( The generator used with this prime is g = 2. The group order q is \(p) s 5 558 M ( - 1\) / 2.) s 5 536 M (8. Key Re-Exchange) s 5 514 M ( Key re-exchange is started by sending an SSH_MSG_KEXINIT packet when) s 5 503 M ( not already doing a key exchange \(as described in Section Section) s 5 492 M ( 6.1\). When this message is received, a party MUST respond with its) s 5 481 M ( own SSH_MSG_KEXINIT message except when the received SSH_MSG_KEXINIT) s 5 470 M ( already was a reply. Either party MAY initiate the re-exchange, but) s 5 459 M ( roles MUST NOT be changed \(i.e., the server remains the server, and) s 5 448 M ( the client remains the client\).) s 5 415 M ( Key re-exchange is performed using whatever encryption was in effect) s 5 404 M ( when the exchange was started. Encryption, compression, and MAC) s 5 393 M ( methods are not changed before a new SSH_MSG_NEWKEYS is sent after) s 5 382 M ( the key exchange \(as in the initial key exchange\). Re-exchange is) s 5 371 M ( processed identically to the initial key exchange, except for the) s 5 360 M ( session identifier that will remain unchanged. It is permissible to) s 5 349 M ( change some or all of the algorithms during the re-exchange. Host) s 5 338 M ( keys can also change. All keys and initialization vectors are) s 5 327 M ( recomputed after the exchange. Compression and encryption contexts) s 5 316 M ( are reset.) s 5 283 M ( It is recommended that the keys are changed after each gigabyte of) s 5 272 M ( transmitted data or after each hour of connection time, whichever) s 5 261 M ( comes sooner. However, since the re-exchange is a public key) s 5 250 M ( operation, it requires a fair amount of processing power and should) s 5 239 M ( not be performed too often.) s 5 206 M ( More application data may be sent after the SSH_MSG_NEWKEYS packet) s 5 195 M ( has been sent; key exchange does not affect the protocols that lie) s 5 184 M ( above the SSH transport layer.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 20]) s _R S PStoPSsaved restore %%Page: (20,21) 11 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 21 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (9. Service Request) s 5 668 M ( After the key exchange, the client requests a service. The service is) s 5 657 M ( identified by a name. The format of names and procedures for defining) s 5 646 M ( new names are defined in [SSH-ARCH].) s 5 613 M ( Currently, the following names have been reserved:) s 5 591 M ( ssh-userauth) s 5 580 M ( ssh-connection) s 5 558 M ( Similar local naming policy is applied to the service names, as is) s 5 547 M ( applied to the algorithm names; a local service should use the) s 5 536 M ( "servicename@domain" syntax.) s 5 514 M ( byte SSH_MSG_SERVICE_REQUEST) s 5 503 M ( string service name) s 5 481 M ( If the server rejects the service request, it SHOULD send an) s 5 470 M ( appropriate SSH_MSG_DISCONNECT message and MUST disconnect.) s 5 437 M ( When the service starts, it may have access to the session identifier) s 5 426 M ( generated during the key exchange.) s 5 393 M ( If the server supports the service \(and permits the client to use) s 5 382 M ( it\), it MUST respond with the following:) s 5 360 M ( byte SSH_MSG_SERVICE_ACCEPT) s 5 349 M ( string service name) s 5 327 M ( Message numbers used by services should be in the area reserved for) s 5 316 M ( them \(see Section 6 in [SSH-ARCH]\). The transport level will) s 5 305 M ( continue to process its own messages.) s 5 272 M ( Note that after a key exchange with implicit server authentication,) s 5 261 M ( the client MUST wait for response to its service request message) s 5 250 M ( before sending any further data.) s 5 228 M (10. Additional Messages) s 5 206 M ( Either party may send any of the following messages at any time.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 21]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 22 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (10.1 Disconnection Message) s 5 668 M ( byte SSH_MSG_DISCONNECT) s 5 657 M ( uint32 reason code) s 5 646 M ( string description [RFC2279]) s 5 635 M ( string language tag [RFC3066]) s 5 613 M ( This message causes immediate termination of the connection. All) s 5 602 M ( implementations MUST be able to process this message; they SHOULD be) s 5 591 M ( able to send this message.) s 5 569 M ( The sender MUST NOT send or receive any data after this message, and) s 5 558 M ( the recipient MUST NOT accept any data after receiving this message.) s 5 547 M ( The description field gives a more specific explanation in a) s 5 536 M ( human-readable form. The error code gives the reason in a more) s 5 525 M ( machine-readable format \(suitable for localization\), and can have the) s 5 514 M ( following values:) s 5 492 M ( #define SSH_DISCONNECT_HOST_NOT_ALLOWED_TO_CONNECT 1) s 5 481 M ( #define SSH_DISCONNECT_PROTOCOL_ERROR 2) s 5 470 M ( #define SSH_DISCONNECT_KEY_EXCHANGE_FAILED 3) s 5 459 M ( #define SSH_DISCONNECT_RESERVED 4) s 5 448 M ( #define SSH_DISCONNECT_MAC_ERROR 5) s 5 437 M ( #define SSH_DISCONNECT_COMPRESSION_ERROR 6) s 5 426 M ( #define SSH_DISCONNECT_SERVICE_NOT_AVAILABLE 7) s 5 415 M ( #define SSH_DISCONNECT_PROTOCOL_VERSION_NOT_SUPPORTED 8) s 5 404 M ( #define SSH_DISCONNECT_HOST_KEY_NOT_VERIFIABLE 9) s 5 393 M ( #define SSH_DISCONNECT_CONNECTION_LOST 10) s 5 382 M ( #define SSH_DISCONNECT_BY_APPLICATION 11) s 5 371 M ( #define SSH_DISCONNECT_TOO_MANY_CONNECTIONS 12) s 5 360 M ( #define SSH_DISCONNECT_AUTH_CANCELLED_BY_USER 13) s 5 349 M ( #define SSH_DISCONNECT_NO_MORE_AUTH_METHODS_AVAILABLE 14) s 5 338 M ( #define SSH_DISCONNECT_ILLEGAL_USER_NAME 15) s 5 316 M ( If the description string is displayed, control character filtering) s 5 305 M ( discussed in [SSH-ARCH] should be used to avoid attacks by sending) s 5 294 M ( terminal control characters.) s 5 272 M (10.2 Ignored Data Message) s 5 250 M ( byte SSH_MSG_IGNORE) s 5 239 M ( string data) s 5 217 M ( All implementations MUST understand \(and ignore\) this message at any) s 5 206 M ( time \(after receiving the protocol version\). No implementation is) s 5 195 M ( required to send them. This message can be used as an additional) s 5 184 M ( protection measure against advanced traffic analysis techniques.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 22]) s _R S PStoPSsaved restore %%Page: (22,23) 12 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 23 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (10.3 Debug Message) s 5 668 M ( byte SSH_MSG_DEBUG) s 5 657 M ( boolean always_display) s 5 646 M ( string message [RFC2279]) s 5 635 M ( string language tag [RFC3066]) s 5 613 M ( All implementations MUST understand this message, but they are) s 5 602 M ( allowed to ignore it. This message is used to pass the other side) s 5 591 M ( information that may help debugging. If always_display is TRUE, the) s 5 580 M ( message SHOULD be displayed. Otherwise, it SHOULD NOT be displayed) s 5 569 M ( unless debugging information has been explicitly requested by the) s 5 558 M ( user.) s 5 525 M ( The message doesn't need to contain a newline. It is, however,) s 5 514 M ( allowed to consist of multiple lines separated by CRLF \(Carriage) s 5 503 M ( Return - Line Feed\) pairs.) s 5 470 M ( If the message string is displayed, terminal control character) s 5 459 M ( filtering discussed in [SSH-ARCH] should be used to avoid attacks by) s 5 448 M ( sending terminal control characters.) s 5 426 M (10.4 Reserved Messages) s 5 404 M ( An implementation MUST respond to all unrecognized messages with an) s 5 393 M ( SSH_MSG_UNIMPLEMENTED message in the order in which the messages were) s 5 382 M ( received. Such messages MUST be otherwise ignored. Later protocol) s 5 371 M ( versions may define other meanings for these message types.) s 5 349 M ( byte SSH_MSG_UNIMPLEMENTED) s 5 338 M ( uint32 packet sequence number of rejected message) s 5 305 M (11. Summary of Message Numbers) s 5 283 M ( The following message numbers have been defined in this protocol:) s 5 261 M ( #define SSH_MSG_DISCONNECT 1) s 5 250 M ( #define SSH_MSG_IGNORE 2) s 5 239 M ( #define SSH_MSG_UNIMPLEMENTED 3) s 5 228 M ( #define SSH_MSG_DEBUG 4) s 5 217 M ( #define SSH_MSG_SERVICE_REQUEST 5) s 5 206 M ( #define SSH_MSG_SERVICE_ACCEPT 6) s 5 184 M ( #define SSH_MSG_KEXINIT 20) s 5 173 M ( #define SSH_MSG_NEWKEYS 21) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 23]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 24 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( /* Numbers 30-49 used for kex packets.) s 5 679 M ( Different kex methods may reuse message numbers in) s 5 668 M ( this range. */) s 5 646 M ( #define SSH_MSG_KEXDH_INIT 30) s 5 635 M ( #define SSH_MSG_KEXDH_REPLY 31) s 5 602 M (12. IANA Considerations) s 5 580 M ( This document is part of a set, the IANA considerations for the SSH) s 5 569 M ( protocol as defined in [SSH-ARCH], [SSH-TRANS], [SSH-USERAUTH],) s 5 558 M ( [SSH-CONNECT] are detailed in [SSH-NUMBERS].) s 5 536 M (13. Security Considerations) s 5 514 M ( This protocol provides a secure encrypted channel over an insecure) s 5 503 M ( network. It performs server host authentication, key exchange,) s 5 492 M ( encryption, and integrity protection. It also derives a unique) s 5 481 M ( session id that may be used by higher-level protocols.) s 5 459 M ( Full security considerations for this protocol are provided in) s 5 448 M ( Section 8 of [SSH-ARCH]) s 5 426 M (14. Intellectual Property) s 5 404 M ( The IETF takes no position regarding the validity or scope of any) s 5 393 M ( intellectual property or other rights that might be claimed to) s 5 382 M ( pertain to the implementation or use of the technology described in) s 5 371 M ( this document or the extent to which any license under such rights) s 5 360 M ( might or might not be available; neither does it represent that it) s 5 349 M ( has made any effort to identify any such rights. Information on the) s 5 338 M ( IETF's procedures with respect to rights in standards-track and) s 5 327 M ( standards-related documentation can be found in BCP-11. Copies of) s 5 316 M ( claims of rights made available for publication and any assurances of) s 5 305 M ( licenses to be made available, or the result of an attempt made to) s 5 294 M ( obtain a general license or permission for the use of such) s 5 283 M ( proprietary rights by implementers or users of this specification can) s 5 272 M ( be obtained from the IETF Secretariat.) s 5 250 M ( The IETF has been notified of intellectual property rights claimed in) s 5 239 M ( regard to some or all of the specification contained in this) s 5 228 M ( document. For more information consult the online list of claimed) s 5 217 M ( rights.) s 5 195 M (15. Additional Information) s 5 173 M ( The current document editor is: Darren.Moffat@Sun.COM. Comments on) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 24]) s _R S PStoPSsaved restore %%Page: (24,25) 13 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 25 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( this internet draft should be sent to the IETF SECSH working group,) s 5 679 M ( details at: http://ietf.org/html.charters/secsh-charter.html) s 5 657 M (Normative) s 5 635 M ( [SSH-ARCH]) s 5 624 M ( Ylonen, T., "SSH Protocol Architecture", I-D) s 5 613 M ( draft-ietf-architecture-15.txt, Oct 2003.) s 5 591 M ( [SSH-TRANS]) s 5 580 M ( Ylonen, T., "SSH Transport Layer Protocol", I-D) s 5 569 M ( draft-ietf-transport-17.txt, Oct 2003.) s 5 547 M ( [SSH-USERAUTH]) s 5 536 M ( Ylonen, T., "SSH Authentication Protocol", I-D) s 5 525 M ( draft-ietf-userauth-18.txt, Oct 2003.) s 5 503 M ( [SSH-CONNECT]) s 5 492 M ( Ylonen, T., "SSH Connection Protocol", I-D) s 5 481 M ( draft-ietf-connect-18.txt, Oct 2003.) s 5 459 M ( [SSH-NUMBERS]) s 5 448 M ( Lehtinen, S. and D. Moffat, "SSH Protocol Assigned) s 5 437 M ( Numbers", I-D draft-ietf-secsh-assignednumbers-05.txt, Oct) s 5 426 M ( 2003.) s 5 404 M ( [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate) s 5 393 M ( Requirement Levels", BCP 14, RFC 2119, March 1997.) s 5 371 M (Informative) s 5 349 M ( [FIPS-186]) s 5 338 M ( Federal Information Processing Standards Publication,) s 5 327 M ( "FIPS PUB 186, Digital Signature Standard", May 1994.) s 5 305 M ( [FIPS-197]) s 5 294 M ( NIST, "FIPS PUB 197 Advanced Encryption Standard \(AES\)",) s 5 283 M ( November 2001.) s 5 261 M ( [FIPS-46-3]) s 5 250 M ( U.S. Dept. of Commerce, "FIPS PUB 46-3, Data Encryption) s 5 239 M ( Standard \(DES\)", October 1999.) s 5 217 M ( [RFC2459] Housley, R., Ford, W., Polk, T. and D. Solo, "Internet) s 5 206 M ( X.509 Public Key Infrastructure Certificate and CRL) s 5 195 M ( Profile", RFC 2459, January 1999.) s 5 173 M ( [RFC1034] Mockapetris, P., "Domain names - concepts and facilities",) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 25]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 26 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( STD 13, RFC 1034, November 1987.) s 5 668 M ( [RFC3066] Alvestrand, H., "Tags for the Identification of) s 5 657 M ( Languages", BCP 47, RFC 3066, January 2001.) s 5 635 M ( [RFC1950] Deutsch, L. and J-L. Gailly, "ZLIB Compressed Data Format) s 5 624 M ( Specification version 3.3", RFC 1950, May 1996.) s 5 602 M ( [RFC1951] Deutsch, P., "DEFLATE Compressed Data Format Specification) s 5 591 M ( version 1.3", RFC 1951, May 1996.) s 5 569 M ( [RFC2279] Yergeau, F., "UTF-8, a transformation format of ISO) s 5 558 M ( 10646", RFC 2279, January 1998.) s 5 536 M ( [RFC2104] Krawczyk, H., Bellare, M. and R. Canetti, "HMAC:) s 5 525 M ( Keyed-Hashing for Message Authentication", RFC 2104,) s 5 514 M ( February 1997.) s 5 492 M ( [RFC2144] Adams, C., "The CAST-128 Encryption Algorithm", RFC 2144,) s 5 481 M ( May 1997.) s 5 459 M ( [RFC2440] Callas, J., Donnerhacke, L., Finney, H. and R. Thayer,) s 5 448 M ( "OpenPGP Message Format", RFC 2440, November 1998.) s 5 426 M ( [RFC2693] Ellison, C., Frantz, B., Lampson, B., Rivest, R., Thomas,) s 5 415 M ( B. and T. Ylonen, "SPKI Certificate Theory", RFC 2693,) s 5 404 M ( September 1999.) s 5 382 M ( [RFC3526] Kivinen, T. and M. Kojo, "More Modular Exponential \(MODP\)) s 5 371 M ( Diffie-Hellman groups for Internet Key Exchange \(IKE\)",) s 5 360 M ( RFC 3526, May 2003.) s 5 338 M ( [SCHNEIER]) s 5 327 M ( Schneier, B., "Applied Cryptography Second Edition:) s 5 316 M ( protocols algorithms and source in code in C", 1996.) s 5 294 M ( [TWOFISH] Schneier, B., "The Twofish Encryptions Algorithm: A) s 5 283 M ( 128-Bit Block Cipher, 1st Edition", March 1999.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 26]) s _R S PStoPSsaved restore %%Page: (26,27) 14 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 27 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (Authors' Addresses) s 5 668 M ( Tatu Ylonen) s 5 657 M ( SSH Communications Security Corp) s 5 646 M ( Fredrikinkatu 42) s 5 635 M ( HELSINKI FIN-00100) s 5 624 M ( Finland) s 5 602 M ( EMail: ylo@ssh.com) s 5 569 M ( Darren J. Moffat \(editor\)) s 5 558 M ( Sun Microsystems, Inc) s 5 547 M ( 17 Network Circle) s 5 536 M ( Menlo Park 95025) s 5 525 M ( USA) s 5 503 M ( EMail: Darren.Moffat@Sun.COM) s 5 481 M (Appendix A. Contibutors) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 27]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 28 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M (Intellectual Property Statement) s 5 668 M ( The IETF takes no position regarding the validity or scope of any) s 5 657 M ( intellectual property or other rights that might be claimed to) s 5 646 M ( pertain to the implementation or use of the technology described in) s 5 635 M ( this document or the extent to which any license under such rights) s 5 624 M ( might or might not be available; neither does it represent that it) s 5 613 M ( has made any effort to identify any such rights. Information on the) s 5 602 M ( IETF's procedures with respect to rights in standards-track and) s 5 591 M ( standards-related documentation can be found in BCP-11. Copies of) s 5 580 M ( claims of rights made available for publication and any assurances of) s 5 569 M ( licenses to be made available, or the result of an attempt made to) s 5 558 M ( obtain a general license or permission for the use of such) s 5 547 M ( proprietary rights by implementors or users of this specification can) s 5 536 M ( be obtained from the IETF Secretariat.) s 5 514 M ( The IETF invites any interested party to bring to its attention any) s 5 503 M ( copyrights, patents or patent applications, or other proprietary) s 5 492 M ( rights which may cover technology that may be required to practice) s 5 481 M ( this standard. Please address the information to the IETF Executive) s 5 470 M ( Director.) s 5 448 M ( The IETF has been notified of intellectual property rights claimed in) s 5 437 M ( regard to some or all of the specification contained in this) s 5 426 M ( document. For more information consult the online list of claimed) s 5 415 M ( rights.) s 5 382 M (Full Copyright Statement) s 5 360 M ( Copyright \(C\) The Internet Society \(2003\). All Rights Reserved.) s 5 338 M ( This document and translations of it may be copied and furnished to) s 5 327 M ( others, and derivative works that comment on or otherwise explain it) s 5 316 M ( or assist in its implementation may be prepared, copied, published) s 5 305 M ( and distributed, in whole or in part, without restriction of any) s 5 294 M ( kind, provided that the above copyright notice and this paragraph are) s 5 283 M ( included on all such copies and derivative works. However, this) s 5 272 M ( document itself may not be modified in any way, such as by removing) s 5 261 M ( the copyright notice or references to the Internet Society or other) s 5 250 M ( Internet organizations, except as needed for the purpose of) s 5 239 M ( developing Internet standards in which case the procedures for) s 5 228 M ( copyrights defined in the Internet Standards process must be) s 5 217 M ( followed, or as required to translate it into languages other than) s 5 206 M ( English.) s 5 184 M ( The limited permissions granted above are perpetual and will not be) s 5 173 M ( revoked by the Internet Society or its successors or assignees.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 28]) s _R S PStoPSsaved restore %%Page: (28,29) 15 userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 0.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip /showpage{}def/copypage{}def/erasepage{}def PStoPSxform concat %%BeginPageSetup _S 75 0 translate /pagenum 29 def /fname () def /fdir () def /ftail () def /user_header_p false def %%EndPageSetup 5 723 M (Internet-Draft SSH Transport Layer Protocol Oct 2003) s 5 690 M ( This document and the information contained herein is provided on an) s 5 679 M ( "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING) s 5 668 M ( TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING) s 5 657 M ( BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION) s 5 646 M ( HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF) s 5 635 M ( MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.) s 5 602 M (Acknowledgment) s 5 580 M ( Funding for the RFC Editor function is currently provided by the) s 5 569 M ( Internet Society.) s 5 129 M (Ylonen & Moffat, Editor Expires March 31, 2004 [Page 29]) s _R S PStoPSsaved restore userdict/PStoPSsaved save put PStoPSmatrix setmatrix 595.000000 421.271378 translate 90 rotate 0.706651 dup scale userdict/PStoPSmatrix matrix currentmatrix put userdict/PStoPSclip{0 0 moveto 595.000000 0 rlineto 0 842.000000 rlineto -595.000000 0 rlineto closepath}put initclip PStoPSxform concat showpage PStoPSsaved restore %%Trailer %%Pages: 29 %%DocumentNeededResources: font Courier-Bold Courier %%EOF