Implemented encode/decode support for ssh public key files

1 files changed, 431 insertions, 0 deletions

diff --git a/lib/public_key/src/pubkey_ssh.erl b/lib/public_key/src/pubkey_ssh.erl
new file mode 100644
index 0000000000..f342eab159
--- /dev/null
+++ b/lib/public_key/src/pubkey_ssh.erl
@@ -0,0 +1,431 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2011-2011. All Rights Reserved.
+%%
+%% The contents of this file are subject to the Erlang Public License,
+%% Version 1.1, (the "License"); you may not use this file except in
+%% compliance with the License. You should have received a copy of the
+%% Erlang Public License along with this software. If not, it can be
+%% retrieved online at http://www.erlang.org/.
+%%
+%% Software distributed under the License is distributed on an "AS IS"
+%% basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
+%% the License for the specific language governing rights and limitations
+%% under the License.
+%%
+%% %CopyrightEnd%
+%%
+-module(pubkey_ssh).
+
+-include("public_key.hrl").
+
+-export([decode/2, encode/2]).
+
+-define(UINT32(X), X:32/unsigned-big-integer).
+%% Max encoded line length is 72, but conformance examples use 68
+%% Comment from rfc 4716: "The following are some examples of public
+%% key files that are compliant (note that the examples all wrap
+%% before 72 bytes to meet IETF document requirements; however, they
+%% are still compliant.)" So we choose to use 68 also.
+-define(ENCODED_LINE_LENGTH, 68).
+
+%%====================================================================
+%% Internal application API
+%%====================================================================
+
+%%--------------------------------------------------------------------
+-spec decode(binary(), public_key | ssh_file()) -> [{public_key(), Attributes::list()}].
+%%
+%% Description: Decodes a ssh file-binary.
+%%--------------------------------------------------------------------
+decode(Bin, public_key)->
+    case binary:match(Bin, begin_marker()) of
+	nomatch ->
+	    openssh_decode(Bin, openssh_public_key);
+	_ ->
+	    rfc4716_decode(Bin)
+    end;
+decode(Bin, rfc4716_public_key) ->
+     rfc4716_decode(Bin);
+decode(Bin, Type) ->
+    openssh_decode(Bin, Type).
+
+%%--------------------------------------------------------------------
+-spec encode([{public_key(), Attributes::list()}], ssh_file()) ->
+		    binary().
+%%
+%% Description: Encodes a list of ssh file entries.
+%%--------------------------------------------------------------------
+encode(Entries, Type) ->
+    erlang:iolist_to_binary(lists:map(fun({Key, Attributes}) ->
+					      do_encode(Type, Key, Attributes)
+				      end, Entries)).
+
+%%--------------------------------------------------------------------
+%%% Internal functions
+%%--------------------------------------------------------------------
+begin_marker() ->
+    <<"---- BEGIN SSH2 PUBLIC KEY ----">>.
+end_marker() ->
+    <<"---- END SSH2 PUBLIC KEY ----">>.
+
+rfc4716_decode(Bin) ->
+    Lines = binary:split(Bin, <<"\n">>, [global]),
+    do_rfc4716_decode(Lines, []).
+
+do_rfc4716_decode([<<"---- BEGIN SSH2 PUBLIC KEY ----", _/binary>> | Lines], Acc) ->
+    do_rfc4716_decode(Lines, Acc);
+%% Ignore empty lines before or after begin/end - markers.
+do_rfc4716_decode([<<>> | Lines], Acc) ->
+    do_rfc4716_decode(Lines, Acc);
+do_rfc4716_decode([], Acc) ->
+    lists:reverse(Acc);
+do_rfc4716_decode(Lines, Acc) ->
+    {Headers, PubKey, Rest} = rfc4716_decode_lines(Lines, []),
+    case Headers of
+	[_|_] ->
+	    do_rfc4716_decode(Rest, [{PubKey, [{headers, Headers}]} | Acc]);
+	_  ->
+	    do_rfc4716_decode(Rest, [{PubKey, []} | Acc])
+    end.
+
+rfc4716_decode_lines([Line | Lines], Acc) ->
+    case binary:last(Line) of
+	$\\ ->
+	    NewLine = binary:replace(Line,<<"\\">>, hd(Lines), []),
+	    rfc4716_decode_lines([NewLine | tl(Lines)], Acc);
+	_ ->
+	    rfc4716_decode_line(Line, Lines, Acc)
+    end.
+
+rfc4716_decode_line(Line, Lines, Acc) ->
+    case binary:split(Line, <<":">>) of
+	[Tag, Value] ->
+	    rfc4716_decode_lines(Lines, [{string_decode(Tag), unicode_decode(Value)} | Acc]);
+	_ ->
+	    {Body, Rest} = join_entry([Line | Lines], []),
+	    {lists:reverse(Acc), rfc4716_pubkey_decode(base64:mime_decode(Body)), Rest}
+      end.
+
+join_entry([<<"---- END SSH2 PUBLIC KEY ----", _/binary>>| Lines], Entry) ->
+    {lists:reverse(Entry), Lines};
+join_entry([Line | Lines], Entry) ->
+    join_entry(Lines, [Line | Entry]).
+
+
+rfc4716_pubkey_decode(<<?UINT32(Len), Type:Len/binary,
+	      ?UINT32(SizeE), E:SizeE/binary,
+	      ?UINT32(SizeN), N:SizeN/binary>>) when Type == <<"ssh-rsa">> ->
+    #'RSAPublicKey'{modulus = erlint(SizeN, N),
+		    publicExponent = erlint(SizeE, E)};
+
+rfc4716_pubkey_decode(<<?UINT32(Len), Type:Len/binary,
+	      ?UINT32(SizeP), P:SizeP/binary,
+	      ?UINT32(SizeQ), Q:SizeQ/binary,
+	      ?UINT32(SizeG), G:SizeG/binary,
+	      ?UINT32(SizeY), Y:SizeY/binary>>) when Type == <<"ssh-dss">> ->
+    {erlint(SizeY, Y),
+     #'Dss-Parms'{p = erlint(SizeP, P),
+		  q = erlint(SizeQ, Q),
+		  g = erlint(SizeG, G)}}.
+
+openssh_decode(Bin, FileType) ->
+    Lines = binary:split(Bin, <<"\n">>, [global]),
+    do_openssh_decode(FileType, Lines, []).
+
+do_openssh_decode(_, [], Acc) ->
+    lists:reverse(Acc);
+%% Ignore empty lines
+do_openssh_decode(FileType, [<<>> | Lines], Acc) ->
+    do_openssh_decode(FileType, Lines, Acc);
+%% Ignore lines that start with #
+do_openssh_decode(FileType,[<<"#", _/binary>> | Lines], Acc) ->
+    do_openssh_decode(FileType, Lines, Acc);
+do_openssh_decode(auth_keys = FileType, [Line | Lines], Acc) ->
+    Split = binary:split(Line, <<" ">>, [global]),
+    case mend_split(Split, []) of
+	%% ssh2
+	[Options, KeyType, Base64Enc, Comment] when KeyType == <<"ssh-rsa">>;
+						     KeyType == <<"ssh-dss">> ->
+	    do_openssh_decode(FileType, Lines,
+			      [{openssh_pubkey_decode(KeyType, Base64Enc),
+				[{comment, string_decode(Comment)},
+				 {options, comma_list_decode(Options)}]}
+			       | Acc]);
+
+	[KeyType, Base64Enc, Comment] when KeyType == <<"ssh-rsa">>;
+					    KeyType == <<"ssh-dss">> ->
+	    do_openssh_decode(FileType, Lines,
+			      [{openssh_pubkey_decode(KeyType, Base64Enc),
+				[{comment, string_decode(Comment)}]} | Acc]);
+	%% ssh1
+	[Options, Bits, Exponent, Modulus, Comment] ->
+	    do_openssh_decode(FileType, Lines,
+			      [{ssh1_rsa_pubkey_decode(Modulus, Exponent),
+				[{comment, string_decode(Comment)},
+				 {options, comma_list_decode(Options)},
+				 {bits, integer_decode(Bits)}]} | Acc]);
+	[Bits, Exponent, Modulus, Comment]  ->
+	    do_openssh_decode(FileType, Lines,
+			      [{ssh1_rsa_pubkey_decode(Modulus, Exponent),
+				[{comment, string_decode(Comment)},
+				 {bits, integer_decode(Bits)}]} | Acc])
+	end;
+
+do_openssh_decode(known_hosts = FileType, [Line | Lines], Acc) ->
+    case binary:split(Line, <<" ">>, [global]) of
+	%% ssh 2
+	[HostNames, KeyType, Base64Enc] when KeyType == <<"ssh-rsa">>;
+					     KeyType == <<"ssh-dss">> ->
+	    do_openssh_decode(FileType, Lines,
+			      [{openssh_pubkey_decode(KeyType, Base64Enc),
+				[{hostnames, comma_list_decode(HostNames)}]}| Acc]);
+	[HostNames, KeyType, Base64Enc, Comment] when KeyType == <<"ssh-rsa">>;
+						       KeyType == <<"ssh-dss">> ->
+	    do_openssh_decode(FileType, Lines,
+			      [{openssh_pubkey_decode(KeyType, Base64Enc),
+				[{comment, string_decode(Comment)},
+				 {hostnames, comma_list_decode(HostNames)}]} | Acc]);
+	%% ssh 1
+	[HostNames, Bits, Exponent, Modulus, Comment] ->
+	    do_openssh_decode(FileType, Lines,
+			      [{ssh1_rsa_pubkey_decode(Modulus, Exponent),
+				[{comment, string_decode(Comment)},
+				 {hostnames, comma_list_decode(HostNames)},
+				 {bits, integer_decode(Bits)}]} | Acc]);
+	[HostNames, Bits, Exponent, Modulus]  ->
+	    do_openssh_decode(FileType, Lines,
+			      [{ssh1_rsa_pubkey_decode(Modulus, Exponent),
+				[{comment, []},
+				 {hostnames, comma_list_decode(HostNames)},
+				 {bits, integer_decode(Bits)}]} | Acc])
+	end;
+
+do_openssh_decode(openssh_public_key = FileType, [Line | Lines], Acc) ->
+    case binary:split(Line, <<" ">>, [global]) of
+	[KeyType, Base64Enc, Comment0] when KeyType == <<"ssh-rsa">>;
+					    KeyType == <<"ssh-dss">> ->
+	    Comment = string:strip(binary_to_list(Comment0), right, $\n),
+	    do_openssh_decode(FileType, Lines,
+			      [{openssh_pubkey_decode(KeyType, Base64Enc),
+				[{comment, Comment}]} | Acc])
+    end.
+
+
+openssh_pubkey_decode(<<"ssh-rsa">>, Base64Enc) ->
+    <<?UINT32(StrLen), _:StrLen/binary,
+      ?UINT32(SizeE), E:SizeE/binary,
+      ?UINT32(SizeN), N:SizeN/binary>>
+	= base64:mime_decode(Base64Enc),
+    #'RSAPublicKey'{modulus = erlint(SizeN, N),
+		    publicExponent = erlint(SizeE, E)};
+
+openssh_pubkey_decode(<<"ssh-dss">>, Base64Enc) ->
+    <<?UINT32(StrLen), _:StrLen/binary,
+      ?UINT32(SizeP), P:SizeP/binary,
+      ?UINT32(SizeQ), Q:SizeQ/binary,
+      ?UINT32(SizeG), G:SizeG/binary,
+      ?UINT32(SizeY), Y:SizeY/binary>>
+	= base64:mime_decode(Base64Enc),
+    {erlint(SizeY, Y),
+     #'Dss-Parms'{p = erlint(SizeP, P),
+		  q = erlint(SizeQ, Q),
+		  g = erlint(SizeG, G)}}.
+
+erlint(MPIntSize, MPIntValue) ->
+    Bits= MPIntSize * 8,
+    <<Integer:Bits/integer>> = MPIntValue,
+    Integer.
+
+ssh1_rsa_pubkey_decode(MBin, EBin) ->
+    #'RSAPublicKey'{modulus = integer_decode(MBin),
+		    publicExponent = integer_decode(EBin)}.
+
+integer_decode(BinStr) ->
+    list_to_integer(binary_to_list(BinStr)).
+
+string_decode(BinStr) ->
+    binary_to_list(BinStr).
+
+unicode_decode(BinStr) ->
+    unicode:characters_to_list(BinStr).
+
+comma_list_decode(BinOpts) ->
+    CommaList = binary:split(BinOpts, <<",">>, [global]),
+    lists:map(fun(Item) ->
+		      binary_to_list(Item)
+	      end, CommaList).
+
+do_encode(rfc4716_public_key, Key, Attributes) ->
+    rfc4716_encode(Key, proplists:get_value(headers, Attributes, []), []);
+
+do_encode(Type, Key, Attributes) ->
+    openssh_encode(Type, Key, Attributes).
+
+rfc4716_encode(Key, [],[]) ->
+    erlang:iolist_to_binary([begin_marker(),"\n",
+			     split_lines(base64:encode(ssh2_pubkey_encode(Key))),
+			     "\n", end_marker(), "\n"]);
+rfc4716_encode(Key, [], [_|_] = Acc) ->
+    erlang:iolist_to_binary([begin_marker(), "\n",
+			     lists:reverse(Acc),
+			     split_lines(base64:encode(ssh2_pubkey_encode(Key))),
+			     "\n", end_marker(), "\n"]);
+rfc4716_encode(Key, [ Header | Headers], Acc) ->
+    LinesStr = rfc4716_encode_header(Header),
+    rfc4716_encode(Key, Headers, [LinesStr | Acc]).
+
+rfc4716_encode_header({Tag, Value}) ->
+    TagLen = length(Tag),
+    ValueLen = length(Value),
+    case TagLen + 1 + ValueLen of
+	N when N > ?ENCODED_LINE_LENGTH ->
+	    NumOfChars =  ?ENCODED_LINE_LENGTH - (TagLen + 1),
+	    {First, Rest} = lists:split(NumOfChars, Value),
+	    [Tag,":" , First, [$\\], "\n", rfc4716_encode_value(Rest) , "\n"];
+	_ ->
+	    [Tag, ":", Value, "\n"]
+    end.
+
+rfc4716_encode_value(Value) ->
+    case length(Value) of
+	N when N > ?ENCODED_LINE_LENGTH ->
+	    {First, Rest} = lists:split(?ENCODED_LINE_LENGTH, Value),
+	    [First, [$\\], "\n", rfc4716_encode_value(Rest)];
+	_ ->
+	    Value
+    end.
+
+openssh_encode(openssh_public_key, Key, Attributes) ->
+    Comment = proplists:get_value(comment, Attributes),
+    Enc = base64:encode(ssh2_pubkey_encode(Key)),
+    erlang:iolist_to_binary([key_type(Key), " ",  Enc,  " ", Comment, "\n"]);
+
+openssh_encode(auth_keys, Key, Attributes) ->
+    Comment = proplists:get_value(comment, Attributes, ""),
+    Options = proplists:get_value(options, Attributes, undefined),
+    Bits = proplists:get_value(bits, Attributes, undefined),
+    case Bits of
+	undefined ->
+	    openssh_ssh2_auth_keys_encode(Options, Key, Comment);
+	_ ->
+	    openssh_ssh1_auth_keys_encode(Options, Bits, Key, Comment)
+    end;
+openssh_encode(known_hosts, Key, Attributes) ->
+    Comment = proplists:get_value(comment, Attributes, ""),
+    Hostnames = proplists:get_value(hostnames, Attributes),
+    Bits = proplists:get_value(bits, Attributes, undefined),
+    case Bits of
+	undefined ->
+	    openssh_ssh2_know_hosts_encode(Hostnames, Key, Comment);
+	_ ->
+	    openssh_ssh1_known_hosts_encode(Hostnames, Bits, Key, Comment)
+    end.
+
+openssh_ssh2_auth_keys_encode(undefined, Key, Comment) ->
+    erlang:iolist_to_binary([key_type(Key)," ",  base64:encode(ssh2_pubkey_encode(Key)), line_end(Comment)]);
+openssh_ssh2_auth_keys_encode(Options, Key, Comment) ->
+    erlang:iolist_to_binary([comma_list_encode(Options, []), " ",
+			     key_type(Key)," ", base64:encode(ssh2_pubkey_encode(Key)), line_end(Comment)]).
+
+openssh_ssh1_auth_keys_encode(undefined, Bits,
+			      #'RSAPublicKey'{modulus = N, publicExponent = E},
+			      Comment) ->
+    erlang:iolist_to_binary([integer_to_list(Bits), " ", integer_to_list(E), " ", integer_to_list(N),
+			     line_end(Comment)]);
+openssh_ssh1_auth_keys_encode(Options, Bits,
+			      #'RSAPublicKey'{modulus = N, publicExponent = E},
+			      Comment) ->
+    erlang:iolist_to_binary([comma_list_encode(Options, []), " ", integer_to_list(Bits),
+			     " ", integer_to_list(E), " ", integer_to_list(N), line_end(Comment)]).
+
+openssh_ssh2_know_hosts_encode(Hostnames, Key, Comment) ->
+    erlang:iolist_to_binary([comma_list_encode(Hostnames, []), " ",
+			     key_type(Key)," ",  base64:encode(ssh2_pubkey_encode(Key)), line_end(Comment)]).
+
+openssh_ssh1_known_hosts_encode(Hostnames, Bits,
+			      #'RSAPublicKey'{modulus = N, publicExponent = E},
+			      Comment) ->
+    erlang:iolist_to_binary([comma_list_encode(Hostnames, [])," ", integer_to_list(Bits)," ",
+			     integer_to_list(E)," ", integer_to_list(N), line_end(Comment)]).
+
+line_end("") ->
+    "\n";
+line_end(Comment) ->
+    [" ", Comment, "\n"].
+
+key_type(#'RSAPublicKey'{}) ->
+    <<"ssh-rsa">>;
+key_type({_, #'Dss-Parms'{}}) ->
+    <<"ssh-dss">>.
+
+comma_list_encode([Option], [])  ->
+    Option;
+comma_list_encode([Option], Acc) ->
+    Acc ++ "," ++ Option;
+comma_list_encode([Option | Rest], []) ->
+    comma_list_encode(Rest, Option);
+comma_list_encode([Option | Rest], Acc) ->
+    comma_list_encode(Rest, Acc ++ "," ++ Option).
+
+ssh2_pubkey_encode(#'RSAPublicKey'{modulus = N, publicExponent = E}) ->
+    TypeStr = <<"ssh-rsa">>,
+    StrLen = size(TypeStr),
+    EBin = crypto:mpint(E),
+    NBin = crypto:mpint(N),
+    <<?UINT32(StrLen), TypeStr:StrLen/binary,
+      EBin/binary,
+      NBin/binary>>;
+ssh2_pubkey_encode({Y,  #'Dss-Parms'{p = P, q = Q, g = G}}) ->
+    TypeStr = <<"ssh-dss">>,
+    StrLen = size(TypeStr),
+    PBin = crypto:mpint(P),
+    QBin = crypto:mpint(Q),
+    GBin = crypto:mpint(G),
+    YBin = crypto:mpint(Y),
+    <<?UINT32(StrLen), TypeStr:StrLen/binary,
+      PBin/binary,
+      QBin/binary,
+      GBin/binary,
+      YBin/binary>>.
+
+mend_split([Part1, Part2 | Rest] = List, Acc) ->
+    case option_end(Part1, Part2) of
+	true ->
+	    lists:reverse(Acc) ++ List;
+	false ->
+	    case length(binary:matches(Part1, <<"\"">>)) of
+		N  when N rem 2 == 0 ->
+		    mend_split(Rest, [Part1 | Acc]);
+		_ ->
+		    mend_split([<<Part1/binary, Part2/binary>> | Rest], Acc)
+	    end
+    end.
+
+option_end(Part1, Part2) ->
+    (is_key_field(Part1) orelse is_bits_field(Part1))
+	orelse
+	  (is_key_field(Part2) orelse is_bits_field(Part2)).
+
+is_key_field(<<"ssh-dss">>) ->
+    true;
+is_key_field(<<"ssh-rsa">>) ->
+    true;
+is_key_field(_) ->
+    false.
+
+is_bits_field(Part) ->
+    try list_to_integer(binary_to_list(Part)) of
+	_ ->
+	    true
+    catch _:_ ->
+	    false
+    end.
+
+split_lines(<<Text:?ENCODED_LINE_LENGTH/binary>>) ->
+    [Text];
+split_lines(<<Text:?ENCODED_LINE_LENGTH/binary, Rest/binary>>) ->
+    [Text, $\n | split_lines(Rest)];
+split_lines(Bin) ->
+    [Bin].