From f3fde4cba0bca14a8718f39e7f7c68acd85f4078 Mon Sep 17 00:00:00 2001 From: Hans Nilsson Date: Tue, 31 Jul 2018 16:22:24 +0200 Subject: ssh: Add chacha20-poly1305@openssh.com cipher --- lib/ssh/src/ssh_transport.erl | 177 +++++++++++++++++++++++++++++++++--------- 1 file changed, 139 insertions(+), 38 deletions(-) (limited to 'lib/ssh/src/ssh_transport.erl') diff --git a/lib/ssh/src/ssh_transport.erl b/lib/ssh/src/ssh_transport.erl index b6d7aa0b1b..d6b9142529 100644 --- a/lib/ssh/src/ssh_transport.erl +++ b/lib/ssh/src/ssh_transport.erl @@ -36,7 +36,7 @@ default_algorithms/0, default_algorithms/1, algo_classes/0, algo_class/1, algo_two_spec_classes/0, algo_two_spec_class/1, - handle_packet_part/4, + handle_packet_part/5, handle_hello_version/1, key_exchange_init_msg/1, key_init/3, new_keys_message/1, @@ -114,7 +114,8 @@ default_algorithms(kex) -> default_algorithms(cipher) -> supported_algorithms(cipher, same(['AEAD_AES_128_GCM', - 'AEAD_AES_256_GCM'])); + 'AEAD_AES_256_GCM' + ])); default_algorithms(mac) -> supported_algorithms(mac, same(['AEAD_AES_128_GCM', 'AEAD_AES_256_GCM'])); @@ -160,6 +161,7 @@ supported_algorithms(cipher) -> same( select_crypto_supported( [ + {'chacha20-poly1305@openssh.com', [{ciphers,chacha20}, {macs,poly1305}]}, {'aes256-gcm@openssh.com', [{ciphers,{aes_gcm,256}}]}, {'aes256-ctr', [{ciphers,{aes_ctr,256}}]}, {'aes192-ctr', [{ciphers,{aes_ctr,192}}]}, @@ -982,13 +984,14 @@ select_algorithm(Role, Client, Server, Opts) -> %%% the exchanged MAC algorithms are ignored and there doesn't have to be %%% a matching MAC. -aead_gcm_simultan('aes128-gcm@openssh.com', _) -> {'AEAD_AES_128_GCM', 'AEAD_AES_128_GCM'}; -aead_gcm_simultan('aes256-gcm@openssh.com', _) -> {'AEAD_AES_256_GCM', 'AEAD_AES_256_GCM'}; -aead_gcm_simultan('AEAD_AES_128_GCM', _) -> {'AEAD_AES_128_GCM', 'AEAD_AES_128_GCM'}; -aead_gcm_simultan('AEAD_AES_256_GCM', _) -> {'AEAD_AES_256_GCM', 'AEAD_AES_256_GCM'}; -aead_gcm_simultan(_, 'AEAD_AES_128_GCM') -> {'AEAD_AES_128_GCM', 'AEAD_AES_128_GCM'}; -aead_gcm_simultan(_, 'AEAD_AES_256_GCM') -> {'AEAD_AES_256_GCM', 'AEAD_AES_256_GCM'}; -aead_gcm_simultan(Cipher, Mac) -> {Cipher,Mac}. +aead_gcm_simultan('aes128-gcm@openssh.com', _) -> {'AEAD_AES_128_GCM', 'AEAD_AES_128_GCM'}; +aead_gcm_simultan('aes256-gcm@openssh.com', _) -> {'AEAD_AES_256_GCM', 'AEAD_AES_256_GCM'}; +aead_gcm_simultan('AEAD_AES_128_GCM'=C, _) -> {C, C}; +aead_gcm_simultan('AEAD_AES_256_GCM'=C, _) -> {C, C}; +aead_gcm_simultan(_, 'AEAD_AES_128_GCM'=C) -> {C, C}; +aead_gcm_simultan(_, 'AEAD_AES_256_GCM'=C) -> {C, C}; +aead_gcm_simultan('chacha20-poly1305@openssh.com'=C, _)-> {C, C}; +aead_gcm_simultan(Cipher, Mac) -> {Cipher,Mac}. select_encrypt_decrypt(client, Client, Server) -> @@ -1136,7 +1139,7 @@ pack(PlainText, encrypt = CryptoAlg} = Ssh0, PacketLenDeviationForTests) when is_binary(PlainText) -> {Ssh1, CompressedPlainText} = compress(Ssh0, PlainText), - {EcryptedPacket, MAC, Ssh3} = + {FinalPacket, Ssh3} = case pkt_type(CryptoAlg) of common -> PaddingLen = padding_length(4+1+size(CompressedPlainText), Ssh0), @@ -1145,16 +1148,15 @@ pack(PlainText, PlainPacketData = <>, {Ssh2, EcryptedPacket0} = encrypt(Ssh1, PlainPacketData), MAC0 = mac(MacAlg, MacKey, SeqNum, PlainPacketData), - {EcryptedPacket0, MAC0, Ssh2}; + {<>, Ssh2}; aead -> PaddingLen = padding_length(1+size(CompressedPlainText), Ssh0), Padding = ssh_bits:random(PaddingLen), PlainPacketLen = 1 + PaddingLen + size(CompressedPlainText) + PacketLenDeviationForTests, PlainPacketData = <>, - {Ssh2, {EcryptedPacket0,MAC0}} = encrypt(Ssh1, {<>,PlainPacketData}), - {<>, MAC0, Ssh2} + {Ssh2, {EcryptedPacket0,MAC0}} = encrypt(Ssh1, <>), + {<>, Ssh2} end, - FinalPacket = [EcryptedPacket, MAC], Ssh = Ssh3#ssh{send_sequence = (SeqNum+1) band 16#ffffffff}, {FinalPacket, Ssh}. @@ -1174,31 +1176,31 @@ padding_length(Size, #ssh{encrypt_block_size = BlockSize, -handle_packet_part(<<>>, Encrypted0, undefined, #ssh{decrypt = CryptoAlg} = Ssh0) -> +handle_packet_part(<<>>, Encrypted0, AEAD0, undefined, #ssh{decrypt = CryptoAlg} = Ssh0) -> %% New ssh packet case get_length(pkt_type(CryptoAlg), Encrypted0, Ssh0) of get_more -> %% too short to get the length - {get_more, <<>>, Encrypted0, undefined, Ssh0}; + {get_more, <<>>, Encrypted0, AEAD0, undefined, Ssh0}; - {ok, PacketLen, _, _, _} when PacketLen > ?SSH_MAX_PACKET_SIZE -> + {ok, PacketLen, _, _, _, _} when PacketLen > ?SSH_MAX_PACKET_SIZE -> %% far too long message than expected {error, {exceeds_max_size,PacketLen}}; - {ok, PacketLen, Decrypted, Encrypted1, + {ok, PacketLen, Decrypted, Encrypted1, AEAD, #ssh{recv_mac_size = MacSize} = Ssh1} -> %% enough bytes so we got the length and can calculate how many %% more bytes to expect for a full packet TotalNeeded = (4 + PacketLen + MacSize), - handle_packet_part(Decrypted, Encrypted1, TotalNeeded, Ssh1) + handle_packet_part(Decrypted, Encrypted1, AEAD, TotalNeeded, Ssh1) end; -handle_packet_part(DecryptedPfx, EncryptedBuffer, TotalNeeded, Ssh0) +handle_packet_part(DecryptedPfx, EncryptedBuffer, AEAD, TotalNeeded, Ssh0) when (size(DecryptedPfx)+size(EncryptedBuffer)) < TotalNeeded -> %% need more bytes to finalize the packet - {get_more, DecryptedPfx, EncryptedBuffer, TotalNeeded, Ssh0}; + {get_more, DecryptedPfx, EncryptedBuffer, AEAD, TotalNeeded, Ssh0}; -handle_packet_part(DecryptedPfx, EncryptedBuffer, TotalNeeded, +handle_packet_part(DecryptedPfx, EncryptedBuffer, AEAD, TotalNeeded, #ssh{recv_mac_size = MacSize, decrypt = CryptoAlg} = Ssh0) -> %% enough bytes to decode the packet. @@ -1216,8 +1218,7 @@ handle_packet_part(DecryptedPfx, EncryptedBuffer, TotalNeeded, {packet_decrypted, DecompressedPayload, NextPacketBytes, Ssh} end; aead -> - PacketLenBin = DecryptedPfx, - case decrypt(Ssh0, {PacketLenBin,EncryptedSfx,Mac}) of + case decrypt(Ssh0, {AEAD,EncryptedSfx,Mac}) of {Ssh1, error} -> {bad_mac, Ssh1}; {Ssh1, DecryptedSfx} -> @@ -1234,21 +1235,29 @@ get_length(common, EncryptedBuffer, #ssh{decrypt_block_size = BlockSize} = Ssh0) <> = EncryptedBuffer, {Ssh, <> = Decrypted} = decrypt(Ssh0, EncBlock), - {ok, PacketLen, Decrypted, EncryptedRest, Ssh}; + {ok, PacketLen, Decrypted, EncryptedRest, <<>>, Ssh}; false -> get_more end; + get_length(aead, EncryptedBuffer, Ssh) -> - case size(EncryptedBuffer) >= 4 of - true -> + case {size(EncryptedBuffer) >= 4, Ssh#ssh.decrypt} of + {true, 'chacha20-poly1305@openssh.com'} -> + <> = EncryptedBuffer, + {Ssh1, PacketLenBin} = decrypt(Ssh, {length,EncryptedLen}), + <> = PacketLenBin, + {ok, PacketLen, PacketLenBin, EncryptedRest, EncryptedLen, Ssh1}; + {true, _} -> <> = EncryptedBuffer, - {ok, PacketLen, <>, EncryptedRest, Ssh}; - false -> + {ok, PacketLen, <>, EncryptedRest, <>, Ssh}; + {false, _} -> get_more end. + pkt_type('AEAD_AES_128_GCM') -> aead; pkt_type('AEAD_AES_256_GCM') -> aead; +pkt_type('chacha20-poly1305@openssh.com') -> aead; pkt_type(_) -> common. payload(<>) -> @@ -1353,11 +1362,32 @@ cipher('aes192-ctr') -> cipher('aes256-ctr') -> #cipher_data{key_bytes = 32, iv_bytes = 16, - block_bytes = 16}. + block_bytes = 16}; + +cipher('chacha20-poly1305@openssh.com') -> % FIXME: Verify!! + #cipher_data{key_bytes = 32, + iv_bytes = 12, + block_bytes = 8}. + encrypt_init(#ssh{encrypt = none} = Ssh) -> {ok, Ssh}; +encrypt_init(#ssh{encrypt = 'chacha20-poly1305@openssh.com', role = client} = Ssh) -> + %% chacha20-poly1305@openssh.com uses two independent crypto streams, one (chacha20) + %% for the length used in stream mode, and the other (chacha20-poly1305) as AEAD for + %% the payload and to MAC the length||payload. + %% See draft-josefsson-ssh-chacha20-poly1305-openssh-00 + <> = hash(Ssh, "C", 512), + {ok, Ssh#ssh{encrypt_keys = {K1,K2} + % encrypt_block_size = 16, %default = 8. What to set it to? 64 (openssl chacha.h) + % ctx and iv is setup for each packet + }}; +encrypt_init(#ssh{encrypt = 'chacha20-poly1305@openssh.com', role = server} = Ssh) -> + <> = hash(Ssh, "D", 512), + {ok, Ssh#ssh{encrypt_keys = {K1,K2} + % encrypt_block_size = 16, %default = 8. What to set it to? + }}; encrypt_init(#ssh{encrypt = 'AEAD_AES_128_GCM', role = client} = Ssh) -> IV = hash(Ssh, "A", 12*8), <> = hash(Ssh, "C", 128), @@ -1458,18 +1488,40 @@ encrypt_final(Ssh) -> encrypt(#ssh{encrypt = none} = Ssh, Data) -> {Ssh, Data}; +encrypt(#ssh{encrypt = 'chacha20-poly1305@openssh.com', + encrypt_keys = {K1,K2}, + send_sequence = Seq} = Ssh, + <>) -> + %% Encrypt length + IV1 = <<0:8/unit:8, Seq:8/unit:8>>, + {_,EncLen} = crypto:stream_encrypt(crypto:stream_init(chacha20, K1, IV1), + LenData), + %% Encrypt payload + IV2 = <<1:8/little-unit:8, Seq:8/unit:8>>, + {_,EncPayloadData} = crypto:stream_encrypt(crypto:stream_init(chacha20, K2, IV2), + PayloadData), + + %% MAC tag + {_,PolyKey} = crypto:stream_encrypt(crypto:stream_init(chacha20, K2, <<0:8/unit:8,Seq:8/unit:8>>), + <<0:32/unit:8>>), + EncBytes = <>, + Ctag = crypto:poly1305(PolyKey, EncBytes), + %% Result + {Ssh, {EncBytes,Ctag}}; encrypt(#ssh{encrypt = 'AEAD_AES_128_GCM', encrypt_keys = K, - encrypt_ctx = IV0} = Ssh, Data={_AAD,_Ptext}) -> - Enc = {_Ctext,_Ctag} = crypto:block_encrypt(aes_gcm, K, IV0, Data), + encrypt_ctx = IV0} = Ssh, + <>) -> + {Ctext,Ctag} = crypto:block_encrypt(aes_gcm, K, IV0, {LenData,PayloadData}), IV = next_gcm_iv(IV0), - {Ssh#ssh{encrypt_ctx = IV}, Enc}; + {Ssh#ssh{encrypt_ctx = IV}, {<>,Ctag}}; encrypt(#ssh{encrypt = 'AEAD_AES_256_GCM', encrypt_keys = K, - encrypt_ctx = IV0} = Ssh, Data={_AAD,_Ptext}) -> - Enc = {_Ctext,_Ctag} = crypto:block_encrypt(aes_gcm, K, IV0, Data), + encrypt_ctx = IV0} = Ssh, + <>) -> + {Ctext,Ctag} = crypto:block_encrypt(aes_gcm, K, IV0, {LenData,PayloadData}), IV = next_gcm_iv(IV0), - {Ssh#ssh{encrypt_ctx = IV}, Enc}; + {Ssh#ssh{encrypt_ctx = IV}, {<>,Ctag}}; encrypt(#ssh{encrypt = '3des-cbc', encrypt_keys = {K1,K2,K3}, encrypt_ctx = IV0} = Ssh, Data) -> @@ -1502,6 +1554,14 @@ encrypt(#ssh{encrypt = 'aes256-ctr', decrypt_init(#ssh{decrypt = none} = Ssh) -> {ok, Ssh}; +decrypt_init(#ssh{decrypt = 'chacha20-poly1305@openssh.com', role = client} = Ssh) -> + <> = hash(Ssh, "D", 512), + {ok, Ssh#ssh{decrypt_keys = {K1,K2} + }}; +decrypt_init(#ssh{decrypt = 'chacha20-poly1305@openssh.com', role = server} = Ssh) -> + <> = hash(Ssh, "C", 512), + {ok, Ssh#ssh{decrypt_keys = {K1,K2} + }}; decrypt_init(#ssh{decrypt = 'AEAD_AES_128_GCM', role = client} = Ssh) -> IV = hash(Ssh, "B", 12*8), <> = hash(Ssh, "D", 128), @@ -1602,6 +1662,31 @@ decrypt_final(Ssh) -> decrypt(Ssh, <<>>) -> {Ssh, <<>>}; +decrypt(#ssh{decrypt = 'chacha20-poly1305@openssh.com', + decrypt_keys = {K1,_K2}, + recv_sequence = Seq} = Ssh, {length,EncryptedLen}) -> + {_State,PacketLenBin} = + crypto:stream_decrypt(crypto:stream_init(chacha20, K1, <<0:8/unit:8, Seq:8/unit:8>>), + EncryptedLen), + {Ssh, PacketLenBin}; +decrypt(#ssh{decrypt = 'chacha20-poly1305@openssh.com', + decrypt_keys = {_K1,K2}, + recv_sequence = Seq} = Ssh, {AAD,Ctext,Ctag}) -> + %% The length is already decoded and used to divide the input + %% Check the mac (important that it is timing-safe): + {_,PolyKey} = + crypto:stream_encrypt(crypto:stream_init(chacha20, K2, <<0:8/unit:8,Seq:8/unit:8>>), + <<0:32/unit:8>>), + case equal_const_time(Ctag, crypto:poly1305(PolyKey, <>)) of + true -> + %% MAC is ok, decode + IV2 = <<1:8/little-unit:8, Seq:8/unit:8>>, + {_,PlainText} = + crypto:stream_decrypt(crypto:stream_init(chacha20,K2,IV2), Ctext), + {Ssh, PlainText}; + false -> + {Ssh,error} + end; decrypt(#ssh{decrypt = none} = Ssh, Data) -> {Ssh, Data}; decrypt(#ssh{decrypt = 'AEAD_AES_128_GCM', @@ -1744,7 +1829,7 @@ send_mac_init(SSH) -> Key = hash(SSH, "F", KeySize), {ok, SSH#ssh { send_mac_key = Key }} end; - aead -> + _ -> %% Not applicable {ok, SSH} end. @@ -1765,7 +1850,7 @@ recv_mac_init(SSH) -> Key = hash(SSH, "E", 8*mac_key_bytes(SSH#ssh.recv_mac)), {ok, SSH#ssh { recv_mac_key = Key }} end; - aead -> + _ -> %% Not applicable {ok, SSH} end. @@ -1905,6 +1990,7 @@ mac_key_bytes('hmac-sha2-256')-> 32; mac_key_bytes('hmac-sha2-512')-> 64; mac_key_bytes('AEAD_AES_128_GCM') -> 0; mac_key_bytes('AEAD_AES_256_GCM') -> 0; +mac_key_bytes('chacha20-poly1305@openssh.com') -> 0; mac_key_bytes(none) -> 0. mac_digest_size('hmac-sha1') -> 20; @@ -1915,6 +2001,7 @@ mac_digest_size('hmac-sha2-256') -> 32; mac_digest_size('hmac-sha2-512') -> 64; mac_digest_size('AEAD_AES_128_GCM') -> 16; mac_digest_size('AEAD_AES_256_GCM') -> 16; +mac_digest_size('chacha20-poly1305@openssh.com') -> 16; mac_digest_size(none) -> 0. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% @@ -2026,6 +2113,20 @@ same(Algs) -> [{client2server,Algs}, {server2client,Algs}]. %% %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% +%%% Compare two binaries in a timing safe maner. +%%% The time spent in comparing should not be different depending on where in the binaries they differ. +%%% This is to avoid a certain side-channel attac. +equal_const_time(X1, X2) -> equal_const_time(X1, X2, true). + +equal_const_time(<>, <>, Truth) -> + equal_const_time(R1, R2, Truth and (B1 == B2)); +equal_const_time(<<>>, <<>>, Truth) -> + Truth; +equal_const_time(_, _, _) -> + false. + +%%%-------- Remove CR, LF and following characters from a line + trim_tail(Str) -> lists:takewhile(fun(C) -> C=/=$\r andalso C=/=$\n -- cgit v1.2.3