%%
%% %CopyrightBegin%
%%
%% Copyright Ericsson AB 2007-2018. All Rights Reserved.
%%
%% Licensed under the Apache License, Version 2.0 (the "License");
%% you may not use this file except in compliance with the License.
%% You may obtain a copy of the License at
%%
%% http://www.apache.org/licenses/LICENSE-2.0
%%
%% Unless required by applicable law or agreed to in writing, software
%% distributed under the License is distributed on an "AS IS" BASIS,
%% WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
%% See the License for the specific language governing permissions and
%% limitations under the License.
%%
%% %CopyrightEnd%
-module(tls_record_1_3).
-include("tls_record.hrl").
-include("tls_record_1_3.hrl").
-include("ssl_internal.hrl").
-include("ssl_alert.hrl").
-include("ssl_cipher.hrl").
%% Encoding
-export([encode_handshake/2, encode_alert_record/2,
encode_data/2]).
-export([encode_plain_text/3]).
%% Decoding
-export([decode_cipher_text/2]).
%%====================================================================
%% Encoding
%%====================================================================
%%--------------------------------------------------------------------
-spec encode_handshake(iolist(), ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%
%% Description: Encodes a handshake message to send on the tls-1.3-socket.
%%--------------------------------------------------------------------
encode_handshake(Frag, ConnectionStates) ->
case iolist_size(Frag) of
N when N > ?MAX_PLAIN_TEXT_LENGTH ->
%% TODO: Consider padding here
Data = split_bin(iolist_to_binary(Frag), ?MAX_PLAIN_TEXT_LENGTH),
encode_iolist(?HANDSHAKE, Data, ConnectionStates);
_ ->
encode_plain_text(?HANDSHAKE, Frag, ConnectionStates)
end.
%%--------------------------------------------------------------------
-spec encode_alert_record(#alert{}, ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%%
%% Description: Encodes an alert message to send on the ssl-socket.
%%--------------------------------------------------------------------
encode_alert_record(#alert{level = Level, description = Description},
ConnectionStates) ->
encode_plain_text(?ALERT, <<?BYTE(Level), ?BYTE(Description)>>,
ConnectionStates).
%%--------------------------------------------------------------------
-spec encode_data(binary(), ssl_record:connection_states()) ->
{iolist(), ssl_record:connection_states()}.
%%
%% Description: Encodes data to send on the ssl-socket.
%%--------------------------------------------------------------------
encode_data(Frag, ConnectionStates) ->
Data = split_bin(Frag, ?MAX_PLAIN_TEXT_LENGTH, {3,4}),
encode_iolist(?APPLICATION_DATA, Data, ConnectionStates).
encode_plain_text(Type, Data0, #{current_write := Write0} = ConnectionStates) ->
PadLen = 0, %% TODO where to specify PadLen?
Data = inner_plaintext(Type, Data0, PadLen),
CipherFragment = encode_plain_text(Data, Write0),
{CipherText, Write} = encode_tls_cipher_text(CipherFragment, Write0),
{CipherText, ConnectionStates#{current_write => Write}}.
encode_iolist(Type, Data, ConnectionStates0) ->
{ConnectionStates, EncodedMsg} =
lists:foldl(fun(Text, {CS0, Encoded}) ->
{Enc, CS1} =
encode_plain_text(Type, Text, CS0),
{CS1, [Enc | Encoded]}
end, {ConnectionStates0, []}, Data),
{lists:reverse(EncodedMsg), ConnectionStates}.
%%====================================================================
%% Decoding
%%====================================================================
%%--------------------------------------------------------------------
-spec decode_cipher_text(#ssl_tls{}, ssl_record:connection_states()) ->
{#ssl_tls{}, ssl_record:connection_states()}| #alert{}.
%%
%% Description: Decode cipher text, use legacy type ssl_tls instead of tls_cipher_text
%% in decoding context so that we can reuse the code from erlier versions.
%%--------------------------------------------------------------------
decode_cipher_text(#ssl_tls{type = ?OPAQUE_TYPE,
version = ?LEGACY_VERSION,
fragment = CipherFragment},
#{current_read :=
#{sequence_number := Seq,
cipher_state := #cipher_state{key = Key,
iv = IV,
tag_len = TagLen},
security_parameters :=
#security_parameters{
cipher_type = ?AEAD,
bulk_cipher_algorithm =
BulkCipherAlgo}
} = ReadState0} = ConnectionStates0) ->
case decipher_aead(CipherFragment, BulkCipherAlgo, Key, Seq, IV, TagLen) of
#alert{} = Alert ->
Alert;
PlainFragment ->
ConnectionStates =
ConnectionStates0#{current_read =>
ReadState0#{sequence_number => Seq + 1}},
{decode_inner_plaintext(PlainFragment), ConnectionStates}
end;
decode_cipher_text(#ssl_tls{type = Type,
version = ?LEGACY_VERSION,
fragment = CipherFragment},
#{current_read :=
#{security_parameters :=
#security_parameters{
cipher_suite = ?TLS_NULL_WITH_NULL_NULL}
}} = ConnnectionStates0) ->
{#ssl_tls{type = Type,
version = {3,4}, %% Internally use real version
fragment = CipherFragment}, ConnnectionStates0};
decode_cipher_text(#ssl_tls{type = Type}, _) ->
%% Version mismatch is already asserted
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, {record_type_mismatch, Type}).
%%--------------------------------------------------------------------
%%% Internal functions
%%--------------------------------------------------------------------
split_bin(Bin, ChunkSize) ->
split_bin(Bin, ChunkSize, []).
split_bin(Bin, ChunkSize, _) ->
do_split_bin(Bin, ChunkSize, []).
do_split_bin(<<>>, _, Acc) ->
lists:reverse(Acc);
do_split_bin(Bin, ChunkSize, Acc) ->
case Bin of
<<Chunk:ChunkSize/binary, Rest/binary>> ->
do_split_bin(Rest, ChunkSize, [Chunk | Acc]);
_ ->
lists:reverse(Acc, [Bin])
end.
inner_plaintext(Type, Data, Length) ->
#inner_plaintext{
content = Data,
type = Type,
zeros = zero_padding(Length)
}.
zero_padding(Length)->
binary:copy(<<?BYTE(0)>>, Length).
encode_plain_text(#inner_plaintext{
content = Data,
type = Type,
zeros = Zeros
}, #{cipher_state := #cipher_state{key= Key,
iv = IV,
tag_len = TagLen},
sequence_number := Seq,
security_parameters :=
#security_parameters{
cipher_type = ?AEAD,
bulk_cipher_algorithm = BulkCipherAlgo}
}) ->
PlainText = [Data, Type, Zeros],
Encoded = cipher_aead(PlainText, BulkCipherAlgo, Key, Seq, IV, TagLen),
#tls_cipher_text{opaque_type = 23, %% 23 (application_data) for outward compatibility
legacy_version = {3,3},
encoded_record = Encoded};
encode_plain_text(#inner_plaintext{
content = Data,
type = Type
}, #{security_parameters :=
#security_parameters{
cipher_suite = ?TLS_NULL_WITH_NULL_NULL}
}) ->
%% RFC8446 - 5.1. Record Layer
%% When record protection has not yet been engaged, TLSPlaintext
%% structures are written directly onto the wire.
#tls_cipher_text{opaque_type = Type,
legacy_version = {3,3},
encoded_record = Data};
encode_plain_text(_, CS) ->
exit({cs, CS}).
additional_data(Length) ->
<<?BYTE(?OPAQUE_TYPE), ?BYTE(3), ?BYTE(3),?UINT16(Length)>>.
%% The per-record nonce for the AEAD construction is formed as
%% follows:
%%
%% 1. The 64-bit record sequence number is encoded in network byte
%% order and padded to the left with zeros to iv_length.
%%
%% 2. The padded sequence number is XORed with either the static
%% client_write_iv or server_write_iv (depending on the role).
%%
%% The resulting quantity (of length iv_length) is used as the
%% per-record nonce.
nonce(Seq, IV) ->
Padding = binary:copy(<<0>>, byte_size(IV) - 8),
crypto:exor(<<Padding/binary,?UINT64(Seq)>>, IV).
cipher_aead(Fragment, BulkCipherAlgo, Key, Seq, IV, TagLen) ->
AAD = additional_data(erlang:iolist_size(Fragment) + TagLen),
Nonce = nonce(Seq, IV),
{Content, CipherTag} =
ssl_cipher:aead_encrypt(BulkCipherAlgo, Key, Nonce, Fragment, AAD),
<<Content/binary, CipherTag/binary>>.
encode_tls_cipher_text(#tls_cipher_text{opaque_type = Type,
legacy_version = {MajVer, MinVer},
encoded_record = Encoded}, #{sequence_number := Seq} = Write) ->
Length = erlang:iolist_size(Encoded),
{[<<?BYTE(Type), ?BYTE(MajVer), ?BYTE(MinVer), ?UINT16(Length)>>, Encoded],
Write#{sequence_number => Seq +1}}.
decipher_aead(CipherFragment, BulkCipherAlgo, Key, Seq, IV, TagLen) ->
try
AAD = additional_data(erlang:iolist_size(CipherFragment)),
Nonce = nonce(Seq, IV),
{CipherText, CipherTag} = aead_ciphertext_split(CipherFragment, TagLen),
case ssl_cipher:aead_decrypt(BulkCipherAlgo, Key, Nonce, CipherText, CipherTag, AAD) of
Content when is_binary(Content) ->
Content;
_ ->
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, decryption_failed)
end
catch
_:_ ->
?ALERT_REC(?FATAL, ?BAD_RECORD_MAC, decryption_failed)
end.
aead_ciphertext_split(CipherTextFragment, TagLen)
when is_binary(CipherTextFragment) ->
CipherLen = erlang:byte_size(CipherTextFragment) - TagLen,
<<CipherText:CipherLen/bytes, CipherTag:TagLen/bytes>> = CipherTextFragment,
{CipherText, CipherTag};
aead_ciphertext_split(CipherTextFragment, TagLen)
when is_list(CipherTextFragment) ->
CipherLen = erlang:iolist_size(CipherTextFragment) - TagLen,
<<CipherText:CipherLen/bytes, CipherTag:TagLen/bytes>> =
erlang:iolist_to_binary(CipherTextFragment),
{CipherText, CipherTag}.
decode_inner_plaintext(PlainText) ->
case binary:last(PlainText) of
0 ->
decode_inner_plaintext(init_binary(PlainText));
Type when Type =:= ?APPLICATION_DATA orelse
Type =:= ?HANDSHAKE orelse
Type =:= ?ALERT ->
#ssl_tls{type = Type,
version = {3,4}, %% Internally use real version
fragment = init_binary(PlainText)};
_Else ->
?ALERT_REC(?FATAL, ?UNEXPECTED_MESSAGE, empty_alert)
end.
init_binary(B) ->
{Init, _} =
split_binary(B, byte_size(B) - 1),
Init.
