fix handling of block_decipher/5 failure

A wrong decryption key would cause a badmatch in
generic_block_cipher_from_bin/2. The try in block_decipher/5 was
probably intendend to deal with that, but was misplace for this.

Additionaly, generating a failure alert erly, without computing the
record MAC, creates vector for a timing attack on CBC padding (for
details check TLS 1.2 RFC 5246, Sect. 6.2.3.2.). This attach vector
and the counter meassure applies to all SSL/TLS versions.

As a counter messure, compute the MAC even when decryption or padding
checks fail. A invalid padding will force a MAC failure by intentionaly
invalidating the content.

1 files changed, 163 insertions, 0 deletions

diff --git a/lib/ssl/test/ssl_cipher_SUITE.erl b/lib/ssl/test/ssl_cipher_SUITE.erl
new file mode 100644
index 0000000000..87478e13bc
--- /dev/null
+++ b/lib/ssl/test/ssl_cipher_SUITE.erl
@@ -0,0 +1,163 @@
+%%
+%% %CopyrightBegin%
+%%
+%% Copyright Ericsson AB 2008-2011. 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(ssl_cipher_SUITE).
+
+%% Note: This directive should only be used in test suites.
+-compile(export_all).
+
+-include_lib("common_test/include/ct.hrl").
+
+-include("ssl_internal.hrl").
+-include("ssl_record.hrl").
+-include("ssl_cipher.hrl").
+
+-define(TIMEOUT, 600000).
+
+%% Test server callback functions
+%%--------------------------------------------------------------------
+%% Function: init_per_suite(Config) -> Config
+%% Config - [tuple()]
+%%   A list of key/value pairs, holding the test case configuration.
+%% Description: Initialization before the whole suite
+%%
+%% Note: This function is free to add any key/value pairs to the Config
+%% variable, but should NOT alter/remove any existing entries.
+%%--------------------------------------------------------------------
+init_per_suite(Config) ->
+    try crypto:start() of
+	ok ->
+	    Config
+    catch _:_  ->
+	    {skip, "Crypto did not start"}
+    end.
+%%--------------------------------------------------------------------
+%% Function: end_per_suite(Config) -> _
+%% Config - [tuple()]
+%%   A list of key/value pairs, holding the test case configuration.
+%% Description: Cleanup after the whole suite
+%%--------------------------------------------------------------------
+end_per_suite(_Config) ->
+    ssl:stop(),
+    application:stop(crypto).
+
+%%--------------------------------------------------------------------
+%% Function: init_per_testcase(TestCase, Config) -> Config
+%% Case - atom()
+%%   Name of the test case that is about to be run.
+%% Config - [tuple()]
+%%   A list of key/value pairs, holding the test case configuration.
+%%
+%% Description: Initialization before each test case
+%%
+%% Note: This function is free to add any key/value pairs to the Config
+%% variable, but should NOT alter/remove any existing entries.
+%% Description: Initialization before each test case
+%%--------------------------------------------------------------------
+init_per_testcase(_TestCase, Config0) ->
+    Config = lists:keydelete(watchdog, 1, Config0),
+    Dog = ssl_test_lib:timetrap(?TIMEOUT),
+    [{watchdog, Dog} | Config].
+
+%%--------------------------------------------------------------------
+%% Function: end_per_testcase(TestCase, Config) -> _
+%% Case - atom()
+%%   Name of the test case that is about to be run.
+%% Config - [tuple()]
+%%   A list of key/value pairs, holding the test case configuration.
+%% Description: Cleanup after each test case
+%%--------------------------------------------------------------------
+end_per_testcase(_TestCase, Config) ->
+    Dog = ?config(watchdog, Config),
+    case Dog of 
+	undefined ->
+	    ok;
+	_ ->
+	    test_server:timetrap_cancel(Dog)
+    end.
+
+%%--------------------------------------------------------------------
+%% Function: all(Clause) -> TestCases
+%% Clause - atom() - suite | doc
+%% TestCases - [Case] 
+%% Case - atom()
+%%   Name of a test case.
+%% Description: Returns a list of all test cases in this test suite
+%%--------------------------------------------------------------------
+suite() -> [{ct_hooks,[ts_install_cth]}].
+
+all() -> 
+    [aes_decipher_good, aes_decipher_fail].
+
+groups() -> 
+    [].
+
+init_per_group(_GroupName, Config) ->
+    Config.
+
+end_per_group(_GroupName, Config) ->
+    Config.
+
+
+%% Test cases starts here.
+%%--------------------------------------------------------------------
+aes_decipher_good(doc) -> 
+    ["Decipher a known cryptotext."];
+
+aes_decipher_good(suite) -> 
+    [];
+
+aes_decipher_good(Config) when is_list(Config) ->
+    HashSz = 32,
+    CipherState = #cipher_state{iv = <<59,201,85,117,188,206,224,136,5,109,46,70,104,79,4,9>>,
+				key = <<72,196,247,97,62,213,222,109,210,204,217,186,172,184,197,148>>},
+    Fragment = <<220,193,179,139,171,33,143,245,202,47,123,251,13,232,114,8,
+		 190,162,74,31,186,227,119,155,94,74,119,79,169,193,240,160,
+		 198,181,81,19,98,162,213,228,74,224,253,168,156,59,195,122,
+		 108,101,107,242,20,15,169,150,163,107,101,94,93,104,241,165>>,
+    Version = {3,3},
+    Content = <<183,139,16,132,10,209,67,86,168,100,61,217,145,57,36,56,72,69,76,76,79,10>>,
+    Mac = <<71,136,212,107,223,200,70,232,127,116,148,205,232,35,158,113,237,174,15,217,192,168,35,8,6,107,107,233,25,174,90,111>>,
+    {Content, Mac, CipherState1} = ssl_cipher:decipher(?AES, HashSz, CipherState, Fragment, Version),
+    ok.
+
+%%--------------------------------------------------------------------
+
+aes_decipher_fail(doc) -> 
+    ["Decipher a known cryptotext."];
+
+aes_decipher_fail(suite) -> 
+    [];
+
+%% same as above, last byte of key replaced
+aes_decipher_fail(Config) when is_list(Config) ->
+    HashSz = 32,
+    CipherState = #cipher_state{iv = <<59,201,85,117,188,206,224,136,5,109,46,70,104,79,4,9>>,
+				key = <<72,196,247,97,62,213,222,109,210,204,217,186,172,184,197,254>>},
+    Fragment = <<220,193,179,139,171,33,143,245,202,47,123,251,13,232,114,8,
+		 190,162,74,31,186,227,119,155,94,74,119,79,169,193,240,160,
+		 198,181,81,19,98,162,213,228,74,224,253,168,156,59,195,122,
+		 108,101,107,242,20,15,169,150,163,107,101,94,93,104,241,165>>,
+    Version = {3,3},
+    {Content, Mac, CipherState1} = ssl_cipher:decipher(?AES, HashSz, CipherState, Fragment, Version),
+    32 = byte_size(Content),
+    32 = byte_size(Mac),
+    ok.
+
+%%--------------------------------------------------------------------