diff options
| -rw-r--r-- | include/axolotl/ratchet.hh | 6 | ||||
| -rw-r--r-- | src/ratchet.cpp | 32 | ||||
| -rw-r--r-- | tests/test_ratchet.cpp | 24 |
3 files changed, 40 insertions, 22 deletions
diff --git a/include/axolotl/ratchet.hh b/include/axolotl/ratchet.hh index f7d30d0..eaf1352 100644 --- a/include/axolotl/ratchet.hh +++ b/include/axolotl/ratchet.hh @@ -129,9 +129,9 @@ struct Ratchet { std::uint8_t * input, std::size_t input_length ); - /** The maximum number of bytes of output the encrypt method will write for + /** The number of bytes of output the encrypt method will write for * a given message length. */ - std::size_t encrypt_max_output_length( + std::size_t encrypt_output_length( std::size_t plaintext_length ); @@ -154,7 +154,7 @@ struct Ratchet { /** An upper bound on the number of bytes of plain-text the decrypt method * will write for a given input message length. */ std::size_t decrypt_max_plaintext_length( - std::size_t input_length + std::uint8_t const * input, std::size_t input_length ); /** Decrypt a message. Returns the length of the decrypted plain-text or diff --git a/src/ratchet.cpp b/src/ratchet.cpp index 5097643..91e5ce6 100644 --- a/src/ratchet.cpp +++ b/src/ratchet.cpp @@ -348,7 +348,7 @@ std::size_t axolotl::Ratchet::unpickle( } -std::size_t axolotl::Ratchet::encrypt_max_output_length( +std::size_t axolotl::Ratchet::encrypt_output_length( std::size_t plaintext_length ) { std::size_t counter = 0; @@ -374,7 +374,7 @@ std::size_t axolotl::Ratchet::encrypt( std::uint8_t const * random, std::size_t random_length, std::uint8_t * output, std::size_t max_output_length ) { - std::size_t output_length = encrypt_max_output_length(plaintext_length); + std::size_t output_length = encrypt_output_length(plaintext_length); if (random_length < encrypt_random_length()) { last_error = axolotl::ErrorCode::NOT_ENOUGH_RANDOM; @@ -428,9 +428,19 @@ std::size_t axolotl::Ratchet::encrypt( std::size_t axolotl::Ratchet::decrypt_max_plaintext_length( - std::size_t input_length + std::uint8_t const * input, std::size_t input_length ) { - return input_length; + axolotl::MessageReader reader; + axolotl::decode_message( + reader, input, input_length, ratchet_cipher.mac_length() + ); + + if (!reader.ciphertext) { + last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT; + return std::size_t(-1); + } + + return ratchet_cipher.decrypt_max_plaintext_length(reader.ciphertext_length); } @@ -438,11 +448,6 @@ std::size_t axolotl::Ratchet::decrypt( std::uint8_t const * input, std::size_t input_length, std::uint8_t * plaintext, std::size_t max_plaintext_length ) { - if (max_plaintext_length < decrypt_max_plaintext_length(input_length)) { - last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL; - return std::size_t(-1); - } - axolotl::MessageReader reader; axolotl::decode_message( reader, input, input_length, ratchet_cipher.mac_length() @@ -458,6 +463,15 @@ std::size_t axolotl::Ratchet::decrypt( return std::size_t(-1); } + std::size_t max_length = ratchet_cipher.decrypt_max_plaintext_length( + reader.ciphertext_length + ); + + if (max_plaintext_length < max_length) { + last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL; + return std::size_t(-1); + } + if (reader.ratchet_key_length != KEY_LENGTH) { last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT; return std::size_t(-1); diff --git a/tests/test_ratchet.cpp b/tests/test_ratchet.cpp index e262bfa..e1a0519 100644 --- a/tests/test_ratchet.cpp +++ b/tests/test_ratchet.cpp @@ -54,13 +54,11 @@ std::size_t message_length, random_length, output_length; std::size_t encrypt_length, decrypt_length; { /* Bob sends Alice a message */ - message_length = bob.encrypt_max_output_length(plaintext_length); + message_length = bob.encrypt_output_length(plaintext_length); random_length = bob.encrypt_random_length(); assert_equals(std::size_t(0), random_length); - output_length = alice.decrypt_max_plaintext_length(message_length); std::uint8_t message[message_length]; - std::uint8_t output[output_length]; encrypt_length = bob.encrypt( plaintext, plaintext_length, @@ -69,6 +67,8 @@ std::size_t encrypt_length, decrypt_length; ); assert_equals(message_length, encrypt_length); + output_length = alice.decrypt_max_plaintext_length(message, message_length); + std::uint8_t output[output_length]; decrypt_length = alice.decrypt( message, message_length, output, output_length @@ -80,13 +80,11 @@ std::size_t encrypt_length, decrypt_length; { /* Alice sends Bob a message */ - message_length = alice.encrypt_max_output_length(plaintext_length); + message_length = alice.encrypt_output_length(plaintext_length); random_length = alice.encrypt_random_length(); assert_equals(std::size_t(32), random_length); - output_length = bob.decrypt_max_plaintext_length(message_length); std::uint8_t message[message_length]; - std::uint8_t output[output_length]; std::uint8_t random[] = "This is a random 32 byte string."; encrypt_length = alice.encrypt( @@ -96,6 +94,8 @@ std::size_t encrypt_length, decrypt_length; ); assert_equals(message_length, encrypt_length); + output_length = bob.decrypt_max_plaintext_length(message, message_length); + std::uint8_t output[output_length]; decrypt_length = bob.decrypt( message, message_length, output, output_length @@ -127,7 +127,7 @@ std::size_t encrypt_length, decrypt_length; { /* Alice sends Bob two messages and they arrive out of order */ - message_1_length = alice.encrypt_max_output_length(plaintext_1_length); + message_1_length = alice.encrypt_output_length(plaintext_1_length); random_length = alice.encrypt_random_length(); assert_equals(std::size_t(32), random_length); @@ -140,7 +140,7 @@ std::size_t encrypt_length, decrypt_length; ); assert_equals(message_1_length, encrypt_length); - message_2_length = alice.encrypt_max_output_length(plaintext_2_length); + message_2_length = alice.encrypt_output_length(plaintext_2_length); random_length = alice.encrypt_random_length(); assert_equals(std::size_t(0), random_length); @@ -152,7 +152,9 @@ std::size_t encrypt_length, decrypt_length; ); assert_equals(message_2_length, encrypt_length); - output_length = bob.decrypt_max_plaintext_length(message_2_length); + output_length = bob.decrypt_max_plaintext_length( + message_2, message_2_length + ); std::uint8_t output_1[output_length]; decrypt_length = bob.decrypt( message_2, message_2_length, @@ -161,7 +163,9 @@ std::size_t encrypt_length, decrypt_length; assert_equals(plaintext_2_length, decrypt_length); assert_equals(plaintext_2, output_1, decrypt_length); - output_length = bob.decrypt_max_plaintext_length(message_1_length); + output_length = bob.decrypt_max_plaintext_length( + message_1, message_1_length + ); std::uint8_t output_2[output_length]; decrypt_length = bob.decrypt( message_1, message_1_length, |