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-rw-r--r--src/ratchet.cpp32
1 files changed, 23 insertions, 9 deletions
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);