diff --git a/include/axolotl/account.hh b/include/axolotl/account.hh
index 5edb799709a8802c11c7d2a89f3162e40aac8fe6..dd9c8192d95567dcaf6ce4969f4f8c9761d7449f 100644
--- a/include/axolotl/account.hh
+++ b/include/axolotl/account.hh
@@ -2,6 +2,8 @@
#define AXOLOTL_ACCOUNT_HH_
#include "axolotl/list.hh"
+#include "axolotl/crypto.hh"
+#include "axolotl/error.hh"
#include <cstdint>
@@ -25,16 +27,21 @@ struct Account {
LocalKey identity_key;
LocalKey last_resort_one_time_key;
List<LocalKey, MAX_ONE_TIME_KEYS> one_time_keys;
+ ErrorCode last_error;
/** Number of random bytes needed to create a new account */
std::size_t new_account_random_length();
/** Create a new account. Returns NOT_ENOUGH_RANDOM if the number of random
* bytes is too small. */
- ErrorCode new_account(
+ std::size_t new_account(
uint8_t const * random, std::size_t random_length
);
+ LocalKey const * lookup_key(
+ std::uint32_t id
+ );
+
/** The number of bytes needed to persist this account. */
std::size_t pickle_length();
diff --git a/include/axolotl/crypto.hh b/include/axolotl/crypto.hh
index 42e4b61d518e98d1e33e391cb9504286fdf9f4fd..7564e8f1d0cf4519f38f0a666da6cb6b821060b2 100644
--- a/include/axolotl/crypto.hh
+++ b/include/axolotl/crypto.hh
@@ -12,6 +12,9 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
+#ifndef AXOLOTL_CRYPTO_HH_
+#define AXOLOTL_CRYPTO_HH_
+
#include <cstdint>
#include <cstddef>
@@ -141,3 +144,5 @@ void hkdf_sha256(
);
} // namespace axolotl
+
+#endif /* AXOLOTL_CRYPTO_HH_ */
diff --git a/include/axolotl/error.hh b/include/axolotl/error.hh
index 712b9eb5e520d9ca38a93cf75648d508ad8f304e..3bf0e63780440e5635ca886daf12b19d357bec56 100644
--- a/include/axolotl/error.hh
+++ b/include/axolotl/error.hh
@@ -10,6 +10,7 @@ enum struct ErrorCode {
BAD_MESSAGE_VERSION = 3, /*!< The message version is unsupported */
BAD_MESSAGE_FORMAT = 4, /*!< The message couldn't be decoded */
BAD_MESSAGE_MAC = 5, /*!< The message couldn't be decrypted */
+ BAD_MESSAGE_KEY_ID = 6, /*!< The message references an unknown key id */
};
} // namespace axolotl
diff --git a/include/axolotl/list.hh b/include/axolotl/list.hh
index ae8900c28c2e64164fc0b948b2cbc83f730f4aa5..604f00f880a8be546b56811414995e49c75ce30d 100644
--- a/include/axolotl/list.hh
+++ b/include/axolotl/list.hh
@@ -12,6 +12,9 @@
* See the License for the specific language governing permissions and
* limitations under the License.
*/
+#ifndef AXOLOTL_LIST_HH_
+#define AXOLOTL_LIST_HH_
+
#include <cstddef>
namespace axolotl {
@@ -112,3 +115,5 @@ private:
};
} // namespace axolotl
+
+#endif /* AXOLOTL_LIST_HH_ */
diff --git a/include/axolotl/message.hh b/include/axolotl/message.hh
index 2b9bc991db28fc9d0b380702ea2f009d90c59a20..5bce2777ad42472594838da3fe778c5960b183ac 100644
--- a/include/axolotl/message.hh
+++ b/include/axolotl/message.hh
@@ -88,6 +88,7 @@ struct PreKeyMessageReader {
std::uint8_t const * message; std::size_t message_length;
};
+
/**
* The length of the buffer needed to hold a message.
*/
@@ -99,6 +100,7 @@ std::size_t encode_one_time_key_message_length(
std::size_t message_length
);
+
/**
* Writes the message headers into the output buffer.
* Populates the writer struct with pointers into the output buffer.
diff --git a/include/axolotl/session.hh b/include/axolotl/session.hh
index c69699d42cbe02de19bb9e7078fce0f782e18cb9..1c3395a56a7b129a86b6888f168cbeb80d884543 100644
--- a/include/axolotl/session.hh
+++ b/include/axolotl/session.hh
@@ -5,14 +5,13 @@
namespace axolotl {
+class Account;
+
struct RemoteKey {
std::uint32_t id;
Curve25519PublicKey key;
};
-struct RemoteKeys {
-};
-
enum struct MessageType {
PRE_KEY_MESSAGE = 0,
@@ -21,28 +20,34 @@ enum struct MessageType {
struct Session {
+
+ Session();
+
+ Ratchet ratchet;
+ ErrorCode last_error;
+
bool received_message;
+
RemoteKey alice_identity_key;
- RemoteKey alice_base_key;
- RemoteKey bob_identity_key;
- RemoteKey bob_one_time_key;
- Ratchet ratchet;
+ Curve25519PublicKey alice_base_key;
+ std::uint32_t bob_one_time_key_id;
+
- void initialise_outbound_session_random_length();
+ std::size_t new_outbound_session_random_length();
- void initialise_outbound_session(
+ std::size_t new_outbound_session(
Account const & local_account,
- RemoteKey const & identity_key,
+ Curve25519PublicKey const & identity_key,
RemoteKey const & one_time_key,
std::uint8_t const * random, std::size_t random_length
);
- void initialise_inbound_session(
+ std::size_t new_inbound_session(
Account & local_account,
std::uint8_t const * one_time_key_message, std::size_t message_length
);
- void matches_inbound_session(
+ bool matches_inbound_session(
std::uint8_t const * one_time_key_message, std::size_t message_length
);
diff --git a/src/cipher.cpp b/src/cipher.cpp
index 86cde8835fcefedba28e975a3b5dcb95a47c090a..8b496dff60c7b00249f3fd9c321bf7284ec930c3 100644
--- a/src/cipher.cpp
+++ b/src/cipher.cpp
@@ -26,7 +26,7 @@ static void derive_keys(
std::uint8_t derived_secrets[80];
axolotl::hkdf_sha256(
key, key_length,
- NULL, 0,
+ nullptr, 0,
kdf_info, kdf_info_length,
derived_secrets, sizeof(derived_secrets)
);
diff --git a/src/message.cpp b/src/message.cpp
index fcedd07672d30808cfb0f5367bb0afef0a456343..d9978cb605ac36888610275123452d3aac081dc9 100644
--- a/src/message.cpp
+++ b/src/message.cpp
@@ -198,15 +198,15 @@ void axolotl::decode_message(
) {
std::uint8_t const * pos = input;
std::uint8_t const * end = input + input_length - mac_length;
- std::uint8_t const * unknown = NULL;
+ std::uint8_t const * unknown = nullptr;
if (pos == end) return;
reader.version = *(pos++);
reader.input = input;
reader.input_length = input_length;
reader.has_counter = false;
- reader.ratchet_key = NULL;
- reader.ciphertext = NULL;
+ reader.ratchet_key = nullptr;
+ reader.ciphertext = nullptr;
while (pos != end) {
pos = decode(
@@ -283,15 +283,15 @@ void axolotl::decode_one_time_key_message(
) {
std::uint8_t const * pos = input;
std::uint8_t const * end = input + input_length;
- std::uint8_t const * unknown = NULL;
+ std::uint8_t const * unknown = nullptr;
if (pos == end) return;
reader.version = *(pos++);
reader.has_registration_id = false;
reader.has_one_time_key_id = false;
- reader.identity_key = NULL;
- reader.base_key = NULL;
- reader.message = NULL;
+ reader.identity_key = nullptr;
+ reader.base_key = nullptr;
+ reader.message = nullptr;
while (pos != end) {
pos = decode(
diff --git a/src/ratchet.cpp b/src/ratchet.cpp
index 91e5ce63cfb4c7d252631baa0044dba48b426b7c..87d79b7516e8d52b7948dca4993e896d8d2a2c9b 100644
--- a/src/ratchet.cpp
+++ b/src/ratchet.cpp
@@ -184,7 +184,7 @@ void axolotl::Ratchet::initialise_as_bob(
std::uint8_t derived_secrets[64];
axolotl::hkdf_sha256(
shared_secret, shared_secret_length,
- NULL, 0,
+ nullptr, 0,
kdf_info.root_info, kdf_info.root_info_length,
derived_secrets, sizeof(derived_secrets)
);
@@ -203,7 +203,7 @@ void axolotl::Ratchet::initialise_as_alice(
std::uint8_t derived_secrets[64];
axolotl::hkdf_sha256(
shared_secret, shared_secret_length,
- NULL, 0,
+ nullptr, 0,
kdf_info.root_info, kdf_info.root_info_length,
derived_secrets, sizeof(derived_secrets)
);
@@ -477,7 +477,7 @@ std::size_t axolotl::Ratchet::decrypt(
return std::size_t(-1);
}
- ReceiverChain * chain = NULL;
+ ReceiverChain * chain = nullptr;
for (axolotl::ReceiverChain & receiver_chain : receiver_chains) {
if (0 == std::memcmp(
receiver_chain.ratchet_key.public_key, reader.ratchet_key,
diff --git a/src/session.cpp b/src/session.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..be2bce7e3b842b42a5fb13092f20a7b1ea8ad436
--- /dev/null
+++ b/src/session.cpp
@@ -0,0 +1,319 @@
+#include "axolotl/session.hh"
+#include "axolotl/cipher.hh"
+#include "axolotl/crypto.hh"
+#include "axolotl/account.hh"
+#include "axolotl/memory.hh"
+#include "axolotl/message.hh"
+
+#include <cstring>
+
+namespace {
+
+static const std::size_t KEY_LENGTH = 32;
+static const std::uint8_t PROTOCOL_VERSION = 0x3;
+
+static const std::uint8_t ROOT_KDF_INFO[] = "AXOLOTL_ROOT";
+static const std::uint8_t RATCHET_KDF_INFO[] = "AXOLOTL_RATCHET";
+static const std::uint8_t CIPHER_KDF_INFO[] = "AXOLOTL_KEYS";
+
+static const axolotl::CipherAesSha256 AXOLOTL_CIPHER(
+ CIPHER_KDF_INFO, sizeof(CIPHER_KDF_INFO) -1
+);
+
+static const axolotl::KdfInfo AXOLOTL_KDF_INFO = {
+ ROOT_KDF_INFO, sizeof(ROOT_KDF_INFO) - 1,
+ RATCHET_KDF_INFO, sizeof(RATCHET_KDF_INFO) - 1
+};
+
+} // namespace
+
+axolotl::Session::Session(
+) : ratchet(AXOLOTL_KDF_INFO, AXOLOTL_CIPHER),
+ last_error(axolotl::ErrorCode::SUCCESS),
+ received_message(false),
+ bob_one_time_key_id(0) {
+
+}
+
+
+std::size_t axolotl::Session::new_outbound_session_random_length() {
+ return KEY_LENGTH;
+}
+
+
+std::size_t axolotl::Session::new_outbound_session(
+ axolotl::Account const & local_account,
+ axolotl::Curve25519PublicKey const & identity_key,
+ axolotl::RemoteKey const & one_time_key,
+ std::uint8_t const * random, std::size_t random_length
+) {
+ if (random_length < new_outbound_session_random_length()) {
+ last_error = axolotl::ErrorCode::NOT_ENOUGH_RANDOM;
+ return std::size_t(-1);
+ }
+
+ Curve25519KeyPair base_key;
+ axolotl::generate_key(random, base_key);
+
+ received_message = false;
+ alice_identity_key.id = local_account.identity_key.id;
+ alice_identity_key.key = local_account.identity_key.key;
+ alice_base_key = base_key;
+ bob_one_time_key_id = one_time_key.id;
+
+ std::uint8_t shared_secret[160];
+ std::memset(shared_secret, 0xFF, 32);
+
+ axolotl::curve25519_shared_secret(
+ );
+ axolotl::curve25519_shared_secret(
+ base_key, identity_key, shared_secret + 64
+ );
+ axolotl::curve25519_shared_secret(
+ );
+ axolotl::curve25519_shared_secret(
+ base_key, one_time_key.key, shared_secret + 128
+ );
+
+ axolotl::unset(base_key);
+ axolotl::unset(shared_secret);
+
+ return std::size_t(0);
+}
+
+namespace {
+
+bool check_message_fields(
+ axolotl::PreKeyMessageReader & reader
+) {
+ bool ok = true;
+ ok = ok && reader.identity_key;
+ ok = ok && reader.identity_key_length == KEY_LENGTH;
+ ok = ok && reader.message;
+ ok = ok && reader.base_key;
+ ok = ok && reader.base_key_length == KEY_LENGTH;
+ ok = ok && reader.has_one_time_key_id;
+ ok = ok && reader.has_registration_id;
+ return ok;
+}
+
+} // namespace
+
+
+std::size_t axolotl::Session::new_inbound_session(
+ axolotl::Account & local_account,
+ std::uint8_t const * one_time_key_message, std::size_t message_length
+) {
+ axolotl::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, one_time_key_message, message_length);
+
+ if (!check_message_fields(reader)) {
+ last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+
+ alice_identity_key.id = reader.registration_id;
+ std::memcpy(alice_identity_key.key.public_key, reader.identity_key, 32);
+ std::memcpy(alice_base_key.public_key, reader.base_key, 32);
+ bob_one_time_key_id = reader.one_time_key_id;
+
+
+ axolotl::LocalKey const * bob_one_time_key = local_account.lookup_key(
+ bob_one_time_key_id
+ );
+
+ last_error = axolotl::ErrorCode::BAD_MESSAGE_KEY_ID;
+ return std::size_t(-1);
+ }
+
+ std::uint8_t shared_secret[160];
+ std::memset(shared_secret, 0xFF, 32);
+
+ axolotl::curve25519_shared_secret(
+ );
+ axolotl::curve25519_shared_secret(
+ local_account.identity_key.key, alice_base_key, shared_secret + 64
+ );
+ axolotl::curve25519_shared_secret(
+ );
+ axolotl::curve25519_shared_secret(
+ bob_one_time_key->key, alice_base_key, shared_secret + 128
+ );
+
+
+ return std::size_t(0);
+}
+
+
+bool axolotl::Session::matches_inbound_session(
+ std::uint8_t const * one_time_key_message, std::size_t message_length
+) {
+ axolotl::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, one_time_key_message, message_length);
+
+ if (!check_message_fields(reader)) {
+ return false;
+ }
+
+ bool same = true;
+ same = same && 0 == std::memcmp(
+ reader.identity_key, alice_identity_key.key.public_key, KEY_LENGTH
+ );
+ same = same && 0 == std::memcmp(
+ reader.base_key, alice_base_key.public_key, KEY_LENGTH
+ );
+ same = same && reader.one_time_key_id == bob_one_time_key_id;
+ same = same && reader.registration_id == alice_identity_key.id;
+ return same;
+}
+
+
+axolotl::MessageType axolotl::Session::encrypt_message_type() {
+ if (received_message) {
+ return axolotl::MessageType::MESSAGE;
+ } else {
+ return axolotl::MessageType::PRE_KEY_MESSAGE;
+ }
+}
+
+
+std::size_t axolotl::Session::encrypt_message_length(
+ std::size_t plaintext_length
+) {
+ std::size_t message_length = ratchet.encrypt_output_length(
+ plaintext_length
+ );
+
+ if (received_message) {
+ return message_length;
+ }
+
+ return encode_one_time_key_message_length(
+ alice_identity_key.id,
+ bob_one_time_key_id,
+ KEY_LENGTH,
+ KEY_LENGTH,
+ message_length
+ );
+}
+
+
+std::size_t axolotl::Session::encrypt_random_length() {
+ return ratchet.encrypt_random_length();
+}
+
+
+std::size_t axolotl::Session::encrypt(
+ std::uint8_t const * plaintext, std::size_t plaintext_length,
+ std::uint8_t const * random, std::size_t random_length,
+ std::uint8_t * message, std::size_t message_length
+) {
+ if (message_length < encrypt_message_length(plaintext_length)) {
+ last_error = axolotl::ErrorCode::OUTPUT_BUFFER_TOO_SMALL;
+ return std::size_t(-1);
+ }
+ std::uint8_t * message_body;
+ std::size_t message_body_length = ratchet.encrypt_output_length(
+ plaintext_length
+ );
+
+ if (received_message) {
+ message_body = message;
+ } else {
+ axolotl::PreKeyMessageWriter writer;
+ encode_one_time_key_message(
+ writer,
+ PROTOCOL_VERSION,
+ alice_identity_key.id,
+ bob_one_time_key_id,
+ KEY_LENGTH,
+ KEY_LENGTH,
+ message_body_length,
+ message
+ );
+ std::memcpy(
+ writer.identity_key, alice_identity_key.key.public_key, KEY_LENGTH
+ );
+ std::memcpy(
+ writer.base_key, alice_base_key.public_key, KEY_LENGTH
+ );
+ message_body = writer.message;
+ }
+
+ std::size_t result = ratchet.encrypt(
+ plaintext, plaintext_length,
+ random, random_length,
+ message_body, message_body_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = axolotl::ErrorCode::SUCCESS;
+ }
+ return result;
+}
+
+
+std::size_t axolotl::Session::decrypt_max_plaintext_length(
+ MessageType message_type,
+ std::uint8_t const * message, std::size_t message_length
+) {
+ std::uint8_t const * message_body;
+ std::size_t message_body_length;
+ if (message_type == axolotl::MessageType::MESSAGE) {
+ message_body = message;
+ message_body_length = message_length;
+ } else {
+ axolotl::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, message, message_length);
+ if (!reader.message) {
+ last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+ message_body = reader.message;
+ message_body_length = reader.message_length;
+ }
+
+ std::size_t result = ratchet.decrypt_max_plaintext_length(
+ message_body, message_body_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = axolotl::ErrorCode::SUCCESS;
+ }
+ return result;
+}
+
+
+std::size_t axolotl::Session::decrypt(
+ axolotl::MessageType message_type,
+ std::uint8_t const * message, std::size_t message_length,
+ std::uint8_t * plaintext, std::size_t max_plaintext_length
+) {
+ std::uint8_t const * message_body;
+ std::size_t message_body_length;
+ if (message_type == axolotl::MessageType::MESSAGE) {
+ message_body = message;
+ message_body_length = message_length;
+ } else {
+ axolotl::PreKeyMessageReader reader;
+ decode_one_time_key_message(reader, message, message_length);
+ if (!reader.message) {
+ last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
+ return std::size_t(-1);
+ }
+ message_body = reader.message;
+ message_body_length = reader.message_length;
+ }
+
+ std::size_t result = ratchet.decrypt(
+ message_body, message_body_length, plaintext, max_plaintext_length
+ );
+
+ if (result == std::size_t(-1)) {
+ last_error = ratchet.last_error;
+ ratchet.last_error = axolotl::ErrorCode::SUCCESS;
+ }
+ return result;
+}