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Implement the session key exchange

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This commit is contained in:
Mark Haines 2015-06-22 14:30:46 +01:00 committed by Mark Haines
parent 6ecea67718
commit 28541dd82a
1 changed files with 31 additions and 14 deletions
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45
src/session.cpp
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@ -37,7 +37,7 @@ axolotl::Session::Session(
std::size_t axolotl::Session::new_outbound_session_random_length() { std::size_t axolotl::Session::new_outbound_session_random_length() {
return KEY_LENGTH; return KEY_LENGTH * 2;
} }
@ -55,27 +55,31 @@ std::size_t axolotl::Session::new_outbound_session(
Curve25519KeyPair base_key; Curve25519KeyPair base_key;
axolotl::generate_key(random, base_key); axolotl::generate_key(random, base_key);
Curve25519KeyPair ratchet_key;
axolotl::generate_key(random + 32, ratchet_key);
received_message = false; received_message = false;
alice_identity_key.id = local_account.identity_key.id; alice_identity_key.id = local_account.identity_key.id;
alice_identity_key.key = local_account.identity_key.key; alice_identity_key.key = local_account.identity_key.key;
alice_base_key = base_key; alice_base_key = base_key;
bob_one_time_key_id = one_time_key.id; bob_one_time_key_id = one_time_key.id;
std::uint8_t shared_secret[160]; std::uint8_t shared_secret[96];
std::memset(shared_secret, 0xFF, 32);
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
local_account.identity_key.key, one_time_key.key, shared_secret
); );
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
base_key, identity_key, shared_secret + 64 base_key, identity_key, shared_secret + 32
); );
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
base_key, one_time_key.key, shared_secret + 64
); );
axolotl::curve25519_shared_secret(
base_key, one_time_key.key, shared_secret + 128 ratchet.initialise_as_alice(shared_secret, 96, ratchet_key);
);
axolotl::unset(base_key); axolotl::unset(base_key);
axolotl::unset(ratchet_key);
axolotl::unset(shared_secret); axolotl::unset(shared_secret);
return std::size_t(0); return std::size_t(0);
@ -112,34 +116,47 @@ std::size_t axolotl::Session::new_inbound_session(
return std::size_t(-1); return std::size_t(-1);
} }
axolotl::MessageReader message_reader;
decode_message(
message_reader, reader.message, reader.message_length,
ratchet.ratchet_cipher.mac_length()
);
if (!message_reader.ratchet_key
|| message_reader.ratchet_key_length != KEY_LENGTH) {
last_error = axolotl::ErrorCode::BAD_MESSAGE_FORMAT;
return std::size_t(-1);
}
alice_identity_key.id = reader.registration_id; alice_identity_key.id = reader.registration_id;
std::memcpy(alice_identity_key.key.public_key, reader.identity_key, 32); std::memcpy(alice_identity_key.key.public_key, reader.identity_key, 32);
std::memcpy(alice_base_key.public_key, reader.base_key, 32); std::memcpy(alice_base_key.public_key, reader.base_key, 32);
bob_one_time_key_id = reader.one_time_key_id; bob_one_time_key_id = reader.one_time_key_id;
axolotl::Curve25519PublicKey ratchet_key;
std::memcpy(ratchet_key.public_key, message_reader.ratchet_key, 32);
axolotl::LocalKey const * bob_one_time_key = local_account.lookup_key( axolotl::LocalKey const * bob_one_time_key = local_account.lookup_key(
bob_one_time_key_id bob_one_time_key_id
); );
if (!bob_one_time_key) {
last_error = axolotl::ErrorCode::BAD_MESSAGE_KEY_ID; last_error = axolotl::ErrorCode::BAD_MESSAGE_KEY_ID;
return std::size_t(-1); return std::size_t(-1);
} }
std::uint8_t shared_secret[160]; std::uint8_t shared_secret[96];
std::memset(shared_secret, 0xFF, 32);
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
bob_one_time_key->key, alice_identity_key.key, shared_secret
); );
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
local_account.identity_key.key, alice_base_key, shared_secret + 64 local_account.identity_key.key, alice_base_key, shared_secret + 32
); );
axolotl::curve25519_shared_secret( axolotl::curve25519_shared_secret(
); bob_one_time_key->key, alice_base_key, shared_secret + 64
axolotl::curve25519_shared_secret(
bob_one_time_key->key, alice_base_key, shared_secret + 128
); );
ratchet.initialise_as_bob(shared_secret, 96, ratchet_key);
return std::size_t(0); return std::size_t(0);
} }