diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/inbound_group_session.c | 27 | ||||
| -rw-r--r-- | src/outbound_group_session.c | 41 |
2 files changed, 40 insertions, 28 deletions
diff --git a/src/inbound_group_session.c b/src/inbound_group_session.c index 11e3dbe..82ff66f 100644 --- a/src/inbound_group_session.c +++ b/src/inbound_group_session.c @@ -30,7 +30,7 @@ #define OLM_PROTOCOL_VERSION 3 #define PICKLE_VERSION 1 -#define SESSION_KEY_VERSION 1 +#define SESSION_KEY_VERSION 2 struct OlmInboundGroupSession { /** our earliest known ratchet value */ @@ -71,12 +71,12 @@ size_t olm_clear_inbound_group_session( } #define SESSION_KEY_RAW_LENGTH \ - (1 + MEGOLM_RATCHET_LENGTH + ED25519_PUBLIC_KEY_LENGTH) + (1 + 4 + MEGOLM_RATCHET_LENGTH + ED25519_PUBLIC_KEY_LENGTH\ + + ED25519_SIGNATURE_LENGTH) /** init the session keys from the un-base64-ed session keys */ static size_t _init_group_session_keys( OlmInboundGroupSession *session, - uint32_t message_index, const uint8_t *key_buf ) { const uint8_t *ptr = key_buf; @@ -87,13 +87,27 @@ static size_t _init_group_session_keys( return (size_t)-1; } - megolm_init(&session->initial_ratchet, ptr, message_index); - megolm_init(&session->latest_ratchet, ptr, message_index); + uint32_t counter = 0; + // Decode counter as a big endian 32-bit number. + for (unsigned i = 0; i < 4; i++) { + counter <<= 8; counter |= *ptr++; + } + + megolm_init(&session->initial_ratchet, ptr, counter); + megolm_init(&session->latest_ratchet, ptr, counter); + ptr += MEGOLM_RATCHET_LENGTH; memcpy( session->signing_key.public_key, ptr, ED25519_PUBLIC_KEY_LENGTH ); ptr += ED25519_PUBLIC_KEY_LENGTH; + + if (!_olm_crypto_ed25519_verify( + &session->signing_key, key_buf, ptr - key_buf, ptr + )) { + session->last_error = OLM_BAD_SIGNATURE; + return (size_t)-1; + } return 0; } @@ -117,7 +131,7 @@ size_t olm_init_inbound_group_session( } _olm_decode_base64(session_key, session_key_length, key_buf); - result = _init_group_session_keys(session, message_index, key_buf); + result = _init_group_session_keys(session, key_buf); _olm_unset(key_buf, SESSION_KEY_RAW_LENGTH); return result; } @@ -288,7 +302,6 @@ static size_t _decrypt( return (size_t)-1; } - max_length = megolm_cipher->ops->decrypt_max_plaintext_length( megolm_cipher, decoded_results.ciphertext_length diff --git a/src/outbound_group_session.c b/src/outbound_group_session.c index a605fa6..4e4561a 100644 --- a/src/outbound_group_session.c +++ b/src/outbound_group_session.c @@ -29,10 +29,9 @@ #include "olm/pickle_encoding.h" #define OLM_PROTOCOL_VERSION 3 -#define SESSION_ID_RANDOM_BYTES 4 -#define GROUP_SESSION_ID_LENGTH (sizeof(struct timeval) + SESSION_ID_RANDOM_BYTES) +#define GROUP_SESSION_ID_LENGTH ED25519_PUBLIC_KEY_LENGTH #define PICKLE_VERSION 1 -#define SESSION_KEY_VERSION 1 +#define SESSION_KEY_VERSION 2 struct OlmOutboundGroupSession { /** the Megolm ratchet providing the encryption keys */ @@ -41,9 +40,6 @@ struct OlmOutboundGroupSession { /** The ed25519 keypair used for signing the messages */ struct _olm_ed25519_key_pair signing_key; - /** unique identifier for this session */ - uint8_t session_id[GROUP_SESSION_ID_LENGTH]; - enum OlmErrorCode last_error; }; @@ -80,8 +76,6 @@ static size_t raw_pickle_length( length += _olm_pickle_uint32_length(PICKLE_VERSION); length += megolm_pickle_length(&(session->ratchet)); length += _olm_pickle_ed25519_key_pair_length(&(session->signing_key)); - length += _olm_pickle_bytes_length(session->session_id, - GROUP_SESSION_ID_LENGTH); return length; } @@ -108,7 +102,6 @@ size_t olm_pickle_outbound_group_session( pos = _olm_pickle_uint32(pos, PICKLE_VERSION); pos = megolm_pickle(&(session->ratchet), pos); pos = _olm_pickle_ed25519_key_pair(pos, &(session->signing_key)); - pos = _olm_pickle_bytes(pos, session->session_id, GROUP_SESSION_ID_LENGTH); return _olm_enc_output(key, key_length, pickled, raw_length); } @@ -138,7 +131,6 @@ size_t olm_unpickle_outbound_group_session( } pos = megolm_unpickle(&(session->ratchet), pos, end); pos = _olm_unpickle_ed25519_key_pair(pos, end, &(session->signing_key)); - pos = _olm_unpickle_bytes(pos, end, session->session_id, GROUP_SESSION_ID_LENGTH); if (end != pos) { /* We had the wrong number of bytes in the input. */ @@ -157,8 +149,7 @@ size_t olm_init_outbound_group_session_random_length( * session id. */ return MEGOLM_RATCHET_LENGTH + - ED25519_RANDOM_LENGTH + - SESSION_ID_RANDOM_BYTES; + ED25519_RANDOM_LENGTH; } size_t olm_init_outbound_group_session( @@ -177,13 +168,6 @@ size_t olm_init_outbound_group_session( _olm_crypto_ed25519_generate_key(random, &(session->signing_key)); random += ED25519_RANDOM_LENGTH; - /* initialise the session id. This just has to be unique. We use the - * current time plus some random data. - */ - gettimeofday((struct timeval *)(session->session_id), NULL); - memcpy((session->session_id) + sizeof(struct timeval), - random, SESSION_ID_RANDOM_BYTES); - return 0; } @@ -314,7 +298,9 @@ size_t olm_outbound_group_session_id( return (size_t)-1; } - return _olm_encode_base64(session->session_id, GROUP_SESSION_ID_LENGTH, id); + return _olm_encode_base64( + session->signing_key.public_key.public_key, GROUP_SESSION_ID_LENGTH, id + ); } uint32_t olm_outbound_group_session_message_index( @@ -324,7 +310,8 @@ uint32_t olm_outbound_group_session_message_index( } #define SESSION_KEY_RAW_LENGTH \ - (1 + MEGOLM_RATCHET_LENGTH + ED25519_PUBLIC_KEY_LENGTH) + (1 + 4 + MEGOLM_RATCHET_LENGTH + ED25519_PUBLIC_KEY_LENGTH\ + + ED25519_SIGNATURE_LENGTH) size_t olm_outbound_group_session_key_length( const OlmOutboundGroupSession *session @@ -349,6 +336,12 @@ size_t olm_outbound_group_session_key( raw = ptr = key + encoded_length - SESSION_KEY_RAW_LENGTH; *ptr++ = SESSION_KEY_VERSION; + uint32_t counter = session->ratchet.counter; + // Encode counter as a big endian 32-bit number. + for (unsigned i = 0; i < 4; i++) { + *ptr++ = 0xFF & (counter >> 24); counter <<= 8; + } + memcpy(ptr, megolm_get_data(&session->ratchet), MEGOLM_RATCHET_LENGTH); ptr += MEGOLM_RATCHET_LENGTH; @@ -358,5 +351,11 @@ size_t olm_outbound_group_session_key( ); ptr += ED25519_PUBLIC_KEY_LENGTH; + /* sign the whole thing with the ed25519 key. */ + _olm_crypto_ed25519_sign( + &(session->signing_key), + raw, ptr - raw, ptr + ); + return _olm_encode_base64(raw, SESSION_KEY_RAW_LENGTH, key); } |