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-rw-r--r--src/inbound_group_session.c49
-rw-r--r--src/outbound_group_session.c41
2 files changed, 61 insertions, 29 deletions
diff --git a/src/inbound_group_session.c b/src/inbound_group_session.c
index 11e3dbe..bf00008 100644
--- a/src/inbound_group_session.c
+++ b/src/inbound_group_session.c
@@ -29,8 +29,9 @@
#define OLM_PROTOCOL_VERSION 3
+#define GROUP_SESSION_ID_LENGTH ED25519_PUBLIC_KEY_LENGTH
#define PICKLE_VERSION 1
-#define SESSION_KEY_VERSION 1
+#define SESSION_KEY_VERSION 2
struct OlmInboundGroupSession {
/** our earliest known ratchet value */
@@ -71,12 +72,12 @@ 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;
@@ -87,19 +88,32 @@ 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;
}
size_t olm_init_inbound_group_session(
OlmInboundGroupSession *session,
- uint32_t message_index,
const uint8_t * session_key, size_t session_key_length
) {
uint8_t key_buf[SESSION_KEY_RAW_LENGTH];
@@ -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
@@ -351,3 +364,23 @@ size_t olm_group_decrypt(
plaintext, max_plaintext_length
);
}
+
+size_t olm_inbound_group_session_id_length(
+ const OlmInboundGroupSession *session
+) {
+ return _olm_encode_base64_length(GROUP_SESSION_ID_LENGTH);
+}
+
+size_t olm_inbound_group_session_id(
+ OlmInboundGroupSession *session,
+ uint8_t * id, size_t id_length
+) {
+ if (id_length < olm_inbound_group_session_id_length(session)) {
+ session->last_error = OLM_OUTPUT_BUFFER_TOO_SMALL;
+ return (size_t)-1;
+ }
+
+ return _olm_encode_base64(
+ session->signing_key.public_key, GROUP_SESSION_ID_LENGTH, id
+ );
+}
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);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-10 07:03:41 +0000