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Add Multistream mode key generation

This commit is contained in:
Aaro Altonen 2020-07-23 13:19:54 +03:00
parent ffc24e6b49
commit 00d10cd0b7
2 changed files with 55 additions and 5 deletions
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8
include/zrtp.hh
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@ -210,8 +210,12 @@ namespace uvg_rtp {
/* Create private/public key pair and generate random values for retained secrets */
void generate_secrets();
/* Calculate DHResult, total_hash, and s0 according to rules defined in RFC 6189 */
void generate_shared_secrets();
/* Calculate DHResult, total_hash, and s0
* according to rules defined in RFC 6189 for Diffie-Hellman mode*/
void generate_shared_secrets_dh();
/* Calculate shared secrets for Multistream Mode */
void generate_shared_secrets_msm();
/* Compare our and remote's hvi values to determine who is the initiator */
bool are_we_initiator(uint8_t *our_hvi, uint8_t *their_hvi);

52
src/zrtp.cc
View File

@ -126,7 +126,7 @@ void uvg_rtp::zrtp::generate_secrets()
uvg_rtp::crypto::random::generate_random(session_.secrets.rpbx, 32);
}
void uvg_rtp::zrtp::generate_shared_secrets()
void uvg_rtp::zrtp::generate_shared_secrets_dh()
{
cctx_.dh->set_remote_pk(session_.dh_ctx.remote_public, 384);
cctx_.dh->get_shared_secret(session_.dh_ctx.dh_result, 384);
@ -204,6 +204,48 @@ void uvg_rtp::zrtp::generate_shared_secrets()
derive_key("Responder HMAC key", 256, session_.key_ctx.hmac_keyr);
}
void uvg_rtp::zrtp::generate_shared_secrets_msm()
{
if (session_.role == INITIATOR) {
cctx_.sha256->update((uint8_t *)session_.r_msg.hello.second, session_.r_msg.hello.first);
cctx_.sha256->update((uint8_t *)session_.l_msg.commit.second, session_.l_msg.commit.first);
} else {
cctx_.sha256->update((uint8_t *)session_.l_msg.hello.second, session_.l_msg.hello.first);
cctx_.sha256->update((uint8_t *)session_.r_msg.commit.second, session_.r_msg.commit.first);
}
cctx_.sha256->final((uint8_t *)session_.hash_ctx.total_hash);
/* Finally calculate s0 which is considered to be the final keying material (Section 4.4.3.2)
*
* It consist of the following information:
* - "ZRTP MSK"
* - ZID of initiator
* - ZID of responder
* - total hash (calculated above)
* - negotiated hash length (256)
*/
uint32_t length = htonl(256);
const char *kdf = "ZRTP MSK";
cctx_.sha256->update((uint8_t *)kdf, strlen(kdf));
if (session_.role == INITIATOR) {
cctx_.sha256->update((uint8_t *)session_.o_zid, 12);
cctx_.sha256->update((uint8_t *)session_.r_zid, 12);
} else {
cctx_.sha256->update((uint8_t *)session_.r_zid, 12);
cctx_.sha256->update((uint8_t *)session_.o_zid, 12);
}
cctx_.sha256->update((uint8_t *)session_.hash_ctx.total_hash, sizeof(session_.hash_ctx.total_hash));
cctx_.sha256->update((uint8_t *)&length, sizeof(length));
/* Calculate digest for s0
*
* Caller can now generate SRTP session keys for the media stream */
cctx_.sha256->final((uint8_t *)session_.secrets.s0);
}
rtp_error_t uvg_rtp::zrtp::verify_hash(uint8_t *key, uint8_t *buf, size_t len, uint64_t mac)
{
uint64_t truncated = 0;
@ -462,7 +504,7 @@ rtp_error_t uvg_rtp::zrtp::dh_part1()
/* parse_msg() above extracted the public key of remote and saved it to session_.
* Now we must generate shared secrets (DHResult, total_hash, and s0) */
generate_shared_secrets();
generate_shared_secrets_dh();
return RTP_OK;
}
@ -489,7 +531,7 @@ rtp_error_t uvg_rtp::zrtp::dh_part2()
/* parse_msg() above extracted the public key of remote and saved it to session_.
* Now we must generate shared secrets (DHResult, total_hash, and s0) */
generate_shared_secrets();
generate_shared_secrets_dh();
for (int i = 0; i < 10; ++i) {
set_timeout(rto);
@ -718,11 +760,15 @@ rtp_error_t uvg_rtp::zrtp::init_msm(uint32_t ssrc, socket_t& socket, sockaddr_in
}
if (session_.role == INITIATOR) {
generate_shared_secrets_msm();
if ((ret = initiator_finalize_session()) != RTP_OK) {
LOG_ERROR("Failed to finalize session using Confirm2");
return ret;
}
} else {
generate_shared_secrets_msm();
if ((ret = responder_finalize_session()) != RTP_OK) {
LOG_ERROR("Failed to finalize session using Confirm1/Conf2ACK");
return ret;