commit c39688de6c5d4bf19739ecffb2e98aa560a4630a Author: Nick Mathewson <nickm@torproject.org> Date: Tue Sep 13 13:46:21 2011 -0400 Function to extract the TLSSECRETS field for v3 handshakes --- src/common/tortls.c | 30 ++++++++++++++++++++++++++++++ src/common/tortls.h | 1 + 2 files changed, 31 insertions(+), 0 deletions(-) diff --git a/src/common/tortls.c b/src/common/tortls.c index b711967..2b12eea 100644 --- a/src/common/tortls.c +++ b/src/common/tortls.c @@ -1985,6 +1985,36 @@ tor_tls_server_got_renegotiate(tor_tls_t *tls) return tls->got_renegotiate; } +/** Set the DIGEST256_LEN buffer at <b>secrets_out</b> to the value used in + * the v3 handshake to prove that the client knows the TLS secrets for the + * connection <b>tls</b>. Return 0 on success, -1 on failure. + */ +int +tor_tls_get_tlssecrets(tor_tls_t *tls, uint8_t *secrets_out) +{ +#define TLSSECRET_MAGIC "Tor V3 handshake TLS cross-certification" + char buf[128]; + size_t len; + tor_assert(tls); + tor_assert(tls->ssl); + tor_assert(tls->ssl->s3); + tor_assert(tls->ssl->session); + /* + The value is an HMAC, using the TLS master key as the HMAC key, of + client_random | server_random | TLSSECRET_MAGIC + */ + memcpy(buf + 0, tls->ssl->s3->client_random, 32); + memcpy(buf + 32, tls->ssl->s3->server_random, 32); + memcpy(buf + 64, TLSSECRET_MAGIC, strlen(TLSSECRET_MAGIC) + 1); + len = 64 + strlen(TLSSECRET_MAGIC) + 1; + crypto_hmac_sha256((char*)secrets_out, + (char*)tls->ssl->session->master_key, + tls->ssl->session->master_key_length, + buf, len); + memset(buf, 0, sizeof(buf)); + return 0; +} + /** Examine the amount of memory used and available for buffers in <b>tls</b>. * Set *<b>rbuf_capacity</b> to the amount of storage allocated for the read * buffer and *<b>rbuf_bytes</b> to the amount actually used. diff --git a/src/common/tortls.h b/src/common/tortls.h index c55da4a..a6aed29 100644 --- a/src/common/tortls.h +++ b/src/common/tortls.h @@ -90,6 +90,7 @@ void tor_tls_get_buffer_sizes(tor_tls_t *tls, int tor_tls_used_v1_handshake(tor_tls_t *tls); int tor_tls_get_num_server_handshakes(tor_tls_t *tls); int tor_tls_server_got_renegotiate(tor_tls_t *tls); +int tor_tls_get_tlssecrets(tor_tls_t *tls, uint8_t *secrets_out); /* Log and abort if there are unhandled TLS errors in OpenSSL's error stack. */