Method deriveKeys

extra/yassl/src/yassl_int.cpp:1039–1077

derive mac, write, and iv keys for server and client, see page 34, 6.2.2

// derive mac, write, and iv keys for server and client, see page 34, 6.2.2
void SSL::deriveKeys()
{
    int length = 2 * secure_.get_parms().hash_size_ + 
                 2 * secure_.get_parms().key_size_  +
                 2 * secure_.get_parms().iv_size_;
    int rounds = (length + MD5_LEN - 1 ) / MD5_LEN;
    input_buffer key_data(rounds * MD5_LEN);

    opaque sha_output[SHA_LEN];
    opaque md5_input[SECRET_LEN + SHA_LEN];
    opaque sha_input[KEY_PREFIX + SECRET_LEN + 2 * RAN_LEN];
  
    MD5 md5;
    SHA sha;

    memcpy(md5_input, secure_.get_connection().master_secret_, SECRET_LEN);

    for (int i = 0; i < rounds; ++i) {
        int j = i + 1;
        if (!setPrefix(sha_input, i)) {
            SetError(prefix_error);
            return;
        }

        memcpy(&sha_input[j], secure_.get_connection().master_secret_,
               SECRET_LEN);
        memcpy(&sha_input[j+SECRET_LEN],
               secure_.get_connection().server_random_, RAN_LEN);
        memcpy(&sha_input[j + SECRET_LEN + RAN_LEN],
               secure_.get_connection().client_random_, RAN_LEN);
        sha.get_digest(sha_output, sha_input,
                       sizeof(sha_input) - KEY_PREFIX + j);

        memcpy(&md5_input[SECRET_LEN], sha_output, SHA_LEN);
        md5.get_digest(key_data.get_buffer() + i * MD5_LEN,
                       md5_input, sizeof(md5_input));
    }
    storeKeys(key_data.get_buffer());
}


// derive mac, write, and iv keys for server and client