Function p_hash

extra/yassl/src/handshake.cpp:423–455

compute p_hash for MD5 or SHA-1 for TLSv1 PRF

// compute p_hash for MD5 or SHA-1 for TLSv1 PRF
void p_hash(output_buffer& result, const output_buffer& secret,
            const output_buffer& seed, MACAlgorithm hash)
{
    uint   len = hash == md5 ? MD5_LEN : SHA_LEN;
    uint   times = result.get_capacity() / len;
    uint   lastLen = result.get_capacity() % len;
    opaque previous[SHA_LEN];  // max size
    opaque current[SHA_LEN];   // max size
    mySTL::auto_ptr<Digest> hmac;

    if (lastLen) times += 1;

    if (hash == md5)
        hmac.reset(NEW_YS HMAC_MD5(secret.get_buffer(), secret.get_size()));
    else
        hmac.reset(NEW_YS HMAC_SHA(secret.get_buffer(), secret.get_size()));
                                                                   // A0 = seed
    hmac->get_digest(previous, seed.get_buffer(), seed.get_size());// A1
    uint lastTime = times - 1;

    for (uint i = 0; i < times; i++) {
        hmac->update(previous, len);  
        hmac->get_digest(current, seed.get_buffer(), seed.get_size());

        if (lastLen && (i == lastTime))
            result.write(current, lastLen);
        else {
            result.write(current, len);
            //memcpy(previous, current, len);
            hmac->get_digest(previous, previous, len);
        }
    }
}


// calculate XOR for TLSv1 PRF