// TLS type HAMC
void TLS_hmac(SSL& ssl, byte* digest, const byte* buffer, uint sz,
ContentType content, bool verify)
{
mySTL::auto_ptr<Digest> hmac;
opaque seq[SEQ_SZ] = { 0x00, 0x00, 0x00, 0x00 };
opaque length[LENGTH_SZ];
opaque inner[SIZEOF_ENUM + VERSION_SZ + LENGTH_SZ]; // type + version + len
c16toa(sz, length);
c32toa(ssl.get_SEQIncrement(verify), &seq[sizeof(uint32)]);
MACAlgorithm algo = ssl.getSecurity().get_parms().mac_algorithm_;
if (algo == sha)
hmac.reset(NEW_YS HMAC_SHA(ssl.get_macSecret(verify), SHA_LEN));
else if (algo == rmd)
hmac.reset(NEW_YS HMAC_RMD(ssl.get_macSecret(verify), RMD_LEN));
else
hmac.reset(NEW_YS HMAC_MD5(ssl.get_macSecret(verify), MD5_LEN));
hmac->update(seq, SEQ_SZ); // seq_num
inner[0] = content; // type
inner[SIZEOF_ENUM] = ssl.getSecurity().get_connection().version_.major_;
inner[SIZEOF_ENUM + SIZEOF_ENUM] =
ssl.getSecurity().get_connection().version_.minor_; // version
memcpy(&inner[SIZEOF_ENUM + VERSION_SZ], length, LENGTH_SZ); // length
hmac->update(inner, sizeof(inner));
hmac->get_digest(digest, buffer, sz); // content
}
/* compute SSLv3 HMAC into digest see
* buffer is of sz size and includes HandShake Header but not a Record Header
* verify means to check peers hmac
*/
void hmac(SSL& ssl, byte* digest, const byte* buffer, uint sz,
ContentType content, bool verify)
{
Digest& mac = ssl.useCrypto().use_digest();
opaque inner[SHA_LEN + PAD_MD5 + SEQ_SZ + SIZEOF_ENUM + LENGTH_SZ];
opaque outer[SHA_LEN + PAD_MD5 + SHA_LEN];
opaque result[SHA_LEN]; // max possible sizes
uint digestSz = mac.get_digestSize(); // actual sizes
uint padSz = mac.get_padSize();
uint innerSz = digestSz + padSz + SEQ_SZ + SIZEOF_ENUM + LENGTH_SZ;
uint outerSz = digestSz + padSz + digestSz;
// data
const opaque* mac_secret = ssl.get_macSecret(verify);
opaque seq[SEQ_SZ] = { 0x00, 0x00, 0x00, 0x00 };
opaque length[LENGTH_SZ];
c16toa(sz, length);
c32toa(ssl.get_SEQIncrement(verify), &seq[sizeof(uint32)]);
// make inner
memcpy(inner, mac_secret, digestSz);
memcpy(&inner[digestSz], PAD1, padSz);
memcpy(&inner[digestSz + padSz], seq, SEQ_SZ);
inner[digestSz + padSz + SEQ_SZ] = content;
memcpy(&inner[digestSz + padSz + SEQ_SZ + SIZEOF_ENUM], length, LENGTH_SZ);
mac.update(inner, innerSz);
mac.get_digest(result, buffer, sz); // append content buffer
// make outer
memcpy(outer, mac_secret, digestSz);
memcpy(&outer[digestSz], PAD2, padSz);
memcpy(&outer[digestSz + padSz], result, digestSz);
mac.get_digest(digest, outer, outerSz);
}
