ByteArray HKDF::expand(const ByteArray &prk, const ByteArray &info, int outputSize) const
{
int iterations = std::ceil((float)outputSize / HKDF::HASH_OUTPUT_SIZE);
ByteArray mixin;
ByteArray results;
int remainingBytes = outputSize;
for (int i = iterationStartOffset; i < (iterations + iterationStartOffset); i++) {
ByteArray message(mixin);
if (!info.empty()) {
message += info;
}
message += ByteArray(1, (char)(i % 256));
unsigned char out[32];
HMAC_SHA256((unsigned char*)message.c_str(), message.size(), (unsigned char*)prk.c_str(), prk.size(), out);
ByteArray stepResult((const char*)out, 32);
int stepSize = std::min((int)remainingBytes, (int)stepResult.size());
results += stepResult.substr(0, stepSize);
mixin = stepResult;
remainingBytes -= stepSize;
}
return results;
}
void OpenPGPCryptoHashHMAC::reset(void) {
std::string key(m_keyBuf.rawBuffer(), m_keyLen);
switch (m_hashType) {
case (XSECCryptoHash::HASH_SHA1) :
mp_md.reset(HMAC_SHA1(key));
break;
case (XSECCryptoHash::HASH_MD5) :
mp_md.reset(HMAC_MD5(key));
break;
case (XSECCryptoHash::HASH_SHA224) :
mp_md.reset(HMAC_SHA224(key));
break;
case (XSECCryptoHash::HASH_SHA256) :
mp_md.reset(HMAC_SHA256(key));
break;
case (XSECCryptoHash::HASH_SHA384) :
mp_md.reset(HMAC_SHA384(key));
break;
case (XSECCryptoHash::HASH_SHA512) :
mp_md.reset(HMAC_SHA512(key));
break;
default :
mp_md.reset();
}
if(!mp_md) {
throw XSECCryptoException(XSECCryptoException::MDError,
"OpenPGP:HashHMAC - Error loading Message Digest");
}
}
ByteArray HKDF::extract(const ByteArray &salt, const ByteArray &inputKeyMaterial) const
{
unsigned char out[32];
HMAC_SHA256((unsigned char*)inputKeyMaterial.c_str(), inputKeyMaterial.size(), (unsigned char*)salt.c_str(), salt.size(), out);
return ByteArray((const char*)out, 32);
}
ByteArray SenderChainKey::getDerivative(const ByteArray &seed, const ByteArray &key) const
{
unsigned char out[32];
HMAC_SHA256((unsigned char*)seed.c_str(), seed.size(), (unsigned char*)key.c_str(), key.size(), out);
return ByteArray((const char*)out, 32);
}
