TrimSignature(byte[] buf)
{
return(BufArray.SubArray(
buf,
Hmac512.SignatureByteLength,
buf.Length - Hmac512.SignatureByteLength
));
}
ComputeSignature(byte[] key, byte[] buf)
{
using (HMACSHA512 hmac = new HMACSHA512(key))
{
byte[] signature = hmac.ComputeHash(buf);
BufArray.Wipe0(hmac.Key);
// wipe key?
return(signature);
}
}
VerifyTrim(byte[] key, byte[] buf)
{
if (!Hmac512.Verify(key, buf))
{
return(null);
}
return(BufArray.SubArray(
buf,
Hmac512.SignatureByteLength,
buf.Length - Hmac512.SignatureByteLength
));
}
Verify(byte[] key, byte[] buf)
{
if (key == null)
{
throw new ArgumentException("Hmac key must not be null.");
}
if (buf == null | buf.Length < Hmac512.SignatureByteLength + 1)
{
throw new ArgumentException("Hmac input buffer's length is too short or null.");
}
using (HMACSHA512 hmac = new HMACSHA512(key))
{
// Skip the prepended hmac signature.
byte[] computedSignature = hmac.ComputeHash(
buf, Hmac512.SignatureByteLength,
buf.Length - Hmac512.SignatureByteLength
);
bool ret;
if (!BufArray.Compare(
buf, 0,
computedSignature, 0,
Hmac512.SignatureByteLength)
)
{
ret = false;
}
else
{
ret = true;
}
BufArray.Wipe0(hmac.Key);
return(ret);
}
}
SignPrepend(byte[] key, byte[] buf)
{
if (buf.Length < 1)
{
throw new Exception("Input buffer's length is too small.");
}
byte[] signature = ComputeSignature(key, buf);
byte[] signed_data = BufArray.Combine(signature, buf);
return(signed_data);
//using (HMACSHA512 hmac = new HMACSHA512(key))
//{
// byte[] signature = hmac.ComputeHash(buf);
// BufArray.Wipe0(hmac.Key);
// byte[] signed_data = BufArray.Combine(signature, buf);
// return signed_data;
//}
}
