public KdfResult DeriveKey(IAns942Parameters param)
{
if (!(param is ConcatAns942Parameters concatParams))
{
return(new KdfResult("Unable to parse concat parameters"));
}
if (concatParams.KeyLen <= 0 || concatParams.KeyLen > 65536)
{
return(new KdfResult($"KeyLen must be between [1, 65536]. Value given was: {concatParams.KeyLen}"));
}
var d = (int)System.Math.Ceiling(concatParams.KeyLen / (decimal)_sha.HashFunction.OutputLen);
var counter = BitString.To32BitString(1);
var h = new BitString(0);
for (var i = 1; i <= d; i++)
{
// H[i] = Hash(ZZ || counter || otherInfo)
var hashInput = concatParams.Zz.ConcatenateBits(counter).ConcatenateBits(concatParams.OtherInfo);
h = h.ConcatenateBits(_sha.HashMessage(hashInput).Digest);
counter = counter.BitStringAddition(BitString.One());
}
return(new KdfResult(h.GetMostSignificantBits(concatParams.KeyLen)));
}
public KdfResult DeriveKey(IAns942Parameters param)
{
if (!(param is DerAns942Parameters derParams))
{
return(new KdfResult("Unable to parse der parameters"));
}
if (derParams.KeyLen <= 0 || derParams.KeyLen > 65536)
{
return(new KdfResult($"KeyLen must be between [1, 65536]. Value given was: {derParams.KeyLen}"));
}
var d = (int)System.Math.Ceiling(derParams.KeyLen / (decimal)_sha.HashFunction.OutputLen);
var h = new BitString(0);
var counter = BitString.To32BitString(0);
for (var i = 1; i <= d; i++)
{
// Increment Counter
counter = counter.BitStringAddition(BitString.One());
// Prepare ANS.1/DER encoded OtherInfo
var derEncodedOtherInfo = DerEncode(derParams, counter);
var str = derEncodedOtherInfo.ToHex();
// H[i] = Hash(ZZ || otherInfo)
h = h.ConcatenateBits(_sha.HashMessage(derParams.Zz.ConcatenateBits(derEncodedOtherInfo)).Digest);
}
return(new KdfResult(h.GetMostSignificantBits(derParams.KeyLen)));
}
