public virtual int GenerateBytes(byte[] outBytes, int outOff, int len)
{
// TODO Create an ASN.1 class for this (RFC3278)
// ECC-CMS-SharedInfo
DerSequence s = new DerSequence(
new AlgorithmIdentifier(algorithm, DerNull.Instance),
new DerTaggedObject(true, 2, new DerOctetString(Pack.UInt32_To_BE((uint)keySize))));
kdf.Init(new KdfParameters(z, s.GetDerEncoded()));
return kdf.GenerateBytes(outBytes, outOff, len);
}
public virtual int GenerateBytes(byte[] outBytes, int outOff, int len)
{
if ((outBytes.Length - len) < outOff)
{
throw new DataLengthException("output buffer too small");
}
long oBytes = len;
int outLen = digest.GetDigestSize();
//
// this is at odds with the standard implementation, the
// maximum value should be hBits * (2^32 - 1) where hBits
// is the digest output size in bits. We can't have an
// array with a long index at the moment...
//
if (oBytes > ((2L << 32) - 1))
{
throw new ArgumentException("Output length too large");
}
int cThreshold = (int)((oBytes + outLen - 1) / outLen);
byte[] dig = new byte[digest.GetDigestSize()];
uint counter = 1;
for (int i = 0; i < cThreshold; i++)
{
digest.BlockUpdate(z, 0, z.Length);
// KeySpecificInfo
DerSequence keyInfo = new DerSequence(
algorithm,
new DerOctetString(Pack.UInt32_To_BE(counter)));
// OtherInfo
Asn1EncodableVector v1 = new Asn1EncodableVector(keyInfo);
if (partyAInfo != null)
{
v1.Add(new DerTaggedObject(true, 0, new DerOctetString(partyAInfo)));
}
v1.Add(new DerTaggedObject(true, 2, new DerOctetString(Pack.UInt32_To_BE((uint)keySize))));
byte[] other = new DerSequence(v1).GetDerEncoded();
digest.BlockUpdate(other, 0, other.Length);
digest.DoFinal(dig, 0);
if (len > outLen)
{
Array.Copy(dig, 0, outBytes, outOff, outLen);
outOff += outLen;
len -= outLen;
}
else
{
Array.Copy(dig, 0, outBytes, outOff, len);
}
counter++;
}
digest.Reset();
return (int)oBytes;
}
public override Asn1Object ToAsn1Object()
{
DerSequence hashSeq = new DerSequence(datagroupHash);
Asn1EncodableVector v = new Asn1EncodableVector(version, digestAlgorithmIdentifier, hashSeq);
if (versionInfo != null)
{
v.Add(versionInfo);
}
return new DerSequence(v);
}