130 lines
2.8 KiB
C#
130 lines
2.8 KiB
C#
using System;
|
|
|
|
using Org.BouncyCastle.Asn1;
|
|
|
|
namespace Org.BouncyCastle.Crypto.Agreement.Kdf
|
|
{
|
|
/**
|
|
* RFC 2631 Diffie-hellman KEK derivation function.
|
|
*/
|
|
public class DHKekGenerator
|
|
: IDerivationFunction
|
|
{
|
|
private readonly IDigest digest;
|
|
|
|
private DerObjectIdentifier algorithm;
|
|
private int keySize;
|
|
private byte[] z;
|
|
private byte[] partyAInfo;
|
|
|
|
public DHKekGenerator(
|
|
IDigest digest)
|
|
{
|
|
this.digest = digest;
|
|
}
|
|
|
|
public void Init(
|
|
IDerivationParameters param)
|
|
{
|
|
DHKdfParameters parameters = (DHKdfParameters)param;
|
|
|
|
this.algorithm = parameters.Algorithm;
|
|
this.keySize = parameters.KeySize;
|
|
this.z = parameters.GetZ(); // TODO Clone?
|
|
this.partyAInfo = parameters.GetExtraInfo(); // TODO Clone?
|
|
}
|
|
|
|
public IDigest Digest
|
|
{
|
|
get { return digest; }
|
|
}
|
|
|
|
public 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()];
|
|
|
|
int counter = 1;
|
|
|
|
for (int i = 0; i < cThreshold; i++)
|
|
{
|
|
digest.BlockUpdate(z, 0, z.Length);
|
|
|
|
// KeySpecificInfo
|
|
DerSequence keyInfo = new DerSequence(
|
|
algorithm,
|
|
new DerOctetString(integerToBytes(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(integerToBytes(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 len;
|
|
}
|
|
|
|
private byte[] integerToBytes(
|
|
int keySize)
|
|
{
|
|
byte[] val = new byte[4];
|
|
|
|
val[0] = (byte)(keySize >> 24);
|
|
val[1] = (byte)(keySize >> 16);
|
|
val[2] = (byte)(keySize >> 8);
|
|
val[3] = (byte)keySize;
|
|
|
|
return val;
|
|
}
|
|
}
|
|
}
|