ECDHKekGenerator
using Org.BouncyCastle.Asn1;
using Org.BouncyCastle.Asn1.X509;
using Org.BouncyCastle.Crypto.Generators;
using Org.BouncyCastle.Crypto.Parameters;
using Org.BouncyCastle.Crypto.Utilities;
using System;
namespace Org.BouncyCastle.Crypto.Agreement.Kdf
{
public sealed class ECDHKekGenerator : IDerivationFunction
{
private readonly IDerivationFunction m_kdf;
private DerObjectIdentifier algorithm;
private int keySize;
private byte[] z;
public IDigest Digest => m_kdf.Digest;
public ECDHKekGenerator(IDigest digest)
{
m_kdf = new Kdf2BytesGenerator(digest);
}
public void Init(IDerivationParameters param)
{
DHKdfParameters dHKdfParameters = (DHKdfParameters)param;
algorithm = dHKdfParameters.Algorithm;
keySize = dHKdfParameters.KeySize;
z = dHKdfParameters.GetZ();
}
public int GenerateBytes(byte[] outBytes, int outOff, int length)
{
Check.OutputLength(outBytes, outOff, length, "output buffer too short");
return GenerateBytes(outBytes.AsSpan(outOff, length));
}
public int GenerateBytes(Span<byte> output)
{
DerSequence derSequence = new DerSequence(new AlgorithmIdentifier(algorithm, DerNull.Instance), new DerTaggedObject(true, 2, new DerOctetString(Pack.UInt32_To_BE((uint)keySize))));
m_kdf.Init(new KdfParameters(z, derSequence.GetDerEncoded()));
return m_kdf.GenerateBytes(output);
}
}
}