47 lines
1.3 KiB
C#
47 lines
1.3 KiB
C#
using System;
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using Org.BouncyCastle.Asn1;
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using Org.BouncyCastle.Asn1.X9;
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using Org.BouncyCastle.Crypto.Agreement.Kdf;
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using Org.BouncyCastle.Math;
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using Org.BouncyCastle.Security;
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namespace Org.BouncyCastle.Crypto.Agreement;
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public class ECDHWithKdfBasicAgreement : ECDHBasicAgreement
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{
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private readonly string algorithm;
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private readonly IDerivationFunction kdf;
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public ECDHWithKdfBasicAgreement(string algorithm, IDerivationFunction kdf)
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{
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if (algorithm == null)
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{
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throw new ArgumentNullException("algorithm");
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}
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if (kdf == null)
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{
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throw new ArgumentNullException("kdf");
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}
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this.algorithm = algorithm;
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this.kdf = kdf;
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}
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public override BigInteger CalculateAgreement(ICipherParameters pubKey)
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{
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BigInteger r = base.CalculateAgreement(pubKey);
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int defaultKeySize = GeneratorUtilities.GetDefaultKeySize(algorithm);
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DHKdfParameters parameters = new DHKdfParameters(new DerObjectIdentifier(algorithm), defaultKeySize, BigIntToBytes(r));
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kdf.Init(parameters);
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byte[] array = new byte[defaultKeySize / 8];
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kdf.GenerateBytes(array, 0, array.Length);
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return new BigInteger(1, array);
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}
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private byte[] BigIntToBytes(BigInteger r)
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{
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int byteLength = X9IntegerConverter.GetByteLength(privKey.Parameters.Curve);
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return X9IntegerConverter.IntegerToBytes(r, byteLength);
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}
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}
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