69 lines
1.9 KiB
C#
69 lines
1.9 KiB
C#
using System;
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using System.Collections;
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using Org.BouncyCastle.Asn1;
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using Org.BouncyCastle.Asn1.Nist;
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using Org.BouncyCastle.Asn1.Pkcs;
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using Org.BouncyCastle.Crypto.Agreement.Kdf;
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using Org.BouncyCastle.Crypto.Parameters;
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using Org.BouncyCastle.Math;
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namespace Org.BouncyCastle.Crypto.Agreement
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{
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public class ECDHWithKdfBasicAgreement
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: ECDHBasicAgreement
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{
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private static readonly Hashtable algorithms = new Hashtable();
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static ECDHWithKdfBasicAgreement()
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{
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algorithms.Add(NistObjectIdentifiers.IdAes128Cbc.Id, 128);
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algorithms.Add(NistObjectIdentifiers.IdAes192Cbc.Id, 192);
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algorithms.Add(NistObjectIdentifiers.IdAes256Cbc.Id, 256);
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algorithms.Add(NistObjectIdentifiers.IdAes128Wrap.Id, 128);
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algorithms.Add(NistObjectIdentifiers.IdAes192Wrap.Id, 192);
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algorithms.Add(NistObjectIdentifiers.IdAes256Wrap.Id, 256);
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algorithms.Add(PkcsObjectIdentifiers.IdAlgCms3DesWrap.Id, 192);
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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(
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string algorithm,
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IDerivationFunction kdf)
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{
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if (algorithm == null)
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throw new ArgumentNullException("algorithm");
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if (!algorithms.Contains(algorithm))
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throw new ArgumentException("Unknown algorithm", "algorithm");
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if (kdf == null)
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throw new ArgumentNullException("kdf");
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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(
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ICipherParameters pubKey)
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{
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BigInteger result = base.CalculateAgreement(pubKey);
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int keySize = (int) algorithms[algorithm];
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DHKdfParameters dhKdfParams = new DHKdfParameters(
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new DerObjectIdentifier(algorithm),
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keySize,
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// TODO Fix the way bytes are derived from the secret
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result.ToByteArrayUnsigned());
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kdf.Init(dhKdfParams);
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byte[] keyBytes = new byte[keySize / 8];
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kdf.GenerateBytes(keyBytes, 0, keyBytes.Length);
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return new BigInteger(1, keyBytes);
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}
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}
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}
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