65 lines
2.2 KiB
C#
65 lines
2.2 KiB
C#
#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
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using System;
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using Org.BouncyCastle.Math;
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using Org.BouncyCastle.Math.EC;
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using Org.BouncyCastle.Crypto;
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using Org.BouncyCastle.Crypto.Parameters;
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namespace Org.BouncyCastle.Crypto.Agreement
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{
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/**
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* P1363 7.2.1 ECSVDP-DH
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*
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* ECSVDP-DH is Elliptic Curve Secret Value Derivation Primitive,
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* Diffie-Hellman version. It is based on the work of [DH76], [Mil86],
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* and [Kob87]. This primitive derives a shared secret value from one
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* party's private key and another party's public key, where both have
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* the same set of EC domain parameters. If two parties correctly
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* execute this primitive, they will produce the same output. This
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* primitive can be invoked by a scheme to derive a shared secret key;
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* specifically, it may be used with the schemes ECKAS-DH1 and
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* DL/ECKAS-DH2. It assumes that the input keys are valid (see also
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* Section 7.2.2).
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*/
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public class ECDHBasicAgreement
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: IBasicAgreement
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{
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protected internal ECPrivateKeyParameters privKey;
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public virtual void Init(
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ICipherParameters parameters)
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{
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if (parameters is ParametersWithRandom)
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{
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parameters = ((ParametersWithRandom)parameters).Parameters;
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}
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this.privKey = (ECPrivateKeyParameters)parameters;
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}
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public virtual int GetFieldSize()
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{
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return (privKey.Parameters.Curve.FieldSize + 7) / 8;
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}
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public virtual BigInteger CalculateAgreement(
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ICipherParameters pubKey)
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{
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ECPublicKeyParameters pub = (ECPublicKeyParameters) pubKey;
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if (!pub.Parameters.Equals(privKey.Parameters))
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throw new InvalidOperationException("ECDH public key has wrong domain parameters");
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ECPoint P = pub.Q.Multiply(privKey.D).Normalize();
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if (P.IsInfinity)
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throw new InvalidOperationException("Infinity is not a valid agreement value for ECDH");
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return P.AffineXCoord.ToBigInteger();
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}
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}
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}
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#endif
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