77 lines
2.5 KiB
C#
77 lines
2.5 KiB
C#
#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
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#pragma warning disable
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using System;
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using BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Parameters;
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using BestHTTP.SecureProtocol.Org.BouncyCastle.Math;
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using BestHTTP.SecureProtocol.Org.BouncyCastle.Security;
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namespace BestHTTP.SecureProtocol.Org.BouncyCastle.Crypto.Agreement
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{
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/**
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* a Diffie-Hellman key agreement class.
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* <p>
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* note: This is only the basic algorithm, it doesn't take advantage of
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* long term public keys if they are available. See the DHAgreement class
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* for a "better" implementation.</p>
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*/
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public class DHBasicAgreement
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: IBasicAgreement
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{
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private DHPrivateKeyParameters key;
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private DHParameters dhParams;
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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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if (!(parameters is DHPrivateKeyParameters))
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{
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throw new ArgumentException("DHEngine expects DHPrivateKeyParameters");
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}
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this.key = (DHPrivateKeyParameters) parameters;
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this.dhParams = key.Parameters;
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}
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public virtual int GetFieldSize()
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{
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return (key.Parameters.P.BitLength + 7) / 8;
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}
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/**
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* given a short term public key from a given party calculate the next
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* message in the agreement sequence.
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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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if (this.key == null)
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throw new InvalidOperationException("Agreement algorithm not initialised");
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DHPublicKeyParameters pub = (DHPublicKeyParameters)pubKey;
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if (!pub.Parameters.Equals(dhParams))
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throw new ArgumentException("Diffie-Hellman public key has wrong parameters.");
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BigInteger p = dhParams.P;
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BigInteger peerY = pub.Y;
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if (peerY == null || peerY.CompareTo(BigInteger.One) <= 0 || peerY.CompareTo(p.Subtract(BigInteger.One)) >= 0)
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throw new ArgumentException("Diffie-Hellman public key is weak");
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BigInteger result = peerY.ModPow(key.X, p);
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if (result.Equals(BigInteger.One))
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throw new InvalidOperationException("Shared key can't be 1");
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return result;
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}
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}
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}
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#pragma warning restore
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#endif
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