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Assets/BestHTTP/SecureProtocol/crypto/generators/ECKeyPairGenerator.cs

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+#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
+
+using System;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.Nist;
+using Org.BouncyCastle.Asn1.Sec;
+using Org.BouncyCastle.Asn1.TeleTrust;
+using Org.BouncyCastle.Asn1.X9;
+using Org.BouncyCastle.Crypto;
+using Org.BouncyCastle.Crypto.EC;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Math;
+using Org.BouncyCastle.Math.EC;
+using Org.BouncyCastle.Math.EC.Multiplier;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities;
+
+namespace Org.BouncyCastle.Crypto.Generators
+{
+    public class ECKeyPairGenerator
+        : IAsymmetricCipherKeyPairGenerator
+    {
+        private readonly string algorithm;
+
+        private ECDomainParameters parameters;
+        private DerObjectIdentifier publicKeyParamSet;
+        private SecureRandom random;
+
+        public ECKeyPairGenerator()
+            : this("EC")
+        {
+        }
+
+        public ECKeyPairGenerator(
+            string algorithm)
+        {
+            if (algorithm == null)
+                throw new ArgumentNullException("algorithm");
+
+            this.algorithm = ECKeyParameters.VerifyAlgorithmName(algorithm);
+        }
+
+        public void Init(
+            KeyGenerationParameters parameters)
+        {
+            if (parameters is ECKeyGenerationParameters)
+            {
+                ECKeyGenerationParameters ecP = (ECKeyGenerationParameters) parameters;
+
+                this.publicKeyParamSet = ecP.PublicKeyParamSet;
+                this.parameters = ecP.DomainParameters;
+            }
+            else
+            {
+                DerObjectIdentifier oid;
+                switch (parameters.Strength)
+                {
+                    case 192:
+                        oid = X9ObjectIdentifiers.Prime192v1;
+                        break;
+                    case 224:
+                        oid = SecObjectIdentifiers.SecP224r1;
+                        break;
+                    case 239:
+                        oid = X9ObjectIdentifiers.Prime239v1;
+                        break;
+                    case 256:
+                        oid = X9ObjectIdentifiers.Prime256v1;
+                        break;
+                    case 384:
+                        oid = SecObjectIdentifiers.SecP384r1;
+                        break;
+                    case 521:
+                        oid = SecObjectIdentifiers.SecP521r1;
+                        break;
+                    default:
+                        throw new InvalidParameterException("unknown key size.");
+                }
+
+                X9ECParameters ecps = FindECCurveByOid(oid);
+
+                this.publicKeyParamSet = oid;
+                this.parameters = new ECDomainParameters(
+                    ecps.Curve, ecps.G, ecps.N, ecps.H, ecps.GetSeed());
+            }
+
+            this.random = parameters.Random;
+
+            if (this.random == null)
+            {
+                this.random = new SecureRandom();
+            }
+        }
+
+        /**
+         * Given the domain parameters this routine generates an EC key
+         * pair in accordance with X9.62 section 5.2.1 pages 26, 27.
+         */
+        public AsymmetricCipherKeyPair GenerateKeyPair()
+        {
+            BigInteger n = parameters.N;
+            BigInteger d;
+            int minWeight = n.BitLength >> 2;
+
+            for (;;)
+            {
+                d = new BigInteger(n.BitLength, random);
+
+                if (d.CompareTo(BigInteger.Two) < 0 || d.CompareTo(n) >= 0)
+                    continue;
+
+                if (WNafUtilities.GetNafWeight(d) < minWeight)
+                    continue;
+
+                break;
+            }
+
+            ECPoint q = CreateBasePointMultiplier().Multiply(parameters.G, d);
+
+            if (publicKeyParamSet != null)
+            {
+                return new AsymmetricCipherKeyPair(
+                    new ECPublicKeyParameters(algorithm, q, publicKeyParamSet),
+                    new ECPrivateKeyParameters(algorithm, d, publicKeyParamSet));
+            }
+
+            return new AsymmetricCipherKeyPair(
+                new ECPublicKeyParameters(algorithm, q, parameters),
+                new ECPrivateKeyParameters(algorithm, d, parameters));
+        }
+
+        protected virtual ECMultiplier CreateBasePointMultiplier()
+        {
+            return new FixedPointCombMultiplier();
+        }
+
+        internal static X9ECParameters FindECCurveByOid(DerObjectIdentifier oid)
+        {
+            // TODO ECGost3410NamedCurves support (returns ECDomainParameters though)
+
+            X9ECParameters ecP = CustomNamedCurves.GetByOid(oid);
+            if (ecP == null)
+            {
+                ecP = ECNamedCurveTable.GetByOid(oid);
+            }
+            return ecP;
+        }
+
+        internal static ECPublicKeyParameters GetCorrespondingPublicKey(
+            ECPrivateKeyParameters privKey)
+        {
+            ECDomainParameters ec = privKey.Parameters;
+            ECPoint q = new FixedPointCombMultiplier().Multiply(ec.G, privKey.D);
+
+            if (privKey.PublicKeyParamSet != null)
+            {
+                return new ECPublicKeyParameters(privKey.AlgorithmName, q, privKey.PublicKeyParamSet);
+            }
+
+            return new ECPublicKeyParameters(privKey.AlgorithmName, q, ec);
+        }
+    }
+}
+
+#endif