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Assets/BestHTTP/SecureProtocol/crypto/tls/TlsRsaKeyExchange.cs

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+#if !BESTHTTP_DISABLE_ALTERNATE_SSL && (!UNITY_WEBGL || UNITY_EDITOR)
+
+using System;
+using System.Collections;
+using System.IO;
+
+using Org.BouncyCastle.Asn1;
+using Org.BouncyCastle.Asn1.X509;
+using Org.BouncyCastle.Crypto.Encodings;
+using Org.BouncyCastle.Crypto.Engines;
+using Org.BouncyCastle.Crypto.Parameters;
+using Org.BouncyCastle.Security;
+using Org.BouncyCastle.Utilities.IO;
+
+namespace Org.BouncyCastle.Crypto.Tls
+{
+    /// <summary>(D)TLS and SSLv3 RSA key exchange.</summary>
+    public class TlsRsaKeyExchange
+        :   AbstractTlsKeyExchange
+    {
+        protected AsymmetricKeyParameter mServerPublicKey = null;
+
+        protected RsaKeyParameters mRsaServerPublicKey = null;
+
+        protected TlsEncryptionCredentials mServerCredentials = null;
+
+        protected byte[] mPremasterSecret;
+
+        public TlsRsaKeyExchange(IList supportedSignatureAlgorithms)
+            :   base(KeyExchangeAlgorithm.RSA, supportedSignatureAlgorithms)
+        {
+        }
+
+        public override void SkipServerCredentials()
+        {
+            throw new TlsFatalAlert(AlertDescription.unexpected_message);
+        }
+
+        public override void ProcessServerCredentials(TlsCredentials serverCredentials)
+        {
+            if (!(serverCredentials is TlsEncryptionCredentials))
+                throw new TlsFatalAlert(AlertDescription.internal_error);
+
+            ProcessServerCertificate(serverCredentials.Certificate);
+
+            this.mServerCredentials = (TlsEncryptionCredentials)serverCredentials;
+        }
+
+        public override void ProcessServerCertificate(Certificate serverCertificate)
+        {
+            if (serverCertificate.IsEmpty)
+                throw new TlsFatalAlert(AlertDescription.bad_certificate);
+
+            X509CertificateStructure x509Cert = serverCertificate.GetCertificateAt(0);
+
+            SubjectPublicKeyInfo keyInfo = x509Cert.SubjectPublicKeyInfo;
+            try
+            {
+                this.mServerPublicKey = PublicKeyFactory.CreateKey(keyInfo);
+            }
+            catch (Exception e)
+            {
+                throw new TlsFatalAlert(AlertDescription.unsupported_certificate, e);
+            }
+
+            // Sanity check the PublicKeyFactory
+            if (this.mServerPublicKey.IsPrivate)
+                throw new TlsFatalAlert(AlertDescription.internal_error);
+
+            this.mRsaServerPublicKey = ValidateRsaPublicKey((RsaKeyParameters)this.mServerPublicKey);
+
+            TlsUtilities.ValidateKeyUsage(x509Cert, KeyUsage.KeyEncipherment);
+
+            base.ProcessServerCertificate(serverCertificate);
+        }
+
+        public override void ValidateCertificateRequest(CertificateRequest certificateRequest)
+        {
+            byte[] types = certificateRequest.CertificateTypes;
+            for (int i = 0; i < types.Length; ++i)
+            {
+                switch (types[i])
+                {
+                case ClientCertificateType.rsa_sign:
+                case ClientCertificateType.dss_sign:
+                case ClientCertificateType.ecdsa_sign:
+                    break;
+                default:
+                    throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+                }
+            }
+        }
+
+        public override void ProcessClientCredentials(TlsCredentials clientCredentials)
+        {
+            if (!(clientCredentials is TlsSignerCredentials))
+                throw new TlsFatalAlert(AlertDescription.internal_error);
+        }
+
+        public override void GenerateClientKeyExchange(Stream output)
+        {
+            this.mPremasterSecret = TlsRsaUtilities.GenerateEncryptedPreMasterSecret(mContext, mRsaServerPublicKey, output);
+        }
+
+        public override void ProcessClientKeyExchange(Stream input)
+        {
+            byte[] encryptedPreMasterSecret;
+            if (TlsUtilities.IsSsl(mContext))
+            {
+                // TODO Do any SSLv3 clients actually include the length?
+                encryptedPreMasterSecret = Streams.ReadAll(input);
+            }
+            else
+            {
+                encryptedPreMasterSecret = TlsUtilities.ReadOpaque16(input);
+            }
+
+            this.mPremasterSecret = mServerCredentials.DecryptPreMasterSecret(encryptedPreMasterSecret);
+        }
+
+        public override byte[] GeneratePremasterSecret()
+        {
+            if (this.mPremasterSecret == null)
+                throw new TlsFatalAlert(AlertDescription.internal_error);
+
+            byte[] tmp = this.mPremasterSecret;
+            this.mPremasterSecret = null;
+            return tmp;
+        }
+
+        protected virtual RsaKeyParameters ValidateRsaPublicKey(RsaKeyParameters key)
+        {
+            // TODO What is the minimum bit length required?
+            // key.Modulus.BitLength;
+
+            if (!key.Exponent.IsProbablePrime(2))
+                throw new TlsFatalAlert(AlertDescription.illegal_parameter);
+
+            return key;
+        }
+    }
+}
+
+#endif