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Hcs.Client/GostCryptography/Asn1/Gost/Gost_R3410/Gost_R3410_KeyExchange.cs

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+using GostCryptography.Asn1.Ber;
+using GostCryptography.Asn1.Gost.Gost_28147_89;
+using GostCryptography.Asn1.Gost.PublicKey;
+using GostCryptography.Properties;
+using System;
+
+namespace GostCryptography.Asn1.Gost.Gost_R3410
+{
+    /// <summary>
+    /// Информация о ключе цифровой подписи ГОСТ Р 34.10
+    /// </summary>
+    public abstract class Gost_R3410_KeyExchange
+    {
+        /// <summary>
+        /// Информация о зашифрованном ключе ГОСТ 28147-89
+        /// </summary>
+        public Gost_28147_89_KeyExchangeInfo SessionEncryptedKey { get; set; }
+
+        /// <summary>
+        /// Параметры ключа цифровой подписи ГОСТ Р 34.10
+        /// </summary>
+        public Gost_R3410_KeyExchangeParams TransportParameters { get; set; }
+
+        protected abstract OidValue KeyAlgorithm { get; }
+
+        protected abstract Gost_R3410_PublicKeyParams CreatePublicKeyParams();
+
+        protected abstract Gost_R3410_KeyExchangeParams CreateKeyExchangeParams();
+
+        /// <summary>
+        /// Расшифровать информацию о ключе
+        /// </summary>
+        public void Decode(byte[] data)
+        {
+            if (data == null)
+            {
+                throw ExceptionUtility.ArgumentNull(nameof(data));
+            }
+
+            try
+            {
+                var asnDecoder = new Asn1BerDecodeBuffer(data);
+                var keyTransport = new Gost_R3410_KeyTransport();
+                keyTransport.Decode(asnDecoder);
+                DecodeSessionKey(keyTransport);
+                DecodePublicKey(keyTransport);
+            }
+            catch (Exception exception)
+            {
+                throw ExceptionUtility.CryptographicException(exception, Resources.Asn1DecodeError, nameof(Gost_R3410_KeyTransport));
+            }
+        }
+
+        private void DecodeSessionKey(Gost_R3410_KeyTransport keyTransport)
+        {
+            SessionEncryptedKey = new Gost_28147_89_KeyExchangeInfo
+            {
+                EncryptionParamSet = keyTransport.TransportParams.EncryptionParamSet.Oid.Value,
+                EncryptedKey = keyTransport.SessionEncryptedKey.EncryptedKey.Value,
+                Mac = keyTransport.SessionEncryptedKey.MacKey.Value,
+                Ukm = keyTransport.TransportParams.Ukm.Value
+            };
+        }
+
+        private void DecodePublicKey(Gost_R3410_KeyTransport keyTransport)
+        {
+            var publicKeyInfo = keyTransport.TransportParams.EphemeralPublicKey;
+            var publicKeyAlgOid = publicKeyInfo.Algorithm.Algorithm.Oid.Value;
+
+            if (!publicKeyAlgOid.Equals(KeyAlgorithm.Value))
+            {
+                throw ExceptionUtility.CryptographicException(Resources.Asn1DecodeAlg, publicKeyAlgOid);
+            }
+
+            var choice = publicKeyInfo.Algorithm.Parameters as Asn1Choice;
+
+            if (choice == null)
+            {
+                throw ExceptionUtility.CryptographicException(Resources.Asn1DecodeAlgorithmParameters);
+            }
+
+            var publicKeyParams = choice.GetElement() as Gost_R3410_PublicKeyParams;
+
+            if (publicKeyParams == null)
+            {
+                throw ExceptionUtility.CryptographicException(Resources.Asn1DecodeAlgorithmParameters);
+            }
+
+            var asnDecoder = new Asn1BerDecodeBuffer(publicKeyInfo.SubjectPublicKey.Value);
+            var publicKey = new Asn1OctetString();
+            publicKey.Decode(asnDecoder);
+
+            TransportParameters = CreateKeyExchangeParams();
+            TransportParameters.PublicKeyParamSet = publicKeyParams.PublicKeyParamSet.Oid.Value;
+            TransportParameters.DigestParamSet = publicKeyParams.DigestParamSet?.Oid.Value;
+            TransportParameters.EncryptionParamSet = publicKeyParams.EncryptionParamSet?.Oid.Value;
+            TransportParameters.PublicKey = publicKey.Value;
+            TransportParameters.PrivateKey = null;
+        }
+
+        /// <summary>
+        /// Зашифровать информацию о ключе
+        /// </summary>
+        public byte[] Encode()
+        {
+            var asnEncoder = new Asn1BerEncodeBuffer();
+            var keyTransport = new Gost_R3410_KeyTransport();
+
+            try
+            {
+                keyTransport.SessionEncryptedKey = new Gost_28147_89_EncryptedKey
+                {
+                    EncryptedKey = new Gost_28147_89_Key(SessionEncryptedKey.EncryptedKey),
+                    MacKey = new Gost_28147_89_Mac(SessionEncryptedKey.Mac)
+                };
+
+                keyTransport.TransportParams = new Gost_R3410_TransportParams
+                {
+                    EncryptionParamSet = Asn1ObjectIdentifier.FromString(SessionEncryptedKey.EncryptionParamSet),
+                    EphemeralPublicKey = EncodePublicKey(TransportParameters),
+                    Ukm = new Asn1OctetString(SessionEncryptedKey.Ukm)
+                };
+
+                keyTransport.Encode(asnEncoder);
+            }
+            catch (Exception exception)
+            {
+                throw ExceptionUtility.CryptographicException(exception, Resources.Asn1EncodeError, nameof(Gost_R3410_KeyTransport));
+            }
+
+            return asnEncoder.MsgCopy;
+        }
+
+        private SubjectPublicKeyInfo EncodePublicKey(Gost_R3410_KeyExchangeParams transportParameters)
+        {
+            var asnEncoder = new Asn1BerEncodeBuffer();
+            var publicKey = new Asn1OctetString(transportParameters.PublicKey);
+            publicKey.Encode(asnEncoder);
+
+            var publicKeyValue = asnEncoder.MsgCopy;
+
+            var publicKeyInfo = new SubjectPublicKeyInfo
+            {
+                SubjectPublicKey = new Asn1BitString(publicKeyValue.Length * 8, publicKeyValue)
+            };
+
+            var publicKeyParams = CreatePublicKeyParams();
+            publicKeyParams.PublicKeyParamSet = Asn1ObjectIdentifier.FromString(transportParameters.PublicKeyParamSet);
+            publicKeyParams.DigestParamSet = Asn1ObjectIdentifier.FromString(transportParameters.DigestParamSet);
+            publicKeyParams.EncryptionParamSet = Asn1ObjectIdentifier.FromString(transportParameters.EncryptionParamSet);
+
+            asnEncoder.Reset();
+            publicKeyParams.Encode(asnEncoder);
+
+            var publicKeyAlgOid = new Asn1ObjectIdentifier(KeyAlgorithm);
+            publicKeyInfo.Algorithm = new AlgorithmIdentifier(publicKeyAlgOid, new Asn1OpenType(asnEncoder.MsgCopy));
+
+            return publicKeyInfo;
+        }
+    }
+}