Imported Upstream version 4.6.0.125

Former-commit-id: a2155e9bd80020e49e72e86c44da02a8ac0e57a4

mcs/class/referencesource/System.Data/System/Data/SqlClient/SqlAes256CbcFactory.cs

@@ -0,0 +1,85 @@
+//------------------------------------------------------------------------------
+// <copyright file="SqlAeadAes256CbcHmac256Factory.cs" company="Microsoft">
+//     Copyright (c) Microsoft Corporation.  All rights reserved.
+// </copyright>
+// <owner current="true" primary="true">balnee</owner>
+// <owner current="true" primary="false">krishnib</owner>
+//------------------------------------------------------------------------------
+namespace System.Data.SqlClient
+{
+    using System;
+    using System.Collections.Concurrent;
+    using System.Data.SqlClient;
+    using System.Diagnostics;
+    using System.Text;
+
+    /// <summary>
+    /// This is a factory class for AES_256_CBC.
+    /// </summary>
+    internal class SqlAes256CbcFactory : SqlAeadAes256CbcHmac256Factory
+    {
+        /// <summary>
+        /// Factory classes caches the SqlAeadAes256CbcHmac256EncryptionKey objects to avoid computation of the derived keys
+        /// </summary>
+        private readonly ConcurrentDictionary<string, SqlAes256CbcAlgorithm> _encryptionAlgorithms =
+            new ConcurrentDictionary<string, SqlAes256CbcAlgorithm>(concurrencyLevel: 4 * Environment.ProcessorCount /* default value in ConcurrentDictionary*/, capacity: 2);
+
+        /// <summary>
+        /// Creates an instance of SqlAes256CbcAlgorithm class with a given key
+        /// </summary>
+        /// <param name="encryptionKey">Root key</param>
+        /// <param name="encryptionType">Encryption Type. Expected values are either Determinitic or Randomized.</param>
+        /// <param name="encryptionAlgorithm">Encryption Algorithm.</param>
+        /// <returns></returns>
+        internal override SqlClientEncryptionAlgorithm Create(SqlClientSymmetricKey encryptionKey, SqlClientEncryptionType encryptionType, string encryptionAlgorithm)
+        {
+            // Callers should have validated the encryption algorithm and the encryption key
+            Debug.Assert(encryptionKey != null);
+            Debug.Assert(string.Equals(encryptionAlgorithm, SqlAes256CbcAlgorithm.AlgorithmName, StringComparison.OrdinalIgnoreCase) == true);
+
+            // Validate encryption type
+            if (!((encryptionType == SqlClientEncryptionType.Deterministic) || (encryptionType == SqlClientEncryptionType.Randomized)))
+            {
+                throw SQL.InvalidEncryptionType(SqlAes256CbcAlgorithm.AlgorithmName,
+                                                encryptionType,
+                                                SqlClientEncryptionType.Deterministic,
+                                                SqlClientEncryptionType.Randomized);
+            }
+
+            // Get the cached encryption algorithm if one exists or create a new one, add it to cache and use it
+            //
+            // For now, we only have one version. In future, we may need to parse the algorithm names to derive the version byte.
+            const byte algorithmVersion = 0x1;
+
+            StringBuilder algorithmKeyBuilder = new StringBuilder(Convert.ToBase64String(encryptionKey.RootKey), SqlSecurityUtility.GetBase64LengthFromByteLength(encryptionKey.RootKey.Length) + 4/*separators, type and version*/);
+
+#if DEBUG
+            int capacity = algorithmKeyBuilder.Capacity;
+#endif //DEBUG
+
+            algorithmKeyBuilder.Append(":");
+            algorithmKeyBuilder.Append((int)encryptionType);
+            algorithmKeyBuilder.Append(":");
+            algorithmKeyBuilder.Append(algorithmVersion);
+
+            string algorithmKey = algorithmKeyBuilder.ToString();
+
+#if DEBUG
+            Debug.Assert(algorithmKey.Length <= capacity, "We needed to allocate a larger array");
+#endif //DEBUG
+
+            SqlAes256CbcAlgorithm aesAlgorithm;
+            if (!_encryptionAlgorithms.TryGetValue(algorithmKey, out aesAlgorithm))
+            {
+                SqlAeadAes256CbcHmac256EncryptionKey encryptedKey = new SqlAeadAes256CbcHmac256EncryptionKey(encryptionKey.RootKey, SqlAes256CbcAlgorithm.AlgorithmName);
+                aesAlgorithm = new SqlAes256CbcAlgorithm(encryptedKey, encryptionType, algorithmVersion);
+
+                // In case multiple threads reach here at the same time, the first one adds the value
+                // the second one will be a no-op, the allocated memory will be claimed by Garbage Collector.
+                _encryptionAlgorithms.TryAdd(algorithmKey, aesAlgorithm);
+            }
+
+            return aesAlgorithm;
+        }
+    }
+}