81 lines
4.4 KiB
C#
81 lines
4.4 KiB
C#
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//------------------------------------------------------------------------------
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// <copyright file="SqlAeadAes256CbcHmac256Factory.cs" company="Microsoft">
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// Copyright (c) Microsoft Corporation. All rights reserved.
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// </copyright>
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// <owner current="true" primary="true">balnee</owner>
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// <owner current="true" primary="false">krishnib</owner>
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//------------------------------------------------------------------------------
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namespace System.Data.SqlClient {
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using System;
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using System.Collections.Concurrent;
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using System.Data.SqlClient;
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using System.Diagnostics;
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using System.Text;
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/// <summary>
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/// This is a factory class for AEAD_AES_256_CBC_HMAC_SHA256
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/// </summary>
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internal class SqlAeadAes256CbcHmac256Factory : SqlClientEncryptionAlgorithmFactory {
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/// <summary>
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/// Factory classes caches the SqlAeadAes256CbcHmac256EncryptionKey objects to avoid computation of the derived keys
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/// </summary>
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private readonly ConcurrentDictionary<string, SqlAeadAes256CbcHmac256Algorithm> _encryptionAlgorithms =
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new ConcurrentDictionary<string, SqlAeadAes256CbcHmac256Algorithm>(concurrencyLevel: 4 * Environment.ProcessorCount /* default value in ConcurrentDictionary*/, capacity: 2);
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/// <summary>
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/// Creates an instance of AeadAes256CbcHmac256Algorithm class with a given key
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/// </summary>
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/// <param name="encryptionKey">Root key</param>
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/// <param name="encryptionType">Encryption Type. Expected values are either Determinitic or Randomized.</param>
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/// <param name="encryptionAlgorithm">Encryption Algorithm.</param>
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/// <returns></returns>
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internal override SqlClientEncryptionAlgorithm Create(SqlClientSymmetricKey encryptionKey, SqlClientEncryptionType encryptionType, string encryptionAlgorithm) {
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// Callers should have validated the encryption algorithm and the encryption key
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Debug.Assert(encryptionKey != null);
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Debug.Assert(string.Equals(encryptionAlgorithm, SqlAeadAes256CbcHmac256Algorithm.AlgorithmName, StringComparison.OrdinalIgnoreCase) == true);
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// Validate encryption type
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if (!((encryptionType == SqlClientEncryptionType.Deterministic) || (encryptionType == SqlClientEncryptionType.Randomized))) {
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throw SQL.InvalidEncryptionType(SqlAeadAes256CbcHmac256Algorithm.AlgorithmName,
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encryptionType,
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SqlClientEncryptionType.Deterministic,
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SqlClientEncryptionType.Randomized);
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}
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// Get the cached encryption algorithm if one exists or create a new one, add it to cache and use it
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//
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// For now, we only have one version. In future, we may need to parse the algorithm names to derive the version byte.
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const byte algorithmVersion = 0x1;
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StringBuilder algorithmKeyBuilder = new StringBuilder(Convert.ToBase64String(encryptionKey.RootKey), SqlSecurityUtility.GetBase64LengthFromByteLength(encryptionKey.RootKey.Length) + 4/*separators, type and version*/);
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#if DEBUG
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int capacity = algorithmKeyBuilder.Capacity;
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#endif //DEBUG
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algorithmKeyBuilder.Append(":");
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algorithmKeyBuilder.Append((int)encryptionType);
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algorithmKeyBuilder.Append(":");
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algorithmKeyBuilder.Append(algorithmVersion);
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string algorithmKey = algorithmKeyBuilder.ToString();
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#if DEBUG
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Debug.Assert(algorithmKey.Length <= capacity, "We needed to allocate a larger array");
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#endif //DEBUG
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SqlAeadAes256CbcHmac256Algorithm aesAlgorithm;
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if (!_encryptionAlgorithms.TryGetValue(algorithmKey, out aesAlgorithm)) {
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SqlAeadAes256CbcHmac256EncryptionKey encryptedKey = new SqlAeadAes256CbcHmac256EncryptionKey(encryptionKey.RootKey, SqlAeadAes256CbcHmac256Algorithm.AlgorithmName);
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aesAlgorithm = new SqlAeadAes256CbcHmac256Algorithm(encryptedKey, encryptionType, algorithmVersion);
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// In case multiple threads reach here at the same time, the first one adds the value
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// the second one will be a no-op, the allocated memory will be claimed by Garbage Collector.
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_encryptionAlgorithms.TryAdd(algorithmKey, aesAlgorithm);
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}
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return aesAlgorithm;
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}
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}
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}
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