//******************************************************************************************************//  SymmetricAlgorithmExtensions.cs - Gbtc////  Copyright © 2012, Grid Protection Alliance.  All Rights Reserved.////  Licensed to the Grid Protection Alliance (GPA) under one or more contributor license agreements. See//  the NOTICE file distributed with this work for additional information regarding copyright ownership.//  The GPA licenses this file to you under the MIT License (MIT), the "License"; you may//  not use this file except in compliance with the License. You may obtain a copy of the License at:////      http://www.opensource.org/licenses/MIT////  Unless agreed to in writing, the subject software distributed under the License is distributed on an//  "AS-IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. Refer to the//  License for the specific language governing permissions and limitations.////  Code Modification History://  ----------------------------------------------------------------------------------------------------//  09/19/2008 - J. Ritchie Carroll//       Generated original version of source code.//  09/14/2009 - Stephen C. Wills//       Added new header and license agreement.//  12/14/2012 - Starlynn Danyelle Gilliam//       Modified Header.////****************************************************************************************************** using System.IO;using System.Security.Cryptography;using GSF.IO; namespace GSF.Security.Cryptography{    /// <summary>    /// Defines extension functions related to cryptographic <see cref="SymmetricAlgorithm"/> objects.    /// </summary>    public static class SymmetricAlgorithmExtensions    {        /// <summary>        /// Returns a binary array of encrypted data for the given parameters.        /// </summary>        /// <param name="algorithm"><see cref="SymmetricAlgorithm"/> to use for encryption.</param>        /// <param name="data">Source buffer containing data to encrypt.</param>        /// <param name="startIndex">Offset into <paramref name="data"/> buffer.</param>        /// <param name="length">Number of bytes in <paramref name="data"/> buffer to encrypt starting from <paramref name="startIndex"/> offset.</param>        /// <param name="key">The secret key to use for the symmetric algorithm.</param>        /// <param name="iv">The initialization vector to use for the symmetric algorithm.</param>        /// <returns>Encrypted version of <paramref name="data"/> buffer.</returns>        public static byte[] Encrypt(this SymmetricAlgorithm algorithm, byte[] data, int startIndex, int length, byte[] key, byte[] iv)        {            // Fastest to use existing buffer in non-expandable memory stream for source and large block allocated memory stream for destination            using (MemoryStream source = new MemoryStream(data, startIndex, length))            using (BlockAllocatedMemoryStream destination = new BlockAllocatedMemoryStream())            {                algorithm.Encrypt(source, destination, key, iv);                return destination.ToArray();            }        }         /// <summary>        /// Encrypts input stream onto output stream for the given parameters.        /// </summary>        /// <param name="algorithm"><see cref="SymmetricAlgorithm"/> to use for encryption.</param>        /// <param name="source">Source stream that contains data to encrypt.</param>        /// <param name="destination">Destination stream used to hold encrypted data.</param>        /// <param name="key">The secret key to use for the symmetric algorithm.</param>        /// <param name="iv">The initialization vector to use for the symmetric algorithm.</param>        public static void Encrypt(this SymmetricAlgorithm algorithm, Stream source, Stream destination, byte[] key, byte[] iv)        {            byte[] buffer = new byte[Standard.BufferSize];            CryptoStream encodeStream = new CryptoStream(destination, algorithm.CreateEncryptor(key, iv), CryptoStreamMode.Write);            int read;             // Encrypts data onto output stream.            read = source.Read(buffer, 0, Standard.BufferSize);             while (read > 0)            {                encodeStream.Write(buffer, 0, read);                read = source.Read(buffer, 0, Standard.BufferSize);            }             encodeStream.FlushFinalBlock();        }         /// <summary>        /// Returns a binary array of decrypted data for the given parameters.        /// </summary>        /// <param name="algorithm"><see cref="SymmetricAlgorithm"/> to use for decryption.</param>        /// <param name="data">Source buffer containing data to decrypt.</param>        /// <param name="startIndex">Offset into <paramref name="data"/> buffer.</param>        /// <param name="length">Number of bytes in <paramref name="data"/> buffer to decrypt starting from <paramref name="startIndex"/> offset.</param>        /// <param name="key">The secret key to use for the symmetric algorithm.</param>        /// <param name="iv">The initialization vector to use for the symmetric algorithm.</param>        /// <returns>Decrypted version of <paramref name="data"/> buffer.</returns>        public static byte[] Decrypt(this SymmetricAlgorithm algorithm, byte[] data, int startIndex, int length, byte[] key, byte[] iv)        {            // Fastest to use existing buffer in non-expandable memory stream for source and large block allocated memory stream for destination            using (MemoryStream source = new MemoryStream(data, startIndex, length))            using (BlockAllocatedMemoryStream destination = new BlockAllocatedMemoryStream())            {                algorithm.Decrypt(source, destination, key, iv);                return destination.ToArray();            }        }         /// <summary>        /// Decrypts input stream onto output stream for the given parameters.        /// </summary>        /// <param name="algorithm"><see cref="SymmetricAlgorithm"/> to use for decryption.</param>        /// <param name="source">Source stream that contains data to decrypt.</param>        /// <param name="destination">Destination stream used to hold decrypted data.</param>        /// <param name="key">The secret key to use for the symmetric algorithm.</param>        /// <param name="iv">The initialization vector to use for the symmetric algorithm.</param>        public static void Decrypt(this SymmetricAlgorithm algorithm, Stream source, Stream destination, byte[] key, byte[] iv)        {            byte[] buffer = new byte[Standard.BufferSize];            CryptoStream decodeStream = new CryptoStream(destination, algorithm.CreateDecryptor(key, iv), CryptoStreamMode.Write);            int read;             // Decrypts data onto output stream.            read = source.Read(buffer, 0, Standard.BufferSize);             while (read > 0)            {                decodeStream.Write(buffer, 0, read);                read = source.Read(buffer, 0, Standard.BufferSize);            }             decodeStream.FlushFinalBlock();        }    }}