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/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / Core / System / Security / Cryptography / BCryptHashAlgorithm.cs / 1305376 / BCryptHashAlgorithm.cs
// ==++== // // Copyright (c) Microsoft Corporation. All rights reserved. // // ==--== using System; using System.Diagnostics; using System.Diagnostics.CodeAnalysis; using System.IO; using System.Runtime.CompilerServices; using System.Runtime.InteropServices; using System.Diagnostics.Contracts; using Microsoft.Win32.SafeHandles; namespace System.Security.Cryptography { ////// Implementation of a generic BCrypt hashing algorithm, concrete HashAlgorithm classes /// implemented by BCrypt can contain an instance of this class and delegate the work to it. /// internal sealed class BCryptHashAlgorithm : IDisposable { private SafeBCryptAlgorithmHandle m_algorithmHandle; private SafeBCryptHashHandle m_hashHandle; //// [System.Security.SecurityCritical] public BCryptHashAlgorithm(CngAlgorithm algorithm, string implementation) { Contract.Requires(algorithm != null); Contract.Requires(!String.IsNullOrEmpty(implementation)); Contract.Ensures(m_algorithmHandle != null && !m_algorithmHandle.IsInvalid && !m_algorithmHandle.IsClosed); Contract.Ensures(m_hashHandle != null && !m_hashHandle.IsInvalid && !m_hashHandle.IsClosed); // Make sure CNG is supported on this platform if (!BCryptNative.BCryptSupported) { throw new PlatformNotSupportedException(SR.GetString(SR.Cryptography_PlatformNotSupported)); } m_algorithmHandle = BCryptNative.OpenAlgorithm(algorithm.Algorithm, implementation); Initialize(); } ///// // // // // // // /// Clean up the hash algorithm /// //// [System.Security.SecurityCritical] public void Dispose() { Contract.Ensures(m_hashHandle == null || m_hashHandle.IsClosed); Contract.Ensures(m_algorithmHandle == null || m_algorithmHandle.IsClosed); if (m_hashHandle != null) { m_hashHandle.Dispose(); } if (m_algorithmHandle != null) { m_algorithmHandle.Dispose(); } } ///// // // // /// Reset the hash algorithm to begin hashing a new set of data /// //// [System.Security.SecurityCritical] [SuppressMessage("Microsoft.Security", "CA2122:DoNotIndirectlyExposeMethodsWithLinkDemands", Justification = "Reviewed")] public void Initialize() { Contract.Ensures(m_hashHandle != null && !m_hashHandle.IsInvalid && !m_hashHandle.IsClosed); Contract.Assert(m_algorithmHandle != null); // Try to create a new hash algorithm to use SafeBCryptHashHandle newHashAlgorithm = null; IntPtr hashObjectBuffer = IntPtr.Zero; // Creating a BCRYPT_HASH_HANDLE requires providing a buffer to hold the hash object in, which // is tied to the lifetime of the hash handle. Wrap this in a CER so we can tie the lifetimes together // safely. RuntimeHelpers.PrepareConstrainedRegions(); try { int hashObjectSize = BCryptNative.GetInt32Property(m_algorithmHandle, BCryptNative.ObjectPropertyName.ObjectLength); Debug.Assert(hashObjectSize > 0, "hashObjectSize > 0"); // Allocate in a CER because we could fail between the alloc and the assignment RuntimeHelpers.PrepareConstrainedRegions(); try { } finally { hashObjectBuffer = Marshal.AllocCoTaskMem(hashObjectSize); } BCryptNative.ErrorCode error = BCryptNative.UnsafeNativeMethods.BCryptCreateHash(m_algorithmHandle, out newHashAlgorithm, hashObjectBuffer, hashObjectSize, IntPtr.Zero, 0, 0); if (error != BCryptNative.ErrorCode.Success) { throw new CryptographicException((int)error); } newHashAlgorithm.HashObject = hashObjectBuffer; } finally { // Make sure we've successfully transfered ownership of the hash object buffer to the safe handle if (hashObjectBuffer != IntPtr.Zero && (newHashAlgorithm == null || newHashAlgorithm.HashObject == IntPtr.Zero)) { Marshal.FreeCoTaskMem(hashObjectBuffer); } } // If we could create it, dispose of any old hash handle we had and replace it with the new one if (m_hashHandle != null) { m_hashHandle.Dispose(); } m_hashHandle = newHashAlgorithm; } ///// // // // // // // // // // // // // /// Hash a block of data /// //// [System.Security.SecurityCritical] public void HashCore(byte[] array, int ibStart, int cbSize) { Contract.Assert(m_hashHandle != null); if (array == null) { throw new ArgumentNullException("array"); } if (ibStart < 0 || ibStart > array.Length - cbSize) { throw new ArgumentOutOfRangeException("ibStart"); } if (cbSize < 0 || cbSize > array.Length) { throw new ArgumentOutOfRangeException("cbSize"); } byte[] hashData = new byte[cbSize]; Buffer.BlockCopy(array, ibStart, hashData, 0, cbSize); BCryptNative.ErrorCode error = BCryptNative.UnsafeNativeMethods.BCryptHashData(m_hashHandle, hashData, hashData.Length, 0); if (error != BCryptNative.ErrorCode.Success) { throw new CryptographicException((int)error); } } ///// // /// Complete the hash, returning its value /// //// [System.Security.SecurityCritical] public byte[] HashFinal() { Contract.Ensures(Contract.Result// // // () != null); Contract.Assert(m_hashHandle != null); int hashSize = BCryptNative.GetInt32Property(m_hashHandle, BCryptNative.HashPropertyName.HashLength); byte[] hashValue = new byte[hashSize]; BCryptNative.ErrorCode error = BCryptNative.UnsafeNativeMethods.BCryptFinishHash(m_hashHandle, hashValue, hashValue.Length, 0); if (error != BCryptNative.ErrorCode.Success) { throw new CryptographicException((int)error); } return hashValue; } // // [System.Security.SecurityCritical] public void HashStream(Stream stream) { Contract.Requires(stream != null); // Read the data 4KB at a time, providing similar read characteristics to a standard HashAlgorithm byte[] buffer = new byte[4096]; int bytesRead = 0; do { bytesRead = stream.Read(buffer, 0, buffer.Length); if (bytesRead > 0) { HashCore(buffer, 0, bytesRead); } } while (bytesRead > 0); } } } // File provided for Reference Use Only by Microsoft Corporation (c) 2007.//
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