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// ==++==
//
// Copyright (c) Microsoft Corporation. All rights reserved.
//
// ==--==
// <OWNER>Microsoft</OWNER>
//
//
// HMACSHA512.cs
//
namespace System.Security.Cryptography {
[System.Runtime.InteropServices.ComVisible(true)]
public class HMACSHA512 : HMAC {
private bool m_useLegacyBlockSize = Utils._ProduceLegacyHmacValues();
//
// public constructors
//
public HMACSHA512 () : this (Utils.GenerateRandom(128)) {}
[System.Security.SecuritySafeCritical] // auto-generated
public HMACSHA512 (byte[] key) {
m_hashName = "SHA512";
m_hash1 = GetHashAlgorithmWithFipsFallback(() => new SHA512Managed(), () => HashAlgorithm.Create("System.Security.Cryptography.SHA512CryptoServiceProvider"));
m_hash2 = GetHashAlgorithmWithFipsFallback(() => new SHA512Managed(), () => HashAlgorithm.Create("System.Security.Cryptography.SHA512CryptoServiceProvider"));
HashSizeValue = 512;
BlockSizeValue = BlockSize;
base.InitializeKey(key);
}
private int BlockSize {
get { return m_useLegacyBlockSize ? 64 : 128; }
}
/// <summary>
/// In Whidbey we incorrectly used a block size of 64 bytes for HMAC-SHA-384 and HMAC-SHA-512,
/// rather than using the correct value of 128 bytes. Setting this to true causes us to fall
/// back to the Whidbey mode which produces incorrect HMAC values.
///
/// This value should be set only once, before hashing has begun, since we need to reset the key
/// buffer for the block size change to take effect.
///
/// The default vaue is off, however this can be toggled for the application by setting the
/// legacyHMACMode config switch.
/// </summary>
public bool ProduceLegacyHmacValues {
get { return m_useLegacyBlockSize; }
set {
m_useLegacyBlockSize = value;
BlockSizeValue = BlockSize;
InitializeKey(KeyValue);
}
}
}
}
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