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//------------------------------------------------------------------------------
// <copyright file="CryptoAlgorithms.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Security.Cryptography {
using System;
using System.Diagnostics.CodeAnalysis;
using System.Security.Cryptography;
// Utility class to provide the "one true way" of getting instances of
// cryptographic algorithms, like SymmetricAlgorithm and HashAlgorithm.
// From discussions with Microsoft and the crypto board, we should prefer
// the CNG implementations of algorithms, then the CAPI implementations,
// then finally managed implementations if there are no CNG / CAPI
// implementations. The CNG / CAPI implementations are preferred for
// expandability, FIPS-compliance, and performance.
//
// .NET Framework 4.5 allows us to make two core assumptions:
// - The built-in HMAC classes have been updated for FIPS compliance.
// - Since .NET 4.5 requires Windows Server 2008 or greater, we can
// assume that CNG is available on the box.
//
// Note that some algorithms (MD5, DES, etc.) aren't FIPS-compliant
// under any circumstance. Calling these methods when the OS is
// configured to allow only FIPS-compliant algorithms will result
// in an exception being thrown.
//
// The .NET Framework's built-in algorithms don't need to be created
// under the application impersonation context since they don't depend
// on the impersonated identity.
internal static class CryptoAlgorithms {
internal static Aes CreateAes() {
return new AesCryptoServiceProvider();
}
[SuppressMessage("Microsoft.Cryptographic.Standard", "CA5351:DESCannotBeUsed", Justification = @"This is only used by legacy code; new features do not use this algorithm.")]
[Obsolete("DES is deprecated and MUST NOT be used by new features. Consider using AES instead.")]
internal static DES CreateDES() {
return new DESCryptoServiceProvider();
}
[SuppressMessage("Microsoft.Security.Cryptography", "CA5354:SHA1CannotBeUsed", Justification = @"This is only used by legacy code; new features do not use this algorithm.")]
internal static HMACSHA1 CreateHMACSHA1() {
return new HMACSHA1();
}
internal static HMACSHA256 CreateHMACSHA256() {
return new HMACSHA256();
}
internal static HMACSHA384 CreateHMACSHA384() {
return new HMACSHA384();
}
internal static HMACSHA512 CreateHMACSHA512() {
return new HMACSHA512();
}
internal static HMACSHA512 CreateHMACSHA512(byte[] key) {
return new HMACSHA512(key);
}
[SuppressMessage("Microsoft.Cryptographic.Standard", "CA5350:MD5CannotBeUsed", Justification = @"This is only used by legacy code; new features do not use this algorithm.")]
[Obsolete("MD5 is deprecated and MUST NOT be used by new features. Consider using a SHA-2 algorithm instead.")]
internal static MD5 CreateMD5() {
return new MD5Cng();
}
[SuppressMessage("Microsoft.Cryptographic.Standard", "CA5354:SHA1CannotBeUsed", Justification = @"This is only used by legacy code; new features do not use this algorithm.")]
[Obsolete("SHA1 is deprecated and MUST NOT be used by new features. Consider using a SHA-2 algorithm instead.")]
internal static SHA1 CreateSHA1() {
return new SHA1Cng();
}
internal static SHA256 CreateSHA256() {
return new SHA256Cng();
}
internal static SHA384 CreateSHA384() {
return new SHA384Cng();
}
internal static SHA512 CreateSHA512() {
return new SHA512Cng();
}
[SuppressMessage("Microsoft.Cryptographic.Standard", "CA5353:TripleDESCannotBeUsed", Justification = @"This is only used by legacy code; new features do not use this algorithm.")]
[Obsolete("3DES is deprecated and MUST NOT be used by new features. Consider using AES instead.")]
internal static TripleDES CreateTripleDES() {
return new TripleDESCryptoServiceProvider();
}
}
}
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