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// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
using System.Runtime.Versioning;
using Microsoft.AspNetCore.Cryptography;
using Microsoft.Extensions.Logging.Abstractions;
namespace Microsoft.AspNetCore.DataProtection.AuthenticatedEncryption.ConfigurationModel;
/// <summary>
/// Represents a configured authenticated encryption mechanism which uses
/// Windows CNG algorithms in CBC encryption + HMAC authentication modes.
/// </summary>
[SupportedOSPlatform("windows")]
public sealed class CngCbcAuthenticatedEncryptorConfiguration : AlgorithmConfiguration, IInternalAlgorithmConfiguration
{
/// <summary>
/// The name of the algorithm to use for symmetric encryption.
/// This property corresponds to the 'pszAlgId' parameter of BCryptOpenAlgorithmProvider.
/// This property is required to have a value.
/// </summary>
/// <remarks>
/// The algorithm must support CBC-style encryption and must have a block size of 64 bits
/// or greater.
/// The default value is 'AES'.
/// </remarks>
[ApplyPolicy]
public string EncryptionAlgorithm { get; set; } = Constants.BCRYPT_AES_ALGORITHM;
/// <summary>
/// The name of the provider which contains the implementation of the symmetric encryption algorithm.
/// This property corresponds to the 'pszImplementation' parameter of BCryptOpenAlgorithmProvider.
/// This property is optional.
/// </summary>
/// <remarks>
/// The default value is null.
/// </remarks>
[ApplyPolicy]
public string? EncryptionAlgorithmProvider { get; set; } = null;
/// <summary>
/// The length (in bits) of the key that will be used for symmetric encryption.
/// This property is required to have a value.
/// </summary>
/// <remarks>
/// The key length must be 128 bits or greater.
/// The default value is 256.
/// </remarks>
[ApplyPolicy]
public int EncryptionAlgorithmKeySize { get; set; } = 256;
/// <summary>
/// The name of the algorithm to use for hashing data.
/// This property corresponds to the 'pszAlgId' parameter of BCryptOpenAlgorithmProvider.
/// This property is required to have a value.
/// </summary>
/// <remarks>
/// The algorithm must support being opened in HMAC mode and must have a digest length
/// of 128 bits or greater.
/// The default value is 'SHA256'.
/// </remarks>
[ApplyPolicy]
public string HashAlgorithm { get; set; } = Constants.BCRYPT_SHA256_ALGORITHM;
/// <summary>
/// The name of the provider which contains the implementation of the hash algorithm.
/// This property corresponds to the 'pszImplementation' parameter of BCryptOpenAlgorithmProvider.
/// This property is optional.
/// </summary>
/// <remarks>
/// The default value is null.
/// </remarks>
[ApplyPolicy]
public string? HashAlgorithmProvider { get; set; } = null;
/// <inheritdoc />
public override IAuthenticatedEncryptorDescriptor CreateNewDescriptor()
{
var internalConfiguration = (IInternalAlgorithmConfiguration)this;
return internalConfiguration.CreateDescriptorFromSecret(Secret.Random(KDK_SIZE_IN_BYTES));
}
IAuthenticatedEncryptorDescriptor IInternalAlgorithmConfiguration.CreateDescriptorFromSecret(ISecret secret)
{
return new CngCbcAuthenticatedEncryptorDescriptor(this, secret);
}
/// <summary>
/// Validates that this <see cref="CngCbcAuthenticatedEncryptorConfiguration"/> is well-formed, i.e.,
/// that the specified algorithms actually exist and that they can be instantiated properly.
/// An exception will be thrown if validation fails.
/// </summary>
void IInternalAlgorithmConfiguration.Validate()
{
var factory = new CngCbcAuthenticatedEncryptorFactory(NullLoggerFactory.Instance);
// Run a sample payload through an encrypt -> decrypt operation to make sure data round-trips properly.
using var secret = Secret.Random(512 / 8);
using var encryptor = factory.CreateAuthenticatedEncryptorInstance(secret, this);
encryptor.PerformSelfTest();
}
}
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