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//------------------------------------------------------------------------------
// <copyright file="MachineKeyDataProtectorFactory.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
//------------------------------------------------------------------------------
namespace System.Web.Security.Cryptography {
using System;
using System.Security.Cryptography;
using System.Web.Configuration;
// Can create DataProtector instances from a given <machineKey> element
internal sealed class MachineKeyDataProtectorFactory : IDataProtectorFactory {
private static readonly Purpose _creationTestingPurpose = new Purpose("test-1", "test-2", "test-3");
private Func<Purpose, DataProtector> _dataProtectorFactory;
private readonly MachineKeySection _machineKeySection;
public MachineKeyDataProtectorFactory(MachineKeySection machineKeySection) {
_machineKeySection = machineKeySection;
}
public DataProtector GetDataProtector(Purpose purpose) {
if (_dataProtectorFactory == null) {
_dataProtectorFactory = GetDataProtectorFactory();
}
return _dataProtectorFactory(purpose);
}
private Func<Purpose, DataProtector> GetDataProtectorFactory() {
string applicationName = _machineKeySection.ApplicationName;
string dataProtectorTypeName = _machineKeySection.DataProtectorType;
Func<Purpose, DataProtector> factory = purpose => {
// Since the custom implementation might depend on the impersonated
// identity, we must instantiate it under app-level impersonation.
using (new ApplicationImpersonationContext()) {
return DataProtector.Create(dataProtectorTypeName, applicationName, purpose.PrimaryPurpose, purpose.SpecificPurposes);
}
};
// Invoke the factory once to make sure there aren't any configuration errors.
Exception factoryCreationException = null;
try {
DataProtector dataProtector = factory(_creationTestingPurpose);
if (dataProtector != null) {
IDisposable disposable = dataProtector as IDisposable;
if (disposable != null) {
disposable.Dispose();
}
return factory; // we know at this point the factory is good
}
}
catch (Exception ex) {
factoryCreationException = ex;
}
// If we reached this point, there was a failure:
// the factory returned null, threw, or did something else unexpected.
throw ConfigUtil.MakeConfigurationErrorsException(
message: SR.GetString(SR.MachineKeyDataProtectorFactory_FactoryCreationFailed),
innerException: factoryCreationException, // can be null
configProperty: _machineKeySection.ElementInformation.Properties["dataProtectorType"]);
}
}
}
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