ProtectedData Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Provides methods for encrypting and decrypting data. This class cannot be inherited.

Inheritance Hierarchy

System.Object
  System.Security.Cryptography.ProtectedData

Namespace:  System.Security.Cryptography
Assembly:  mscorlib.Extensions (in mscorlib.Extensions.dll)

Syntax

'Declaration
Public NotInheritable Class ProtectedData

public static class ProtectedData

The ProtectedData type exposes the following members.

Methods

	Name	Description
	Protect	Encrypts the data in a specified byte array and returns a byte array that contains the encrypted data.
	Unprotect	Decrypts the data in a specified byte array and returns a byte array that contains the decrypted data.

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Remarks

This class provides access to the Data Protection API (DPAPI). This is a service that is provided by the operating system and does not require additional libraries. It provides protection using the user or machine credentials to encrypt or decrypt data.

 In Silverlight for Windows Phone, both the user and machine credentials are used to encrypt or decrypt data.

The class consists of two wrappers for the unmanaged DPAPI, Protect and Unprotect. These two methods can be used to encrypt and decrypt data such as passwords, keys, and connection strings.

If you use these methods during impersonation, you may receive the following error: "Key not valid for use in specified state." This occurs because the DPAPI stores the key data in user profiles. If the profile is not loaded, DPAPI won’t be able to perform the decryption. To prevent this error, load the profile of the user you want to impersonate before calling either method. Using DPAPI with impersonation can incur significant complication and requires careful design choices.

For information about how to encrypt and decrypt data in a Windows Phone application, see How to: Encrypt Data in a Windows Phone Application.

Topic	Location
How to: Use Data Protection	.NET Framework: Security
How to: Use Data Protection	.NET Framework: Security
How to: Use Data Protection	.NET Framework: Security

Version Information

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Thread Safety

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

See Also

Reference

System.Security.Cryptography Namespace

Other Resources

How to: Encrypt Data in a Windows Phone Application