ProtectedMemory.Unprotect Method (Byte(), MemoryProtectionScope)


Unprotects data in memory that was protected using the Protect method.

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

Public Shared Sub Unprotect (
	encryptedData As Byte(),
	scope As MemoryProtectionScope


Type: System.Byte()

The byte array in memory to unencrypt.

Type: System.Security.Cryptography.MemoryProtectionScope

One of the enumeration values that specifies the scope of memory protection.

Exception Condition

The operating system does not support this method. This method can be used only with the Windows 2000 or later operating systems.


encryptedData is null.


encryptedData is empty.


This call was not implemented.


NTSTATUS contains an error.

This method can be used to unencrypt data in memory that was encrypted using the Protect method.

Support for this method is available in the Windows XP and later operating systems.

The following example shows how to use data protection.

Imports System
Imports System.Security.Cryptography

Public Class MemoryProtectionSample

    Public Shared Sub Main()
        ' Create the original data to be encrypted (The data length should be a multiple of 16).
        Dim secret As Byte() = {1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4}

        ' Encrypt the data in memory. The result is stored in the same same array as the original data.
        ProtectedMemory.Protect(secret, MemoryProtectionScope.SameLogon)

        ' Decrypt the data in memory and store in the original array.
        ProtectedMemory.Unprotect(secret, MemoryProtectionScope.SameLogon)

    End Sub
End Class

.NET Framework
Available since 2.0
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