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ProtectedData.Protect Method (Byte[], Byte[], DataProtectionScope)

Encrypts the data in a specified byte array and returns a byte array that contains the encrypted data.

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

public static byte[] Protect(
	byte[] userData,
	byte[] optionalEntropy,
	DataProtectionScope scope
)

Parameters

userData
Type: System.Byte[]

A byte array that contains data to encrypt.

optionalEntropy
Type: System.Byte[]

An optional additional byte array used to increase the complexity of the encryption, or null for no additional complexity.

scope
Type: System.Security.Cryptography.DataProtectionScope

One of the enumeration values that specifies the scope of encryption.

Return Value

Type: System.Byte[]
A byte array representing the encrypted data.

ExceptionCondition
ArgumentNullException

The userData parameter is null.

CryptographicException

The encryption failed.

NotSupportedException

The operating system does not support this method.

OutOfMemoryException

The system ran out of memory while encrypting the data.

This method can be used to encrypt data such as passwords, keys, or connection strings. The optionalEntropy parameter enables you to add data to increase the complexity of the encryption; specify null for no additional complexity. If provided, this information must also be used when decrypting the data using the Unprotect method.

NoteNote

If you use this method during impersonation, you may receive the following error: "Key not valid for use in specified state." To prevent this error, load the profile of the user you want to impersonate before calling the method.

The following example shows how to use data protection.

using System;
using System.Security.Cryptography;

public class DataProtectionSample
{
// Create byte array for additional entropy when using Protect method. 
	static byte [] s_aditionalEntropy = { 9, 8, 7, 6, 5 };

	public static void Main()
	{
// Create a simple byte array containing data to be encrypted. 
		
byte [] secret = { 0, 1, 2, 3, 4, 1, 2, 3, 4 };

//Encrypt the data. 
		byte [] encryptedSecret = Protect( secret );
		Console.WriteLine("The encrypted byte array is:");
		PrintValues(encryptedSecret);
		
// Decrypt the data and store in a byte array. 
		byte [] originalData = Unprotect( encryptedSecret );
		Console.WriteLine("{0}The original data is:", Environment.NewLine);
		PrintValues(originalData);

	}

	public static byte [] Protect( byte [] data )
	{
		try
		{
			// Encrypt the data using DataProtectionScope.CurrentUser. The result can be decrypted 
			//  only by the same current user. 
			return ProtectedData.Protect( data, s_aditionalEntropy, DataProtectionScope.CurrentUser );
		} 
		catch (CryptographicException e)
		{
			Console.WriteLine("Data was not encrypted. An error occurred.");
			Console.WriteLine(e.ToString());
			return null;
		}
	}

	public static byte [] Unprotect( byte [] data )
	{
		try
		{
			//Decrypt the data using DataProtectionScope.CurrentUser. 
			return ProtectedData.Unprotect( data, s_aditionalEntropy, DataProtectionScope.CurrentUser );
		} 
		catch (CryptographicException e)
		{
			Console.WriteLine("Data was not decrypted. An error occurred.");
			Console.WriteLine(e.ToString());
			return null;
		}
	}

	public static void PrintValues( Byte[] myArr )  
	{
	      foreach ( Byte i in myArr )  
		  	{
		         Console.Write( "\t{0}", i );
			 }
      Console.WriteLine();
	 }

}

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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