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

Definition

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

C#
public static byte[] Protect(byte[] userData, byte[]? optionalEntropy, System.Security.Cryptography.DataProtectionScope scope);
C#
public static byte[] Protect(byte[] userData, byte[] optionalEntropy, System.Security.Cryptography.DataProtectionScope scope);

Parameters

userData
Byte[]

A byte array that contains data to encrypt.

optionalEntropy
Byte[]

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

scope
DataProtectionScope

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

Returns

Byte[]

A byte array representing the encrypted data.

Exceptions

The userData parameter is null.

The encryption failed.

The operating system does not support this method.

The system ran out of memory while encrypting the data.

.NET Core and .NET 5+ only: Calls to the Protect method are supported on Windows operating systems only.

Examples

The following example shows how to use data protection.

C#
using System;
using System.Security.Cryptography;

public class DataProtectionSample
{
    // Create byte array for additional entropy when using Protect method.
    static byte [] s_additionalEntropy = { 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_additionalEntropy, 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_additionalEntropy, 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();
    }
}

Remarks

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.

Note

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.

Applies to

Product Versions
.NET Core 1.0, Core 1.1, 8 (package-provided), 9 (package-provided)
.NET Framework 2.0, 3.0, 3.5, 4.0, 4.5, 4.5.1, 4.5.2, 4.6, 4.6.1, 4.6.2, 4.7 (package-provided), 4.7, 4.7.1 (package-provided), 4.7.1, 4.7.2 (package-provided), 4.7.2, 4.8 (package-provided), 4.8, 4.8.1
.NET Standard 2.0 (package-provided)
Windows Desktop 3.0, 3.1, 5, 6, 7, 8, 9