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SymmetricAlgorithm.LegalKeySizes Property

Gets the key sizes, in bits, that are supported by the symmetric algorithm.

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

public virtual KeySizes[] LegalKeySizes { get; }

Property Value

Type: System.Security.Cryptography.KeySizes[]
An array that contains the key sizes supported by the algorithm.

The symmetric algorithm supports only key sizes that match an entry in this array.

The following example shows the value of LegalKeySizes for the symmetric algorithms.

using System;
using System.Security.Cryptography;
namespace SymmetricAlgo
{
    class Program
    {
        static void Main(string[] args)
        {
            AesManaged aes = new AesManaged();
            Console.WriteLine("AesManaged ");
            KeySizes[] ks = aes.LegalKeySizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min key size = " + k.MinSize);
                Console.WriteLine("\tLegal max key size = " + k.MaxSize);
            }
            ks = aes.LegalBlockSizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min block size = " + k.MinSize);
                Console.WriteLine("\tLegal max block size = " + k.MaxSize);
            }
            DESCryptoServiceProvider des = new DESCryptoServiceProvider();
            Console.WriteLine("DESCryptoServiceProvider ");
            ks = des.LegalKeySizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min key size = " + k.MinSize);
                Console.WriteLine("\tLegal max key size = " + k.MaxSize);
            }
            ks = des.LegalBlockSizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min block size = " + k.MinSize);
                Console.WriteLine("\tLegal max block size = " + k.MaxSize);
            }
            RC2CryptoServiceProvider rc2 = new RC2CryptoServiceProvider();
            Console.WriteLine("RC2CryptoServiceProvider ");
            ks = rc2.LegalKeySizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min key size = " + k.MinSize);
                Console.WriteLine("\tLegal max key size = " + k.MaxSize);
            }
            ks = rc2.LegalBlockSizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min block size = " + k.MinSize);
                Console.WriteLine("\tLegal max block size = " + k.MaxSize);
            }
            RijndaelManaged rij = new RijndaelManaged();
            Console.WriteLine("RijndaelManaged ");
            ks = rij.LegalKeySizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min key size = " + k.MinSize);
                Console.WriteLine("\tLegal max key size = " + k.MaxSize);
            }
            ks = rij.LegalBlockSizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min block size = " + k.MinSize);
                Console.WriteLine("\tLegal max block size = " + k.MaxSize);
            }
            TripleDESCryptoServiceProvider tsp = new TripleDESCryptoServiceProvider();
            Console.WriteLine("TripleDESCryptoServiceProvider ");
            ks = tsp.LegalKeySizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min key size = " + k.MinSize);
                Console.WriteLine("\tLegal max key size = " + k.MaxSize);
            }
            ks = tsp.LegalBlockSizes;
            foreach (KeySizes k in ks)
            {
                Console.WriteLine("\tLegal min block size = " + k.MinSize);
                Console.WriteLine("\tLegal max block size = " + k.MaxSize);
            }

        }
    }
}
//This sample produces the following output: 
//AesManaged 
//        Legal min key size = 128 
//        Legal max key size = 256 
//        Legal min block size = 128 
//        Legal max block size = 128 
//DESCryptoServiceProvider 
//        Legal min key size = 64 
//        Legal max key size = 64 
//        Legal min block size = 64 
//        Legal max block size = 64 
//RC2CryptoServiceProvider 
//        Legal min key size = 40 
//        Legal max key size = 128 
//        Legal min block size = 64 
//        Legal max block size = 64 
//RijndaelManaged 
//        Legal min key size = 128 
//        Legal max key size = 256 
//        Legal min block size = 128 
//        Legal max block size = 256 
//TripleDESCryptoServiceProvider 
//        Legal min key size = 128 
//        Legal max key size = 192 
//        Legal min block size = 64 
//        Legal max block size = 64

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone 8, Silverlight 8.1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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