This documentation is archived and is not being maintained.

KeySizes Class

Determines the set of valid key sizes for the symmetric cryptographic algorithms.

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

public sealed class KeySizes

The following example shows the use of members of the KeySizes class.

using System;
using System.Security.Cryptography;

namespace Contoso
    class KeySizesMembers
        static void Main(string[] args)
            // Initializes a new instance of the KeySizes class with the 
            // specified key values. 
            int minSize = 64;
            int maxSize = 1024;
            int skipSize = 64;
            KeySizes keySizes = new KeySizes(minSize, maxSize, skipSize);

            // Show the values of the keys.
            ShowKeys(new KeySizes[1]{keySizes}, "Custom Keys");

            // Create a new symmetric algorithm and display its key values.
            SymmetricAlgorithm rijn = SymmetricAlgorithm.Create();
            ShowKeys(rijn.LegalKeySizes, rijn.ToString());
            Console.WriteLine("rijn.blocksize:" + rijn.BlockSize);

            // Create a new RSA algorithm and display its key values.
            RSACryptoServiceProvider rsaCSP = 
                new RSACryptoServiceProvider(384);
            ShowKeys(rsaCSP.LegalKeySizes, rsaCSP.ToString());
            Console.WriteLine("RSACryptoServiceProvider KeySize = " + 

            Console.WriteLine("This sample completed successfully; " +
                "press Enter to exit.");

        // Display specified KeySize properties to the console. 
        private static void ShowKeys(KeySizes[] keySizes, string objectName)
            // Retrieve the first KeySizes in the array.
            KeySizes firstKeySize = keySizes[0];

            // Retrieve the minimum key size in bits. 
            int minKeySize = firstKeySize.MinSize;

            // Retrieve the maximum key size in bits. 
            int maxKeySize = firstKeySize.MaxSize;

            // Retrieve the interval between valid key size in bits. 
            int skipKeySize = firstKeySize.SkipSize;

            Console.Write("\n KeySizes retrieved from the ");
            Console.WriteLine(objectName + " object.");
            Console.WriteLine("Minimum key size bits: " + minKeySize);
            Console.WriteLine("Maximum key size bits: " + maxKeySize);
            Console.WriteLine("Interval between key size bits: " + 
// This sample produces the following output: 
// KeySizes retrieved from the Custom Keys object. 
// Minimum key size bits: 64 
// Maximum key size bits: 1024 
// Interval between key size bits: 64 
// KeySizes retrieved from the System.Security.Cryptography.RijndaelManaged 
// object. 
// Minimum key size bits: 128 
// Maximum key size bits: 256 
// Interval between key size bits: 64 
// rijn.blocksize:128 
// KeySizes retrieved from the 
// System.Security.Cryptography.RSACryptoServiceProvider object. 
// Minimum key size bits: 384 
// Maximum key size bits: 16384 
// Interval between key size bits: 8 
// RSACryptoServiceProvider KeySize = 384 
// This sample completed successfully; press Enter to exit.


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

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0