This documentation is archived and is not being maintained.

DES.IsWeakKey Method

Determines whether the specified key is weak.

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

public static bool IsWeakKey (
	byte[] rgbKey
public static boolean IsWeakKey (
	byte[] rgbKey
public static function IsWeakKey (
	rgbKey : byte[]
) : boolean
Not applicable.



The secret key to test for weakness.

Return Value

true if the key is weak; otherwise, false.

Exception typeCondition


The size of the rgbKey parameter is not valid.

Weak keys are keys that result in ciphers that are easy to break. If text is encrypted with a weak key, encrypting the resulting cipher again with the same weak key returns the original text. There are four known weak keys for the Data Encryption Standard (DES) algorithm; this method checks for those weak keys.

Attempting to set a weak key results in a CryptographicException. When GenerateKey is called to create a random key, a weak key will never be returned.

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

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0