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DES.IsWeakKey Method

Determines whether the specified key is weak.

[Visual Basic]
Public Shared Function IsWeakKey( _
   ByVal rgbKey() As Byte _
) As Boolean
public static bool IsWeakKey(
 byte[] rgbKey
public: static bool IsWeakKey(
 unsigned char rgbKey __gc[]
public static function IsWeakKey(
   rgbKey : Byte[]
) : Boolean;


The secret key to be tested for weakness.

Return Value

true if the key is weak; otherwise, false.


Exception Type Condition
CryptographicException 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.

An attempt to set a weak key will result in a CryptographicException. When GenerateKey is called to create a random key, a weak key will never be returned.


Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family

See Also

DES Class | DES Members | System.Security.Cryptography Namespace | Cryptographic Services