PaddingMode Enumeration

 

Specifies the type of padding to apply when the message data block is shorter than the full number of bytes needed for a cryptographic operation.

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

[SerializableAttribute]
[ComVisibleAttribute(true)]
public enum class PaddingMode

Member nameDescription
ANSIX923

The ANSIX923 padding string consists of a sequence of bytes filled with zeros before the length.

ISO10126

The ISO10126 padding string consists of random data before the length.

None

No padding is done.

PKCS7

The PKCS #7 padding string consists of a sequence of bytes, each of which is equal to the total number of padding bytes added.

Zeros

The padding string consists of bytes set to zero.

Most plain text messages do not consist of a number of bytes that completely fill blocks. Often, there are not enough bytes to fill the last block. When this happens, a padding string is added to the text. For example, if the block length is 64 bits and the last block contains only 40 bits, 24 bits of padding are added.

Some encryption standards specify a particular padding scheme. The following example shows how these modes work. Given a blocklength of 8, a data length of 9, the number of padding octets equal to 7, and the data equal to FF FF FF FF FF FF FF FF FF:

Data: FF FF FF FF FF FF FF FF FF

X923 padding: FF FF FF FF FF FF FF FF FF 00 00 00 00 00 00 07

PKCS7 padding: FF FF FF FF FF FF FF FF FF 07 07 07 07 07 07 07

ISO10126 padding: FF FF FF FF FF FF FF FF FF 7D 2A 75 EF F8 EF 07

.NET Framework
Available since 1.1
Return to top
Show: