PaddingMode Enumeration (System.Security.Cryptography)

PaddingMode Enumeration

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

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)

Syntax

Visual Basic (Declaration)

<SerializableAttribute> _
<ComVisibleAttribute(True)> _
Public Enumeration PaddingMode

Visual Basic (Usage)

Dim instance As PaddingMode

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

Visual C++

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

JScript

public enum PaddingMode

Members

	Member name	Description
	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. 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 PKCS7 padding: FF FF FF FF FF FF FF FF FF 07 07 07 07 07 07 07
	Zeros	The padding string consists of bytes set to zero.
	ANSIX923	The ANSIX923 padding string consists of a sequence of bytes filled with zeros before the length. The following example shows how this mode works. 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
	ISO10126	The ISO10126 padding string consists of random data before the length. The following example shows how this mode works. 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 ISO10126 padding: FF FF FF FF FF FF FF FF FF 7D 2A 75 EF F8 EF 07

Remarks

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

Platforms

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.

Version Information

.NET Framework

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

.NET Compact Framework

Supported in: 3.5, 2.0

Reference

System.Security.Cryptography Namespace

Other Resources

Cryptographic Services