pad

Documentation

Overview

Package pad implements some padding schemes for block ciphers.

Index

• type Padding
  • func NewISO10126(blocksize int, rand io.Reader) Padding
  • func NewPKCS7(blocksize int) Padding
  • func NewX923(blocksize int) Padding

Types

type Padding

type Padding interface {

	// BlockSize returns the block size of the padding.
	BlockSize() int

	// Returns the overhead, the padding will cause
	// by padding the given byte slice. The overhead
	// will always be between 1 and BlockSize() inclusively.
	Overhead(src []byte) int

	// Pads the last (may incomplete) block of the src slice
	// to a padded and complete block, appends the padding bytes
	// to the src slice and returns this slice.
	// The length of the returned slice is len(src) + Overhead(src)
	Pad(src []byte) []byte

	// Takes a slice and tries to remove the padding bytes
	// form the last block. Therefore the length of the
	// src argument must be a multiply of the blocksize.
	// If the returned error is nil, the padding could be
	// removed successfully. The returned slice holds the
	// unpadded src bytes.
	Unpad(src []byte) ([]byte, error)
}

The Padding interface represents a padding scheme.

func NewISO10126

func NewISO10126(blocksize int, rand io.Reader) Padding

NewISO10126 returns a new pad.Padding, which uses the padding scheme described in ISO 10126. The padding bytes are taken form the given rand argument. If rand is nil, crypto/rand will be used. Only block sizes between 1 and 255 are valid.

func NewPKCS7

func NewPKCS7(blocksize int) Padding

NewPKCS7 returns a new pad.Padding implementing the PKCS 7 scheme. Only block sizes between 1 and 255 are valid.

func NewX923

func NewX923(blocksize int) Padding

NewX923 returns a new pad.Padding implementing the ANSI X.923 scheme. Only block sizes between 1 and 255 are valid.