pkcs5padding.go

package goEncrypt

import (
	"bytes"
)

/*
@Time : 2018/11/1 21:16 
@Author : wuman
@File : padding
@Software: GoLand
*/
/**
1. Group plaintext
	If the blocksize is not an integer multiple of blocksize, the blocksize bit should be considered
    If des algorithm is used, the block size is 8 bytes
	With the AES algorithm, 16 bytes of fast size are filled in
    A tool for populating data when using block encryption mode
 */

// It is populated using pkcs5

func PKCS5Padding(plainText []byte, blockSize int) []byte{
	padding := blockSize - (len(plainText)%blockSize)
	padText := bytes.Repeat([]byte{byte(padding)}, padding)
	newText := append(plainText, padText...)
	return newText
}

func PKCS5UnPadding(plainText []byte)([]byte,error){
	length := len(plainText)
	number:= int(plainText[length-1])
	if number>=length{
		return nil,ErrPaddingSize
	}
	return plainText[:length-number],nil
}