/
des.go
88 lines (72 loc) · 1.75 KB
/
des.go
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
package main
import (
"bytes"
"crypto/des"
"errors"
"log"
)
const (
DES_KEY = "pre0[COM"
)
func DesEncrypt(src, key []byte) ([]byte, error) {
block, err := des.NewCipher(key)
if err != nil {
log.Printf("[des encrypt] NewCipher error, %v", err)
return nil, err
}
bs := block.BlockSize()
src = ZeroPadding(src, bs)
// src = PKCS5Padding(src, bs)
if len(src)%bs != 0 {
return nil, errors.New("Need a multiple of the blocksize")
}
out := make([]byte, len(src))
dst := out
for len(src) > 0 {
block.Encrypt(dst, src[:bs])
src = src[bs:]
dst = dst[bs:]
}
return out, nil
}
func DesDecrypt(src, key []byte) ([]byte, error) {
block, err := des.NewCipher(key)
if err != nil {
log.Printf("[des decrypt] NewCipher error, %v", err)
return nil, err
}
out := make([]byte, len(src))
dst := out
bs := block.BlockSize()
if len(src)%bs != 0 {
return nil, errors.New("crypto/cipher: input not full blocks")
}
for len(src) > 0 {
block.Decrypt(dst, src[:bs])
src = src[bs:]
dst = dst[bs:]
}
out = ZeroUnPadding(out)
// out = PKCS5UnPadding(out)
return out, nil
}
func ZeroPadding(ciphertext []byte, blockSize int) []byte {
padding := blockSize - len(ciphertext)%blockSize
padtext := bytes.Repeat([]byte{0}, padding)
return append(ciphertext, padtext...)
}
func ZeroUnPadding(origData []byte) []byte {
return bytes.TrimFunc(origData, func(r rune) bool {
return r == rune(0)
})
}
func PKCS5Padding(ciphertext []byte, blockSize int) []byte {
padding := blockSize - len(ciphertext)%blockSize
padtext := bytes.Repeat([]byte{byte(padding)}, padding)
return append(ciphertext, padtext...)
}
func PKCS5UnPadding(origData []byte) []byte {
length := len(origData)
unpadding := int(origData[length-1])
return origData[:(length - unpadding)]
}