forked from snail007/goproxy
/
aes.go
84 lines (67 loc) · 1.7 KB
/
aes.go
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// Playbook - http://play.golang.org/p/3wFl4lacjX
package goaes
import (
"bytes"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
"errors"
"io"
"strings"
)
func addBase64Padding(value string) string {
m := len(value) % 4
if m != 0 {
value += strings.Repeat("=", 4-m)
}
return value
}
func removeBase64Padding(value string) string {
return strings.Replace(value, "=", "", -1)
}
func Pad(src []byte) []byte {
padding := aes.BlockSize - len(src)%aes.BlockSize
padtext := bytes.Repeat([]byte{byte(padding)}, padding)
return append(src, padtext...)
}
func Unpad(src []byte) ([]byte, error) {
length := len(src)
unpadding := int(src[length-1])
if unpadding > length {
return nil, errors.New("unpad error. This could happen when incorrect encryption key is used")
}
return src[:(length - unpadding)], nil
}
func Encrypt(key []byte, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
msg := Pad(text)
ciphertext := make([]byte, aes.BlockSize+len(msg))
iv := ciphertext[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
cfb := cipher.NewCFBEncrypter(block, iv)
cfb.XORKeyStream(ciphertext[aes.BlockSize:], []byte(msg))
return ciphertext, nil
}
func Decrypt(key []byte, text []byte) ([]byte, error) {
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
}
if (len(text) % aes.BlockSize) != 0 {
return nil, errors.New("blocksize must be multipe of decoded message length")
}
iv := text[:aes.BlockSize]
msg := text[aes.BlockSize:]
cfb := cipher.NewCFBDecrypter(block, iv)
cfb.XORKeyStream(msg, msg)
unpadMsg, err := Unpad(msg)
if err != nil {
return nil, err
}
return unpadMsg, nil
}