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sm4.go
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sm4.go
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// Copyright 2022 s1ren@github.com/hxx258456.
package sm4
import (
"bytes"
"crypto/cipher"
"crypto/rand"
"errors"
"fmt"
"io"
)
// 根据pkcs7标准填充明文
func PKCS7Padding(src []byte) []byte {
padding := BlockSize - len(src)%BlockSize
padtext := bytes.Repeat([]byte{byte(padding)}, padding)
return append(src, padtext...)
}
// 根据pkcs7标准去除填充
func PKCS7UnPadding(src []byte) ([]byte, error) {
length := len(src)
if length == 0 {
return nil, errors.New("invalid pkcs7 padding (len(padtext) == 0)")
}
unpadding := int(src[length-1])
if unpadding > BlockSize || unpadding == 0 {
return nil, fmt.Errorf("invalid pkcs7 padding (unpadding > BlockSize || unpadding == 0). unpadding: %d, BlockSize: %d", unpadding, BlockSize)
}
pad := src[len(src)-unpadding:]
for i := 0; i < unpadding; i++ {
if pad[i] != byte(unpadding) {
return nil, errors.New("invalid pkcs7 padding (pad[i] != unpadding)")
}
}
return src[:(length - unpadding)], nil
}
// sm4加密,CBC模式
func Sm4EncryptCbc(plainData, key []byte) (iv, encryptData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, nil, err
}
paddedData := PKCS7Padding(plainData)
encryptData = make([]byte, len(paddedData))
iv = make([]byte, BlockSize)
if _, err = io.ReadFull(rand.Reader, iv); err != nil {
return nil, nil, err
}
mode := cipher.NewCBCEncrypter(block, iv)
mode.CryptBlocks(encryptData, paddedData)
return
}
// sm4解密,CBC模式
func Sm4DecryptCbc(encryptData, key, iv []byte) (plainData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, err
}
// 长度检查
length := len(encryptData)
if length < BlockSize || length%BlockSize != 0 {
return nil, fmt.Errorf("sm4.Sm4DecryptCbc: 密文长度不正确,不是Block字节数的整数倍. Block字节数: [%d]", BlockSize)
}
paddedData := make([]byte, len(encryptData))
mode := cipher.NewCBCDecrypter(block, iv)
mode.CryptBlocks(paddedData, encryptData)
plainData, err = PKCS7UnPadding(paddedData)
if err != nil {
return nil, err
}
return
}
// sm4加密,CFB模式
func Sm4EncryptCfb(plainData, key []byte) (iv, encryptData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, nil, err
}
encryptData = make([]byte, len(plainData))
iv = make([]byte, BlockSize)
if _, err = io.ReadFull(rand.Reader, iv); err != nil {
return nil, nil, err
}
mode := cipher.NewCFBEncrypter(block, iv)
mode.XORKeyStream(encryptData, plainData)
return
}
// sm4解密,CFB模式
func Sm4DecryptCfb(encryptData, key, iv []byte) (plainData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, err
}
plainData = make([]byte, len(encryptData))
mode := cipher.NewCFBDecrypter(block, iv)
mode.XORKeyStream(plainData, encryptData)
return
}
// sm4加密,OFB模式
func Sm4EncryptOfb(plainData, key []byte) (iv, encryptData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, nil, err
}
encryptData = make([]byte, len(plainData))
iv = make([]byte, BlockSize)
if _, err = io.ReadFull(rand.Reader, iv); err != nil {
return nil, nil, err
}
mode := cipher.NewOFB(block, iv)
mode.XORKeyStream(encryptData, plainData)
return
}
// sm4解密,OFB模式
func Sm4DecryptOfb(encryptData, key, iv []byte) (plainData []byte, err error) {
block, err := NewCipher(key)
if err != nil {
return nil, err
}
plainData = make([]byte, len(encryptData))
mode := cipher.NewOFB(block, iv)
mode.XORKeyStream(plainData, encryptData)
return
}
// sm4加密,GCM模式
func Sm4EncryptGcm(plainData, key []byte) (nonce, encryptData []byte, err error) {
block, err := NewCipher([]byte(key))
if err != nil {
return nil, nil, err
}
sm4gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, nil, err
}
nonce = make([]byte, sm4gcm.NonceSize())
io.ReadFull(rand.Reader, nonce)
out := sm4gcm.Seal(nonce, nonce, plainData, nil)
encryptData = out[sm4gcm.NonceSize():]
return
}
// sm4解密,GCM模式
func Sm4DecryptGcm(encryptData, key, nonce []byte) ([]byte, error) {
block, err := NewCipher([]byte(key))
if err != nil {
return nil, err
}
sm4gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
// nonce, ciphertext := data[:sm4gcm.NonceSize()], data[sm4gcm.NonceSize():]
out, err := sm4gcm.Open(nil, nonce, encryptData, nil)
if err != nil {
return nil, err
}
return out, nil
}
// sm4加密,GCM模式
func Sm4EncryptGcmWithNonce(plainData, key, nonce, dst []byte) (encryptData []byte, err error) {
block, err := NewCipher([]byte(key))
if err != nil {
return nil, err
}
sm4gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
out := sm4gcm.Seal(dst, nonce, plainData, dst)
encryptData = out[len(dst):]
return
}
// sm4解密,GCM模式
func Sm4DecryptGcmWithNonce(encryptData, key, nonce, dst []byte) ([]byte, error) {
block, err := NewCipher([]byte(key))
if err != nil {
return nil, err
}
sm4gcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
}
out, err := sm4gcm.Open(encryptData[:0], nonce, encryptData, dst)
if err != nil {
return nil, err
}
return out, nil
}