golang AES加密函数的使用
- 什么是AES
AES： Advanced Encryption Standard
高阶加密标准，是用来代替 老的DES的。
AES加密算法的加密块必须是16字节(128bit)，所以不足部分需要填充，常用的填充算法是PKCS7。
AES加密算法的key可以是16字节(AES128)，或者24字节(AES192)，或者是32字节(AES256)
- AES算法的具体实现种类
ECB：Electronic Codebook Book
CBC：Cipher Block Chaining：这是最常见的块加密实现
CTR：Counter
CFB：Cipher FeedBack
OFB：Output FeedBack
具体的差异我也没去弄明白，知道这么个意思，加密算法稍后差异。
- golang crypt库实现的加密函数
包括AES，CBC，CTR，OFB，CFB，GCM。
这其中GCM不需要加密块必须16字节长度，可以是任意长度，其他的都需要16字节对其，所以不足部分都需要补充。
package main
import (
"io"
"fmt"
"crypto/aes"
"crypto/cipher"
"crypto/rand"
)
func main() {
key := []byte("12345678901234567890123456789012") // 32 bytes long
plainText := []byte("123")
fmt.Printf("Original Text: [%s]\n",plainText)
cipherText, _ := AESEncrypt(key, plainText) // replace with corresponding encrypt implementation
decryptText, _ := AESDecrypt(key, cipherText)
fmt.Printf("AES Decrypted Text: [%s]\n", decryptText)
}
3.1 AES
func AESEncrypt(key []byte, data[]byte) ([]byte, error) {
data = pad(data, aes.BlockSize)
c, _ := aes.NewCipher(key)
out := make([]byte, len(data))
c.Encrypt(out, []byte(data))
return out, nil
}
func AESDecrypt(key []byte, data[]byte) ([]byte, error) {
c, _ := aes.NewCipher(key)
out := make([]byte, len(data))
c.Decrypt(out, data)
out, _ = unpad(out)
return out, nil
}
3.2 CBC
func CBCEncrypt(key []byte, data []byte) ([]byte, error) {
data = pad(data, aes.BlockSize)
block, _ := aes.NewCipher(key)
out := make([]byte, aes.BlockSize + len(data))
iv := out[:aes.BlockSize]
io.ReadFull(rand.Reader, iv)
mode := cipher.NewCBCEncrypter(block, iv)
mode.CryptBlocks(out[aes.BlockSize:], []byte(data))
return out, nil
}
func CBCDecrypt(key []byte, data []byte) ([]byte, error) {
block, _ := aes.NewCipher(key)
iv := data[:aes.BlockSize]
data = data[aes.BlockSize:]
if len(data) % aes.BlockSize != 0 {
return nil, fmt.Errorf("data is not a multiple of the block size")
}
out := make([]byte, len(data))
mode := cipher.NewCBCDecrypter(block, iv)
mode.CryptBlocks(out, data)
out, _ = unpad(out)
return out, nil
}
3.3 CTR
func CTREncrypt(key []byte, data[]byte) ([]byte, error) {
data = pad(data, aes.BlockSize)
block, _ := aes.NewCipher([]byte(key))
out := make([]byte, aes.BlockSize + len(data))
iv := out[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
stream := cipher.NewCTR(block, iv)
stream.XORKeyStream(out[aes.BlockSize:], data)
return out, nil
}
func CTRDecrypt(key []byte, data[]byte) ([]byte, error) {
block, _ := aes.NewCipher([]byte(key))
iv := data[:aes.BlockSize]
data = data[aes.BlockSize:]
if len(data) % aes.BlockSize != 0 {
return nil, fmt.Errorf("data is not a multiple of the block size")
}
out := make([]byte, len(data))
mode := cipher.NewCTR(block, iv)
mode.XORKeyStream(out, data)
out, _ = unpad(out)
return out, nil
}
3.4 OFB
func OFBEncrypt(key []byte, data[]byte) ([]byte, error) {
data = pad(data, aes.BlockSize)
block, _ := aes.NewCipher([]byte(key))
out := make([]byte, aes.BlockSize + len(data))
iv := out[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
stream := cipher.NewOFB(block, iv)
stream.XORKeyStream(out[aes.BlockSize:], data)
return out, nil
}
func OFBDecrypt(key []byte, data[]byte) ([]byte, error) {
block, _ := aes.NewCipher([]byte(key))
iv := data[:aes.BlockSize]
data = data[aes.BlockSize:]
if len(data) % aes.BlockSize != 0 {
return nil, fmt.Errorf("data is not a multiple of the block size")
}
out := make([]byte, len(data))
mode := cipher.NewOFB(block, iv)
mode.XORKeyStream(out, data)
out, _ = unpad(out)
return out, nil
}
3.5 CFB
func CFBEncrypt(key []byte, data[]byte) ([]byte, error) {
data = pad(data, aes.BlockSize)
block, _ := aes.NewCipher([]byte(key))
out := make([]byte, aes.BlockSize + len(data))
iv := out[:aes.BlockSize]
if _, err := io.ReadFull(rand.Reader, iv); err != nil {
return nil, err
}
stream := cipher.NewCFBEncrypter(block, iv)
stream.XORKeyStream(out[aes.BlockSize:], data)
return out, nil
}
func CFBDecrypt(key []byte, data[]byte) ([]byte, error) {
block, _ := aes.NewCipher([]byte(key))
iv := data[:aes.BlockSize]
data = data[aes.BlockSize:]
if len(data) % aes.BlockSize != 0 {
return nil, fmt.Errorf("data is not a multiple of the block size")
}
out := make([]byte, len(data))
mode := cipher.NewCFBDecrypter(block, iv)
mode.XORKeyStream(out, data)
out, _ = unpad(out)
return out, nil
}
3.6 GCM
GCM实现算法不需要pad。
func GCMEncrypt(key []byte, data[]byte) ([]byte, error) {
block, _ := aes.NewCipher([]byte(key))
aesgcm, _ := cipher.NewGCM(block)
nonce := make([]byte, aesgcm.NonceSize())
io.ReadFull(rand.Reader, nonce)
out := aesgcm.Seal(nonce, nonce, data, nil)
return out, nil
}
func GCMDecrypt(key []byte, data[]byte) ([]byte, error) {
block, _ := aes.NewCipher([]byte(key))
aesgcm, _ := cipher.NewGCM(block)
nonce, ciphertext := data[:aesgcm.NonceSize()], data[aesgcm.NonceSize():]
out, err := aesgcm.Open(nil, nonce, ciphertext, nil)
return out, nil
}
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