Golang AES-256-CBC加密和解密

[hunter-ji]

一. 前言

项目开发中遇到该问题，网上的文章太乱，为了节省下次踩坑时间，特此记录。

二. 加解密

1. 填充函数

该函数在加解密中都需要用到。

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

2. 加密

func Ase256Encrypt(plaintext string, key string, iv string, blockSize int) string {
    bKey := []byte(key)
    bIV := []byte(iv)
    bPlaintext := PKCS5Padding([]byte(plaintext), blockSize)
    block, _ := aes.NewCipher(bKey)
    ciphertext := make([]byte, len(bPlaintext))
    mode := cipher.NewCBCEncrypter(block, bIV)
    mode.CryptBlocks(ciphertext, bPlaintext)

    return base64.StdEncoding.EncodeToString(ciphertext)
}

3. 解密

func Aes256Decrypt(cryptData, key, iv string) ([]byte, error) {
    ciphertext, err := base64.StdEncoding.DecodeString(cryptData)
    if err != nil {
        return nil, err
    }

    block, err := aes.NewCipher([]byte(key))
    if err != nil {
        return nil, err
    }

    if len(ciphertext)%aes.BlockSize != 0 {
        err = errors.New("ciphertext is not a multiple of the block size")
        return nil, err
    }

    mode := cipher.NewCBCDecrypter(block, []byte(iv))
    mode.CryptBlocks(ciphertext, ciphertext)

    return ciphertext, err
}

4. 全部代码

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

// 加密
func Ase256(plaintext string, key string, iv string, blockSize int) string {
    bKey := []byte(key)
    bIV := []byte(iv)
    bPlaintext := PKCS5Padding([]byte(plaintext), blockSize)
    block, _ := aes.NewCipher(bKey)
    ciphertext := make([]byte, len(bPlaintext))
    mode := cipher.NewCBCEncrypter(block, bIV)
    mode.CryptBlocks(ciphertext, bPlaintext)

    return base64.StdEncoding.EncodeToString(ciphertext)
}

// 解密
func Aes256Decrypt(cryptData, key, iv string) ([]byte, error) {
    ciphertext, err := base64.StdEncoding.DecodeString(cryptData)
    if err != nil {
        return nil, err
    }

    block, err := aes.NewCipher([]byte(key))
    if err != nil {
        return nil, err
    }

    if len(ciphertext)%aes.BlockSize != 0 {
        err = errors.New("ciphertext is not a multiple of the block size")
        return nil, err
    }

    mode := cipher.NewCBCDecrypter(block, []byte(iv))
    mode.CryptBlocks(ciphertext, ciphertext)

    return ciphertext, err
}

三. 调用

1. 加密

result := Ase256Encrypt("<需要加密的数据>", "<key>", "<iv>", aes.BlockSize)

2. 解密

result, err := Aes256Decrypt("<需要解密的数据>", "<key>", "<iv>")