golang中使用aes加密的过程

key := []byte("32-byte-long-key-here-1234567890") // AES-256 密钥

import (
    "crypto/aes"
    "crypto/cipher"
    "crypto/rand"
    "io"
)
func encrypt(plaintext []byte, key []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    // 填充数据到块大小
    plaintext = pkcs7Pad(plaintext, aes.BlockSize)
    // 生成随机 IV
    ciphertext := make([]byte, aes.BlockSize+len(plaintext))
    iv := ciphertext[:aes.BlockSize]
    if _, err := io.ReadFull(rand.Reader, iv); err != nil {
        return nil, err
    }
    // 加密
    mode := cipher.NewCBCEncrypter(block, iv)
    mode.CryptBlocks(ciphertext[aes.BlockSize:], plaintext)
    return ciphertext, nil
}
// PKCS7 填充
func pkcs7Pad(data []byte, blockSize int) []byte {
    padding := blockSize - len(data)%blockSize
    padText := bytes.Repeat([]byte{byte(padding)}, padding)
    return append(data, padText...)
}

func decrypt(ciphertext []byte, key []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    if len(ciphertext) < aes.BlockSize {
        return nil, fmt.Errorf("ciphertext too short")
    }
    iv := ciphertext[:aes.BlockSize]
    ciphertext = ciphertext[aes.BlockSize:]
    // 解密
    mode := cipher.NewCBCDecrypter(block, iv)
    mode.CryptBlocks(ciphertext, ciphertext)
    // 移除填充
    ciphertext = pkcs7Unpad(ciphertext)
    return ciphertext, nil
}
// PKCS7 去填充
func pkcs7Unpad(data []byte) []byte {
    length := len(data)
    unpadding := int(data[length-1])
    return data[:(length - unpadding)]
}

func encryptGCM(plaintext []byte, key []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    gcm, err := cipher.NewGCM(block)
    if err != nil {
        return nil, err
    }
    nonce := make([]byte, gcm.NonceSize())
    if _, err := io.ReadFull(rand.Reader, nonce); err != nil {
        return nil, err
    }
    return gcm.Seal(nonce, nonce, plaintext, nil), nil
}
func decryptGCM(ciphertext []byte, key []byte) ([]byte, error) {
    block, err := aes.NewCipher(key)
    if err != nil {
        return nil, err
    }
    gcm, err := cipher.NewGCM(block)
    if err != nil {
        return nil, err
    }
    nonceSize := gcm.NonceSize()
    if len(ciphertext) < nonceSize {
        return nil, fmt.Errorf("ciphertext too short")
    }
    nonce, ciphertext := ciphertext[:nonceSize], ciphertext[nonceSize:]
    return gcm.Open(nil, nonce, ciphertext, nil)
}