crypto.go

package eutil

import (
	"bytes"
	"crypto/aes"
	"crypto/cipher"
	"crypto/md5"
	"crypto/sha256"
	"crypto/sha512"
	"encoding/hex"
)

func MD5(content string) string {
	h := md5.New()
	h.Write([]byte(content))
	return hex.EncodeToString(h.Sum(nil))
}

func SHA256(content string) string {
	h := sha256.New()
	h.Write([]byte(content))
	return hex.EncodeToString(h.Sum(nil))
}

func SHA512(content string) string {
	h := sha512.New()
	h.Write([]byte(content))
	return hex.EncodeToString(h.Sum(nil))
}

func pkcs7Padding(data []byte, blockSize int) []byte {
	padding := blockSize - len(data)%blockSize
	padtext := bytes.Repeat([]byte{byte(padding)}, padding)
	return append(data, padtext...)
}

// AES加密函数
func AesEncrypt(plaintext []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	blockSize := block.BlockSize()
	plaintext = pkcs7Padding(plaintext, blockSize)

	ciphertext := make([]byte, len(plaintext))
	mode := cipher.NewCBCEncrypter(block, key[:blockSize])
	mode.CryptBlocks(ciphertext, plaintext)

	return ciphertext, nil
}

// 去填充函数，去除填充的数据
func pkcs7Unpadding(data []byte) []byte {
	length := len(data)
	unpadding := int(data[length-1])
	return data[:length-unpadding]
}

// AES解密函数
func AesDecrypt(ciphertext []byte, key []byte) ([]byte, error) {
	block, err := aes.NewCipher(key)
	if err != nil {
		return nil, err
	}

	blockSize := block.BlockSize()
	mode := cipher.NewCBCDecrypter(block, key[:blockSize])

	plaintext := make([]byte, len(ciphertext))
	mode.CryptBlocks(plaintext, ciphertext)

	plaintext = pkcs7Unpadding(plaintext)

	return plaintext, nil
}