C#之AES256位加密解密

原文：https://www.cnblogs.com/slyzly/articles/4548292.html

密码学中的高级加密标准（Advanced Encryption Standard，AES），又称Rijndael加密法，是美国联邦政府采用的一种区块加密标准。这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。

AES加密代码

/// <summary>
        /// AES加密
        /// </summary>
        /// <param name="encryptStr">明文</param>
        /// <param name="key">密钥</param>
        /// <returns></returns>
        public static string Encrypt(string encryptStr,string key)
        {
            byte[] keyArray = UTF8Encoding.UTF8.GetBytes(key);
            byte[] toEncryptArray = UTF8Encoding.UTF8.GetBytes(encryptStr);
            RijndaelManaged rDel = new RijndaelManaged();
            rDel.Key = keyArray;
            rDel.Mode = CipherMode.ECB;
            rDel.Padding = PaddingMode.PKCS7;
            ICryptoTransform cTransform = rDel.CreateEncryptor();
            byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
            return Convert.ToBase64String(resultArray, 0, resultArray.Length);
        }

AES解密代码

/// <summary>
        /// AES解密
        /// </summary>
        /// <param name="decryptStr">密文</param>
        /// <param name="key">密钥</param>
        /// <returns></returns>
        public static string Decrypt(string decryptStr,string key)
        {
            byte[] keyArray = UTF8Encoding.UTF8.GetBytes(key);
            byte[] toEncryptArray = Convert.FromBase64String(decryptStr);
            RijndaelManaged rDel = new RijndaelManaged();
            rDel.Key = keyArray;
            rDel.Mode = CipherMode.ECB;
            rDel.Padding = PaddingMode.PKCS7;
            ICryptoTransform cTransform = rDel.CreateDecryptor();
            byte[] resultArray = cTransform.TransformFinalBlock(toEncryptArray, 0, toEncryptArray.Length);
            return UTF8Encoding.UTF8.GetString(resultArray);
        }

主程序入口，测试代码

static void Main(string[] args)
        {
            string encryptStr,decryptStr, key;
            key = "ae125efkk4454eeff444ferfkny6oxi8";
            encryptStr = "C#AES加密字符串";
            Console.WriteLine("==============  256位AES加密  ============
");
            Console.WriteLine("加密前的字符串："+encryptStr);
            Console.WriteLine("密钥：" + key);
            Console.WriteLine();
            decryptStr = Program.Encrypt(encryptStr,key);
            Console.WriteLine("加密后的字符串：" + decryptStr);
            
            encryptStr = Program.Decrypt(decryptStr, key);
            Console.WriteLine("解密后的字符串：" + encryptStr);
            Console.ReadKey();
        }

注意事项

密钥必须是32个字符(非中文)，换句话说每个字符只能占1Byte。

基于向量的AES加密解密方法，采用CBC/PKCS5Padding加密

秘钥规则如下：
1、 algorithm采用“AES”。
2、 秘钥长度采用128byte，即秘钥固定16位字节。
3、 偏移量位固定值 。
4、 编码格式：UTF-8
5、 AES加密结果使用base64编码

        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="text">明文字符串</param>
        /// <param name="key">秘钥</param>
        /// <param name="iv">加密辅助向量</param>
        /// <returns>密文</returns>
        public static string AESEncrypt(string text, string key, string iv)
        {
            RijndaelManaged rijndaelCipher = new RijndaelManaged();
            rijndaelCipher.Mode = CipherMode.CBC;
            rijndaelCipher.Padding = PaddingMode.PKCS7;
            rijndaelCipher.KeySize = 128;
            rijndaelCipher.BlockSize = 128;
            byte[] pwdBytes = System.Text.Encoding.UTF8.GetBytes(key);
            byte[] keyBytes = new byte[16];
            int len = pwdBytes.Length;
            if (len > keyBytes.Length) len = keyBytes.Length;
            System.Array.Copy(pwdBytes, keyBytes, len);
            rijndaelCipher.Key = keyBytes;
            byte[] ivBytes = System.Text.Encoding.UTF8.GetBytes(iv);
            rijndaelCipher.IV = ivBytes;
            ICryptoTransform transform = rijndaelCipher.CreateEncryptor();
            byte[] plainText = Encoding.UTF8.GetBytes(text);
            byte[] cipherBytes = transform.TransformFinalBlock(plainText, 0, plainText.Length);
            return Convert.ToBase64String(cipherBytes);
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="text">加密字符串</param>
        /// <param name="key">秘钥</param>
        /// <param name="iv">加密辅助向量</param>
        /// <returns>明文</returns>
        public static string AESDecrypt(string text, string key, string iv)
        {
            RijndaelManaged rijndaelCipher = new RijndaelManaged();
            rijndaelCipher.Mode = CipherMode.CBC;
            rijndaelCipher.Padding = PaddingMode.PKCS7;
            rijndaelCipher.KeySize = 128;
            rijndaelCipher.BlockSize = 128;
            byte[] encryptedData = Convert.FromBase64String(text);
            byte[] pwdBytes = System.Text.Encoding.UTF8.GetBytes(key);
            byte[] keyBytes = new byte[16];
            int len = pwdBytes.Length;
            if (len > keyBytes.Length) len = keyBytes.Length;
            System.Array.Copy(pwdBytes, keyBytes, len);
            rijndaelCipher.Key = keyBytes;
            byte[] ivBytes = System.Text.Encoding.UTF8.GetBytes(iv);
            rijndaelCipher.IV = ivBytes;
            ICryptoTransform transform = rijndaelCipher.CreateDecryptor();
            byte[] plainText = transform.TransformFinalBlock(encryptedData, 0, encryptedData.Length);
            return Encoding.UTF8.GetString(plainText);
        }