安全性之加密算法

浏览数：17 / 时间：2015年06月08日

信息安全越来越重要的今天，系统设计和开发过程当中必要的加密技术必不可少，根据项目中的实际经验总结一下实际项目中安全使用场景。

系统内部密码使用md5加密，密码不可逆，不可使用任何手段让任何人获取用户的密码，如果安全级别更高一些可以多次md5或混合加密。

特殊字段的安全保密使用对称加密算法，常用的有DES/AES，对于当今的计算机发展速度，DES加密相对已经容易被破解，所以推荐使用AES进行加解密。

.Net的DES加密算法实现

/// <summary>
        /// 获取密钥
        /// </summary>
        private static string Key
        {
            get { return @"ads{}[]19123456789123456789a},ds"; }
        }

        /// <summary>
        /// 获取向量
        /// </summary>
        private static string IV
        {
            get { return @"123456789{},‘;s"; }
        }

        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="plainStr">明文字符串</param>
        /// <returns>密文</returns>
        public static string AESEncrypt(string plainStr)
        {
            byte[] bKey = Encoding.UTF8.GetBytes(Key);
            byte[] bIV = Encoding.UTF8.GetBytes(IV);
            byte[] byteArray = Encoding.UTF8.GetBytes(plainStr);

            string encrypt = null;
            Rijndael aes = Rijndael.Create();
            try
            {
                using (MemoryStream mStream = new MemoryStream())
                {
                    using (CryptoStream cStream = new CryptoStream(mStream, aes.CreateEncryptor(bKey, bIV), CryptoStreamMode.Write))
                    {
                        cStream.Write(byteArray, 0, byteArray.Length);
                        cStream.FlushFinalBlock();
                        encrypt = Convert.ToBase64String(mStream.ToArray());
                    }
                }
            }
            catch { }
            aes.Clear();

            return encrypt;
        }

        /// <summary>
        /// AES加密
        /// </summary>
        /// <param name="plainStr">明文字符串</param>
        /// <param name="returnNull">加密失败时是否返回 null，false 返回 String.Empty</param>
        /// <returns>密文</returns>
        public static string AESEncrypt(string plainStr, bool returnNull)
        {
            string encrypt = AESEncrypt(plainStr);
            return returnNull ? encrypt : (encrypt == null ? String.Empty : encrypt);
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="encryptStr">密文字符串</param>
        /// <returns>明文</returns>
        public static string AESDecrypt(string encryptStr)
        {
            byte[] bKey = Encoding.UTF8.GetBytes(Key);
            byte[] bIV = Encoding.UTF8.GetBytes(IV);
            byte[] byteArray = Convert.FromBase64String(encryptStr);

            string decrypt = null;
            Rijndael aes = Rijndael.Create();
            try
            {
                using (MemoryStream mStream = new MemoryStream())
                {
                    using (CryptoStream cStream = new CryptoStream(mStream, aes.CreateDecryptor(bKey, bIV), CryptoStreamMode.Write))
                    {
                        cStream.Write(byteArray, 0, byteArray.Length);
                        cStream.FlushFinalBlock();
                        decrypt = Encoding.UTF8.GetString(mStream.ToArray());
                    }
                }
            }
            catch { }
            aes.Clear();

            return decrypt;
        }

        /// <summary>
        /// AES解密
        /// </summary>
        /// <param name="encryptStr">密文字符串</param>
        /// <param name="returnNull">解密失败时是否返回 null，false 返回 String.Empty</param>
        /// <returns>明文</returns>
        public static string AESDecrypt(string encryptStr, bool returnNull)
        {
            string decrypt = AESDecrypt(encryptStr);
            return returnNull ? decrypt : (decrypt == null ? String.Empty : decrypt);
        }

非对称加密.net的实现：

第一步:根据上面的原理性介绍，我们需要生成公钥(发信方需要)和私钥(收信方需要)，实现代码如下:
//制造公钥和私钥的方法如下:
RSACryptoServiceProvider crypt = new RSACryptoServiceProvider();
string  publickey = crypt.ToXmlString(false);//公钥
string  privatekey = crypt.ToXmlString(true);//私钥
crypt.Clear();
 
第二步:发信方使用公钥对明文进行加密，实现代码如下:
StreamReader sr = new StreamReader(Server.MapPath("a.txt"), UTF8Encoding.UTF8);
string readpublickey = sr.ReadToEnd(); //包含 RSA 密钥信息的 XML 字符串。
sr.Close();
UTF8Encoding enc = new UTF8Encoding();
byte[] bytes = enc.GetBytes(TextBox1.Text.Trim());
RSACryptoServiceProvider crypt = new RSACryptoServiceProvider();
crypt.FromXmlString(readpublickey);
bytes = crypt.Encrypt(bytes, false);
string encryttext = Convert.ToBase64String(bytes);
string abb = Server.UrlEncode(encryttext);
Response.Write("密文为:" + abb);
 
第三步:收信方使用私钥对密文进行解密，实现代码如下:
StreamReader sr = new StreamReader(Server.MapPath("b.txt"), UTF8Encoding.UTF8);
string readprivatekey = sr.ReadToEnd();
sr.Close();
RSACryptoServiceProvider crypt = new RSACryptoServiceProvider();
UTF8Encoding enc = new UTF8Encoding();
byte[] bytes = Convert.FromBase64String(@Server.UrlDecode(TextBox1.Text.Trim()));
crypt.FromXmlString(readprivatekey);
byte[] decryptbyte = crypt.Decrypt(bytes, false);
string decrypttext = enc.GetString(decryptbyte);
Response.Write("明文为:" + decrypttext);