加密算法解析：MD5、DES和RAS的工作原理与特点-五八三

一、MD5不可逆加密

1.1-理解MD5

MD5公开的算法，任何语言实现后其实都是一样的、通用的
不可逆加密：原文——加密——密文，密文无法解密出原文

1.2-MD5封装

using System.IO;using System.Security.Cryptography;	 	/// <summary>    /// 不可逆加密    /// 1 防止被篡改    /// 2 防止明文存储    /// 3 防止抵赖，数字签名    /// </summary>    public class MD5Encrypt    {        #region MD5        /// <summary>        /// MD5加密,和动网上的16/32位MD5加密结果相同,        /// 使用的UTF8编码        /// </summary>        /// <param name="source">待加密字串</param>        /// <param name="length">16或32值之一,其它则采用.net默认MD5加密算法</param>        /// <returns>加密后的字串</returns>        public static string Encrypt(string source, int length = 32)//默认参数        {            if (string.IsNullOrEmpty(source)) return string.Empty;            HashAlgorithm provider = CryptoConfig.CreateFromName("MD5") as HashAlgorithm;            byte[] bytes = Encoding.UTF8.GetBytes(source);//这里需要区别编码的            byte[] hashValue = provider.ComputeHash(bytes);            StringBuilder sb = new StringBuilder();            switch (length)            {                case 16://16位密文是32位密文的9到24位字符                    for (int i = 4; i < 12; i++)                    {                        sb.Append(hashValue[i].ToString("x2"));                    }                    break;                case 32:                    for (int i = 0; i < 16; i++)                    {                        sb.Append(hashValue[i].ToString("x2"));                    }                    break;                default:                    for (int i = 0; i < hashValue.Length; i++)                    {                        sb.Append(hashValue[i].ToString("x2"));                    }                    break;            }            return sb.ToString();        }        #endregion MD5         #region MD5摘要        /// <summary>        /// 获取文件的MD5摘要        /// </summary>        /// <param name="fileName"></param>        /// <returns></returns>        public static string AbstractFile(string fileName)        {            using (FileStream file = new FileStream(fileName, FileMode.Open))            {                return AbstractFile(file);            }        }                /// <summary>        /// 根据stream获取文件摘要        /// </summary>        /// <param name="stream"></param>        /// <returns></returns>        public static string AbstractFile(Stream stream)        {            MD5 md5 = new MD5CryptoServiceProvider();            byte[] retVal = md5.ComputeHash(stream);             StringBuilder sb = new StringBuilder();            for (int i = 0; i < retVal.Length; i++)            {                sb.Append(retVal[i].ToString("x2"));            }            return sb.ToString();        }        #endregion    }

1.3-MD5总结

相同原文加密的结果是一样的
不同长度的内容加密后都是32位，可以自行改变长度
原文件改动差别很小，结果差别很大
不管文件多大，都能产生32位长度的【摘要】，就是更具文件流进行加密的结果
- 文件内容有一点改动，结果变化非常大
- 文件内容不变，文件名变了，结果是不变的

1.4-MD5用途？

防篡改
1. 源代码管理器
2. 急速秒传
  1. 在本地进行MD5摘要，到服务器上去检查，如果存在就不需要上传，直接在服务器上复制一份，或者指向路径跳转一下。
密码保存：防止看到明文
1. 密文是可见的，所以要求密码不能太检查；加盐（特殊字符+字母+数字）
2. MD5是无法全部穷举出来的，无法全部解密出来的，像网上有很多这种；

防止抵赖，数字签名
1. 吧一些内容摘要一下，不能抵赖。

二、对称可逆加密DES

2.1-理解DES

对称可逆加密是公开的算法，任何语言实现后其实都一样，通用的。
加密后能解密会原文，但是需要一个Key
加密key和加密Key是同一个，也就是开门和锁门都要用同一吧钥匙
优点：加密解密的速度快
缺点：问题是秘钥的安全（key在网络中传输呗窃取），不是很安全

理解什么是对称可逆加密：

对称：加密/解密是key要一模一样的
可逆：原文加密到密文，密文解密到原文

2.2-DES封装

 	/// <summary>    /// Des加密    /// </summary>    public class DesCrypto    {         //密钥        private const string sKey = "qJzGEh6hESZDVJeCnFPGuxzaiB7NLQM3";        //矢量，矢量可以为空        private const string sIV = "qcDY6X+aPLw=";          //构造一个对称算法        private SymmetricAlgorithm mCSP = new TripleDESCryptoServiceProvider();         /// <summary>        /// 构造函数        /// </summary>        public DesCrypto() {                }         #region public string EncryptString(string Value)        /// <summary>        /// 加密字符串        /// </summary>        /// <param name="Value">输入的字符串</param>        /// <returns>加密后的字符串</returns>        public string EncryptString(string Value)        {            ICryptoTransform ct;            MemoryStream ms;            CryptoStream cs;            byte[] byt;            mCSP.Key = Convert.FromBase64String(sKey);            mCSP.IV = Convert.FromBase64String(sIV);            //指定加密的运算模式            mCSP.Mode = System.Security.Cryptography.CipherMode.ECB;            //获取或设置加密算法的填充模式            mCSP.Padding = System.Security.Cryptography.PaddingMode.PKCS7;            ct = mCSP.CreateEncryptor(mCSP.Key, mCSP.IV);            byt = Encoding.UTF8.GetBytes(Value);            ms = new MemoryStream();            cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);            cs.Write(byt, 0, byt.Length);            cs.FlushFinalBlock();            cs.Close();            return Convert.ToBase64String(ms.ToArray());        }        #endregion          #region public string DecryptString(string Value)        /// <summary>        /// 解密字符串        /// </summary>        /// <param name="Value">加过密的字符串</param>        /// <returns>解密后的字符串</returns>        public string DecryptString(string Value)        {            ICryptoTransform ct;            MemoryStream ms;            CryptoStream cs;            byte[] byt;            mCSP.Key = Convert.FromBase64String(sKey);            mCSP.IV = Convert.FromBase64String(sIV);            mCSP.Mode = System.Security.Cryptography.CipherMode.ECB;            mCSP.Padding = System.Security.Cryptography.PaddingMode.PKCS7;            ct = mCSP.CreateDecryptor(mCSP.Key, mCSP.IV);            byt = Convert.FromBase64String(Value);            ms = new MemoryStream();            cs = new CryptoStream(ms, ct, CryptoStreamMode.Write);            cs.Write(byt, 0, byt.Length);            cs.FlushFinalBlock();            cs.Close();            return Encoding.UTF8.GetString(ms.ToArray());        }        #endregion    }

三、非对称可逆加密RSA

2.1-理解RSA

非对称可逆加密公开的算法，任何语言实现后其实都一样，通用的；
加密key和解密key不是一个，而是一对
加密key和解密key不能相互推到，有密文，没有解密key，也推导不出原文
缺点：速度不快
优点：安全性好

2.2-RSA封装

/// <summary>    /// RSA加密解密及RSA签名和验证    /// </summary>    public class RsaEncrypt    {         public RsaEncrypt()        {        }         #region RSA 的密钥产生        /// <summary>        /// RSA 的密钥产生 产生私钥 和公钥        /// </summary>        /// <param name="xmlKeys"></param>        /// <param name="xmlPublicKey"></param>        public void RSAKey(out string xmlKeys, out string xmlPublicKey)        {            System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();            xmlKeys = rsa.ToXmlString(true);            xmlPublicKey = rsa.ToXmlString(false);        }        #endregion          #region RSA的加密函数        //##############################################################################        //RSA 方式加密        //说明KEY必须是XML的行式,返回的是字符串        //在有一点需要说明！！该加密方式有 长度 限制的！！        //##############################################################################         //RSA的加密函数  string        public string RSAEncrypt(string xmlPublicKey, string m_strEncryptString)        {             byte[] PlainTextBArray;            byte[] CypherTextBArray;            string Result;            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();            rsa.FromXmlString(xmlPublicKey);            PlainTextBArray = (new UnicodeEncoding()).GetBytes(m_strEncryptString);            CypherTextBArray = rsa.Encrypt(PlainTextBArray, false);            Result = Convert.ToBase64String(CypherTextBArray);            return Result;         }         //RSA的加密函数 byte[]        public string RSAEncrypt(string xmlPublicKey, byte[] EncryptString)        {             byte[] CypherTextBArray;            string Result;            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();            rsa.FromXmlString(xmlPublicKey);            CypherTextBArray = rsa.Encrypt(EncryptString, false);            Result = Convert.ToBase64String(CypherTextBArray);            return Result;        }        #endregion          #region RSA的解密函数        //RSA的解密函数  string        public string RSADecrypt(string xmlPrivateKey, string m_strDecryptString)        {            byte[] PlainTextBArray;            byte[] DypherTextBArray;            string Result;            System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();            rsa.FromXmlString(xmlPrivateKey);            PlainTextBArray = Convert.FromBase64String(m_strDecryptString);            DypherTextBArray = rsa.Decrypt(PlainTextBArray, false);            Result = (new UnicodeEncoding()).GetString(DypherTextBArray);            return Result;        }         //RSA的解密函数  byte        public string RSADecrypt(string xmlPrivateKey, byte[] DecryptString)        {            byte[] DypherTextBArray;            string Result;            System.Security.Cryptography.RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();            rsa.FromXmlString(xmlPrivateKey);            DypherTextBArray = rsa.Decrypt(DecryptString, false);            Result = (new UnicodeEncoding()).GetString(DypherTextBArray);            return Result;         }        #endregion          #region RSA数字签名            #region 获取Hash描述表            //获取Hash描述表 ，outofmemory.cn            public bool GetHash(string m_strSource, ref byte[] HashData)            {                //从字符串中取得Hash描述                byte[] Buffer;                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");                Buffer = System.Text.Encoding.GetEncoding("GB2312").GetBytes(m_strSource);                HashData = MD5.ComputeHash(Buffer);                 return true;            }             //获取Hash描述表            public bool GetHash(string m_strSource, ref string strHashData)            {                 //从字符串中取得Hash描述                byte[] Buffer;                byte[] HashData;                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");                Buffer = System.Text.Encoding.GetEncoding("GB2312").GetBytes(m_strSource);                HashData = MD5.ComputeHash(Buffer);                 strHashData = Convert.ToBase64String(HashData);                return true;             }             //获取Hash描述表            public bool GetHash(System.IO.FileStream objFile, ref byte[] HashData)            {                 //从文件中取得Hash描述                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");                HashData = MD5.ComputeHash(objFile);                objFile.Close();                 return true;             }             //获取Hash描述表            public bool GetHash(System.IO.FileStream objFile, ref string strHashData)            {                 //从文件中取得Hash描述                byte[] HashData;                System.Security.Cryptography.HashAlgorithm MD5 = System.Security.Cryptography.HashAlgorithm.Create("MD5");                HashData = MD5.ComputeHash(objFile);                objFile.Close();                 strHashData = Convert.ToBase64String(HashData);                 return true;             }            #endregion             #region RSA签名            //RSA签名            public bool SignatureFormatter(string p_strKeyPrivate, byte[] HashbyteSignature, ref byte[] EncryptedSignatureData)            {                 System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPrivate);                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);                //设置签名的算法为MD5                RSAFormatter.SetHashAlgorithm("MD5");                //执行签名                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);                 return true;             }             //RSA签名            public bool SignatureFormatter(string p_strKeyPrivate, byte[] HashbyteSignature, ref string m_strEncryptedSignatureData)            {                 byte[] EncryptedSignatureData;                 System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPrivate);                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);                //设置签名的算法为MD5                RSAFormatter.SetHashAlgorithm("MD5");                //执行签名                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);                 m_strEncryptedSignatureData = Convert.ToBase64String(EncryptedSignatureData);                 return true;             }             //RSA签名            public bool SignatureFormatter(string p_strKeyPrivate, string m_strHashbyteSignature, ref byte[] EncryptedSignatureData)            {                 byte[] HashbyteSignature;                 HashbyteSignature = Convert.FromBase64String(m_strHashbyteSignature);                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPrivate);                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);                //设置签名的算法为MD5                RSAFormatter.SetHashAlgorithm("MD5");                //执行签名                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);                 return true;             }             //RSA签名            public bool SignatureFormatter(string p_strKeyPrivate, string m_strHashbyteSignature, ref string m_strEncryptedSignatureData)            {                 byte[] HashbyteSignature;                byte[] EncryptedSignatureData;                 HashbyteSignature = Convert.FromBase64String(m_strHashbyteSignature);                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPrivate);                System.Security.Cryptography.RSAPKCS1SignatureFormatter RSAFormatter = new System.Security.Cryptography.RSAPKCS1SignatureFormatter(RSA);                //设置签名的算法为MD5                RSAFormatter.SetHashAlgorithm("MD5");                //执行签名                EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature);                 m_strEncryptedSignatureData = Convert.ToBase64String(EncryptedSignatureData);                 return true;             }            #endregion             #region RSA 签名验证            public bool SignatureDeformatter(string p_strKeyPublic, byte[] HashbyteDeformatter, byte[] DeformatterData)            {                 System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPublic);                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);                //指定解密的时候HASH算法为MD5                RSADeformatter.SetHashAlgorithm("MD5");                 if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))                {                    return true;                }                else                {                    return false;                }             }             public bool SignatureDeformatter(string p_strKeyPublic, string p_strHashbyteDeformatter, byte[] DeformatterData)            {                 byte[] HashbyteDeformatter;                 HashbyteDeformatter = Convert.FromBase64String(p_strHashbyteDeformatter);                 System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPublic);                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);                //指定解密的时候HASH算法为MD5                RSADeformatter.SetHashAlgorithm("MD5");                 if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))                {                    return true;                }                else                {                    return false;                }             }             public bool SignatureDeformatter(string p_strKeyPublic, byte[] HashbyteDeformatter, string p_strDeformatterData)            {                 byte[] DeformatterData;                 System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPublic);                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);                //指定解密的时候HASH算法为MD5                RSADeformatter.SetHashAlgorithm("MD5");                 DeformatterData = Convert.FromBase64String(p_strDeformatterData);                 if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))                {                    return true;                }                else                {                    return false;                }             }             public bool SignatureDeformatter(string p_strKeyPublic, string p_strHashbyteDeformatter, string p_strDeformatterData)            {                 byte[] DeformatterData;                byte[] HashbyteDeformatter;                 HashbyteDeformatter = Convert.FromBase64String(p_strHashbyteDeformatter);                System.Security.Cryptography.RSACryptoServiceProvider RSA = new System.Security.Cryptography.RSACryptoServiceProvider();                 RSA.FromXmlString(p_strKeyPublic);                System.Security.Cryptography.RSAPKCS1SignatureDeformatter RSADeformatter = new System.Security.Cryptography.RSAPKCS1SignatureDeformatter(RSA);                //指定解密的时候HASH算法为MD5                RSADeformatter.SetHashAlgorithm("MD5");                 DeformatterData = Convert.FromBase64String(p_strDeformatterData);                 if (RSADeformatter.VerifySignature(HashbyteDeformatter, DeformatterData))                {                    return true;                }                else                {                    return false;                }             }            #endregion        #endregion    }