MD5 DES RSA

加密

MD5

不可逆加密，加密后可以是16位，也可以是32位，任何语言的MD5加密后结果相同。

private static string MD5(string str)
{
    var md5 = System.Security.Cryptography.MD5.Create();
    //计算字符串的散列值
    var bytes = md5.ComputeHash(Encoding.UTF8.GetBytes(str));
    var stringBuilder = new StringBuilder();
    foreach (var b in bytes)
    {
        stringBuilder.Append(b.ToString("x2"));
    }

    return stringBuilder.ToString();
}

DES

可逆对称加密，优点：速度快。缺点：密钥管理不方便，要求共享密钥。特点：不同写法对应的加密值不同。

    /// <summary>
    /// DES  for encryption and decryption
    /// </summary>
    public static class DesHelper
    {
        /// <summary>
        /// DES encryption
        /// </summary>
        /// <param name="pToEncrypt"></param>
        /// <returns></returns>
        public static string DesEncrypt(string pToEncrypt)
        {
            var sKey = GetKey();
            var des = new DESCryptoServiceProvider();
            var inputByteArray = Encoding.Default.GetBytes(pToEncrypt);
            des.Key = Encoding.ASCII.GetBytes(sKey);
            des.IV = Encoding.ASCII.GetBytes(sKey);
            var ms = new MemoryStream();
            var cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            var ret = new StringBuilder();
            foreach (var b in ms.ToArray())
            {
                ret.AppendFormat("{0:X2}", b);
            }
            return ret.ToString();
        }

        /// <summary>
        /// DES decryption
        /// </summary>
        /// <param name="pToDecrypt"></param>
        /// <returns></returns>
        public static string DesDecrypt(string pToDecrypt)
        {
            var sKey = GetKey();
            var des = new DESCryptoServiceProvider();
            var inputByteArray = new byte[pToDecrypt.Length / 2];
            for (var x = 0; x < pToDecrypt.Length / 2; x++)
            {
                var i = (Convert.ToInt32(pToDecrypt.Substring(x * 2, 2), 16));
                inputByteArray[x] = (byte)i;
            }
            des.Key = Encoding.ASCII.GetBytes(sKey);
            des.IV = Encoding.ASCII.GetBytes(sKey);
            var ms = new MemoryStream();
            var cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write);
            cs.Write(inputByteArray, 0, inputByteArray.Length);
            cs.FlushFinalBlock();
            return Encoding.Default.GetString(ms.ToArray());
        }

        /// <summary>
        /// get Key
        /// </summary>
        /// <returns></returns>
        private static string GetKey()
        {
            return "str";
        }
    }

RSA

可逆非对称加密，需要两个key,公钥和私钥，每次产生的公钥和私钥不一致，加密的结果就不一致

优点：密钥方便管理，缺点：速度慢

特性：需要通过代码生成一对公钥（加密key）和私钥（解密key，公钥私钥只与是否公开有关：

A：如果公开公钥（加密key）：只有我接受加密信息才有用，因为只有我有私钥（解密key），能解密。

B：如果公开私钥（解密key）：用于签名，表示加密数据一定是我发的，因为只有公钥（加密key）。

 

public static class RsaEncrypt
{
    /// <summary>
    /// 生成公钥和私钥
    /// </summary>
    /// <returns></returns>
    public static KeyValuePair<string, string> GetKeyPair()
    {
        var rsa = new RSACryptoServiceProvider();
        var publicKey = rsa.ToXmlString(false);
        var privateKey = rsa.ToXmlString(true);
        return new KeyValuePair<string, string>(publicKey, privateKey);
    }

    /// <summary>
    /// 加密：内容+公钥,事先需要生成公钥和私钥
    /// </summary>
    /// <param name="content">加密内容</param>
    /// <param name="publicKey">公钥</param>
    /// <returns></returns>
    public static string Encrypt(string content, string publicKey)
    {
        var rsa = new RSACryptoServiceProvider();
        rsa.FromXmlString(publicKey);
        var unicodeEncoding = new UnicodeEncoding();
        var dataToEncrypt = unicodeEncoding.GetBytes(content);
        var resultBytes = rsa.Encrypt(dataToEncrypt, false);
        return Convert.ToBase64String(resultBytes);
    }

    /// <summary>
    /// 解密-内容+私钥
    /// </summary>
    /// <param name="content"></param>
    /// <param name="privateKey"></param>
    /// <returns></returns>
    public static string Decrypt(string content, string privateKey)
    {
        var dataToDecrypt = Convert.FromBase64String(content);
        var rsa = new RSACryptoServiceProvider();
        rsa.FromXmlString(privateKey);
        var resultBytes = rsa.Decrypt(dataToDecrypt, false);
        var byteConverter = new UnicodeEncoding();
        return byteConverter.GetString(resultBytes);
    }
}

//调用
static void Main()
{
    //方式一：先生成公钥和私钥,然后加密和解密
    //KeyValuePair是一个键值对, myKey.Key 代表的公钥；myKey.Value 代表的私钥
    var myKey = RsaEncrypt.GetKeyPair();
    var msg1 = "mr1";
    //加密
    var result1 = RsaEncrypt.Encrypt(msg1, myKey.Key);
    //解密
    var result2 = RsaEncrypt.Decrypt(result1, myKey.Value);
    Console.WriteLine(result1);
    Console.WriteLine(result2);
    Console.Read();
}