C#中常用加密算法、md5、sha1、rsa、base64、des 简介本文主要讲解一下C#常用的那些加密算法，包括MD5加密、SHA1加密、Base64加密、Des加密、RSA加密等，需要的朋友可以参考下MD5MD5加密是最常见的加密方式，因为MD5是不可逆的，所以很多系统的密码都是用MD5加密保存的。虽然MD5是不可以解码的，但因为MD5加密的字符串是固定的，所以，理论上只需要建立一个庞大的数据库，把所有的字符串都加密一遍，那就可以解码所有的MD5密文了。虽然建立一个可以解码全部MD5的数据库不太现实，但一个五六百亿数据量的数据库就可以解码绝大部分字符串了，毕竟大部分情况下，我们的密码也是有长度限制的。实际应用中MD5有64位和32位加密之分。public static string GetMd532(string ConvertString) { MD5CryptoServiceProvider md5 = new MD5CryptoServiceProvider(); string t2 = BitConverter.ToString(md5.ComputeHash(UTF8Encoding.Default.GetBytes(ConvertString)), 4, 8); t2 = t2.Replace("-", ""); return t2; } public static string Get64Md5(string str) { string cl = str; string pwd = ""; var md5 = MD5.Create(); byte[] s = md5.ComputeHash(Encoding.UTF8.GetBytes(cl)); for (int i = 0; i < s.Length; i++) { pwd = pwd + s[i].ToString("X2"); } return pwd; } SHA1SHA1加密算法与MD5加密类似，都是不可逆的，只是算法不同。所以也和MD5一样，存在容易被大数据解码的问题。private static readonly Encoding Encoder = Encoding.UTF8; public static String Sha1(String content ) { try { SHA1 sha1 = new SHA1CryptoServiceProvider();//创建SHA1对象 byte[] bytes_in = Encoder.GetBytes(content);//将待加密字符串转为byte类型 byte[] bytes_out = sha1.ComputeHash(bytes_in);//Hash运算 sha1.Dispose();//释放当前实例使用的所有资源 String result = BitConverter.ToString(bytes_out);//将运算结果转为string类型 result = result.Replace("-", "").ToUpper(); return result; } catch (Exception ex) { return ex.Message; } }Base64准确的来说，Base64是一种编码，而不是加密，通常Base64编码后字符串会用于传输数据。不过也因为Base64编码后字符串具有不可读性，所以，不少人也把他当做加密算法来使用。 private static readonly Encoding Encoder = Encoding.UTF8; /// <summary> /// base64编码 /// </summary> /// <param name="result"></param> /// <returns></returns> public static string EncodeBase64(string source) { string target = ""; byte[] bytes = Encoder.GetBytes(source); try { target = Convert.ToBase64String(bytes); } catch { target = source; } return target; } /// <summary> /// base64解码 /// </summary> /// <param name="result"></param> /// <returns></returns> public static string DecodeBase64(string result) { string decode = ""; byte[] bytes = Convert.FromBase64String(result); try { decode = Encoder.GetString(bytes); } catch { decode = result; } return decode; } DESDES加密算法是对密钥进行保密，而公开算法，即只有拥有相同密钥的人才能解密。DES加密算法对密钥有要求，必须是8个字符，如12345678这样的。DESCryptoServiceProvider类的Mode属性可以指定加密运算模式，加密运算模式如下。CBC：密码块链模式。ECB：电子密码本模式。OFB：输出反馈模式。CFB：密码反馈模式。CTS：密码文本窃取模式。public static string Encrypt(string stringToEncrypt, string shortKey) { DESCryptoServiceProvider des = new DESCryptoServiceProvider(); byte[] inputByteArray = Encoding.GetEncoding("UTF-8").GetBytes(stringToEncrypt); des.Key = ASCIIEncoding.UTF8.GetBytes(shortKey); des.IV = ASCIIEncoding.UTF8.GetBytes(shortKey); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(), CryptoStreamMode.Write); cs.Write(inputByteArray, 0, inputByteArray.Length); cs.FlushFinalBlock(); StringBuilder ret = new StringBuilder(); foreach (byte b in ms.ToArray()) { ret.AppendFormat("{0:X2}", b); } ret.ToString(); return ret.ToString(); } public static string Decrypt(string stringToDecrypt, string sKey) { DESCryptoServiceProvider des = new DESCryptoServiceProvider(); byte[] inputByteArray = new byte[stringToDecrypt.Length / 2]; for (int x = 0; x < stringToDecrypt.Length / 2; x++) { int i = (Convert.ToInt32(stringToDecrypt.Substring(x * 2, 2), 16)); inputByteArray[x] = (byte)i; } des.Key = ASCIIEncoding.UTF8.GetBytes(sKey); des.IV = ASCIIEncoding.UTF8.GetBytes(sKey); MemoryStream ms = new MemoryStream(); CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(), CryptoStreamMode.Write); cs.Write(inputByteArray, 0, inputByteArray.Length); cs.FlushFinalBlock(); StringBuilder ret = new StringBuilder(); return System.Text.Encoding.Default.GetString(ms.ToArray()); }RSARSA加密采用公钥加密，私钥解密的模式。Https的数字证书也是使用这种模式加密的。public static string RSADecrypt(string xmlPrivateKey, string enptStr) { RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); provider.FromXmlString(xmlPrivateKey); byte[] rgb = Convert.FromBase64String(enptStr); byte[] bytes = provider.Decrypt(rgb, RSAEncryptionPadding.OaepSHA1); return new UnicodeEncoding().GetString(bytes); } public static string RSAEncrypt(string xmlPublicKey, string enptStr) { RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); provider.FromXmlString(xmlPublicKey); byte[] bytes = new UnicodeEncoding().GetBytes(enptStr); return Convert.ToBase64String(provider.Encrypt(bytes, RSAEncryptionPadding.OaepSHA1)); }但是RSA加密有个特点，就是他对被加密的字符串有长度限制；待加密的字节数不能超过密钥的长度值除以8再减去11（即：RSACryptoServiceProvider.KeySize / 8 - 11，而加密后得到密文的字节数，正好是密钥的长度值除以 8（即：RSACryptoServiceProvider.KeySize / 8）。注：该长度指的是byte[]数组的长度，而不是字符串的长度，简单来说，就是被加密字符串不能太长。但是，在真实的业务中，我们需要加密的字符串往往会很长，那么，RSA又对被加密字符串有长度限制，我们该怎么办呢？很简单，把待加密的字符串拆开，每段长度都小于等于限制长度，然后分段加密，这样，问题就解决了。public static String SubRSAEncrypt(string xmlPublicKey, string enptStr) { RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); provider.FromXmlString(xmlPublicKey); Byte[] bytes = Encoder.GetBytes(enptStr); int MaxBlockSize = provider.KeySize / 8 - 11; //加密块最大长度限制 if (bytes.Length <= MaxBlockSize) return Convert.ToBase64String(provider.Encrypt(bytes, false)); using (MemoryStream PlaiStream = new MemoryStream(bytes)) using (MemoryStream CrypStream = new MemoryStream()) { Byte[] Buffer = new Byte[MaxBlockSize]; int BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize); while (BlockSize > 0) { Byte[] ToEncrypt = new Byte[BlockSize]; Array.Copy(Buffer, 0, ToEncrypt, 0, BlockSize); Byte[] Cryptograph = provider.Encrypt(ToEncrypt, false); CrypStream.Write(Cryptograph, 0, Cryptograph.Length); BlockSize = PlaiStream.Read(Buffer, 0, MaxBlockSize); } return Convert.ToBase64String(CrypStream.ToArray(), Base64FormattingOptions.None); } } /// /// 分段解密，应对长字符串 /// /// /// /// public static String SubRSADecrypt(string xmlPublicKey, string enptStr) { RSACryptoServiceProvider provider = new RSACryptoServiceProvider(); provider.FromXmlString(xmlPublicKey); Byte[] bytes = Convert.FromBase64String(enptStr); int MaxBlockSize = provider.KeySize / 8; //解密块最大长度限制 if (bytes.Length <= MaxBlockSize) return Encoder.GetString(provider.Decrypt(bytes, false)); using (MemoryStream CrypStream = new MemoryStream(bytes)) using (MemoryStream PlaiStream = new MemoryStream()) { Byte[] Buffer = new Byte[MaxBlockSize]; int BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize); while (BlockSize > 0) { Byte[] ToDecrypt = new Byte[BlockSize]; Array.Copy(Buffer, 0, ToDecrypt, 0, BlockSize); Byte[] Plaintext = provider.Decrypt(ToDecrypt, false); PlaiStream.Write(Plaintext, 0, Plaintext.Length); BlockSize = CrypStream.Read(Buffer, 0, MaxBlockSize); } return Encoder.GetString(PlaiStream.ToArray()); } }