标签:sae action from 标准 等价 相同 image name close
一:非对称加密的由来
RSA公钥加密算法是1977年由Ron Rivest、Adi Shamirh和LenAdleman在(美国麻省理工学院)开发的。RSA取名来自开发他们三者的名字。RSA是目前最有影响力的公钥加密算法,它能够抵抗到目前为止已知的所有密码攻击,已被ISO推荐为公钥数据加密标准。RSA算法基于一个十分简单的数论事实:将两个大素数相乘十分容易,但那时想要对其乘积进行因式分解却极其困难,因此可以将乘积公开作为加密密钥。RSA算法是第一个能同时用于加密和数字签名的算法,也易于理解和操作。
RSA是被研究得最广泛的公钥算法,从提出到现在已近二十年,经历了各种攻击的考验,逐渐为人们接受,普遍认为是目前最优秀的公钥方案之一。RSA的安全性依赖于大数的因子分解,但并没有从理论上证明破译RSA的难度与大数分解难度等价。即RSA的重大缺陷是无法从理论上把握它的保密性能如何,而且密码学界多数人士倾向于因子分解不是NPC问题。
二:RSA的缺点主要有:
A)产生密钥很麻烦,受到素数产生技术的限制,因而难以做到一次一密。
B)分组长度太大,为保证安全性,n 至少也要 600bits以上,使运算代价很高,尤其是速度较慢,较对称密码算法慢几个数量级;且随着大数分解技术的发展,这个
长度还在增加,不利于数据格式的标准化。目前,SET(Secure Electronic Transaction)协议中要求CA采用2048bits长的密钥,其他实体使用1024比特的密钥。C)RSA密钥长度随着保密级别提高,增加很快。下表列出了对同一安全级别所对应的密钥长度。
保密级别 | 对称密钥长度(bit) | RSA密钥长度(bit) | ECC密钥长度(bit) | 保密年限 |
80 | 80 | 1024 | 160 | 2010 |
112 | 112 | 2048 | 224 | 2030 |
128 | 128 | 3072 | 256 | 2040 |
192 | 192 | 7680 | 384 | 2080 |
256 | 256 | 15360 | 512 | 2120 |
三:算法操作
RSA算法是一种非对称密码算法,所谓非对称,就是指该算法需要一对密钥,使用其中一个加密,则需要用另一个才能解密。
四:算法栗子
//非对称加密 public class RSAEncrypted { /// <summary> /// RSA产生密钥 /// </summary> public void RSAKey() { try { RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); var xmlKeys = rsa.ToXmlString(true); var xmlPublicKey = rsa.ToXmlString(false); var str = "明月几时有,把酒问青天,不知道天上今夕是何年"; //1.1有长度限制的加密 var cipherText = RSAEncryptLimitLength(xmlPublicKey, str); //1.2有长度限制的解密 var txt = RSADecryptLimitLength(xmlKeys, cipherText); //2.1加密 var cipherText1 = RSAEncrypt(xmlPublicKey, str); var txt1 = RSADecrypt(xmlKeys, cipherText1); //3.1字符串,hash描述表 //var hashTxt = GetHashStr(str); //3.1文件,hash描述表 var hashTxt = GetHashFile(); //3.2进行签名 var signTxt = SignatureFormatterStr(xmlKeys, hashTxt); //3.3签名验证 var defSign = SignatureDeformatterStr(xmlPublicKey, hashTxt, signTxt); } catch (Exception ex) { throw ex; } } /// <summary> /// 文件,hash描述表 /// </summary> /// <returns></returns> public string GetHashFile() { try { var path = @"C:\xxx\xxxx\xxx\图解HTTP 上野宣著.pdf"; FileStream objFile = new FileStream(path, FileMode.Open); //从文件中取得Hash描述 HashAlgorithm MD5 = HashAlgorithm.Create("MD5"); //返回字节数组 byte[] HashData = MD5.ComputeHash(objFile); objFile.Close();//必须有 //返回签名字符串 var result = Convert.ToBase64String(HashData); return result; } catch (Exception ex) { throw ex; } } #region 字符串的hash描述,签名及验证 /// <summary> /// 字符串,hash描述表 /// </summary> /// <param name="strSource">待签名的字符串</param> /// <returns></returns> public string GetHashStr(string strSource) { try { HashAlgorithm MD5 = HashAlgorithm.Create("MD5"); byte[] buffer = Encoding.GetEncoding("GB2312").GetBytes(strSource); //返回字节数组 var hashData = MD5.ComputeHash(buffer); //返回string var hashStr = Convert.ToBase64String(hashData); return hashStr; } catch (Exception ex) { throw ex; } } /// <summary> /// RSA签名 /// </summary> /// <param name="strKeyPrivate">私钥</param> /// <param name="HashbyteSignature">待签名Hash描述</param> /// <returns></returns> public string SignatureFormatterStr(string strKeyPrivate, string hashbyteSignatureStr) { try { byte[] HashbyteSignature = Convert.FromBase64String(hashbyteSignatureStr); byte[] EncryptedSignatureData; RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(); RSA.FromXmlString(strKeyPrivate); RSAPKCS1SignatureFormatter RSAFormatter = new RSAPKCS1SignatureFormatter(RSA); //设置签名的算法为MD5 RSAFormatter.SetHashAlgorithm("MD5"); //执行签名 //返回字节数据 EncryptedSignatureData = RSAFormatter.CreateSignature(HashbyteSignature); return Convert.ToBase64String(EncryptedSignatureData); } catch (Exception ex) { throw ex; } } /// <summary> /// RSA签名验证 /// </summary> /// <param name="strKeyPublic">公钥</param> /// <param name="strHashbyteDeformatter">Hash描述</param> /// <param name="deformatterDataStr">签名后的结果</param> /// <returns></returns> public bool SignatureDeformatterStr(string strKeyPublic, string strHashbyteDeformatter, string deformatterDataStr) { try { byte[] DeformatterData = Convert.FromBase64String(deformatterDataStr); byte[] HashbyteDeformatter = Convert.FromBase64String(strHashbyteDeformatter); RSACryptoServiceProvider RSA = new RSACryptoServiceProvider(); RSA.FromXmlString(strKeyPublic); RSAPKCS1SignatureDeformatter RSADeformatter = new 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; } } catch (Exception ex) { throw ex; } } #endregion #region RSA加密 /// <summary> /// RSA的加密函数 /// </summary> /// <param name="xmlPublicKey">公钥</param> /// <param name="encryptString">待加密的字节数组</param> /// <returns></returns> public string RSAEncrypt(string xmlPublicKey, string encryptString) { try { byte[] encrypt = Encoding.Default.GetBytes(encryptString); RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); rsa.FromXmlString(xmlPublicKey); var cypherTextBArray = rsa.Encrypt(encrypt, false); return Convert.ToBase64String(cypherTextBArray); } catch (Exception ex) { throw ex; } } /// <summary> /// RSA的解密函数 /// </summary> /// <param name="xmlPrivateKey">私钥</param> /// <param name="decryptString">待解密的字节数组</param> /// <returns></returns> public string RSADecrypt(string xmlPrivateKey, string decryptString) { try { byte[] decrypt = Convert.FromBase64String(decryptString); RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); rsa.FromXmlString(xmlPrivateKey); var dypherTextBArray = rsa.Decrypt(decrypt, false); // return (new UnicodeEncoding()).GetString(dypherTextBArray); return Encoding.Default.GetString(dypherTextBArray); } catch (Exception ex) { throw ex; } } #endregion #region RSA加密,有长度限制 /// <summary> /// RSA的加密函数,该加密方式有长度限制的 /// </summary> /// <param name="xmlPublicKey">公钥</param> /// <param name="encryptString">待加密的字符串</param> /// <returns></returns> public string RSAEncryptLimitLength(string xmlPublicKey, string encryptString) { try { RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); rsa.FromXmlString(xmlPublicKey); byte[] plainTextBArray = (new UnicodeEncoding()).GetBytes(encryptString); byte[] cypherTextBArray = rsa.Encrypt(plainTextBArray, false); return Convert.ToBase64String(cypherTextBArray); } catch (Exception ex) { throw ex; } } /// <summary> /// RSA的解密函数 /// </summary> /// <param name="xmlPrivateKey">私钥</param> /// <param name="decryptString">待解密的字符串</param> /// <returns></returns> public string RSADecryptLimitLength(string xmlPrivateKey, string decryptString) { try { RSACryptoServiceProvider rsa = new RSACryptoServiceProvider(); rsa.FromXmlString(xmlPrivateKey); byte[] plainTextBArray = Convert.FromBase64String(decryptString); byte[] dypherTextBArray = rsa.Decrypt(plainTextBArray, false); return (new UnicodeEncoding()).GetString(dypherTextBArray); } catch (Exception ex) { throw ex; } } #endregion }
文章参考:http://www.cnblogs.com/linzheng/archive/2011/02/20/1959123.html
http://www.cnblogs.com/sydeveloper/archive/2012/08/11/2633624.html
标签:sae action from 标准 等价 相同 image name close
原文地址:http://www.cnblogs.com/xiaoyaodijun/p/6549148.html