des | 易学教程

BitShifting with BigIntegers in Java

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问题 I am implementing DES Encryption in Java with use of BigIntegers. I am left shifting binary keys with Java BigIntegers by doing the BigInteger.leftShift(int n) method. Key of N (Kn) is dependent on the result of the shift of Kn-1. The problem I am getting is that I am printing out the results after each key is generated and the shifting is not the expected out put. The key is split in 2 Cn and Dn (left and right respectively). I am specifically attempting this: "To do a left shift, move each

iOS中DES与MD5加密方案

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MD5算法和DES算法是常见的两种加密算法。 MD5：MD5是一种不可逆的加密算法，按我的理解，所谓不可逆，就是不能解密，那么它有什么用的，它的用处大了，大多数的登录功能都会使用到这种算法。后面根据我的项目经验来介绍。 DES：一种使用密钥加密的块算法，所以，使用它加密时，需要一个密钥，加上一些设置和你需要加密的文段。在IOS中，使用这两种加密算法非常简单，系统的 <CommonCrypto/CommonCrypto.h> 库给我们提供的边界的接口。在很多移动项目中，安卓平台和IOS平台的后台服务是统一的，比如一个登录功能是这样的流程： 1、客户端向服务端请求密钥，请求的参数是双方约定好的一个MD5加密的字符串。我们可以通过下面的进行第一步加密： - (NSString *)MD5Digest { //要进行UTF8的转码 const char* input = [self UTF8String]; unsigned char result[CC_MD5_DIGEST_LENGTH]; CC_MD5(input, (CC_LONG)strlen(input), result); NSMutableString *digest = [NSMutableString stringWithCapacity:CC_MD5_DIGEST_LENGTH * 2]; for

C# - Serializing/Deserializing a DES encrypted file from a stream

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问题 Does anyone have any examples of how to encrypt serialized data to a file and then read it back using DES? I've written some code already that isn't working, but I'd rather see a fresh attempt instead of pursuing my code. EDIT : Sorry, forgot to mention I need an example using XmlSerializer.Serialize/Deserialize. 回答1: Encryption public static void EncryptAndSerialize(string filename, MyObject obj, SymmetricAlgorithm key) { using(FileStream fs = File.Open(filename, FileMode.Create)) { using

DES Send and Receive Modes for DESFire Authentication

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问题 I'm trying to authenticate DESFire card with my android application. I use the example in this link to decypher the bytes I got from the card. For that, I ruled out padding in decryption (commented out below), because DESFire documentation points it out. Also, if I don't do so, decryption returns 7 bytes for input of 8 bytes. Below are DES and TripleDES decryption functions I use: public static byte[] TripleDES_Decrypt(byte[] data,byte[][] keys) { int i; byte[] tmp = new byte[data.length];

ASP.NET加密算法(MD5/DES)

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本文讲 ASP.NET的MD5和DES加密和解密算法 #region MD5算法 public string md5(string str, int code) { if (code == 16) //16位MD5加密（取32位加密的9~25字符） { return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower().Substring(8, 16); } if (code == 32) //32位加密 { return System.Web.Security.FormsAuthentication.HashPasswordForStoringInConfigFile(str, "MD5").ToLower(); } return "00000000000000000000000000000000"; } #endregion #region DESEncrypt DES加密 // <summary> /// 进行DES加密。 /// </summary> /// <param name="pToEncrypt">要加密的字符串。</param> /// <param name="sKey">密钥，且必须为8位。</param> ///

常见的加密方式

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DES加密算法： DES加密算法是一种分组密码，以64位为分组对数据加密，它的密钥长度是56位，加密解密用同一算法。DES加密算法是对密钥进行保密，而公开算法，包括加密和解密算法。这样，只有掌握了和发送方相同密钥的人才能解读由DES加密算法加密的密文数据。因此，破译DES加密算法实际上就是搜索密钥的编码。对于56位长度的密钥来说，如果用穷举法来进行搜索的话，其运算次数为256。随着计算机系统能力的不断发展，DES的安全性比它刚出现时会弱得多，然而从非关键性质的实际出发，仍可以认为它是足够的。不过，DES现在仅用于旧系统的鉴定，而更多地选择新的加密标准。 AES加密算法： ES加密算法是密码学中的高级加密标准，该加密算法采用对称分组密码体制，密钥长度的最少支持为128、192、256，分组长度128位，算法应易于各种硬件和软件实现。这种加密算法是美国联邦政府采用的区块加密标准，这个标准用来替代原先的DES，已经被多方分析且广为全世界所使用。 AES加密算法被设计为支持128／192／256位（/32=nb)数据块大小（即分组长度）；支持128／192／256位（/32=nk)密码长度，，在10进制里，对应34×1038、62×1057、1.1×1077个密钥。 RSA加密算法： RSA加密算法是目前最有影响力的公钥加密算法，并且被普遍认为是目前最优秀的公钥方案之一

Is DES or 3DES still being used today?

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问题 I've written a DES implementation as an exercice and am now wondering if and where (triple-)DES is used today. I've read about banking cards using it, but I can't find any reliable source for it. 回答1: Triple-DES is still in use today but is widely considered a legacy encryption algorithm. DES is inherently insecure, while Triple-DES has much better security characteristics but is still considered problematic. NIST is the government organization that standardizes on cryptographic algorithms.

JAVA与.NET DES加密解密

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前几天做了个项目需要在两个系统间采用DES加密，一个系统为JAVA开发的，另外一个.Net开发的在网上找了很多写法但加密出的数据两个系统都无法匹配，在做了小修改以后终于可以用了，已经测试过 JAVA版本 import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; import javax.crypto.spec.IvParameterSpec; public class Des { private byte[] desKey; //解密数据 public static String decrypt(String message,String key) throws Exception { byte[] bytesrc =convertHexString(message); Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding"); DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8")); SecretKeyFactory keyFactory =

JavaScript DES 加密tripledes.js:

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<html> <head> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <title>JS设置DES加密处理</title> <script type="text/javascript" src="js/jquery.min.js"></script> <script src="js/rollups/tripledes.js"></script> <script src="js/components/mode-ecb.js"></script> <script> //DES 解密加密 function encryptByDES(message, key) { var keyHex = CryptoJS.enc.Utf8.parse(key); var encrypted = CryptoJS.DES.encrypt(message, keyHex, { mode: CryptoJS.mode.ECB, padding: CryptoJS.pad.Pkcs7 }); return encrypted.toString(); } //DES 解密 function decryptByDES(ciphertext, key) { var keyHex = CryptoJS.enc.Utf8

Comparison of DES, Triple DES, AES, blowfish encryption for data

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Does anyone have pros and cons together for comparing these encryption algorithms ? Use AES. In more details: DES is the old "data encryption standard" from the seventies. Its key size is too short for proper security (56 effective bits; this can be brute-forced, as has been demonstrated more than ten years ago ). Also, DES uses 64-bit blocks, which raises some potential issues when encrypting several gigabytes of data with the same key (a gigabyte is not that big nowadays). 3DES is a trick to reuse DES implementations, by cascading three instances of DES (with distinct keys). 3DES is believed

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