DES加密算法
DES全称为Data Encryption Standard，即数据加密标准，是一种使用密钥加密的块算法，1976年被美国联邦政府的国家标准局确定为联邦资料处理标准（FIPS），随后在国际上广泛流传开来。
DES算法的入口参数有三个:Key、Data、Mode。其中Key为7个字节共56位,是DES算法的工作密钥;Data为8个字节64位,是要被加密或被解密的数据;Mode为DES的工作方式,有两种:加密或解密。
DES算法把64位的明文输入块变为64位的密文输出块,它所使用的密钥也是56位，其算法主要分为两步：
1）初始置换
其功能是把输入的64位数据块按位重新组合,并把输出分为L0、R0两部分,每部分各长32位,其置换规则为将输入的第58位换到第一位,第50位换到第2位……依此类推,最后一位是原来的第7位。L0、R0则是换位输出后的两部分，L0是输出的左32位,R0是右32位,例:设置换前的输入值为D1D2D3……D64,则经过初始置换后的结果为:L0=D58D50……D8;R0=D57D49……D7。
其置换规则见下表：

58,50,42,34,26,18,10,2,60,52,44,36,28,20,12,4,62,54,46,38,30,22,14,6,64,56,48,40,32,24,16,8,57,49,41,33,25,17,9,1,59,51,43,35,27,19,11,3,61,53,45,37,29,21,13,5,63,55,47,39,31,23,15,7,

2）逆置换
经过16次迭代运算后,得到L16、R16,将此作为输入,进行逆置换,逆置换正好是初始置换的逆运算，由此即得到密文输出。
此算法是对称加密算法体系中的代表,在计算机网络系统中广泛使用.

Java基本实现

package com.stone.security; import java.security.Key; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; import javax.crypto.spec.IvParameterSpec; /** * DES 算法 1972美国IBM研制，对称加密算法 */ public class DES { // 算法名称 public static final String KEY_ALGORITHM = "DES"; // 算法名称/加密模式/填充方式 public static final String CIPHER_ALGORITHM_ECB = "DES/ECB/PKCS5Padding"; public static final String CIPHER_ALGORITHM_CBC = "DES/CBC/PKCS5Padding"; public static void main(String[] args) throws Exception { /* * 使用 ECB mode * 密钥生成器 生成密钥 * ECB mode cannot use IV */ byte[] key = generateKey(); byte[] encrypt = encrypt("胃炎F#*（x）".getBytes(), key); System.out.println(new String(decrypt(encrypt, key))); /* * 使用CBC mode * 使用密钥工厂生成密钥，加密 解密 * iv: DES in CBC mode and RSA ciphers with OAEP encoding operation. */ DESKeySpec dks = new DESKeySpec(generateKey()); SecretKeyFactory factory = SecretKeyFactory.getInstance(KEY_ALGORITHM); SecretKey secretKey = factory.generateSecret(dks); Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC); cipher.init(Cipher.ENCRYPT_MODE, secretKey, new IvParameterSpec(getIV())); byte[] enc = cipher.doFinal("胃炎A%F#*（x）".getBytes()); //加密 cipher.init(Cipher.DECRYPT_MODE, secretKey, new IvParameterSpec(getIV())); byte[] dec = cipher.doFinal(enc); // 解密 System.out.println(new String(dec)); } static byte[] getIV() { String iv = "asdfivh7"; //IV length: must be 8 bytes long return iv.getBytes(); } /** * 生成密钥 * * @return * @throws Exception */ private static byte[] generateKey() throws Exception { KeyGenerator keyGenerator = KeyGenerator.getInstance(KEY_ALGORITHM); keyGenerator.init(56); //des 必须是56, 此初始方法不必须调用 SecretKey secretKey = keyGenerator.generateKey(); return secretKey.getEncoded(); } /** * 还原密钥 * * @param key * @return * @throws Exception */ private static Key toKey(byte[] key) throws Exception { DESKeySpec des = new DESKeySpec(key); SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(KEY_ALGORITHM); SecretKey secretKey = keyFactory.generateSecret(des); return secretKey; } /** * 加密 * @param data 原文 * @param key * @return 密文 * @throws Exception */ public static byte[] encrypt(byte[] data, byte[] key) throws Exception { Key k = toKey(key); Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB); cipher.init(Cipher.ENCRYPT_MODE, k, new SecureRandom()); return cipher.doFinal(data); } /** * 解密 * @param data 密文 * @param key * @return 明文、原文 * @throws Exception */ public static byte[] decrypt(byte[] data, byte[] key) throws Exception { Key k = toKey(key); Cipher cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB); cipher.init(Cipher.DECRYPT_MODE, k, new SecureRandom()); return cipher.doFinal(data); } }

Java三重DES实现：

package com.stone.security; import javax.crypto.Cipher; import javax.crypto.KeyGenerator; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESedeKeySpec; import javax.crypto.spec.IvParameterSpec; /** * 三重加密 3DES也作 Triple DES, */ public class TripleDES { // 算法名称 public static final String KEY_ALGORITHM = "DESede"; // 算法名称/加密模式/填充方式 public static final String CIPHER_ALGORITHM_ECB = "DESede/ECB/PKCS5Padding"; public static final String CIPHER_ALGORITHM_CBC = "DESede/CBC/PKCS5Padding"; private KeyGenerator keyGen; private SecretKey secretKey; private SecretKey secretKey2; private Cipher cipher; private static byte[] encryptData; public static void main(String[] args) throws Exception { TripleDES tripleDES = new TripleDES("ECB"); tripleDES.encrypt("sau8jzxlcvm,'123`98(*^&%^^JCB ZX>>A<S<}}{"); System.out.println("加密后：" + new String(encryptData)); System.out.println("解密后："+ new String(tripleDES.decrypt(encryptData))); tripleDES = new TripleDES("CBC"); tripleDES.encrypt2("sau8jzxlc DQV#><«|vm,'123`98(*^&%^^JCB ZX>>A<S<}}{"); System.out.println("加密后：" + new String(encryptData)); System.out.println("解密后："+ new String(tripleDES.decrypt2(encryptData))); } public TripleDES(String mode) throws Exception { if ("ECB".equals(mode)) { // cipher = Cipher.getInstance(KEY_ALGORITHM); cipher = Cipher.getInstance(CIPHER_ALGORITHM_ECB); keyGen = KeyGenerator.getInstance(KEY_ALGORITHM); secretKey = keyGen.generateKey(); } else if("CBC".equals(mode)) { cipher = Cipher.getInstance(CIPHER_ALGORITHM_CBC); keyGen = KeyGenerator.getInstance(KEY_ALGORITHM); DESedeKeySpec spec = new DESedeKeySpec(keyGen.generateKey().getEncoded()); secretKey2 = SecretKeyFactory.getInstance(KEY_ALGORITHM).generateSecret(spec); } } /** * 加密 * @param str * @return * @throws Exception */ public byte[] encrypt(String str) throws Exception { cipher.init(Cipher.ENCRYPT_MODE, secretKey); return encryptData = cipher.doFinal(str.getBytes()); } /** * 解密 * @param encrypt * @return * @throws Exception */ public byte[] decrypt(byte[] encrypt) throws Exception { cipher.init(Cipher.DECRYPT_MODE, secretKey); return encryptData = cipher.doFinal(encrypt); } byte[] getIV() { return "administ".getBytes(); } /** * 加密 * @param str * @return * @throws Exception */ public byte[] encrypt2(String str) throws Exception { cipher.init(Cipher.ENCRYPT_MODE, secretKey2, new IvParameterSpec(getIV())); return encryptData = cipher.doFinal(str.getBytes()); } /** * 解密 * @param encrypt * @return * @throws Exception */ public byte[] decrypt2(byte[] encrypt) throws Exception { cipher.init(Cipher.DECRYPT_MODE, secretKey2, new IvParameterSpec(getIV())); return encryptData = cipher.doFinal(encrypt); } }