DES、MD5、RSA加密算法
本篇主要是实现标题中的三个加密算法，至于机制大家自行百度吧。
一、DES
实现类：DES.java
package com.kale.des; import java.security.SecureRandom; import javax.crypto.Cipher; import javax.crypto.SecretKey; import javax.crypto.SecretKeyFactory; import javax.crypto.spec.DESKeySpec; /* * DES加密介绍 DES是一种对称加密算法，所谓对称加密算法即：加密和解密使用相同密钥的算法。 DES加密算法出自IBM的研究，后来被美国政府正式采用，之后开始广泛流传，但是近些年使用越来越少， 因为DES使用56位密钥，以现代计算能力，24小时内即可被破解。虽然如此，在某些简单应用中，我们还是可 以 使用DES加密算法，本文简单讲解DES的JAVA实现。 */ public class DES{ /** * 加密过程，密钥长度都必须是8的倍数 * @param datasource * @param password * @return 加密后的结果 */ public static byte[] desLock(byte[] datasource, String password) { try{ SecureRandom random = new SecureRandom(); DESKeySpec desKey = new DESKeySpec(password.getBytes()); //创建一个密匙工厂，然后用它把DESKeySpec转换成 SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES"); SecretKey securekey = keyFactory.generateSecret(desKey); //Cipher对象实际完成加密操作 Cipher cipher = Cipher.getInstance("DES"); //用密匙初始化Cipher对象 cipher.init(Cipher.ENCRYPT_MODE, securekey, random); //现在，获取数据并加密 //正式执行加密操作 return cipher.doFinal(datasource); }catch(Throwable e){ e.printStackTrace(); } return null; } /** * 解密过程，密钥长度都必须是8的倍数 * @param src * @param password * @return 解密后的内容 * @throws Exception */ public static byte[] desUnclock(byte[] src, String password) throws Exception { // DES算法要求有一个可信任的随机数源 SecureRandom random = new SecureRandom(); // 创建一个DESKeySpec对象 DESKeySpec desKey = new DESKeySpec(password.getBytes()); // 创建一个密匙工厂 SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES"); // 将DESKeySpec对象转换成SecretKey对象 SecretKey securekey = keyFactory.generateSecret(desKey); // Cipher对象实际完成解密操作 Cipher cipher = Cipher.getInstance("DES"); // 用密匙初始化Cipher对象 cipher.init(Cipher.DECRYPT_MODE, securekey, random); // 真正开始解密操作 return cipher.doFinal(src); } }
测试类：DesTest.java
package com.kale.des; public class DesTest { /** * @param args */ public static void main(String[] args) { // TODO 自动生成的方法存根 //待加密内容 String str = "kale123456789"; //密码，长度要是8的倍数 String password = "12345678"; byte[] result = null; try{ result = DES.desLock(str.getBytes(),password); System.out.println("加密后内容为："+new String(result)); } catch(Exception e){ System.out.println("加密失败！"); } //解密 try { byte[] unLockResult = DES.desUnclock(result, password); System.out.println("解密后内容为："+new String(unLockResult)); } catch (Exception e1) { //e1.printStackTrace(); System.out.println("密钥错误，无法解密！"); } } }
结果：
加密后内容为：S��:�3@d!�A��.
解密后内容为：kale123456789
二、MD5
实现类：MD5.java
package com.kale.md5; import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class MD5 { /* * MD5加密 */ public static String getMD5Str(String str) { MessageDigest messageDigest = null; try { messageDigest = MessageDigest.getInstance("MD5"); messageDigest.reset(); messageDigest.update(str.getBytes("UTF-8")); } catch (NoSuchAlgorithmException e) { System.out.println("NoSuchAlgorithmException caught!"); System.exit(-1); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } byte[] byteArray = messageDigest.digest(); StringBuffer md5StrBuff = new StringBuffer(); for (int i = 0; i < byteArray.length; i++) { if (Integer.toHexString(0xFF & byteArray[i]).length() == 1) md5StrBuff.append("0").append(Integer.toHexString(0xFF & byteArray[i])); else md5StrBuff.append(Integer.toHexString(0xFF & byteArray[i])); } //16位加密，从第9位到25位 return md5StrBuff.substring(8, 24).toString().toUpperCase(); } }
测试类：Md5Test.java
package com.kale.md5; public class Md5Test { /** * @param args */ public static void main(String[] args) { String password = "123456789"; String result = MD5.getMD5Str(password); System.out.println(result.toLowerCase()); } }
结果：323b453885f5181f
三、RSA
实现类：RSA.java
package com.kale.rsa; import java.math.BigInteger; import java.security.KeyFactory; import java.security.KeyPair; import java.security.KeyPairGenerator; import java.security.NoSuchAlgorithmException; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.security.spec.RSAPrivateKeySpec; import java.security.spec.RSAPublicKeySpec; import java.util.HashMap; import javax.crypto.Cipher; public class RSA{ /** * 生成公钥和私钥 * @throws NoSuchAlgorithmException * */ public static HashMap<String, Object> getKeys() throws NoSuchAlgorithmException{ HashMap<String, Object> map = new HashMap<String, Object>(); KeyPairGenerator keyPairGen = KeyPairGenerator.getInstance("RSA"); keyPairGen.initialize(1024); KeyPair keyPair = keyPairGen.generateKeyPair(); RSAPublicKey publicKey = (RSAPublicKey) keyPair.getPublic(); RSAPrivateKey privateKey = (RSAPrivateKey) keyPair.getPrivate(); map.put("public", publicKey); map.put("private", privateKey); return map; } /** * 使用模和指数生成RSA公钥 * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA * /None/NoPadding】 * * @param modulus * 模 * @param exponent * 指数 * @return */ public static RSAPublicKey getPublicKey(String modulus, String exponent) { try { BigInteger b1 = new BigInteger(modulus); BigInteger b2 = new BigInteger(exponent); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPublicKeySpec keySpec = new RSAPublicKeySpec(b1, b2); return (RSAPublicKey) keyFactory.generatePublic(keySpec); } catch (Exception e) { e.printStackTrace(); return null; } } /** * 使用模和指数生成RSA私钥 * 注意：【此代码用了默认补位方式，为RSA/None/PKCS1Padding，不同JDK默认的补位方式可能不同，如Android默认是RSA * /None/NoPadding】 * * @param modulus * 模 * @param exponent * 指数 * @return */ public static RSAPrivateKey getPrivateKey(String modulus, String exponent) { try { BigInteger b1 = new BigInteger(modulus); BigInteger b2 = new BigInteger(exponent); KeyFactory keyFactory = KeyFactory.getInstance("RSA"); RSAPrivateKeySpec keySpec = new RSAPrivateKeySpec(b1, b2); return (RSAPrivateKey) keyFactory.generatePrivate(keySpec); } catch (Exception e) { e.printStackTrace(); return null; } } /** * 公钥加密 * * @param data * @param publicKey * @return * @throws Exception */ public static String encryptByPublicKey(String data, RSAPublicKey publicKey) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.ENCRYPT_MODE, publicKey); // 模长 int key_len = publicKey.getModulus().bitLength() / 8; // 加密数据长度 <= 模长-11 String[] datas = splitString(data, key_len - 11); String mi = ""; //如果明文长度大于模长-11则要分组加密 for (String s : datas) { mi += bcd2Str(cipher.doFinal(s.getBytes())); } return mi; } /** * 私钥解密 * * @param data * @param privateKey * @return * @throws Exception */ public static String decryptByPrivateKey(String data, RSAPrivateKey privateKey) throws Exception { Cipher cipher = Cipher.getInstance("RSA"); cipher.init(Cipher.DECRYPT_MODE, privateKey); //模长 int key_len = privateKey.getModulus().bitLength() / 8; byte[] bytes = data.getBytes(); byte[] bcd = ASCII_To_BCD(bytes, bytes.length); System.err.println(bcd.length); //如果密文长度大于模长则要分组解密 String ming = ""; byte[][] arrays = splitArray(bcd, key_len); for(byte[] arr : arrays){ ming += new String(cipher.doFinal(arr)); } return ming; } /** * ASCII码转BCD码 * */ public static byte[] ASCII_To_BCD(byte[] ascii, int asc_len) { byte[] bcd = new byte[asc_len / 2]; int j = 0; for (int i = 0; i < (asc_len + 1) / 2; i++) { bcd[i] = asc_to_bcd(ascii[j++]); bcd[i] = (byte) (((j >= asc_len) ? 0x00 : asc_to_bcd(ascii[j++])) + (bcd[i] << 4)); } return bcd; } public static byte asc_to_bcd(byte asc) { byte bcd; if ((asc >= '0') && (asc <= '9')) bcd = (byte) (asc - '0'); else if ((asc >= 'A') && (asc <= 'F')) bcd = (byte) (asc - 'A' + 10); else if ((asc >= 'a') && (asc <= 'f')) bcd = (byte) (asc - 'a' + 10); else bcd = (byte) (asc - 48); return bcd; } /** * BCD转字符串 */ public static String bcd2Str(byte[] bytes) { char temp[] = new char[bytes.length * 2], val; for (int i = 0; i < bytes.length; i++) { val = (char) (((bytes[i] & 0xf0) >> 4) & 0x0f); temp[i * 2] = (char) (val > 9 ? val + 'A' - 10 : val + '0'); val = (char) (bytes[i] & 0x0f); temp[i * 2 + 1] = (char) (val > 9 ? val + 'A' - 10 : val + '0'); } return new String(temp); } /** * 拆分字符串 */ public static String[] splitString(String string, int len) { int x = string.length() / len; int y = string.length() % len; int z = 0; if (y != 0) { z = 1; } String[] strings = new String[x + z]; String str = ""; for (int i=0; i<x+z; i++) { if (i==x+z-1 && y!=0) { str = string.substring(i*len, i*len+y); }else{ str = string.substring(i*len, i*len+len); } strings[i] = str; } return strings; } /** *拆分数组 */ public static byte[][] splitArray(byte[] data,int len){ int x = data.length / len; int y = data.length % len; int z = 0; if(y!=0){ z = 1; } byte[][] arrays = new byte[x+z][]; byte[] arr; for(int i=0; i<x+z; i++){ arr = new byte[len]; if(i==x+z-1 && y!=0){ System.arraycopy(data, i*len, arr, 0, y); }else{ System.arraycopy(data, i*len, arr, 0, len); } arrays[i] = arr; } return arrays; } }
测试类：RsaTest.java
package com.kale.rsa; import java.security.interfaces.RSAPrivateKey; import java.security.interfaces.RSAPublicKey; import java.util.HashMap; public class RsaTest { public static void main(String[] args) throws Exception { // TODO Auto-generated method stub HashMap<String, Object> map = RSA.getKeys(); //生成公钥和私钥 RSAPublicKey publicKey = (RSAPublicKey) map.get("public"); RSAPrivateKey privateKey = (RSAPrivateKey) map.get("private"); //模 String modulus = publicKey.getModulus().toString(); //公钥指数 String public_exponent = publicKey.getPublicExponent().toString(); //私钥指数 String private_exponent = privateKey.getPrivateExponent().toString(); //明文 String ming = "kale123456789"; //使用模和指数生成公钥和私钥 RSAPublicKey pubKey = RSA.getPublicKey(modulus, public_exponent); RSAPrivateKey priKey = RSA.getPrivateKey(modulus, private_exponent); //加密后的密文 String mi = RSA.encryptByPublicKey(ming, pubKey); System.out.println(mi); //解密后的明文 ming = RSA.decryptByPrivateKey(mi, priKey); System.out.println(ming); } }
结果：
81169AA3AF3CEC80AAA685B0500A2BF058AB13BDEBA62A3D38AD382C444F66EC3DCA3C7E0225DF73C529EB94DDB978B761A87FB26518DEAC7FF85678BFB2B117B765E32E8E7A23864D2D69E9E351AA8FAA26F02F9964DA6275744833D7C8ABF2552DA83DBE66E682CE0592D3595220FAD9E4D56D849867135DE0CD3BDDFDCAF2
128
kale123456789
源码下载：http://download.csdn.net/detail/shark0017/8075485
