微分 2012-01-13
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提出问题:MD5,SHA算法是常用的两种加密算法。以前看过很多人写的md5算法,要么过于难懂,要么过于冗长,而且不能切换为其他加密算法,非常不给力。
分析和解决问题:于是,决定自己写一个简单好用的加密算法。翻看JDK1.5的API文档,惊喜的发现,在java.security这个包下面有一个MessageDigest类:此 MessageDigest 类为应用程序提供信息摘要算法的功能,如 MD5 或 SHA 算法。bingo!参考了部分网友的代码,本人的代码如下,不足之处,请大家批评指正。JDK/JRE版本:1.5+package common.util.security; import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class EncryptUtil { public static void main(String[] args) { //md5加密测试 String md5_1 = md5("123" ); String md5_2 = md5("abc" ); System.out.println(md5_1 + "\n" + md5_2); System.out.println("md5 length: " + md5_1.length()); //sha加密测试 String sha_1 = sha("123" ); String sha_2 = sha("abc" ); System.out.println(sha_1 + "\n" + sha_2); System.out.println("sha length: " + sha_1.length()); } // md5加密 public static String md5(String inputText) { return encrypt(inputText, "md5" ); } // sha加密 public static String sha(String inputText) { return encrypt(inputText, "sha-1" ); } /** * md5或者sha-1加密 * * @param inputText * 要加密的内容 * @param algorithmName * 加密算法名称:md5或者sha-1,不区分大小写 * @return */ private static String encrypt(String inputText, String algorithmName) { if (inputText == null || "" .equals(inputText.trim())) { throw new IllegalArgumentException( "请输入要加密的内容" ); } if (algorithmName == null || "" .equals(algorithmName.trim())) { algorithmName = "md5" ; } String encryptText = null ; try { MessageDigest m = MessageDigest.getInstance(algorithmName); m.update(inputText.getBytes("UTF8" )); byte s[] = m.digest(); // m.digest(inputText.getBytes("UTF8")); return hex(s); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return encryptText; } // 返回十六进制字符串 private static String hex( byte [] arr) { StringBuffer sb = new StringBuffer(); for ( int i = 0 ; i < arr.length; ++i) { sb.append(Integer.toHexString((arr[i] & 0xFF ) | 0x100 ).substring( 1 , 3 )); } return sb.toString(); }
package common.util.security; import java.io.UnsupportedEncodingException; import java.security.MessageDigest; import java.security.NoSuchAlgorithmException; public class EncryptUtil { public static void main(String[] args) { //md5加密测试 String md5_1 = md5("123"); String md5_2 = md5("abc"); System.out.println(md5_1 + "\n" + md5_2); System.out.println("md5 length: " + md5_1.length()); //sha加密测试 String sha_1 = sha("123"); String sha_2 = sha("abc"); System.out.println(sha_1 + "\n" + sha_2); System.out.println("sha length: " + sha_1.length()); } // md5加密 public static String md5(String inputText) { return encrypt(inputText, "md5"); } // sha加密 public static String sha(String inputText) { return encrypt(inputText, "sha-1"); } /** * md5或者sha-1加密 * * @param inputText * 要加密的内容 * @param algorithmName * 加密算法名称:md5或者sha-1,不区分大小写 * @return */ private static String encrypt(String inputText, String algorithmName) { if (inputText == null || "".equals(inputText.trim())) { throw new IllegalArgumentException("请输入要加密的内容"); } if (algorithmName == null || "".equals(algorithmName.trim())) { algorithmName = "md5"; } String encryptText = null; try { MessageDigest m = MessageDigest.getInstance(algorithmName); m.update(inputText.getBytes("UTF8")); byte s[] = m.digest(); // m.digest(inputText.getBytes("UTF8")); return hex(s); } catch (NoSuchAlgorithmException e) { e.printStackTrace(); } catch (UnsupportedEncodingException e) { e.printStackTrace(); } return encryptText; } // 返回十六进制字符串 private static String hex(byte[] arr) { StringBuffer sb = new StringBuffer(); for (int i = 0; i < arr.length; ++i) { sb.append(Integer.toHexString((arr[i] & 0xFF) | 0x100).substring(1, 3)); } return sb.toString(); }
上述代码的运行结果: 202cb962ac59075b964b07152d234b70 900150983cd24fb0d6963f7d28e17f72 md5 length: 32 40bd001563085fc35165329ea1ff5c5ecbdbbeef a9993e364706816aba3e25717850c26c9cd0d89d sha length: 40
由此可见,MD5和SHA-1加密后生成的字符串长度分别为32和40。