| 關鍵詞:md5 由於訊息摘要唯一性和無法復原性的特點，所以不失為一種簡單的常用的加密手段，比如你可以用md5來加密你的應用中的使用者口令。
- package test;
- import java.security.MessageDigest;
- /**
- * <p>Title: </p>
- * <p>Description: </p>
- * <p>Copyright: Copyright (c) 2003</p>
- * <p>Company: </p>
- * @author unascribed
- * @version 1.0
- */
- public class StringUtil {
- private final static String[] hexDigits = {
- "0", "1", "2", "3", "4", "5", "6", "7",
- "8", "9", "a", "b", "c", "d", "e", "f"};
- /**
- * 轉換位元組數組為16進位字串
- * @param b 位元組數組
- * @return 16進位字串
- */
- public static String byteArrayToHexString(byte[] b) {
- StringBuffer resultSb = new StringBuffer();
- for (int i = 0; i < b.length; i++) {
- resultSb.append(byteToHexString(b[i]));
- }
- return resultSb.toString();
- }
- private static String byteToHexString(byte b) {
- int n = b;
- if (n < 0)
- n = 256 + n;
- int d1 = n / 16;
- int d2 = n % 16;
- return hexDigits[d1] + hexDigits[d2];
- }
- public static String MD5Encode(String origin) {
- String resultString = null;
- try {
- resultString=new String(origin);
- MessageDigest md = MessageDigest.getInstance("MD5");
- resultString=byteArrayToHexString(md.digest(resultString.getBytes()));
- }
- catch (Exception ex) {
- }
- return resultString;
- }
- public static void main(String[] args){
- System.err.println(MD5Encode("a"));
- }
- }
在RFC 1321中，給出了Test suite用來檢驗你的實現是否正確： MD5 ("") = d41d8cd98f00b204e9800998ecf8427e
MD5 ("a") = 0cc175b9c0f1b6a831c399e269772661
MD5 ("abc") = 900150983cd24fb0d6963f7d28e17f72
MD5 ("message digest") = f96b697d7cb7938d525a2f31aaf161d0
MD5 ("abcdefghijklmnopqrstuvwxyz") = c3fcd3d76192e4007dfb496cca67e13b 參考資料:《java security handbook》 jamie jaworski |
