HmacMd5.java

package com.feebe.lib;


import java.security.MessageDigest;

public class HmacMd5
{


  private final static String[] hexDigits = {
       "0", "1", "2", "3", "4", "5", "6", "7",
       "8", "9", "a", "b", "c", "d", "e", "f"}; 
       
   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 byteArrayToHexString(byte[] b) {
    StringBuffer resultSb = new StringBuffer();
     for (int i = 0; i < b.length; i++) {
       resultSb.append(byteToHexString(b[i]));
     }
     return resultSb.toString();
   } 

    private final static int HMAC_BLKL = 64;
    private final static int HMAC_MD5L = 16;
    private final static byte IPAD = 0x36;
    private final static byte OPAD = 0x5C;
    public static String HMAC(String origin, String key) throws Exception {
            byte[] keyBytes = key.getBytes();
            byte[] orgBytes = origin.getBytes();
            byte[] iBytes = new byte[HMAC_BLKL];
            int conLength2 = HMAC_BLKL + HMAC_MD5L;
            byte[] oBytes = new byte[conLength2];
            int keyLength = keyBytes.length;
            int orgLength = orgBytes.length;
            int conLength = HMAC_BLKL + orgLength;
            byte[] conBytes = new byte[conLength];
            for (int i = 0; i < HMAC_BLKL; i++) {
                if (i < keyLength) {
                    iBytes[i] = (byte) (keyBytes[i] ^ IPAD);
                    oBytes[i] = (byte) (keyBytes[i] ^ OPAD);
                } else {
                    iBytes[i] = IPAD;
                    oBytes[i] = OPAD;
                }
                conBytes[i] = iBytes[i];
            }
            for (int i = HMAC_BLKL; i < conLength; i++) {
                conBytes[i] = orgBytes[i - HMAC_BLKL];
            }
            MessageDigest md = MessageDigest.getInstance("MD5");
            byte[] res1 = md.digest(conBytes);
            for (int i = HMAC_BLKL; i < conLength2; i++) {
                oBytes[i] = res1[i - HMAC_BLKL];
            }
            byte[] res = md.digest(oBytes);
            String result = byteArrayToHexString(res);
            return result;
        }

}