哪位大哥帮忙翻译成PHP?

哪位大哥帮忙翻译成PHP? JAVA不懂, 对方没有PHP SDK谢谢了.

/**   * 签名算法   *    * @return   * @throws Exception   */   public static String createSign(String param) throws Exception {       StringBuffer result = new StringBuffer();       MessageDigest md5 = MessageDigest.getInstance("MD5");       md5.update(param.getBytes("UTF-8"));       byte[] b = md5.digest();       for(int i=0;i< b.length;++i) {           int x = b[i]&0xFF;           int h = x>>>4;           int l = x&0x0F;           result.append((char)(h+((h<10)?'0':'a'-10)));           result.append((char)(l+((l<10)?'0':'a'-10)));       }       return result.toString().substring(8, 24);   }