Help please what im i doing wrong here (encryption)

Question

Hi All,
I wonder if anyone here can help me. I have an algorithm to decrypt a password from a string and i am struggling to decrypt it. The algorithm itself shows an example and i tried the example but i cant get the results that were shown in the example to match with the result in my sample code.
Here is the algorithm.
1.First get the bytes of the original password, assuming a "Latin-1" encoding. For the password "Baltimore1," these bytes are: 66 97 108 116 105 109 111 114 101 49 44 (i.e. the value of "B" is 66, "a" is 97, etc).
2.Then get the MD5 hash of these bytes. MD5 is a standard, public algorithm. Once again, for the password "Baltimore1," these bytes work out as: 223 238 161 24 62 121 39 143 115 167 51 163 245 231 226 94
3.Finally, create the new password by forming a string whose Latin-1 encoding is the bytes from the previous step. For the "Baltimore1," password, if this is string is written to the screen, it looks like: ���_>y'?s�3����^(i.e. the 62 above is a ">", the 121 is a "y", etc).
To try the above, i tried to get the string shown in step 3 using the "Baltimore1," password. Here is the code that i wrote.
  public static void main() throws NoSuchAlgorithmException, UnsupportedEncodingException {
      String enteredPassword = new String("Baltimore1,");
            String enteredPasswordBytes = new String();
            String enteredPasswordBytesMD5Hash = new String();
            String enteredPasswordBytesMD5HashBytes = new String();
      //Step 1 - get the bytes of Baltimore1,          
            for ( int i = 0; i < enteredPassword.length(); ++i ) {
                    char c = enteredPassword.charAt( i );
                    int j = (int) c;
                    enteredPasswordBytes = enteredPasswordBytes.concat(Integer.toString(j));                   
      System.out.println("1. Baltimore1, in plain text = " + enteredPassword);
            System.out.println("2. Baltimore1, in bytes = " + enteredPasswordBytes);
      //Step 2 - Get the MD5 Hash of the bytes
      enteredPasswordBytesMD5Hash = MD5(enteredPasswordBytes);     
      System.out.println("3. MD5 Hash of Baltimore1,'s bytes = " + enteredPasswordBytesMD5Hash);
      //Step 3 - Get the bytes of the MD5 Hash
      for ( int i = 0; i < enteredPasswordBytesMD5Hash.length(); ++i ) {
                    char c = enteredPasswordBytesMD5Hash.charAt( i );
                    int j = (int) c;
                    enteredPasswordBytesMD5HashBytes = enteredPasswordBytesMD5HashBytes.concat(Integer.toString(j));                   
      System.out.println("4. bytes of the MD5 Hash of Baltimore1,'s bytes = " + enteredPasswordBytesMD5Hash);
     public static String MD5(String text)
     throws NoSuchAlgorithmException, UnsupportedEncodingException  {
          MessageDigest md;
          md = MessageDigest.getInstance("MD5");
          byte[] md5hash = new byte[32];
          md.update(text.getBytes("iso-8859-1"), 0, text.length());
          md5hash = md.digest();
          //return convertToHex(md5hash);
          return md5hash.toString();
     }      And here is the output of the above program.
1. Baltimore1, in plain text = Baltimore1,
2. Baltimore1, in bytes = 66971081161051091111141014944
3. MD5 Hash of Baltimore1,'s bytes = [B@923e30
4. bytes of the MD5 Hash of Baltimore1,'s bytes = 9166645750511015148As you can see, the output of line 1 is correct. The bytes are exactly as described in the example. I was expecting the output on line 4 to be 223 238 161 24 62 121 39 143 115 167 51 163 245 231 226 94 as shown in the example. Does anyone know what i am doing wrong?
Edited by: ziggy on Jul 4, 2008 1:14 PM
Edited by: ziggy on Jul 4, 2008 1:14 PM

Answer 1

Thanks guys for your help. I followed some of your advice and changed the code as shown below as an example.
It looks like im almost there but not quite yet.
import java.security.*;
public class Pkcs12{
     public static void main(String[] args){
          //String to be converted
              String originalString = "Baltimore1,";
          byte[] originalStringInBytes = new byte[8];
          byte[] md5 = null;
          originalStringInBytes = originalString.getBytes();
          System.out.println("1. OriginalString= " + originalString);                   
          System.out.println("2. OriginalStringInBytes= " + originalStringInBytes);
          for (int i=0; i<=originalStringInBytes.length-1; i++){
               System.out.print("["+(int )(originalStringInBytes[i] )+"] ");
          try{
               md5 = MD5(originalStringInBytes);
          }catch(NoSuchAlgorithmException e){
          System.out.println();
          for (int i=0; i<md5.length-1; i++){
               System.out.print("["+((int)md5)+"] ");
     //223 238 161 24 62 121 39 143 115 167 51 163 245 231 226 94
     public static byte[] MD5(byte[] bytes) throws NoSuchAlgorithmException{
          MessageDigest md;
          md = MessageDigest.getInstance("MD5");
          byte[] md5hash = new byte[32];
          md.update(bytes);
          md5hash = md.digest();
          return md5hash;
And here is the output from the above program
1. OriginalString= Baltimore1,
2. OriginalStringInBytes= [B@3e25a5
[66] [97] [108] [116] [105] [109] [111] [114] [101] [49] [44]
[-33] [-18] [-95] [24] [62] [121] [39] [-113] [115] [-89] [51] [-93] [-11] [-25]
[-30]
The bytes shown in line 3 are corect.
The bytes shown in line 4 are partially correct in that the positive numbers are correct. Im not sure why the others have come out as negative numbers. Whats interesting is that when i add 256 to the negative numbers the answer becomes correct. Why does this happen? Have i used a variable that is the wrong size?
Edited by: ziggy on Jul 5, 2008 12:32 PM
Edited by: ziggy on Jul 5, 2008 12:33 PM
Edited by: ziggy on Jul 5, 2008 12:34 PM