[TriLUG] MD5 silly question
Brent Verner
brent at rcfile.org
Thu Jul 8 10:57:03 EDT 2004
[2004-07-08 10:43] Brian Henning said:
| Hi y'all,
| I'll readily admit that MD5 is quite FM to me yet, but this particular
| thing struck me as odd... I have a php script which uses the php md5(...)
| function, and a Java app that uses the MD5 functionality of the
| java.security.MessageDigest class. When I create a hash (of a password
| string, in this case) using the php script and compare it to the hash of the
| same string created by the Java app, they're not the same. I always sort of
| thought a hash was a hash, and as long as the input was the same, the output
| would be the same... Would someone mind giving me just a brief explanation
| (I'm not asking for anything in-depth here) of why two different MD5
| programs (for lack of a better word) would generate different hashes for the
| same input? Could it be something like salting?
encoding. Java's MessageDigest does not hex encode the output
as, I believe, php's md5 is doing.
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class MD5 {
/* returns hex encoded md5 cipher of input string */
public static String crypt(String str)
throws NoSuchAlgorithmException, IllegalArgumentException
{
MessageDigest digester;
digester = MessageDigest.getInstance("MD5");
if (str == null || str.length() == 0) {
throw new IllegalArgumentException("String to cipher cannot be null or zero length");
}
digester.update(str.getBytes());
byte[] hash = digester.digest();
StringBuffer hexString = new StringBuffer();
for (int i = 0; i < hash.length; i++) {
if ((0xff & hash[i]) < 0x10) {
hexString.append("0" + Integer.toHexString((0xFF & hash[i])));
}
else {
hexString.append(Integer.toHexString(0xFF & hash[i]));
}
}
return hexString.toString();
}
}
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