How to convert SHA1 output to a HEX string?

Question

I am trying to generate sha1 of a string by referring to the example in this link - http://www.sha1-online.com/sha1-java/

public class HashTextTest {

/**
 * @param args
 * @throws NoSuchAlgorithmException 
 */
public static void main(String[] args) throws NoSuchAlgorithmException {
    System.out.println(sha1("test string to sha1"));
}

static String sha1(String input) throws NoSuchAlgorithmException {
    MessageDigest mDigest = MessageDigest.getInstance("SHA1");
    byte[] result = mDigest.digest(input.getBytes());
    StringBuffer sb = new StringBuffer();
    for (int i = 0; i < result.length; i++) {
        sb.append(Integer.toString((result[i] & 0xff) + 0x100, 16).substring(1));
    }

    return sb.toString(); 

   }
}

I dont want to have this messy line of code from string buffer - sb.append(Integer.toString((result[i] & 0xff) + 0x100, 16).substring(1));.

Is there any alternate way to doing this?

Nothing to do with SHA1. Instead you're simply looking how to turn a `byte[]` into a *textual hex representation* (or some variant with the odd `+ 0x100` ..). — user2864740, Jan 03 '14 at 06:06
Yes, see this answer: http://stackoverflow.com/a/4895922/495796 — Robin Green, Jan 03 '14 at 06:07
@user2864740 - Agree. It has nothing to do with sha1 string. In the code, I am basically looking for a more graceful way of converting Byte Array to Hex String. — rickygrimes, Jan 03 '14 at 06:09
A few variants, one is very similar (but in a tidy function), one using EncodingTool and one with BigInteger. I think there is also an Apache Commons approach floating about. YMMV: http://stackoverflow.com/questions/11822402/how-do-i-convert-a-large-string-into-hex-and-then-into-byte?rq=1 and snother similar post http://stackoverflow.com/questions/9655181/convert-from-byte-array-to-hex-string-in-java?rq=1 (with some different implementations) — user2864740, Jan 03 '14 at 06:09
@DavidWallace sigh... java has signed bytes. This should work sb.append(Integer.toString(512+result[i],16).substring(1); // deleted old comment to prevent its use — Hafthor, Jan 03 '14 at 06:58

Buddhima Gamlath · Accepted Answer · 2014-01-03T06:31:24.647

2

What you need here is to format a byte as two hex digits.

sb.append(String.format("%02x", result[i])); would do it.

If you need uppercase hex digits, use

sb.append(String.format("%02X", result[i]));

Additionaly if you do not mind spaces between encoded bytes, you can use

new sun.misc.HexDumpEncoder().encode(result).substring(6);

to encode the whole byte[] at once.

edited Jan 03 '14 at 06:31

answered Jan 03 '14 at 06:12

Buddhima Gamlath

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It should be pointed out that using any sun.* class is a bad idea. Those classes are private to the Java implementation, and may change or even disappear in any future release of Java, even a minor update. – VGR Jan 04 '14 at 03:36

How to convert SHA1 output to a HEX string?

1 Answers1