How to get the md5sum of a file on Amazon's S3

Question

If I have existing files on Amazon\'s S3, what\'s the easiest way to get their md5sum without having to download the files?

Thanks

Answer 1

Here is the code to get MD5 hash as per 2017

import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import org.apache.commons.codec.binary.Base64;
public class GenerateMD5 {
public static void main(String args[]) throws Exception{
    String s = "  http://www.example.com PUT POST DELETE * 3000   * GET * 3000  ";

        MessageDigest md = MessageDigest.getInstance("MD5");
        md.update(s.getBytes());
        byte[] digest = md.digest();
        StringBuffer sb = new StringBuffer();
        /*for (byte b : digest) {
            sb.append(String.format("%02x", b & 0xff));
        }*/
        System.out.println(sb.toString());
        StringBuffer sbi = new StringBuffer();
        byte [] bytes = Base64.encodeBase64(digest);
        String finalString = new String(bytes);
        System.out.println(finalString);
    }
}

The commented code is where most people get it wrong changing it to hex