There are multiple ways to generate MD5 hash in Java program. Not only
Java API provides convenient method to generate MD5 hash, you can also use
popular open source frameworks, like Spring and Apache
commons Codec to generate MD5 digest in Java. MD5 is popular Message Digest Algorithm,
which is most commonly used to check data integrity e.g. comparing MD5 check-sum
to see, if any file is altered or not. Though, MD5 was not considered a good
cryptographic algorithm for security purpose due to several vulnerability found
on it, it's still good enough or checking integrity of file. MD5 hashing
algorithm generate a 128 bit or 16 byte long hash value. MD5 hash values, also
known as MD5 digest is mostly represented as 32 character Hex String. You can
generate MD5 hash from a byte array, or String directly using Java,
Spring and Apache commons codec. Spring and Apache commons codec has identical
API e.g. class name DigestUtils is same and allows you to
directly generate MD5 hash as Hex String, while if you use Java than you need
to convert byte array to Hex String, as java.security.MessageDigest.digest() method
returns MD5 hash as byte array. Earlier we have seen, How to encode and decode String in base64
encoding, and In this Java tutorial we will see, How to generate MD5 hash or digest using Java, Spring and Apache
commons code library.
How to Generate MD5 hash in Java - example
In this part, we will see some example to generate MD5 hash in Java.Following Java program generates MD5 hash or digest of a String, by converting
into byte array. Java Security package provides MessageDigest, which can
generate MD5 hash. MessageDigest's digest() method
accept a byte array, and return a byte array of hash value. Since many times we
need MD5 hash as Hex String, I have converted that byte array into Hex String. Apart from core
Java example, which doesn't use any dependency, there are couple of more open
source solution of generating MD5 digest. Two of the most popular open source
library, Apache Commons Codec and Spring Framework provides utility method to
create MD5 Hash in both byte array and Hex String format. Both Apache commons
code and Spring provides, DigestUtils class with overloaded method md5() and md5Hex(), which can
accept either String or byte array and can
return either 16 element byte array or 32 characters Hex String. If you are
already using either Spring or Apache Commons Codec, than its best to use DigestUtil, as it
only need a line of code to generate MD5 hash in Java. here is complete code
example of generating MD5 digest in Java.
import java.io.UnsupportedEncodingException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.util.logging.Level;
import java.util.logging.Logger;
import org.apache.commons.codec.digest.DigestUtils;
/**
* Java program to generate MD5 hash or digest for String. In this example
* we will see 3 ways to create MD5 hash or digest using standard Java API,
* Spring framework and open source library, Apache commons codec utilities.
* Generally MD5 has are represented as Hex String so each of this function
* will return MD5 hash in hex format.
*
* @author Javin Paul
*/
public class MD5Hash {
public static void main(String args[]) {
String password = "password";
System.out.println("MD5 hash generated using Java : " + md5Java(password));
System.out.println("MD5 digest generated using : " + md5Spring(password));
System.out.println("MD5 message created by Apache commons codec : " + md5ApacheCommonsCodec(password));
}
public static String md5Java(String message){
String digest = null;
try {
MessageDigest md = MessageDigest.getInstance("MD5");
byte[] hash = md.digest(message.getBytes("UTF-8"));
//converting byte array to Hexadecimal String
StringBuilder sb = new StringBuilder(2*hash.length);
for(byte b : hash){
sb.append(String.format("%02x", b&0xff));
}
digest = sb.toString();
} catch (UnsupportedEncodingException ex) {
Logger.getLogger(StringReplace.class.getName()).log(Level.SEVERE, null, ex);
} catch (NoSuchAlgorithmException ex) {
Logger.getLogger(StringReplace.class.getName()).log(Level.SEVERE, null, ex);
}
return digest;
}
/*
* Spring framework also provides overloaded md5 methods. You can pass input
* as String or byte array and Spring can return hash or digest either as byte
* array or Hex String. Here we are passing String as input and getting
* MD5 hash as hex String.
*/
public static String md5Spring(String text){
return DigestUtils.md5Hex(text);
}
/*
* Apache commons code provides many overloaded methods to generate md5 hash. It contains
* md5 method which can accept String, byte[] or InputStream and can return hash as 16 element byte
* array or 32 character hex String.
*/
public static String md5ApacheCommonsCodec(String content){
return DigestUtils.md5Hex(content);
}
}
Output:
MD5 hash generated using Java : 5f4dcc3b5aa765d61d8327deb882cf99
MD5 digest generated using : 5f4dcc3b5aa765d61d8327deb882cf99
MD5 message created by Apache commons code : 5f4dcc3b5aa765d61d8327deb882cf99
That's all on How to generate MD5 hash or digest in Java. As you
have seen, there is more than one way to generate MD5 digest, both in byte
array as well as Hex String format. Just remember to specify file encoding to String.getBytes() method, until you have not using any application wide character encoding. Since String.getBytes() uses
platform specific encoding which could be different in your windows development
machine and production Linux Server. Also, consider using Spring or Apache
Commons Code to generate MD5 Hash value, if you are already using these
libraries. It's always best to reuse library code than writing your own MD5
hash function, to avoid testing overhead.
Other Java Programming Tutorials from Javarevisited Blog
Source:http://javarevisited.blogspot.com/2013/03/generate-md5-hash-in-java-string-byte-array-example-tutorial.html
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