Java SHA256

Definition: In cryptography, SHA is a hash function that takes 20 bytes of input and produces an approximate 40-digit hexadecimal integer as the hash result.

Class for Message Digest:

Java's MessageDigest Class, which is part of the java. security package, is used to determine cryptographic hashing values.

To determine the hash value of a text, the MessagDigest Class includes the following cryptographic hash functions:

1. MD5
2. SHA-1
3. SHA-256

The static function getInstance() initialises this algorithm. It calculates the digest value after choosing the algorithm and returns the results in a byte array.

The generated byte array is transformed itself into the sign-magnitude representation using the BigInteger class. To obtain the MessageDigest, this representation is translated to hex format.

Examples:

Input : JavaTpoint

Output : f9142e5ca706378c1c7f9daf6782dcff8197ef1ecfd4075b63dae2f40186afa6

Input : Deekshitha

Output : b9a7b716a303aaf0d9aca444ed2952cab3a0b0b43d280569d125b2f2f9c65a2f

Input : heanchek

Output: dab257e7e013412044748a4279ba69a7df04205c81a33247de9681fb2becac62

Java Program

import java.math.BigInteger;
import java.nio.charset.StandardCharsets;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
 
// SHA hash value calculation in Java
 
class JavaSha256expl {
    public static byte[] getSHA(String input) throws NoSuchAlgorithmException
    {
        // With SHA hashing, the static getInstance function is called.
        MessageDigest m = MessageDigest.getInstance("SHA-256");
 
        // Message digest of such an 
// input is calculated using the 
// digest() method, which returns 
// an array of bytes.
        return m.digest(input.getBytes(StandardCharsets.UTF_8));
    }
     
    public static String toHexString(byte[] hash)
    {
        // Convert byte array into signum representation
        BigInteger n = new BigInteger(1, hash);
 
        // message digest -> hex value conversion
        StringBuilder hexString = new StringBuilder(n.toString(16));
 
        // Add leading zeros to the pad
        while (hexString.length() < 64)
        {
            hexString.insert(0, '0');
        }
 
        return hexString.toString();
    }
 
    // Driver code
    public static void main(String args[])
    {
        try
     { System.out.println(" SHA-256 generated a hash code for: ");
String s0 = "JavaTpoint";
            System.out.println("\n" + s0 + " : " + toHexString(getSHA(s0)));
 
            String s1 = "Deekshitha";
            System.out.println("\n" + s1 + " : " + toHexString(getSHA(s1)));
             
            String s2 = "heanchek"; 
            System.out.println("\n" + s2 + " : " + toHexString(getSHA(s2)));
        }  // due to incorrectly spec'ing message digest algorithms
        catch (NoSuchAlgorithmException e) {
            System.out.println(" An error in the algorithm resulted in an exception: " + e);
        }
    }
}

Output:

Application:

Data Integrity and Cryptography are the areas where JavaSha256 is majorly used.