Java SHA-256

 Cryptographic hash functions are mathematical operations run on digital data; by comparing the computed hash (i.e., the output produced by executing a hashing algorithm) to a known and expected hash value, a person can determine the data's integrity. For example, computing the hash of a downloaded file and comparing the result to a previously published hash result can show whether the download has been modified or tampered with. In addition, cryptographic hash functions are extremely collision-resistant; in other words, it should be extremely difficult to produce the same hash output from two different input values using a cryptographic hash function.

Secure Hash Algorithm 2 (SHA-2) is a set of cryptographic hash functions designed by the National Security Agency (NSA). It consists of six identical hashing algorithms (i.e., SHA-256, SHA-512, SHA-224, SHA-384, SHA-512/224, SHA-512/256) with a variable digest size. SHA-256 is a -bit ( byte) hashing algorithm which can calculate a hash code for an input of up to  bits. It undergoes  rounds of hashing and calculates a hash code that is a -digit hexadecimal number.

Given a string, , print its SHA-256 hash value.

Input Format

A single alphanumeric string denoting .

Constraints

• String  consists of English alphabetic letters (i.e.,  and/or decimal digits (i.e.,  through ) only.

Output Format

Print the SHA-256 encryption value of  on a new line.

Sample Input 0

HelloWorld

Sample Output 0

872e4e50ce9990d8b041330c47c9ddd11bec6b503ae9386a99da8584e9bb12c4

Sample Input 1

Javarmi123

Sample Output 1

f1d5f8d75bb55c777207c251d07d9091dc10fe7d6682db869106aacb4b7df678

SOLUTION:

import java.util.Scanner;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
public class Solution {
    public static void main(String[] args) throws NoSuchAlgorithmException {
        /* Read and save the input String */
        Scanner scan = new Scanner(System.in);
        String str = scan.next();
        scan.close();
        
        /* Encode the String using SHA-256 */
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update(str.getBytes());
        byte[] digest = md.digest();
        
        /* Print the encoded value in hexadecimal */
        for (byte b : digest) {
            System.out.format("%02x", b);
        }
    }
}