Hash String via SHA-256 in Java

Question

By looking around here as well as the internet in general  I have found Bouncy Castle  I want to use Bouncy Castle  or some other freely available utility  to generate a SHA-256 Hash of a String in Java  Looking at their documentation I can t seem to find any good examples of what I want to do  Can anybody here help me out

User · Answer

This is already implemented in the runtime libs.

public static String calc(InputStream is) {
    String output;
    int read;
    byte[] buffer = new byte[8192];

    try {
        MessageDigest digest = MessageDigest.getInstance("SHA-256");
        while ((read = is.read(buffer)) > 0) {
            digest.update(buffer, 0, read);
        }
        byte[] hash = digest.digest();
        BigInteger bigInt = new BigInteger(1, hash);
        output = bigInt.toString(16);
        while ( output.length() < 32 ) {
            output = "0"+output;
        }
    } 
    catch (Exception e) {
        e.printStackTrace(System.err);
        return null;
    }

    return output;
}

In a JEE6+ environment one could also use JAXB DataTypeConverter:

import javax.xml.bind.DatatypeConverter;

String hash = DatatypeConverter.printHexBinary( 
           MessageDigest.getInstance("MD5").digest("SOMESTRING".getBytes("UTF-8")));

User · Answer

You don t necessarily  need the BouncyCastle library  The following code shows how to do so using the Integer toHexString function  public static String sha256 String base        try          MessageDigest digest   MessageDigest getInstance  SHA-256            byte   hash   digest digest base getBytes  UTF-8             StringBuffer hexString   new StringBuffer             for  int i   0  i  lt  hash length  i                  String hex   Integer toHexString 0xff  amp  hash i                if hex length      1  hexString append  0                hexString append hex                      return hexString toString          catch Exception ex          throw new RuntimeException ex             Special thanks to user1452273 from this post  How to hash some string with sha256 in Java   Keep up the good work

User · Answer

When using hashcodes with any jce provider you first try to get an  instance of the algorithm  then update it with the data you want to be hashed  and when you are finished you call digest to get the hash value    MessageDigest sha   MessageDigest getInstance  SHA-256    sha update in getBytes     byte   digest   sha digest      you can use the digest to get a base64 or hex encoded version according to your needs

User · Answer

Using Java 8  MessageDigest digest   null  try       digest   MessageDigest getInstance  SHA-256      catch  NoSuchAlgorithmException e        e printStackTrace      byte   hash   digest digest text getBytes StandardCharsets UTF 8    String encoded   DatatypeConverter printHexBinary hash           System out println encoded toLowerCase

User · Answer

return new String Hex encode digest

User · Answer

Java 8  Base64 available       MessageDigest md   MessageDigest getInstance   SHA-512         md update  inbytes        byte   aMessageDigest   md digest         String outEncoded   Base64 getEncoder   encodeToString  aMessageDigest        return  outEncoded

User · Answer

I suppose you are using a relatively old Java Version without SHA-256  So you must add the BouncyCastle Provider to the already provided  Security Providers  in your java version          NEEDED if you are using a Java version without SHA-256         Security addProvider new BouncyCastleProvider             then go as usual      MessageDigest md   MessageDigest getInstance  SHA-256        String text    my string          md update text getBytes  UTF-8        or UTF-16 if needed     byte   digest   md digest

User · Answer

To hash a string  use the built-in MessageDigest class   import java security MessageDigest  import java security NoSuchAlgorithmException  import java nio charset StandardCharsets  import java math BigInteger   public class CryptoHash     public static void main String   args  throws NoSuchAlgorithmException       MessageDigest md   MessageDigest getInstance  SHA-256        String text    Text to hash  cryptographically            Change this to UTF-16 if needed     md update text getBytes StandardCharsets UTF 8        byte   digest   md digest         String hex   String format   064x   new BigInteger 1  digest        System out println hex           In the snippet above  digest contains the hashed string and hex contains a hexadecimal ASCII string with left zero padding

User · Answer

This will work with  org bouncycastle util encoders Hex  following package   return new String Hex encode digest      Its in bouncycastle jar

[java] Hash String via SHA-256 in Java

Examples related to java

Examples related to bouncycastle

Examples related to sha256

Examples related to jce