Java Development

[arvbhavan]

I am looking to SHA encrypt a string value in BB, but some of the BB classes shows some samples which returns the length of hMAC

ie,

private static int sampleSHA256HMAC( byte[] hashKey, byte[] plainText, byte[] digestData )
        throws CryptoException, IOException
    {
        // Create the keyed hash function key
        HMACKey key = new HMACKey( hashKey );

        // Create an instance of an HMAC
        HMAC hMac = new HMAC( key, new SHA256Digest() );
        
        // Now create the MAC output stream for easy use
        MACOutputStream macStream = new MACOutputStream( hMac, null );
                
        // Write the text to the stream
        macStream.write( plainText );
        
        // Copy the digest data to the digestData byte array and
        // return the length
        hMac.getMAC( digestData, 0 );
        return hMac.getLength();
    }

Is there any way to SHA encrypt a string to return a string value(hash value) of the string as string itself.

[peter_strange]

You should be aware that SHA does not encrypt, it is a hash algorithm which calculates the hash of some bytes.  it is not possible to recover the bytes from the hash. 

I suggest you review the actual specification of this algorithm.  If you are looking for something to encrypt and/or create a String, then you need to look at some other algorithm. 

if you want to stick with SHA-2, then just convert the int to a String. 

[lagunex · Accepted solution]

Hi.

If you consider what peter_strange said about not being an encription algorithm and you still want to use it, try this method. It returns a String

private String sign(String content) throws Exception {
  HMAC sha256 = new HMAC(new HMACKey(secretAccessKey.getBytes()),
    new SHA256Digest());
  sha256.update(content.getBytes());
  byte[] signed = new byte[sha256.getLength()];
  sha256.getMAC(signed, 0);
    	
  String signedbase64 = Base64OutputStream.encodeAsString(signed, 0, signed.length, false, false);
    	
  return signedbase64;
}

 Well, it actually returns a URLUTF8 encode version of the Base64 String but you get the idea.

The secretAccessKey object is a String needed to hash your content. I suppose you'll place your own key there.

In summary:

- Create the HMAC object using your key.

- Fill it with your content.

- Create a byte[] to place the hash.

- Fill the array with the hashed content.

- Convert the bytes to String (I used base 64 but I guess you could simply use new String(byte[]))

I hope it helps.

Cheers.