Hashing a message into an elliptic curve group

I wanted a hash function (h) defined as follows for an implementation that I'm working on these days:

h : {0,1}* → G

This means that h maps a bit string of any length to a point of the the elliptic curve group G.

These sort of functions are quite common in literature and I came up with a quick fix solution for one :-) (and I'm sure there are much better implementations out there).

Here's the code:

import it.unisa.dia.gas.jpbc.Element;
import it.unisa.dia.gas.jpbc.Pairing;
import it.unisa.dia.gas.plaf.jpbc.pairing.CurveParams;
import it.unisa.dia.gas.plaf.jpbc.pairing.PairingFactory;

import java.io.InputStream;
import java.math.BigInteger;

import org.bouncycastle.crypto.digests.SHA256Digest;

public class Digest {

    private Element gElem = null;
    private Pairing pairing = null;
    
    public Digest() throws Exception {
        CurveParams curveParams = new CurveParams();
        curveParams.load(Digest.class.getClassLoader().getResourceAsStream("a_181_603.properties"));

        //Load private key
        InputStream fis = Digest.class.getClassLoader().getResourceAsStream("keys/digest/g");
        byte[] tmp = new byte[1024];
        int read = fis.read(tmp);
        
        byte[] gBytes = new byte[read];
        System.arraycopy(tmp, 0, gBytes, 0, read);
        
        this.pairing = PairingFactory.getPairing(curveParams);
        this.gElem = this.pairing.getG1().newElement();
        this.gElem.setFromBytes(gBytes);
    }


    public byte[] createHash(byte[] data) throws Exception {

        //Create a sha 256 of the message
        SHA256Digest dgst = new SHA256Digest();
        dgst.reset();
        dgst.update(data, 0, data.length);
        int digestSize = dgst.getDigestSize();
        byte[] hash = new byte[digestSize];
        dgst.doFinal(hash, 0);

        BigInteger val = new BigInteger(hash);

        BigInteger order = this.pairing.getG1().getOrder();
        BigInteger fact = val.mod(order);

        Element gen = this.gElem.duplicate();
        Element mul = gen.mul(fact);
        return mul.toBytes();
    }
    
}

This uses the jPBC library.