Intercom Secure Mode Signature

SecureModeSignature.java

package io.intercom.api.secure;

import org.apache.commons.codec.binary.Hex;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.Base64;

public class SecureModeSignature {

    private static final String HMAC_SHA_256 = "HmacSHA256";

    public String createSignatureB64(String key, String data) {
        return Base64.getEncoder().encodeToString(Hex.encodeHexString(createSignatureBytes(key, data, HMAC_SHA_256)).getBytes());
    }

    public String createSignatureHex(String key, String data) {
        return Hex.encodeHexString(createSignatureBytes(key, data, HMAC_SHA_256));
    }

    public byte[] createSignatureBytes(String key, String data, String sha) {
        try {
            final SecretKeySpec keySpec = new SecretKeySpec(key.getBytes(), sha);
            final Mac mac = Mac.getInstance(sha);
            mac.init(keySpec);
            return mac.doFinal(data.getBytes());
        } catch (NoSuchAlgorithmException | InvalidKeyException e) {
            throw new RuntimeException("signature_failure could not create hmac", e);
        }
    }

    public static void main(String[] args) {
        SecureModeSignature sms = new SecureModeSignature();
        final String signatureHex = sms.createSignatureHex("key", "data");
        System.out.println(signatureHex);
    }
}

Thanks a lot for this, works great! Saved me some cipher searching in the PHP documentation