Implementation of Kraken API in Java

Question

So I currently working on an implementation of the Kraken API for Java. I am using this sample code I found on http://pastebin.com/nHJDAbH8.

The general usage as described by Kraken (https://www.kraken.com/help/api) is:

API-Key = API key

API-Sign = Message signature using HMAC-SHA512 of
( URI path + SHA256( nonce + POST data ) ) and base64 decoded secret API key

and

nonce = always increasing unsigned 64 bit integer
otp = two-factor password ( if two-factor enabled, otherwise not required )

however I am facing the following response:

{"error":["EAPI:Invalid key"]}

I already tried a couple of ways ( getting a new API, trying to change the sha256 methods, because I thought something is wrong with the way it is hashed )

So this is the code:

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.UnsupportedEncodingException;
import java.net.HttpURLConnection;
import java.net.URL;
import java.security.InvalidKeyException;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.apache.commons.codec.binary.Base64;

public class KrakenClient {

        protected static String key = "myAPIKey";     // API key
        protected static String secret = "MySecret====";  // API secret
        protected static String url = "api.kraken.com";     // API base URL
        protected static String version = "0"; // API version


        public static void main(String[] args) throws Exception {
                queryPrivateMethod("Balance");
        }

        public static void queryPrivateMethod(String method) throws NoSuchAlgorithmException, IOException{

                long nonce = System.currentTimeMillis();

                String path = "/" + version + "/private/" + method; // The path like "/0/private/Balance"

                String urlComp = "https://"+url+path; // The complete url like "https://api.kraken.com/0/private/Balance"

                String postdata = "nonce="+nonce;

                String sign = createSignature(nonce, path, postdata);

                postConnection(urlComp, sign, postdata);
        }

        /**
         * @param nonce
         * @param path
         * @param postdata
         * @return
         * @throws NoSuchAlgorithmException
         * @throws IOException
         */
        private static String createSignature(long nonce, String path,
                        String postdata) throws NoSuchAlgorithmException, IOException {

                return hmac(path+sha256(nonce + postdata),  new String(Base64.decodeBase64(secret)));
        }

        public static String sha256Hex(String text) throws NoSuchAlgorithmException, IOException{
                return org.apache.commons.codec.digest.DigestUtils.sha256Hex(text);
        }

        public static byte[] sha256(String text) throws NoSuchAlgorithmException, UnsupportedEncodingException{
                MessageDigest md = MessageDigest.getInstance("SHA-256");

                md.update(text.getBytes());
                byte[] digest = md.digest();

                return digest;
        }

        public static void postConnection(String url1, String sign, String postData) throws IOException{

                URL url = new URL( url1 );
                HttpURLConnection connection = (HttpURLConnection) url.openConnection();

                connection.addRequestProperty("API-Key", key);
                connection.addRequestProperty("API-Sign", Base64.encodeBase64String(sign.getBytes()));
                //              connection.addRequestProperty("API-Sign", sign);
                connection.addRequestProperty("User-Agent", "Mozilla/4.0");
                connection.setRequestMethod( "POST" );
                connection.setDoInput( true );
                connection.setDoOutput( true );
                connection.setUseCaches( false );
                //              connection.setRequestProperty( "Content-Type",
                //                              "application/x-www-form-urlencoded" );
                connection.setRequestProperty( "Content-Length", String.valueOf(postData.length()) );

                OutputStreamWriter writer = new OutputStreamWriter( connection.getOutputStream() );
                writer.write( postData );
                writer.flush();


                BufferedReader reader = new BufferedReader(
                                new InputStreamReader(connection.getInputStream()) );

                for ( String line; (line = reader.readLine()) != null; )
                {
                        System.out.println( line );
                }

                writer.close();
                reader.close();
        }


        public static String hmac(String text, String secret){

                Mac mac =null;
                SecretKeySpec key = null;

                // Create a new secret key
                try {
                        key = new SecretKeySpec( secret.getBytes( "UTF-8"), "HmacSHA512" );
                } catch( UnsupportedEncodingException uee) {
                        System.err.println( "Unsupported encoding exception: " + uee.toString());
                        return null;
                }
                // Create a new mac
                try {
                        mac = Mac.getInstance( "HmacSHA512" );
                } catch( NoSuchAlgorithmException nsae) {
                        System.err.println( "No such algorithm exception: " + nsae.toString());
                        return null;
                }

                // Init mac with key.
                try {
                        mac.init( key);
                } catch( InvalidKeyException ike) {
                        System.err.println( "Invalid key exception: " + ike.toString());
                        return null;
                }


                // Encode the text with the secret
                try {

                        return new String( mac.doFinal(text.getBytes( "UTF-8")));
                } catch( UnsupportedEncodingException uee) {
                        System.err.println( "Unsupported encoding exception: " + uee.toString());
                        return null;
                }
        }
}

Answer 1

Here is a working example:

static String key = "---myKey---";
static String secret = "---mySecret---";
String nonce, signature, data, path;
static String domain = "https://api.kraken.com";

void account_balance() {
    nonce = String.valueOf(System.currentTimeMillis());
    data = "nonce=" + nonce;
    path = "/0/private/Balance";
    calculateSignature();
    String answer = post(domain + path, data);
    // on empty accounts, returns {"error":[],"result":{}}
    // this is a known Kraken bug
    ...
}

String post(String address, String output) {
    String answer = "";
    HttpsURLConnection c = null;
    try {
        URL u = new URL(address); 
        c = (HttpsURLConnection)u.openConnection();
        c.setRequestMethod("POST");
        c.setRequestProperty("API-Key", key);
        c.setRequestProperty("API-Sign", signature);
        c.setDoOutput(true);
        DataOutputStream os = new DataOutputStream(c.getOutputStream());
        os.writeBytes(output);
        os.flush();
        os.close();
        BufferedReader br = null;
        if(c.getResponseCode() >= 400) {
            System.exit(1);
        }
        br = new BufferedReader(new InputStreamReader((c.getInputStream())));
        String line;
        while ((line = br.readLine()) != null)
            answer += line;
    } catch (Exception x) {
        System.exit(1);
    } finally {
        c.disconnect();
    }
    return answer;        
}

void calculateSignature() {
    signature = "";
    try {
        MessageDigest md = MessageDigest.getInstance("SHA-256");
        md.update((nonce + data).getBytes());
        Mac mac = Mac.getInstance("HmacSHA512");
        mac.init(new SecretKeySpec(Base64.decodeBase64(secret.getBytes()), "HmacSHA512"));
        mac.update(path.getBytes());
        signature = new String(Base64.encodeBase64(mac.doFinal(md.digest())));
    } catch(Exception e) {}
    return;
}