Java code to sign the URL using the HMAC in SAP PI/SAP CPI

Google API/Google GeoLocation/Signature generation/ Validate signed URL 

Java code to sign the URL using the HMAC with encoding and decoding in SAP PI/CPI

Java code:

import java.io.IOException;

import java.io.UnsupportedEncodingException;

import java.net.URI;

import java.net.URISyntaxException;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;

import java.util.Base64; // JDK 1.8 only - older versions may need to use Apache Commons or similar.

import javax.crypto.Mac;

import javax.crypto.spec.SecretKeySpec;

import java.net.URL;

import java.io.BufferedReader;

import java.io.InputStreamReader;




public class UrlSigner {




// Note: Generally, you should store your private key someplace safe

// and read them into your code




private static String keyString = "Crypto key/Private key";



// The URL shown in these examples is a static URL which should already

// be URL-encoded. In practice, you will likely have code

// which assembles your URL from user or web service input

// and plugs those values into its parameters.

private static String urlString = "http://maps.googleapis.com/maps/api/geocode/json?address=10006+NY&sensor=false&client=<Client ID>";


// This variable stores the binary key, which is computed from the string (Base64) key

private static byte[] key;

public static void main(String[] args) throws IOException,

InvalidKeyException, NoSuchAlgorithmException, URISyntaxException {



BufferedReader input = new BufferedReader(new InputStreamReader(System.in));

String inputUrl, inputKey = null;

// For testing purposes, allow user input for the URL.

// If no input is entered, use the static URL defined above.

/*System.out.println("Enter the URL (must be URL-encoded) to sign: ");

inputUrl = input.readLine();

if (inputUrl.equals("")) {

inputUrl = urlString;

}*/


// Convert the string to a URL so we can parse it

URL url = new URL(urlString);


// For testing purposes, allow user input for the private key.

// If no input is entered, use the static key defined above.

/* System.out.println("Enter the Private key to sign the URL: ");

inputKey = input.readLine();

if (inputKey.equals("")) {

inputKey = keyString;

}*/



UrlSigner signer = new UrlSigner(keyString);

String request = signer.signRequest(url.getPath(),url.getQuery());

System.out.println("Signed URL :" + url.getProtocol() + "://" + url.getHost() + request);

}

public UrlSigner(String keyString) throws IOException {

// Convert the key from 'web safe' base 64 to binary

keyString = keyString.replace('-', '+');

keyString = keyString.replace('_', '/');

// System.out.println("Key: " + keyString);

// Base64 is JDK 1.8 only - older versions may need to use Apache Commons or similar.

this.key = Base64.getDecoder().decode(keyString);

}


public String signRequest(String path, String query) throws NoSuchAlgorithmException,

InvalidKeyException, UnsupportedEncodingException, URISyntaxException {


// Retrieve the proper URL components to sign

String resource = path + '?' + query;


// Get an HMAC-SHA1 signing key from the raw key bytes

SecretKeySpec sha1Key = new SecretKeySpec(key, "HmacSHA1");


// Get an HMAC-SHA1 Mac instance and initialize it with the HMAC-SHA1 key

Mac mac = Mac.getInstance("HmacSHA1");

mac.init(sha1Key);

// compute the binary signature for the request

byte[] sigBytes = mac.doFinal(resource.getBytes());


// base 64 encode the binary signature

// Base64 is JDK 1.8 only - older versions may need to use Apache Commons or similar.

String signature = Base64.getEncoder().encodeToString(sigBytes);


// convert the signature to 'web safe' base 64

signature = signature.replace('+', '-');

signature = signature.replace('/', '_');

return resource + "&signature=" + signature;

}

}