Google Maps API for Business

Authentication and Authorization

Business-specific parameters

When using a Maps API web service in your Maps API for Business application, two parameters are required in addition to the standard parameters:

  • Your client ID. To access the special features of the Google Maps API for Business, you must provide a client ID when accessing any of the API libraries or services. When registering for Google Maps API for Business, you will receive this client ID from Google Enterprise Support. All client IDs begin with a gme- prefix. Your client ID is passed as the value of the client parameter.
  • A unique signature, generated using your cryptographic key. This is passed as the value of the signature parameter. More information about generating a signature can be found below, in the Digital Signatures section.

The Places API and Geolocation API do not use the client and signature parameters. These APIs use a key parameter, obtained from the API Console. For more information, refer to the Places API and Geolocation API documentation.

http://maps.googleapis.com/maps/api/geocode/json
  ?address=1600+Amphitheatre+Parkway,+Mountain+View,+CA
  &sensor=true_or_false
  &client=gme-YOUR_CLIENT_ID
  &signature=YOUR_URL_SIGNATURE

In addition, the following parameter is optional with Maps API for Business requests:

  • channel is used to provide additional reporting detail, by grouping different channels separately in your reports. Refer to the Channel reports section of the Quota and reporting page of this document.

For information about a specific service's standard parameters, please refer to that service's documentation.

Digital signatures

Requests to these Maps API web services by Maps API for Business applications require digital signatures, generated using a cryptographic key provided to you for that purpose. The signing process combines a URL and the key together using an encryption algorithm. The resulting unique signature allows our web services to verify that any site generating requests using your client ID are authorized to do so.

How do I get my signing key?

Your cryptographic URL-signing key will be issued with your client ID and is a "secret shared key" between you and Google. Client IDs are issued to all Maps API for Business customers. This signing key is yours alone and unique to your client ID. For that reason, please keep your signing key secure. This key — though used to generate the signature — should not be passed within any requests, stored on any websites, or posted to any public forum. Anyone obtaining this signing key "in the clear" could spoof requests using your identity.

Note: This cryptographic signing key is not the same as the (freely available) Maps API key (typically beginning with 'ABQ..') that developers without a Maps API for Business license are required to use when loading the Maps JavaScript API V2 and Maps API for Flash, or the keys issued by the Google APIs Console for use with the Google Places API.

If you've lost your signing key, log in to the support portal and click Maps: Manage Client ID to retrieve it.

Generating valid signatures

Attempting to access a web service with an invalid signature will result in a HTTP 403 (Forbidden) error. As you convert your applications to use URL signing, make sure to test your signatures to ensure they initiate a valid request. You should first test whether the original URL is valid (See Building a Valid URL in the Web Services documentation) as well as test whether you generate the correct signatures.

A screencast with a step by step explanation can be found on the Google Developers YouTube channel: Maps for Business: Generating Valid Signatures.

To create a valid signature for your request:

  1. Construct your URL, making sure to include your client and sensor parameters. Note that any non-standard characters will need to be URL-encoded:

    http://maps.googleapis.com/maps/api/staticmap?center=%E4%B8%8A%E6%B5%B7+%E4%B8%AD%E5%9C%8B&size=640x640&zoom=10&client=clientID&sensor=false

  2. Strip off the domain portion of the request, leaving only the path and the query:

    /maps/api/staticmap?center=%E4%B8%8A%E6%B5%B7+%E4%B8%AD%E5%9C%8B&size=640x640&zoom=10&client=clientID&sensor=false

  3. Retrieve your private key, which is encoded in a modified Base64 for URLs, and sign the URL above using the HMAC-SHA1 algorithm. You may need to decode this key into its original binary format. Note that in most cryptographic libraries, the resulting signature will be in binary format.

  4. Encode the resulting binary signature using the modified Base64 for URLs to convert this signature into something that can be passed within a URL.

  5. Attach this signature to the URL within a signature parameter:

    http://maps.googleapis.com/maps/api/staticmap?center=%E4%B8%8A%E6%B5%B7+%E4%B8%AD%E5%9C%8B&size=640x640&zoom=10&client=clientID&sensor=false&signature=base64signature

Signature examples

The following sections show ways to implement URL signing using server-side code. For simplicity, many of these samples have hard-coded URLs and private keys. URLs should always be signed server-side to avoid exposing your cryptographic key to users.

For testing purposes, you can test the following URL and private key to see if it generates the correct signature. Note that this private key is purely for testing purposes and will not be validated by any Google services.

  • URL: http://maps.googleapis.com/maps/api/geocode/json?address=New+York&sensor=false&client=clientID
  • Private Key: vNIXE0xscrmjlyV-12Nj_BvUPaw=
  • URL Portion to Sign: /maps/api/geocode/json?address=New+York&sensor=false&client=clientID
  • Signature: KrU1TzVQM7Ur0i8i7K3huiw3MsA=
  • Full Signed URL: http://maps.googleapis.com/maps/api/geocode/json?address=New+York&sensor=false&client=clientID&signature=KrU1TzVQM7Ur0i8i7K3huiw3MsA=

Python

The example below uses standard Python libraries to sign a URL and output a proper URL request.

#!/usr/bin/python
# coding: utf8

import sys
import hashlib
import urllib
import hmac
import base64
import urlparse

print("")
print("URL Signer 1.0")
print("")

# Convert the URL string to a URL, which we can parse
# using the urlparse() function into path and query
# Note that this URL should already be URL-encoded
url = urlparse.urlparse("YOUR_URL_TO_SIGN")

privateKey = "YOUR_PRIVATE_KEY"

# We only need to sign the path+query part of the string
urlToSign = url.path + "?" + url.query

# Decode the private key into its binary format
decodedKey = base64.urlsafe_b64decode(privateKey)

# Create a signature using the private key and the URL-encoded
# string using HMAC SHA1. This signature will be binary.
signature = hmac.new(decodedKey, urlToSign, hashlib.sha1)

# Encode the binary signature into base64 for use within a URL
encodedSignature = base64.urlsafe_b64encode(signature.digest())
originalUrl = url.scheme + "://" + url.netloc + url.path + "?" + url.query
print("Full URL: " + originalUrl + "&signature=" + encodedSignature)

Download the code from the gmaps-samples project.

Java

The example below uses this public domain Base64 encoding class to sign a URL and output a proper URL request. (Be sure to include that class in your CLASSPATH when compiling the Java code shown below.)

public class UrlSigner {

  // Note: Generally, you should store your private key someplace safe
  // and read them into your code

  private static String keyString = "YOUR_PRIVATE_KEY";

  // The URL shown in these examples must be already
  // 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 = "YOUR_URL_TO_SIGN";

  // 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 {

    // Convert the string to a URL so we can parse it
    URL url = new URL(urlString);

    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);
    this.key = Base64.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
    String signature = Base64.encodeBytes(sigBytes);

    // convert the signature to 'web safe' base 64
    signature = signature.replace('+', '-');
    signature = signature.replace('/', '_');

    return resource + "&signature=" + signature;
  }
}

Download the code from the gmaps-samples project.

C#

The example below uses the default System.Security.Cryptography library to sign a URL request and output a proper URL request. Note that we need to convert the default Base64 encoding to implement an URL-safe version.

using System;
using System.Collections.Generic;
using System.Security.Cryptography;
using System.Text;
using System.Text.RegularExpressions;
using System.Web;

namespace SignUrl {

  public struct GoogleSignedUrl {

    public static string Sign(string url, string keyString) {
      ASCIIEncoding encoding = new ASCIIEncoding();

      // converting key to bytes will throw an exception, need to replace '-' and '_' characters first.
      string usablePrivateKey = keyString.Replace("-", "+").Replace("_", "/");
      byte[] privateKeyBytes = Convert.FromBase64String(usablePrivateKey);

      Uri uri = new Uri(url);
      byte[] encodedPathAndQueryBytes = encoding.GetBytes(uri.LocalPath + uri.Query);

      // compute the hash
      HMACSHA1 algorithm = new HMACSHA1(privateKeyBytes);
      byte[] hash = algorithm.ComputeHash(encodedPathAndQueryBytes);

      // convert the bytes to string and make url-safe by replacing '+' and '/' characters
      string signature = Convert.ToBase64String(hash).Replace("+", "-").Replace("/", "_");

      // Add the signature to the existing URI.
      return uri.Scheme+"://"+uri.Host+uri.LocalPath + uri.Query +"&signature=" + signature;
    }
  }

  class Program {

    static void Main() {

      // Note: Generally, you should store your private key someplace safe
      // and read them into your code

      const string keyString = "YOUR_PRIVATE_KEY";

      // The URL shown here is a static URL which should be already
      // 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.
      const  string urlString = "YOUR_URL_TO_SIGN";

      Console.WriteLine(GoogleSignedUrl.Sign(urlString,keyString));
    }
  }
}

Download the code from gmaps-samples

Examples in additional languages

Examples that cover more languages are available in the gmaps-samples project.

Troubleshooting authentication issues

In the event your request is malformed or supplies an invalid signature, you will encounter an HTTP 403 (Forbidden) error along with the message:

Unable to authenticate the request. Provided 'signature' is not valid for the provided client ID. Learn more:
https://developers.google.com/maps/documentation/business/webservices/auth

To troubleshoot individual URLs, a URL signing debugger is available for the purpose of quickly validating URLs and signatures generated by your application. You can access the tool from:

https://m4b-url-signer.appspot.com/

or by logging in to the support portal and selecting Resources > Google Maps API for Business online tools > URL Signing Debugger for Web Service and Image APIs.

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