客户端 ID 请求签名

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数字签名

数字签名的运行方式

您可以使用 Google Cloud Console 中的网址签名密钥或加密密钥生成数字签名。该密钥本质上是一种私钥,仅在您与 Google 之间共享,并且是您的客户端 ID 独有的。

签名流程使用一种加密算法将网址与您的共享密钥合并。我们的服务器可以通过生成的唯一签名来验证,是否使用您的客户端 ID 生成请求的所有网站都获得了相应授权。

对请求进行签名

对请求进行签名包括以下步骤:

第 1 步:获取您的网址签名密钥

如需获取项目的网址签名密钥,请按以下步骤操作:

  1. 转到 Cloud Console 中的“客户端 ID”页面
  2. 密钥字段包含您当前的客户端 ID 网址签名密钥。

如果您需要重新生成客户端 ID 网址签名密钥,请与支持团队联系

第 2 步:构建未签名请求

构建不带签名的未签名请求网址。

此外,还请务必在 client 参数中添加客户端 ID。例如:

https://maps.googleapis.com/maps/api/staticmap?center=40.714%2c%20-73.998&zoom=12&size=400x400&client=YOUR_CLIENT_ID

生成签名请求

为了进行问题排查,您可以使用可用的立即对网址进行签名微件自动生成数字签名。

对于动态生成的请求,您需要在服务器端进行签名,这需要执行一些额外的中间步骤

无论采用上述哪种方式,最终您的请求网址末尾应附加一个 signature 参数。例如:

https://maps.googleapis.com/maps/api/staticmap?center=40.714%2c%20-73.998&zoom=12&size=400x400&client=YOUR_CLIENT_ID
&signature=BASE64_SIGNATURE
使用“立即对网址进行签名”微件

如需通过下面的立即对网址进行签名微件使用客户端 ID 生成数字签名,请按以下步骤操作:

  1. 获取您的客户端 ID 网址签名密钥,如第 1 步:获取您的网址签名密钥中所述。
  2. 网址字段中,粘贴您在第 2 步:构建未签名请求中获取的未签名请求网址。
  3. 网址签名密钥字段中,粘贴您在第 2 步中获取的网址签名密钥。
    数字签名根据您的未签名请求网址和签名密钥生成,并会附加到您的原始网址中。
  4. 系统随即会显示您的已签名网址字段,其中包含经过数字签名的网址。请务必制作副本。
在服务器端生成数字签名

立即对网址进行签名微件相比,在服务器端生成数字签名时,您需要执行一些额外的操作:

  1. 去除网址的协议架构和主机部分,只留下路径和查询:

  2. /maps/api/staticmap?center=40.714%2c%20-73.998&zoom=12&size=400x400&client=YOUR_CLIENT_ID
    
  3. 显示的网址签名密钥采用改良版网址 Base64 进行编码。

    由于大多数加密库都要求密钥采用原始字节格式,因此您可能需要先将网址签名密钥解码为其最初的原始格式,然后再进行签名。

  4. 使用 HMAC-SHA1 对上述去除后的请求进行签名。
  5. 由于大多数加密库都会生成采用原始字节格式的签名,因此您需要利用改良版网址 Base64 对生成的二进制签名进行编码,将该签名转换成可在网址内传递的内容。

  6. 将 Base64 编码的签名附加到原始未签名请求网址的 signature 参数中。例如:

    https://maps.googleapis.com/maps/api/staticmap?center=40.714%2c%20-73.998&zoom=12&size=400x400&client=YOUR_CLIENT_ID
    &signature=BASE64_SIGNATURE

如需查看展示如何使用服务器端代码实现网址签名的示例,请参阅下面的网址签名示例代码

网址签名示例代码

以下各部分展示了使用服务器端代码实现网址签名的方法。应始终在服务器端对网址进行签名,以免将您的网址签名密钥暴露给用户。

Python

下例使用标准 Python 库对网址进行签名(下载代码)。

#!/usr/bin/python
# -*- coding: utf-8 -*-
""" Signs a URL using a URL signing secret """

import hashlib
import hmac
import base64
import urllib.parse as urlparse

def sign_url(input_url=None, secret=None):
    """ Sign a request URL with a URL signing secret.
      Usage:
      from urlsigner import sign_url
      signed_url = sign_url(input_url=my_url, secret=SECRET)
      Args:
      input_url - The URL to sign
      secret    - Your URL signing secret
      Returns:
      The signed request URL
  """

    if not input_url or not secret:
        raise Exception("Both input_url and secret are required")

    url = urlparse.urlparse(input_url)

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

    # Decode the private key into its binary format
    # We need to decode the URL-encoded private key
    decoded_key = base64.urlsafe_b64decode(secret)

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

    # Encode the binary signature into base64 for use within a URL
    encoded_signature = base64.urlsafe_b64encode(signature.digest())

    original_url = url.scheme + "://" + url.netloc + url.path + "?" + url.query

    # Return signed URL
    return original_url + "&signature=" + encoded_signature.decode()

if __name__ == "__main__":
    input_url = input("URL to Sign: ")
    secret = input("URL signing secret: ")
    print("Signed URL: " + sign_url(input_url, secret))

Java

下例使用从 JDK 1.8 开始提供的 java.util.Base64 类 - 旧版本可能需要使用 Apache Commons 或类似工具(下载代码)。

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 = "YOUR_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 = "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 {

    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(inputUrl);

    // 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(inputKey);
    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;
  }
}

Node.js

下例使用原生节点模块对网址进行签名(下载代码)。

'use strict'

const crypto = require('crypto');
const url = require('url');

/**
 * Convert from 'web safe' base64 to true base64.
 *
 * @param  {string} safeEncodedString The code you want to translate
 *                                    from a web safe form.
 * @return {string}
 */
function removeWebSafe(safeEncodedString) {
  return safeEncodedString.replace(/-/g, '+').replace(/_/g, '/');
}

/**
 * Convert from true base64 to 'web safe' base64
 *
 * @param  {string} encodedString The code you want to translate to a
 *                                web safe form.
 * @return {string}
 */
function makeWebSafe(encodedString) {
  return encodedString.replace(/\+/g, '-').replace(/\//g, '_');
}

/**
 * Takes a base64 code and decodes it.
 *
 * @param  {string} code The encoded data.
 * @return {string}
 */
function decodeBase64Hash(code) {
  // "new Buffer(...)" is deprecated. Use Buffer.from if it exists.
  return Buffer.from ? Buffer.from(code, 'base64') : new Buffer(code, 'base64');
}

/**
 * Takes a key and signs the data with it.
 *
 * @param  {string} key  Your unique secret key.
 * @param  {string} data The url to sign.
 * @return {string}
 */
function encodeBase64Hash(key, data) {
  return crypto.createHmac('sha1', key).update(data).digest('base64');
}

/**
 * Sign a URL using a secret key.
 *
 * @param  {string} path   The url you want to sign.
 * @param  {string} secret Your unique secret key.
 * @return {string}
 */
function sign(path, secret) {
  const uri = url.parse(path);
  const safeSecret = decodeBase64Hash(removeWebSafe(secret));
  const hashedSignature = makeWebSafe(encodeBase64Hash(safeSecret, uri.path));
  return url.format(uri) + '&signature=' + hashedSignature;
}

C#

下例使用默认 System.Security.Cryptography 库对网址请求进行签名。请注意,我们需要转换默认 Base64 编码,才能实现网址安全版本(下载代码)。

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 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.
      const  string urlString = "YOUR_URL_TO_SIGN";

      string inputUrl = null;
      string inputKey = null;

      Console.WriteLine("Enter the URL (must be URL-encoded) to sign: ");
      inputUrl = Console.ReadLine();
      if (inputUrl.Length == 0) {
        inputUrl = urlString;
      }

      Console.WriteLine("Enter the Private key to sign the URL: ");
      inputKey = Console.ReadLine();
      if (inputKey.Length == 0) {
        inputKey = keyString;
      }

      Console.WriteLine(GoogleSignedUrl.Sign(inputUrl,inputKey));
    }
  }
}

其他语言的示例

可在网址签名项目中查看涵盖更多语言的示例。

排查身份验证问题

如果您的请求格式不正确,或者提供的签名无效,则 API 会返回 HTTP 403 (Forbidden) 错误。

如需排查问题,请复制请求网址,去除 signature 查询参数,然后按照上文使用“立即对网址进行签名”微件中的说明重新生成有效签名。