如何从Java在AWS中生成签名

Question

当我从REST客户端调用APIendpoint时，由于涉及Signature而出错。

请求：

主持人:https://xxx.execute-api.ap-southeast-1.amazonaws.com/latest/api/name

授权： AWS4-HMAC-SHA256凭据={AWSKEY}/20160314/ap-东南-1/执行-api/aws4_request， SignedHeaders=host；范围；x-amz-日期，签名={签名}

X-Amz-Date： 20160314T102915Z

回应：

{
"message": "The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details. The Canonical String for this request should have been 'xxx' "
}

在Java代码中，我遵循了AWS关于如何生成签名的参考。

    String secretKey = "{mysecretkey}";
    String dateStamp = "20160314";
    String regionName = "ap-southeast-1";
    String serviceName = "execute-api";

    byte[] signature = getSignatureKey(secretKey, dateStamp, regionName, serviceName);
    System.out.println("Signature : " + Hex.encodeHexString(signature));

    static byte[] HmacSHA256(String data, byte[] key) throws Exception  {
         String algorithm="HmacSHA256";
         Mac mac = Mac.getInstance(algorithm);
         mac.init(new SecretKeySpec(key, algorithm));
         return mac.doFinal(data.getBytes("UTF8"));
    }

    static byte[] getSignatureKey(String key, String dateStamp, String regionName, String serviceName) throws Exception  {
         byte[] kSecret = ("AWS4" + key).getBytes("UTF8");
         byte[] kDate    = HmacSHA256(dateStamp, kSecret);
         byte[] kRegion  = HmacSHA256(regionName, kDate);
         byte[] kService = HmacSHA256(serviceName, kRegion);
         byte[] kSigning = HmacSHA256("aws4_request", kService);
         return kSigning;
    }

我可以知道我在生成签名时出错了吗？

参考如何生成签名：http://docs.aws.amazon.com/general/latest/gr/signature-v4-examples.html#signature-v4示例java

Answer 1

这是可能的使用100%java库没有额外的依赖关系，只需使用这里生成的查询参数：

import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.security.SignatureException;
import java.util.Formatter;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;
import java.util.Base64;

...

private static final String ACCESS_KEY = "...";
private static final String SECRET_KEY = "...";
private static final int expiresTime = 1 * 24 * 60 * 60;
private static final String HMAC_SHA1_ALGORITHM = "HmacSHA1";

public void sign(String protocol, String bucketName, String contentPath) throws Exception {
    Calendar cal = Calendar.getInstance();
    cal.add(Calendar.HOUR_OF_DAY, 24);

    String host = bucketName + ".s3-us-west-2.amazonaws.com";
    long expireTime = cal.getTimeInMillis() / 1000;

    String signString = "GET\n" +
        "\n" +
        "\n" +
        expireTime + "\n" +
        "/" + bucketName + contentPath;

    SecretKeySpec signingKey = new SecretKeySpec(SECRET_KEY.getBytes(), HMAC_SHA1_ALGORITHM);
    Mac mac = Mac.getInstance(HMAC_SHA1_ALGORITHM);
    mac.init(signingKey);
    String signature = URLEncoder.encode(new String(Base64.getEncoder().encode(mac.doFinal(signString.getBytes()))));

    System.out.println(signature);
    String fullPayload = "?AWSAccessKeyId=" + ACCESS_KEY +
        "&Expires=" + expireTime + 
        "&Signature=" + signature;

    System.out.println(protocol + "://" + host + contentPath + fullPayload);
}

...

Answer 2

从上面的代码示例来看，您似乎没有创建规范化请求并将其包含在根据签名的字符串中http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html

您没有亲自实现这一点，而是考虑使用第三方库。

aws-v4-signer-java是一个轻量级的零依赖性库，可以轻松生成aws v4签名。

String contentSha256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855";
HttpRequest request = new HttpRequest("GET", new URI("https://examplebucket.s3.amazonaws.com?max-keys=2&prefix=J"));
String signature = Signer.builder()
        .awsCredentials(new AwsCredentials(ACCESS_KEY, SECRET_KEY))
        .header("Host", "examplebucket.s3.amazonaws.com")
        .header("x-amz-date", "20130524T000000Z")
        .header("x-amz-content-sha256", contentSha256)
        .buildS3(request, contentSha256)
        .getSignature();

免责声明：我是图书馆的作者。

Answer 3

可以使用AWS-java-sdk-core：https://github.com/aws/aws-sdk-java/tree/master/aws-java-sdk-core

更具体地说，是Request、Aws4Signer和其他几个：

//Instantiate the request
Request<Void> request = new DefaultRequest<Void>("es"); //Request to ElasticSearch
request.setHttpMethod(HttpMethodName.GET);
request.setEndpoint(URI.create("http://..."));

//Sign it...
AWS4Signer signer = new AWS4Signer();
signer.setRegionName("...");
signer.setServiceName(request.getServiceName());
signer.sign(request, new AwsCredentialsFromSystem());

//Execute it and get the response...
Response<String> rsp = new AmazonHttpClient(new ClientConfiguration())
    .requestExecutionBuilder()
    .executionContext(new ExecutionContext(true))
    .request(request)
    .errorResponseHandler(new SimpleAwsErrorHandler())
    .execute(new SimpleResponseHandler<String>());

如果您想要一个更干净的设计，您可以使用Decorator模式组合一些优雅的类并隐藏上面的混乱。这里有一个例子：http://www.amihaiemil.com/2017/02/18/decorators-with-tunnels.html