Java SDK使用说明

操作场景

使用Java语言进行后端服务签名时，您需要先获取SDK，然后导入工程，最后参考校验后端签名示例校验签名是否一致。

Java SDK仅支持hmac和basic类型的后端服务签名。

前提条件

已ROMA Connect控制台创建签名密钥，并绑定API，具体请参见配置后端服务的签名校验。
已获取签名密钥的Key和Secret，具体请参见开发准备。
已安装开发工具和Java开发语言环境，具体请参见开发准备。

获取SDK

旧版界面：登录ROMA Connect实例控制台，在“服务集成 APIC > API管理”的“签名密钥”页签中下载SDK。

新版界面：登录ROMA Connect实例控制台，在“服务集成 APIC > 凭据管理”的“SDKs”页签中下载SDK。

导入工程

打开IntelliJ IDEA，在菜单栏选择“File > New > Project from Existing Sources”，选择解压后的“apigateway-backend-signature-demo\pom.xml”文件，单击“OK”。
图1 Select File or Directory to Import
保持默认设置，单击“Next > Next > Next > Next > Finish”，完成工程导入。
在右侧Maven页签，双击“compile”进行编译。
图2 编译工程

返回“BUILD SUCCESS”，表示编译成功。
右键单击BackendSignatureApplication，选择“Run”运行服务。
图3 运行服务

“ApigatewaySignatureFilter.java”为示例代码，请根据实际情况修改参数后使用。具体代码说明请参考校验hmac类型后端签名示例。

校验hmac类型后端签名示例

示例演示如何编写一个基于Spring boot的服务器，作为API的后端，并且实现一个Filter，对APIC的请求做签名校验。
API绑定hmac类型签名密钥后，发给后端的请求中会添加签名信息。

编写一个Controller，路径为/hmac。

// HelloController.java

@RestController
@EnableAutoConfiguration
public class HelloController {

    @RequestMapping("/hmac")
    private String hmac() {
        return "Hmac authorization success";
    }
}

编写一个Filter，匹配所有路径和方法。将允许的签名key和secret对放入一个Map中。

public class ApigatewaySignatureFilter implements Filter {
    private static Map<String, String> secrets = new HashMap<>();
    static {
        // Directly writing AK/SK in code is risky. For security, encrypt your AK/SK and store them in the configuration file or environment variables. 
        // In this example, the AK/SK are stored in environment variables for identity authentication. Before running this example, set environment variables HUAWEICLOUD_SDK_AK1, HUAWEICLOUD_SDK_SK1, and HUAWEICLOUD_SDK_AK2, HUAWEICLOUD_SDK_SK2.
        secrets.put(System.getenv("HUAWEICLOUD_SDK_AK1"), System.getenv("HUAWEICLOUD_SDK_SK1"));
        secrets.put(System.getenv("HUAWEICLOUD_SDK_AK2"), System.getenv("HUAWEICLOUD_SDK_SK2"));
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) {
        //签名校验代码
        ...
    }
}

doFilter函数为签名校验代码。校验流程如下：由于filter中需要读取body，为了使得body可以在后续的filter和controller中再次读取，把request包装起来传给后续的filter和controller。包装类的具体实现可见RequestWrapper.java。
```
RequestWrapper request = new RequestWrapper((HttpServletRequest) servletRequest);
```

使用正则表达式解析Authorization头，得到signingKey和signedHeaders。

private static final Pattern authorizationPattern = Pattern.compile("SDK-HMAC-SHA256\\s+Access=([^,]+),\\s?SignedHeaders=([^,]+),\\s?Signature=(\\w+)");

...

String authorization = request.getHeader("Authorization");
if (authorization == null || authorization.length() == 0) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization not found.");
	return;
}

Matcher m = authorizationPattern.matcher(authorization);
if (!m.find()) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization format incorrect.");
	return;
}
String signingKey = m.group(1);
String signingSecret = secrets.get(signingKey);
if (signingSecret == null) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Signing key not found.");
	return;
}
String[] signedHeaders = m.group(2).split(";");

例如，Authorization头为：

SDK-HMAC-SHA256 Access=signature_key1, SignedHeaders=host;x-sdk-date, Signature=e11adf65a20d1b82c25419b5********8d0ba12fed1ceb13ed00

则解析的结果为：

signingKey=signature_key1
signedHeaders=host;x-sdk-date

通过signingKey找到signingSecret，如果不存在signingKey，则返回认证失败。

String signingSecret = secrets.get(signingKey);
if (signingSecret == null) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Signing key not found.");
	return;
}

新建一个Request对象，将请求method、url、query、signedHeaders对应的请求头放入其中。判断是否需要设置body并设置。

需要读取body的条件为：不存在值为UNSIGNED-PAYLOAD的x-sdk-content-sha256头。

Request apiRequest = new DefaultRequest();
apiRequest.setHttpMethod(HttpMethodName.valueOf(request.getMethod()));
String url = request.getRequestURL().toString();
String queryString = request.getQueryString();
try {
	apiRequest.setEndpoint((new URL(url)).toURI());
	Map<String, String> parametersmap = new HashMap<>();
	if (null != queryString && !"".equals(queryString)) {
		String[] parameterarray = queryString.split("&");
		for (String p : parameterarray) {
			String[] p_split = p.split("=", 2);
			String key = p_split[0];
			String value = "";
			if (p_split.length >= 2) {
				value = p_split[1];
			}
			parametersmap.put(URLDecoder.decode(key, "UTF-8"), URLDecoder.decode(value, "UTF-8"));
		}
		apiRequest.setParameters(parametersmap); //set query
	}
} catch (URISyntaxException e) {
	e.printStackTrace();
}

boolean needbody = true;
String dateHeader = null;
for (int i = 0; i < signedHeaders.length; i++) {
	String headerValue = request.getHeader(signedHeaders[i]);
	if (headerValue == null || headerValue.length() == 0) {
		((HttpServletResponse) response).sendError(HttpServletResponse.SC_UNAUTHORIZED, "signed header" + signedHeaders[i] + " not found.");
	} else {
		apiRequest.addHeader(signedHeaders[i], headerValue);//set header
		if (signedHeaders[i].toLowerCase().equals("x-sdk-content-sha256") && headerValue.equals("UNSIGNED-PAYLOAD")) {
			needbody = false;
		}
		if (signedHeaders[i].toLowerCase().equals("x-sdk-date")) {
			dateHeader = headerValue;
		}
	}
}

if (needbody) {
        apiRequest.setContent(new ByteArrayInputStream(request.getBody()));    //set body
}

校验签名是否过期。从X-Sdk-Date头中取出时间，判断与服务器时间是否相差在15分钟以内。如果signedHeaders中不包含X-Sdk-Date，也返回认证失败。

private static final DateTimeFormatter timeFormatter = DateTimeFormat.forPattern("yyyyMMdd'T'HHmmss'Z'").withZoneUTC();

...

if (dateHeader == null) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Header x-sdk-date not found.");
	return;
}
long date = timeFormatter.parseMillis(dateHeader);
long duration = Math.abs(DateTime.now().getMillis() - date);
if (duration > 15 * 60 * 1000) {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Signature expired.");
	return;
}

将Authorization头也放入Request对象中，调用verify方法校验请求签名。如果校验通过，则执行下一个filter，否则返回认证失败。

DefaultSigner signer = (DefaultSigner) SignerFactory.getSigner();
boolean verify = signer.verify(apiRequest, new BasicCredentials(signingKey, signingSecret));
if (verify) {
	chain.doFilter(request, response);
} else {
	response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "verify authroization failed.");
}

注册filter和路径的映射关系。

@Configuration
public class FilterConfig { 
    @Bean
    public FilterRegistrationBean registApigatewaySignatureFilter() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new ApigatewaySignatureFilter());
        registration.addUrlPatterns("/hmac");
        registration.setName("ApigatewaySignatureFilter");
        return registration;
    }
}

运行服务器，验证代码正确性。下面示例使用JavaScript SDK中的html签名工具生成签名。
填入如图所示字段后，单击“Send request”，复制生成的curl命令，并在命令行中执行，服务器返回“Hello World!”。

如果使用错误的Key和Secret访问，服务器返回401认证不通过。

校验basic类型后端签名示例

示例演示如何编写一个基于Spring boot的服务器，作为API的后端，并且实现一个Filter，对APIC的请求做签名校验。
API绑定basic类型签名密钥后，发给后端的请求中会添加basic认证信息，其中basic认证的用户名为签名密钥的key，密码为签名密钥的secret。

编写一个Controller，路径为/basic。

// HelloController.java

@RestController
@EnableAutoConfiguration
public class HelloController {

    @RequestMapping("/basic")
    private String basic() {
        return "Basic authorization success";
    }
}

编写一个Filter，按照basic认证的规则，Authorization头格式为"Basic "+base64encode(username+":"+password)。以下为根据规则编写的校验代码。

// BasicAuthFilter.java
public class BasicAuthFilter implements Filter {
    private static final String CREDENTIALS_PREFIX = "Basic ";
    private static Map<String, String> secrets = new HashMap<>();

    static {
        secrets.put("signature_key1", "signature_secret1");
        secrets.put("signature_key2", "signature_secret2");
    }

    @Override
    public void doFilter(ServletRequest servletRequest, ServletResponse servletResponse, FilterChain chain) {
        HttpServletRequest request = (HttpServletRequest) servletRequest;
        HttpServletResponse response = (HttpServletResponse) servletResponse;
        try {
            String credentials = request.getHeader("Authorization");
            if (credentials == null || credentials.length() == 0) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization not found.");
                return;
            }

            if (!credentials.startsWith(CREDENTIALS_PREFIX)) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization format incorrect.");
                return;
            }
            String authInfo = credentials.substring(CREDENTIALS_PREFIX.length());
            String decoded;
            try {
                decoded = new String(Base64.getDecoder().decode(authInfo));
            } catch (IllegalArgumentException e) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization format incorrect.");
                return;
            }
            String[] spl = decoded.split(":", 2);
            if (spl.length < 2) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Authorization format incorrect.");
                return;
            }
            String signingSecret = secrets.get(spl[0]);
            if (signingSecret == null) {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Username not found.");
                return;
            }
            if (signingSecret.equals(spl[1])) {
                chain.doFilter(request, response);
            } else {
                response.sendError(HttpServletResponse.SC_UNAUTHORIZED, "Incorrect username or password");
            }
        } catch (Exception e) {
            e.printStackTrace();
            try {
                response.sendError(HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
            } catch (IOException e1) {
            }
        }
    }
}

注册filter和路径的映射关系。

@Configuration
public class FilterConfig { 
    @Bean
    public FilterRegistrationBean registBasicAuthFilter() {
        FilterRegistrationBean registration = new FilterRegistrationBean();
        registration.setFilter(new BasicAuthFilter());
        registration.addUrlPatterns("/basic");
        registration.setName("BasicAuthFilter");
        return registration;
    }  
}