前言
最近在开发文件存储服务，需要符合s3的协议标准，可以直接接入aws-sdk，本文针对sdk发出请求的鉴权信息进行重新组合再签名验证有效性，sdk版本如下
software.amazon.awssdk
s3
2.20.45
算法解析
首先对V4版本签名算法的数据结构及签名流程进行拆解分析，以请求头签名为示例讲解
signature = doSign(waitSignString)
签名示例
请求头签名
AWS4-HMAC-SHA256 Credential=admin/20230530/us-east-1/s3/aws4_request, SignedHeaders=amz-sdk-invocation-id;amz-sdk-request;host;x-amz-content-sha256;x-amz-date, Signature=6f50628a101b46264c7783937be0366762683e0d319830b1844643e40b3b0edUrl签名
http://localhost:8001/s3/kkk/test.docx?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20230531T024715Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=admin%2F20230531%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=038e2ea71073761aa0370215621599649e9228177c332a0a79f784b1a6d9ee39数据结构
waitSignString = doHex（【第一部分】+【第二部分】+【第三部分】+【第四部分】），每部分使用\n换行符连接，第四部分不要加上换行符
第一部分
Algorithm – 用于创建规范请求的哈希的算法，对于 SHA-256，算法是 AWS4-HMAC-SHA256，则这部分的内容固定为
"AWS4-HMAC-SHA256" + "\n"第二部分
RequestDateTime – 在凭证范围内使用的日期和时间，这个时间为请求发出的时间，直接从请求头获取x-amz-date即可，这部分内容为
request.getHeader("x-amz-date") + "\n"第三部分
CredentialScope – 凭证范围，这会将生成的签名限制在指定的区域和服务范围内，该字符串采用以下格式：YYYYMMDD/region/service/aws4_request
这部分由4个内容信息拼接组成
- 请求时间的YYYYMMDD格式
- 存储区域
- 存储服务
- 请求头
这些信息我们都可以从请求头的Authorization凭证提取出Credential部分进行拆分重新组合
String[] parts = authorization.trim().split("\\,");
String credential = parts[0].split("\\=")[1];
String[] credentials = credential.split("\\/");
String accessKey = credentials[0];
if (!accessKeyId.equals(accessKey)) {
return false;
}
String date = credentials[1];
String region = credentials[2];
String service = credentials[3];
String aws4Request = credentials[4];这部分内容为
date + "/" + region + "/" + service + "/" + aws4Request + "\n"第四部分
HashedCanonicalRequest – 规范请求的哈希
这部分内容为
doHex(canonicalRequest)canonicalRequest具体拆解又可以6小部分组成，每部分使用\n换行符连接，最后不要加上换行符
\n
\n
\n
CanonicalHeaders>\n
\n
HTTPMethod
代表请求的HTTP方法，例如GET，POST，DELETE，PUT等，直接从request获取即可
这部分内容为
String HTTPMethod = request.getMethod() + "\n"CanonicalURI
代表请求的路由部分，例如完成请求为http://localhost:8001/s3/aaaa/ccc.txt，则该部分为/s3/aaaa/ccc.txt
需要进行encode操作，我这里直接获取则省略了这部分
这部分内容为
String CanonicalURI = request.getRequestURI().split("\\?")[0] + "\n";CanonicalQueryString
代表请求参数的拼接成字符串key1=value1&key2=value2这种形式，拼接的key需要按照字母排序
value需要进行encode操作，我这里直接获取则省略了这部分
String queryString = ConvertOp.convert2String(request.getQueryString()); if(!StringUtil.isEmpty(queryString)){ MapkeyList = new ArrayList<>(queryStringMap.keySet()); Collections.sort(keyList); StringBuilder queryStringBuilder = new StringBuilder(""); for (String key:keyList) { queryStringBuilder.append(key).append("=").append(queryStringMap.get(key)).append("&"); } queryStringBuilder.deleteCharAt(queryStringBuilder.lastIndexOf("&")); } public static Map 这部分内容为
String CanonicalQueryString = queryStringBuilder.toString() + "\n"CanonicalHeaders
代表请求头拼接成字符串key:value的形式，每个head部分使用\n换行符连接，拼接的key需要按照字母排序
签名的请求头从Authorization解析获取
String signedHeader = parts[1].split("\\=")[1]; String[] signedHeaders = signedHeader.split("\\;");String headString = ""; for (String name : signedHeaders) { headString += name + ":" + request.getHeader(name) + "\n"; }这部分内容为
String CanonicalHeaders = headString + "\n"SignedHeaders
代表请求头的key部分，使用;隔开
这部分内容为从Authorization解析中获取
这部分内容为
String SignedHeaders = signedHeader + "\n"HashedPayload
代表请求body部分的签名，直接从requet的head提取x-amz-content-sha256内容
这部分内容为
String HashedPayload = Stringrequest.getHeader("x-amz-content-sha256")
doHex
本部分只是一个字符串转16进制的一个操作
private String doHex(String data) {
MessageDigest messageDigest;
try {
messageDigest = MessageDigest.getInstance("SHA-256");
messageDigest.update(data.getBytes("UTF-8"));
byte[] digest = messageDigest.digest();
return String.format("%064x", new java.math.BigInteger(1, digest));
} catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
e.printStackTrace();
}
return null;
}签名流程
doSign 的流程为doBytesToHex（doHmacSHA256（signatureKey，waitSignString ））
doBytesToHex为byte转16进制操作
private String doBytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for (int j = 0; j < bytes.length; j++) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars).toLowerCase();
}
doHmacSHA256为签名算法
private byte[] doHmacSHA256(byte[] key, String data) throws Exception {
String algorithm = "HmacSHA256";
Mac mac = Mac.getInstance(algorithm);
mac.init(new SecretKeySpec(key, algorithm));
return mac.doFinal(data.getBytes("UTF8"));
}signatureKey签名密钥由secretAccessKey，请求时间，存储区域，存储服务，请求头这5个要素进行叠加签名生成
byte[] kSecret = ("AWS4" + secretAccessKey).getBytes("UTF8");
byte[] kDate = doHmacSHA256(kSecret, date);
byte[] kRegion = doHmacSHA256(kDate, region);
byte[] kService = doHmacSHA256(kRegion, service);
byte[] signatureKey = doHmacSHA256(kService, aws4Request);将最终生成的再签名与Authorization中解析出的Signature进行比较，一致则鉴权成功
调试位置
调试过程中需要验证每部分的签名是否拼接编码正确，我们需要和sdk生成的内容进行比对找出问题
调试software.amazon.awssdk.auth.signer.internal包下AbstractAws4Signer类的doSign类，获取stringToSign与你待签名字符串比对差异，源码如下
protected Builder doSign(SdkHttpFullRequest request, Aws4SignerRequestParams requestParams, T signingParams, ContentChecksum contentChecksum) {
Builder mutableRequest = request.toBuilder();
AwsCredentials sanitizedCredentials = this.sanitizeCredentials(signingParams.awsCredentials());
if (sanitizedCredentials instanceof AwsSessionCredentials) {
this.addSessionCredentials(mutableRequest, (AwsSessionCredentials)sanitizedCredentials);
}
this.addHostHeader(mutableRequest);
this.addDateHeader(mutableRequest, requestParams.getFormattedRequestSigningDateTime());
mutableRequest.firstMatchingHeader("x-amz-content-sha256").filter((h) -> {
return h.equals("required");
}).ifPresent((h) -> {
mutableRequest.putHeader("x-amz-content-sha256", contentChecksum.contentHash());
});
this.putChecksumHeader(signingParams.checksumParams(), contentChecksum.contentFlexibleChecksum(), mutableRequest, contentChecksum.contentHash());
AbstractAws4Signer.CanonicalRequest canonicalRequest = this.createCanonicalRequest(request, mutableRequest, contentChecksum.contentHash(), signingParams.doubleUrlEncode(), signingParams.normalizePath());
String canonicalRequestString = canonicalRequest.string();
String stringToSign = this.createStringToSign(canonicalRequestString, requestParams);
byte[] signingKey = this.deriveSigningKey(sanitizedCredentials, requestParams);
byte[] signature = this.computeSignature(stringToSign, signingKey);
mutableRequest.putHeader("Authorization", this.buildAuthorizationHeader(signature, sanitizedCredentials, requestParams, canonicalRequest));
this.processRequestPayload(mutableRequest, signature, signingKey, requestParams, signingParams, contentChecksum.contentFlexibleChecksum());
return mutableRequest;
}代码示例
通过拦截器进行验证的过程，完整代码如下，兼容了普通请求的头部验证和文件下载url的签名验证
@Component
public class S3Intecept implements HandlerInterceptor {
@Autowired
private SystemConfig systemConfig;
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
boolean flag = false;
String authorization = request.getHeader("Authorization");
if(!StringUtil.isEmpty(authorization)){
flag = validAuthorizationHead(request, systemConfig.getUsername(), systemConfig.getPassword());
}else{
authorization = request.getParameter("X-Amz-Credential");
if(!StringUtil.isEmpty(authorization)){
flag = validAuthorizationUrl(request, systemConfig.getUsername(), systemConfig.getPassword());
}
}
if(!flag){
response.setStatus(HttpStatus.UNAUTHORIZED.value());
}
return flag;
}
public boolean validAuthorizationHead(HttpServletRequest request, String accessKeyId, String secretAccessKey) throws Exception {
String authorization = request.getHeader("Authorization");
String requestDate = request.getHeader("x-amz-date");
String contentHash = request.getHeader("x-amz-content-sha256");
String httpMethod = request.getMethod();
String uri = request.getRequestURI().split("\\?")[0];
String queryString = ConvertOp.convert2String(request.getQueryString());
//示例
//AWS4-HMAC-SHA256 Credential=admin/20230530/us-east-1/s3/aws4_request, SignedHeaders=amz-sdk-invocation-id;amz-sdk-request;host;x-amz-content-sha256;x-amz-date, Signature=6f50628a101b46264c7783937be0366762683e0d319830b1844643e40b3b0ed
///region authorization拆分
String[] parts = authorization.trim().split("\\,");
//第一部分-凭证范围
String credential = parts[0].split("\\=")[1];
String[] credentials = credential.split("\\/");
String accessKey = credentials[0];
if (!accessKeyId.equals(accessKey)) {
return false;
}
String date = credentials[1];
String region = credentials[2];
String service = credentials[3];
String aws4Request = credentials[4];
//第二部分-签名头中包含哪些字段
String signedHeader = parts[1].split("\\=")[1];
String[] signedHeaders = signedHeader.split("\\;");
//第三部分-生成的签名
String signature = parts[2].split("\\=")[1];
///endregion
///region 待签名字符串
String stringToSign = "";
//签名由4部分组成
//1-Algorithm – 用于创建规范请求的哈希的算法。对于 SHA-256，算法是 AWS4-HMAC-SHA256。
stringToSign += "AWS4-HMAC-SHA256" + "\n";
//2-RequestDateTime – 在凭证范围内使用的日期和时间。
stringToSign += requestDate + "\n";
//3-CredentialScope – 凭证范围。这会将生成的签名限制在指定的区域和服务范围内。该字符串采用以下格式：YYYYMMDD/region/service/aws4_request
stringToSign += date + "/" + region + "/" + service + "/" + aws4Request + "\n";
//4-HashedCanonicalRequest – 规范请求的哈希。
//\n
//\n
//\n
//\n
//\n
//
String hashedCanonicalRequest = "";
//4.1-HTTP Method
hashedCanonicalRequest += httpMethod + "\n";
//4.2-Canonical URI
hashedCanonicalRequest += uri + "\n";
//4.3-Canonical Query String
if(!StringUtil.isEmpty(queryString)){
Map queryStringMap = parseQueryParams(queryString);
List keyList = new ArrayList<>(queryStringMap.keySet());
Collections.sort(keyList);
StringBuilder queryStringBuilder = new StringBuilder("");
for (String key:keyList) {
queryStringBuilder.append(key).append("=").append(queryStringMap.get(key)).append("&");
}
queryStringBuilder.deleteCharAt(queryStringBuilder.lastIndexOf("&"));
hashedCanonicalRequest += queryStringBuilder.toString() + "\n";
}else{
hashedCanonicalRequest += queryString + "\n";
}
//4.4-Canonical Headers
for (String name : signedHeaders) {
hashedCanonicalRequest += name + ":" + request.getHeader(name) + "\n";
}
hashedCanonicalRequest += "\n";
//4.5-Signed Headers
hashedCanonicalRequest += signedHeader + "\n";
//4.6-Hashed Payload
hashedCanonicalRequest += contentHash;
stringToSign += doHex(hashedCanonicalRequest);
///endregion
///region 重新生成签名
//计算签名的key
byte[] kSecret = ("AWS4" + secretAccessKey).getBytes("UTF8");
byte[] kDate = doHmacSHA256(kSecret, date);
byte[] kRegion = doHmacSHA256(kDate, region);
byte[] kService = doHmacSHA256(kRegion, service);
byte[] signatureKey = doHmacSHA256(kService, aws4Request);
//计算签名
byte[] authSignature = doHmacSHA256(signatureKey, stringToSign);
//对签名编码处理
String strHexSignature = doBytesToHex(authSignature);
///endregion
if (signature.equals(strHexSignature)) {
return true;
}
return false;
}
public boolean validAuthorizationUrl(HttpServletRequest request, String accessKeyId, String secretAccessKey) throws Exception {
String requestDate = request.getParameter("X-Amz-Date");
String contentHash = "UNSIGNED-PAYLOAD";
String httpMethod = request.getMethod();
String uri = request.getRequestURI().split("\\?")[0];
String queryString = ConvertOp.convert2String(request.getQueryString());
//示例
//"http://localhost:8001/s3/kkk/%E6%B1%9F%E5%AE%81%E8%B4%A2%E6%94%BF%E5%B1%80%E9%A1%B9%E7%9B%AE%E5%AF%B9%E6%8E%A5%E6%96%87%E6%A1%A3.docx?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Date=20230531T024715Z&X-Amz-SignedHeaders=host&X-Amz-Expires=300&X-Amz-Credential=admin%2F20230531%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Signature=038e2ea71073761aa0370215621599649e9228177c332a0a79f784b1a6d9ee39
///region 参数准备
//第一部分-凭证范围
String credential =request.getParameter("X-Amz-Credential");
String[] credentials = credential.split("\\/");
String accessKey = credentials[0];
if (!accessKeyId.equals(accessKey)) {
return false;
}
String date = credentials[1];
String region = credentials[2];
String service = credentials[3];
String aws4Request = credentials[4];
//第二部分-签名头中包含哪些字段
String signedHeader = request.getParameter("X-Amz-SignedHeaders");
String[] signedHeaders = signedHeader.split("\\;");
//第三部分-生成的签名
String signature = request.getParameter("X-Amz-Signature");
///endregion
///region 验证expire
String expires = request.getParameter("X-Amz-Expires");
DateTimeFormatter formatter = DateTimeFormatter.ofPattern("yyyyMMdd'T'HHmmss'Z'");
LocalDateTime startDate = LocalDateTime.parse(requestDate,formatter);
ZoneId zoneId = ZoneId.systemDefault();
ZonedDateTime localDateTime = startDate.atZone(ZoneId.of("UTC")).withZoneSameInstant(zoneId);
startDate = localDateTime.toLocalDateTime();
LocalDateTime endDate = startDate.plusSeconds(ConvertOp.convert2Int(expires));
if(endDate.isBefore(LocalDateTime.now())){
return false;
}
///endregion
///region 待签名字符串
String stringToSign = "";
//签名由4部分组成
//1-Algorithm – 用于创建规范请求的哈希的算法。对于 SHA-256，算法是 AWS4-HMAC-SHA256。
stringToSign += "AWS4-HMAC-SHA256" + "\n";
//2-RequestDateTime – 在凭证范围内使用的日期和时间。
stringToSign += requestDate + "\n";
//3-CredentialScope – 凭证范围。这会将生成的签名限制在指定的区域和服务范围内。该字符串采用以下格式：YYYYMMDD/region/service/aws4_request
stringToSign += date + "/" + region + "/" + service + "/" + aws4Request + "\n";
//4-HashedCanonicalRequest – 规范请求的哈希。
//\n
//\n
//\n
//\n
//\n
//
String hashedCanonicalRequest = "";
//4.1-HTTP Method
hashedCanonicalRequest += httpMethod + "\n";
//4.2-Canonical URI
hashedCanonicalRequest += uri + "\n";
//4.3-Canonical Query String
if(!StringUtil.isEmpty(queryString)){
Map queryStringMap = parseQueryParams(queryString);
List keyList = new ArrayList<>(queryStringMap.keySet());
Collections.sort(keyList);
StringBuilder queryStringBuilder = new StringBuilder("");
for (String key:keyList) {
if(!key.equals("X-Amz-Signature")){
queryStringBuilder.append(key).append("=").append(queryStringMap.get(key)).append("&");
}
}
queryStringBuilder.deleteCharAt(queryStringBuilder.lastIndexOf("&"));
hashedCanonicalRequest += queryStringBuilder.toString() + "\n";
}else{
hashedCanonicalRequest += queryString + "\n";
}
//4.4-Canonical Headers
for (String name : signedHeaders) {
hashedCanonicalRequest += name + ":" + request.getHeader(name) + "\n";
}
hashedCanonicalRequest += "\n";
//4.5-Signed Headers
hashedCanonicalRequest += signedHeader + "\n";
//4.6-Hashed Payload
hashedCanonicalRequest += contentHash;
stringToSign += doHex(hashedCanonicalRequest);
///endregion
///region 重新生成签名
//计算签名的key
byte[] kSecret = ("AWS4" + secretAccessKey).getBytes("UTF8");
byte[] kDate = doHmacSHA256(kSecret, date);
byte[] kRegion = doHmacSHA256(kDate, region);
byte[] kService = doHmacSHA256(kRegion, service);
byte[] signatureKey = doHmacSHA256(kService, aws4Request);
//计算签名
byte[] authSignature = doHmacSHA256(signatureKey, stringToSign);
//对签名编码处理
String strHexSignature = doBytesToHex(authSignature);
///endregion
if (signature.equals(strHexSignature)) {
return true;
}
return false;
}
private String doHex(String data) {
MessageDigest messageDigest;
try {
messageDigest = MessageDigest.getInstance("SHA-256");
messageDigest.update(data.getBytes("UTF-8"));
byte[] digest = messageDigest.digest();
return String.format("%064x", new java.math.BigInteger(1, digest));
} catch (NoSuchAlgorithmException | UnsupportedEncodingException e) {
e.printStackTrace();
}
return null;
}
private byte[] doHmacSHA256(byte[] key, String data) throws Exception {
String algorithm = "HmacSHA256";
Mac mac = Mac.getInstance(algorithm);
mac.init(new SecretKeySpec(key, algorithm));
return mac.doFinal(data.getBytes("UTF8"));
}
final protected static char[] hexArray = "0123456789ABCDEF".toCharArray();
private String doBytesToHex(byte[] bytes) {
char[] hexChars = new char[bytes.length * 2];
for (int j = 0; j < bytes.length; j++) {
int v = bytes[j] & 0xFF;
hexChars[j * 2] = hexArray[v >>> 4];
hexChars[j * 2 + 1] = hexArray[v & 0x0F];
}
return new String(hexChars).toLowerCase();
}
public static Map parseQueryParams(String queryString) {
Map queryParams = new HashMap<>();
try {
if (queryString != null && !queryString.isEmpty()) {
String[] queryParamsArray = queryString.split("\\&");
for (String param : queryParamsArray) {
String[] keyValue = param.split("\\=");
if (keyValue.length == 1) {
String key = keyValue[0];
String value = "";
queryParams.put(key, value);
}
else if (keyValue.length == 2) {
String key = keyValue[0];
String value = keyValue[1];
queryParams.put(key, value);
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
return queryParams;
}
}