Autenticación de la firma en un encabezado

import java.security.MessageDigest;
import sun.misc.BASE64Encoder;
import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;

public class Md5{
     public static void main(String[] args) {
          try {
                 String exampleString = "blog";
                 MessageDigest messageDigest = MessageDigest.getInstance("MD5"); 
                 BASE64Encoder encoder = new BASE64Encoder(); 
                 String contentMd5 = encoder.encode(messageDigest.digest(exampleString.getBytes("utf-8")));
                 System.out.println("Content-MD5:" + contentMd5);    
          } catch (NoSuchAlgorithmException | UnsupportedEncodingException e) 
          {
                 e.printStackTrace();
          }
     }
}

import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import java.security.InvalidKeyException;
import java.security.NoSuchAlgorithmException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Base64;
import java.util.Collections;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.TreeMap;

import javax.crypto.Mac;
import javax.crypto.spec.SecretKeySpec;

import org.omg.CosNaming.IstringHelper;


public class SignDemo {
	private static final String SIGN_SEP = "\n";
	private static final String OBS_PREFIX = "x-obs-";
 private static final String DEFAULT_ENCODING = "UTF-8";
 private static final List<String> SUB_RESOURCES = Collections.unmodifiableList(Arrays.asList(
   "CDNNotifyConfiguration", "acl", "append", "attname", "backtosource", "cors", "customdomain", "delete",
   "deletebucket", "directcoldaccess", "encryption", "inventory", "length", "lifecycle", "location", "logging",
   "metadata", "mirrorBackToSource", "modify", "name", "notification", "obscompresspolicy", 
   "partNumber", "policy", "position", "quota","rename", "replication", "response-cache-control", 
   "response-content-disposition","response-content-encoding", "response-content-language", "response-content-type", 
   "response-expires","restore", "storageClass", "storagePolicy", "storageinfo", "tagging", "torrent", "truncate",
   "uploadId", "uploads", "versionId", "versioning", "versions", "website", "x-image-process",
   "x-image-save-bucket", "x-image-save-object", "x-obs-security-token", "object-lock", "retention"));
 private String ak;
 private String sk;
  public String urlEncode(String input) throws UnsupportedEncodingException
    {
  return URLEncoder.encode(input, DEFAULT_ENCODING)
        .replaceAll("%7E", "~") //for browser
        .replaceAll("%2F", "/")
        .replaceAll("%20", "+");
    }
 private String join(List<?> items, String delimiter)
    {
        StringBuilder sb = new StringBuilder();
        for (int i = 0; i < items.size(); i++)
        {
 String item = items.get(i).toString();
            sb.append(item);
            if (i < items.size() - 1)
            {
                sb.append(delimiter);
            }
        }
        return sb.toString();
    }
	private boolean isValid(String input) {
		return input != null && !input.equals("");
	}
	public String hamcSha1(String input) throws NoSuchAlgorithmException, InvalidKeyException, UnsupportedEncodingException {
		SecretKeySpec signingKey = new SecretKeySpec(this.sk.getBytes(DEFAULT_ENCODING), "HmacSHA1");
		Mac mac = Mac.getInstance("HmacSHA1");
		mac.init(signingKey);
		return Base64.getEncoder().encodeToString(mac.doFinal(input.getBytes(DEFAULT_ENCODING)));
	}
	private String stringToSign(String httpMethod, Map<String, String[]> headers, Map<String, String> queries,
			String bucketName, String objectName) throws Exception{
		String contentMd5 = "";
		String contentType = "";
		String date = "";
		TreeMap<String, String> canonicalizedHeaders = new TreeMap<String, String>();
		String key;
		List<String> temp = new ArrayList<String>();
		for(Map.Entry<String, String[]> entry : headers.entrySet()) {
			key = entry.getKey();
			if(key == null || entry.getValue() == null || entry.getValue().length == 0) {
				continue;
			}
			key = key.trim().toLowerCase(Locale.ENGLISH);
			if(key.equals("content-md5")) {
				contentMd5 = entry.getValue()[0];
				continue;
			}
			if(key.equals("content-type")) {
				contentType = entry.getValue()[0];
				continue;
			}
			if(key.equals("date")) {
				date = entry.getValue()[0];
				continue;
			}
			if(key.startsWith(OBS_PREFIX)) {
				for(String value : entry.getValue()) {
					if(value != null) {
						temp.add(value.trim());
					}
				}
				canonicalizedHeaders.put(key, this.join(temp, ","));
				temp.clear();
			}
		}
		if(canonicalizedHeaders.containsKey("x-obs-date")) {
			date = "";
		}
		// handle method/content-md5/content-type/date
		StringBuilder stringToSign = new StringBuilder();
		stringToSign.append(httpMethod).append(SIGN_SEP)
			.append(contentMd5).append(SIGN_SEP)
			.append(contentType).append(SIGN_SEP)
			.append(date).append(SIGN_SEP);
		// handle canonicalizedHeaders
		for(Map.Entry<String, String> entry : canonicalizedHeaders.entrySet()) {
			stringToSign.append(entry.getKey()).append(":").append(entry.getValue()).append(SIGN_SEP);
		}
		// handle CanonicalizedResource
		stringToSign.append("/");
		if(this.isValid(bucketName)) {
			stringToSign.append(bucketName).append("/");
			if(this.isValid(objectName)) {
				stringToSign.append(this.urlEncode(objectName));
			}
		}
		TreeMap<String, String> canonicalizedResource = new TreeMap<String, String>();
		for(Map.Entry<String, String> entry : queries.entrySet()) {
			key = entry.getKey();
			if(key == null) {
				continue;
			}
			if(SUB_RESOURCES.contains(key)) {
				canonicalizedResource.put(key, entry.getValue());
			}
		}
		if(canonicalizedResource.size() > 0) {
			stringToSign.append("?");
			for(Map.Entry<String, String> entry : canonicalizedResource.entrySet()) {
				stringToSign.append(entry.getKey());
				if(this.isValid(entry.getValue())) {
					stringToSign.append("=").append(entry.getValue());
				}
                                stringToSign.append("&");
			}
                        stringToSign.deleteCharAt(stringToSign.length()-1);
		}
//		System.out.println(String.format("StringToSign:%s%s", SIGN_SEP, stringToSign.toString()));
		return stringToSign.toString();
	}
	public String headerSignature(String httpMethod, Map<String, String[]> headers, Map<String, String> queries,
			String bucketName, String objectName) throws Exception {

		//1. stringToSign
		String stringToSign = this.stringToSign(httpMethod, headers, queries, bucketName, objectName);
		//2. signature
		return String.format("OBS %s:%s", this.ak, this.hamcSha1(stringToSign));
	}
	public String querySignature(String httpMethod, Map<String, String[]> headers, Map<String, String> queries,
			String bucketName, String objectName, long expires) throws Exception {
		if(headers.containsKey("x-obs-date")) {
			headers.put("x-obs-date", new String[] {String.valueOf(expires)});
		}else {
			headers.put("date", new String[] {String.valueOf(expires)});
		}
		//1. stringToSign
		String stringToSign = this.stringToSign(httpMethod, headers, queries, bucketName, objectName);
		//2. signature
		return this.urlEncode(this.hamcSha1(stringToSign));
	}
	public static void main(String[] args) throws Exception {
		SignDemo demo = new SignDemo();

                /* Hard-coded or plaintext AK and SK are risky. For security purposes, encrypt your AK and SK and store them in the configuration file or environment variables.
                In this example, the AK and SK are stored in environment variables for identity authentication. Before running the code in this example, configure environment variables HUAWEICLOUD_SDK_AK and HUAWEICLOUD_SDK_SK. */
		demo.ak = System.getenv("HUAWEICLOUD_SDK_AK");
		demo.sk = System.getenv("HUAWEICLOUD_SDK_SK");
		String bucketName = "bucket-test";
		String objectName = "hello.jpg";
		Map<String, String[]> headers = new HashMap<String, String[]>();
		headers.put("date", new String[] {"Sat, 12 Oct 2015 08:12:38 GMT"});
		headers.put("x-obs-acl", new String[] {"public-read"});
		headers.put("x-obs-meta-key1", new String[] {"value1"});
		headers.put("x-obs-meta-key2", new String[] {"value2", "value3"});
		Map<String, String> queries = new HashMap<String, String>();
		queries.put("acl", null);
		System.out.println(demo.headerSignature("PUT", headers, queries, bucketName, objectName));
	}
}

import sys
import hashlib
import hmac
import binascii
from datetime import datetime
IS_PYTHON2 = sys.version_info.major == 2 or sys.version < '3'

# Hard-coded or plaintext AK and SK are risky. For security purposes, encrypt your AK and SK and store them in the configuration file or environment variables.
# In this example, the AK and SK are stored in environment variables for identity authentication. Before running the code in this example, configure environment variables HUAWEICLOUD_SDK_AK and HUAWEICLOUD_SDK_SK.
yourSecretAccessKeyID = os.getenv('HUAWEICLOUD_SDK_SK')
httpMethod = "PUT"
contentType = "application/xml"
# "date" is the time when the request was actually generated
date = datetime.utcnow().strftime('%a, %d %b %Y %H:%M:%S GMT')
canonicalizedHeaders = "x-obs-acl:private\n"
CanonicalizedResource = "/newbucketname2"
canonical_string = httpMethod + "\n" + "\n" + contentType + "\n" + date + "\n" + canonicalizedHeaders + CanonicalizedResource
if IS_PYTHON2:    
     hashed = hmac.new(yourSecretAccessKeyID, canonical_string, hashlib.sha1)    
     encode_canonical = binascii.b2a_base64(hashed.digest())[:-1]
else:    
     hashed = hmac.new(yourSecretAccessKeyID.encode('UTF-8'), canonical_string.encode('UTF-8'),hashlib.sha1)    
     encode_canonical = binascii.b2a_base64(hashed.digest())[:-1].decode('UTF-8')
print(encode_canonical)