Using an Authorization Header

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(); 
                 // Base64 encode the MD5 value of the string.
                 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;

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;
    // UTF8 encode the character string.
    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("");
    }

    // Use the SK to calculate the HmacSHA1.
    public String hmacSha1(String input) throws NoSuchAlgorithmException, InvalidKeyException, UnsupportedEncodingException {
        SecretKeySpec signingKey = new SecretKeySpec(this.sk.getBytes(DEFAULT_ENCODING), "HmacSHA1");
        // Obtain a Mac instance and use the getInstance method to specify the HMAC-SHA1 for the algorithm.
        Mac mac = Mac.getInstance("HmacSHA1");
        // Use the SK to initialize the Mac object.
        mac.init(signingKey);
        return Base64.getEncoder().encodeToString(mac.doFinal(input.getBytes(DEFAULT_ENCODING)));
    }

    // Construct a StringToSign.
    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 the header contains x-obs-date, leave the Date header blank.
        if(canonicalizedHeaders.containsKey("x-obs-date")) {
            date = "";
        }	
		
        // Construct the StringToSign by concatenating HTTP-Verb, Content-MD5, Content-Type, and 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);
			
        // Construct the StringToSign by concatenating CanonicalizedHeaders.
        for(Map.Entry<String, String> entry : canonicalizedHeaders.entrySet()) {
            stringToSign.append(entry.getKey()).append(":").append(entry.getValue()).append(SIGN_SEP);
        }
		
        // Construct the StringToSign by concatenating 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 {

    // Construct a StringToSign.
        String stringToSign = this.stringToSign(httpMethod, headers, queries, bucketName, objectName);
		
        // Calculate the signature.
        return String.format("OBS %s:%s", this.ak, this.hmacSha1(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);
	
        //Calculate and print the signature carried in the header.
        System.out.println(demo.headerSignature("PUT", headers, queries, bucketName, objectName));
    }
	
}

import os
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" indicates when the request was generated.
date = datetime.utcnow().strftime('%a, %d %b %Y %H:%M:%S GMT')
canonicalizedHeaders = "x-obs-acl:private\n"
CanonicalizedResource = "/newbucketname2"

# Construct a StringToSign.
canonical_string = httpMethod + "\n" + "\n" + contentType + "\n" + date + "\n" + canonicalizedHeaders + CanonicalizedResource

# Calculate the signature using "Signature = Base64( HMAC-SHA1( YourSecretAccessKeyID, UTF-8-Encoding-Of( StringToSign ) ) )"
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)