The following sample code shows how to generate the Post signature, Post Policy, and other information on the server:
Python
import os
from hashlib import sha1 as sha
import json
import base64
import hmac
import datetime
import time
# Configure the OSS_ACCESS_KEY_ID environment variable.
access_key_id = os.environ.get('OSS_ACCESS_KEY_ID')
# Configure the OSS_ACCESS_KEY_SECRET environment variable.
access_key_secret = os.environ.get('OSS_ACCESS_KEY_SECRET')
# Replace <YOUR_BUCKET> with your bucket name.
bucket = '<YOUR_BUCKET>'
# The host format is bucketname.endpoint. Replace <YOUR_BUCKET> with your bucket name. Replace <YOUR_ENDPOINT> with the OSS endpoint, such as oss-cn-hangzhou.aliyuncs.com.
host = 'https://<YOUR_BUCKET>.<YOUR_ENDPOINT>'
# Specify the prefix for files to upload to OSS.
upload_dir = 'user-dir-prefix/'
# Specify the expiration time in seconds.
expire_time = 3600
def generate_expiration(seconds):
"""
Generate an expiration time by specifying a validity period in seconds.
:param seconds: The validity period in seconds.
:return: An ISO 8601 time string, such as "2014-12-01T12:00:00.000Z".
"""
now = int(time.time())
expiration_time = now + seconds
gmt = datetime.datetime.utcfromtimestamp(expiration_time).isoformat()
gmt += 'Z'
return gmt
def generate_signature(access_key_secret, expiration, conditions, policy_extra_props=None):
"""
Generate a signature string.
:param access_key_secret: The AccessKey secret of an account that has permissions to access the destination bucket.
:param expiration: The signature expiration time, in ISO 8601 format and UTC. Example: "2014-12-01T12:00:00.000Z".
:param conditions: Policy conditions used to limit the allowed values when uploading a form.
:param policy_extra_props: Additional policy parameters. If new parameters are added to the policy, you can pass them as a dictionary.
:return: signature, the signature string.
"""
policy_dict = {
'expiration': expiration,
'conditions': conditions
}
if policy_extra_props is not None:
policy_dict.update(policy_extra_props)
policy = json.dumps(policy_dict).strip()
policy_encode = base64.b64encode(policy.encode())
h = hmac.new(access_key_secret.encode(), policy_encode, sha)
sign_result = base64.b64encode(h.digest()).strip()
return sign_result.decode()
def generate_upload_params():
policy = {
# Validity period.
"expiration": generate_expiration(expire_time),
# Constraints.
"conditions": [
# The status code to return after a successful upload if success_action_redirect is not specified. The default value is 204.
["eq", "$success_action_status", "200"],
# The value of the form field must start with the specified prefix. For example, to specify that the value of key must start with user/user1, you can write ["starts-with", "$key", "user/user1"].
["starts-with", "$key", upload_dir],
# Limit the minimum and maximum allowed size of the uploaded object in bytes.
["content-length-range", 1, 1000000],
# Limit the uploaded file to specified image types.
["in", "$content-type", ["image/jpg", "image/png"]]
]
}
signature = generate_signature(access_key_secret, policy.get('expiration'), policy.get('conditions'))
response = {
'policy': base64.b64encode(json.dumps(policy).encode('utf-8')).decode(),
'ossAccessKeyId': access_key_id,
'signature': signature,
'host': host,
'dir': upload_dir
# You can add other parameters here.
}
return json.dumps(response)
Java
package com.aliyun.sample;
import com.aliyun.oss.ClientException;
import com.aliyun.oss.OSS;
import com.aliyun.oss.OSSException;
import com.aliyun.oss.common.utils.BinaryUtil;
import com.aliyun.oss.model.MatchMode;
import com.aliyun.oss.model.PolicyConditions;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.codehaus.jettison.json.JSONObject;
import java.util.Date;
@Controller
public class PostSignatureController {
@Autowired
private OSS ossClient;
@Autowired
private OssConfig ossConfig;
@GetMapping("/get_post_signature_for_oss_upload")
@ResponseBody
public String generatePostSignature() {
JSONObject response = new JSONObject();
try {
long expireEndTime = System.currentTimeMillis() + ossConfig.getExpireTime() * 1000;
Date expiration = new Date(expireEndTime);
PolicyConditions policyConds = new PolicyConditions();
policyConds.addConditionItem(PolicyConditions.COND_CONTENT_LENGTH_RANGE, 0, 1048576000);
policyConds.addConditionItem(MatchMode.StartWith, PolicyConditions.COND_KEY, ossConfig.getDir());
String postPolicy = ossClient.generatePostPolicy(expiration, policyConds);
byte[] binaryData = postPolicy.getBytes("utf-8");
String encodedPolicy = BinaryUtil.toBase64String(binaryData);
String postSignature = ossClient.calculatePostSignature(postPolicy);
response.put("ossAccessKeyId", ossConfig.getAccessKeyId());
response.put("policy", encodedPolicy);
response.put("signature", postSignature);
response.put("dir", ossConfig.getDir());
response.put("host", ossConfig.getHost());
} catch (OSSException oe) {
System.out.println("Caught an OSSException, which means your request made it to OSS, "
+ "but was rejected with an error response for some reason.");
System.out.println("HTTP Status Code: " + oe.getRawResponseError());
System.out.println("Error Message: " + oe.getErrorMessage());
System.out.println("Error Code: " + oe.getErrorCode());
System.out.println("Request ID: " + oe.getRequestId());
System.out.println("Host ID: " + oe.getHostId());
} catch (ClientException ce) {
System.out.println("Caught an ClientException, which means the client encountered "
+ "a serious internal problem while trying to communicate with OSS, "
+ "such as not being able to access the network.");
System.out.println("Error Message: " + ce.getMessage());
} catch (Exception e) {
System.out.println("Caught an unexpected exception: " + e.getMessage());
}
return response.toString();
}
}
Go
package main
import (
"crypto/hmac"
"crypto/sha1"
"encoding/base64"
"encoding/json"
"fmt"
"io"
"net/http"
"os"
"time"
)
var (
// Configure the OSS_ACCESS_KEY_ID environment variable.
accessKeyId = os.Getenv("OSS_ACCESS_KEY_ID")
// Configure the OSS_ACCESS_KEY_SECRET environment variable.
accessKeySecret = os.Getenv("OSS_ACCESS_KEY_SECRET")
// The host format is bucketname.endpoint. Replace ${your-bucket} with your bucket name. Replace ${your-endpoint} with the OSS endpoint, such as oss-cn-hangzhou.aliyuncs.com.
host = "http://${your-bucket}.${your-endpoint}"
// Specify the prefix for files to upload to OSS.
uploadDir = "user-dir-prefix/"
// Specify the expiration time in seconds.
expireTime = int64(3600)
)
type ConfigStruct struct {
Expiration string `json:"expiration"`
Conditions [][]interface{} `json:"conditions"`
}
type PolicyToken struct {
AccessKeyId string `json:"ossAccessKeyId"`
Host string `json:"host"`
Signature string `json:"signature"`
Policy string `json:"policy"`
Directory string `json:"dir"`
}
func getGMTISO8601(expireEnd int64) string {
return time.Unix(expireEnd, 0).UTC().Format("2006-01-02T15:04:05Z")
}
func getPolicyToken() string {
now := time.Now().Unix()
expireEnd := now + expireTime
tokenExpire := getGMTISO8601(expireEnd)
var config ConfigStruct
config.Expiration = tokenExpire
// Add a file prefix restriction.
config.Conditions = append(config.Conditions, []interface{}{"starts-with", "$key", uploadDir})
// Add a file size restriction, for example, from 1 KB to 10 MB.
minSize := int64(1024)
maxSize := int64(10 * 1024 * 1024)
config.Conditions = append(config.Conditions, []interface{}{"content-length-range", minSize, maxSize})
result, err := json.Marshal(config)
if err != nil {
fmt.Println("callback json err:", err)
return ""
}
encodedResult := base64.StdEncoding.EncodeToString(result)
h := hmac.New(sha1.New, []byte(accessKeySecret))
io.WriteString(h, encodedResult)
signedStr := base64.StdEncoding.EncodeToString(h.Sum(nil))
policyToken := PolicyToken{
AccessKeyId: accessKeyId,
Host: host,
Signature: signedStr,
Policy: encodedResult,
Directory: uploadDir,
}
response, err := json.Marshal(policyToken)
if err != nil {
fmt.Println("json err:", err)
return ""
}
return string(response)
}
func handler(w http.ResponseWriter, r *http.Request) {
if r.URL.Path == "/" {
http.ServeFile(w, r, "templates/index.html")
return
} else if r.URL.Path == "/get_post_signature_for_oss_upload" {
policyToken := getPolicyToken()
w.Header().Set("Content-Type", "application/json")
w.Write([]byte(policyToken))
return
}
http.NotFound(w, r)
}
func main() {
http.HandleFunc("/", handler)
http.ListenAndServe(":8080", nil)
}
PHP
<?php
function gmt_iso8601($time)
{
return str_replace('+00:00', '.000Z', gmdate('c', $time));
}
// Obtain access credentials from environment variables. Before you run this sample code, make sure that the ALIBABA_CLOUD_ACCESS_KEY_ID and ALIBABA_CLOUD_ACCESS_KEY_SECRET environment variables are configured.
$accessKeyId = getenv("ALIBABA_CLOUD_ACCESS_KEY_ID");
$accessKeySecret = getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
// The format of $host is '<YOUR-BUCKET>.<YOUR-ENDPOINT>'. Replace the variables with your actual information.
$host = 'http://<YOUR-BUCKET>.<YOUR-ENDPOINT>';
// The prefix specified by the user when uploading a file.
$dir = 'user-dir-prefix/';
$now = time();
// Set the policy to expire in 10 seconds. After this period, the policy becomes invalid.
$expire = 30;
$end = $now + $expire;
$expiration = gmt_iso8601($end);
// Maximum file size. You can set this yourself.
$condition = array(0 => 'content-length-range', 1 => 0, 2 => 1048576000);
$conditions[] = $condition;
// The uploaded data must start with $dir, otherwise the upload will fail. This step is not required but is recommended for security to prevent users from uploading to other directories through the policy.
$start = array(0 => 'starts-with', 1 => '$key', 2 => $dir);
$conditions[] = $start;
$arr = array('expiration' => $expiration, 'conditions' => $conditions);
$policy = json_encode($arr);
$base64_policy = base64_encode($policy);
$string_to_sign = $base64_policy;
$signature = base64_encode(hash_hmac('sha1', $string_to_sign, $accessKeySecret, true));
$response = array();
$response['ossAccessKeyId'] = $accessKeyId;
$response['host'] = $host;
$response['policy'] = $base64_policy;
$response['signature'] = $signature;
$response['dir'] = $dir;
echo json_encode($response);
Node.js
const express = require("express");
const { Buffer } = require("buffer");
const OSS = require("ali-oss");
const app = express();
const path = require("path");
const config = {
// Configure the ALIBABA_CLOUD_ACCESS_KEY_ID environment variable.
accessKeyId: process.env.ALIBABA_CLOUD_ACCESS_KEY_ID,
// Configure the ALIBABA_CLOUD_ACCESS_KEY_SECRET environment variable.
accessKeySecret: process.env.ALIBABA_CLOUD_ACCESS_KEY_SECRET,
// Replace <YOUR-BUCKET> with your bucket name.
bucket: "<YOUR-BUCKET>",
// Specify the prefix for files to upload to OSS.
dir: "prefix/",
};
app.use(express.static(path.join(__dirname, "templates")));
app.get("/get_post_signature_for_oss_upload", async (req, res) => {
const client = new OSS(config);
const date = new Date();
// Set the validity period of the signature in seconds.
date.setSeconds(date.getSeconds() + 3600);
const policy = {
expiration: date.toISOString(),
conditions: [
// Set the size limit for the uploaded file.
["content-length-range", 0, 1048576000],
// Restrict the bucket to which files can be uploaded.
{ bucket: client.options.bucket },
],
};
const formData = await client.calculatePostSignature(policy);
const host = `http://${config.bucket}.${
(await client.getBucketLocation()).location
}.aliyuncs.com`.toString();
const params = {
policy: formData.policy,
signature: formData.Signature,
ossAccessKeyId: formData.OSSAccessKeyId,
host,
dir: config.dir,
};
res.json(params);
});
app.get(/^(.+)*\.(html|js)$/i, async (req, res) => {
res.sendFile(path.join(__dirname, "./templates", req.originalUrl));
});
app.listen(8000, () => {
console.log("http://127.0.0.1:8000");
});
Ruby
require 'sinatra'
require 'base64'
require 'open-uri'
require 'cgi'
require 'openssl'
require 'json'
require 'sinatra/reloader'
require 'sinatra/content_for'
# Set the path of the public folder to the templates folder in the current directory.
set :public_folder, File.dirname(__FILE__) + '/templates'
# Configure the ALIBABA_CLOUD_ACCESS_KEY_ID environment variable.
$access_key_id = ENV['ALIBABA_CLOUD_ACCESS_ID']
# Configure the ALIBABA_CLOUD_ACCESS_KEY_SECRET environment variable.
$access_key_secret = ENV['ALIBABA_CLOUD_ACCESS_SECRET']
# The format of $host is <bucketname>.<endpoint>. Replace <bucketname> and <endpoint> with your actual information.
$host = 'http://<bucketname>.<endpoint>';
# The prefix for user-uploaded files.
$upload_dir = 'user-dir-prefix/'
# The expiration time in seconds.
$expire_time = 30
$server_ip = "0.0.0.0"
$server_port = 8000
if ARGV.length == 1
$server_port = ARGV[0]
elsif ARGV.length == 2
$server_ip = ARGV[0]
$server_port = ARGV[1]
end
puts "App server is running on: http://#{$server_ip}:#{$server_port}"
def hash_to_jason(source_hash)
jason_string = source_hash.to_json;
jason_string.gsub!("\":[", "\": [")
jason_string.gsub!("\",\"", "\", \"")
jason_string.gsub!("],\"", "], \"")
jason_string.gsub!("\":\"", "\": \"")
jason_string
end
def get_token()
expire_syncpoint = Time.now.to_i + $expire_time
expire = Time.at(expire_syncpoint).utc.iso8601()
response.headers['expire'] = expire
policy_dict = {}
condition_arrary = Array.new
array_item = Array.new
array_item.push('starts-with')
array_item.push('$key')
array_item.push($upload_dir)
condition_arrary.push(array_item)
policy_dict["conditions"] = condition_arrary
policy_dict["expiration"] = expire
policy = hash_to_jason(policy_dict)
policy_encode = Base64.strict_encode64(policy).chomp;
h = OpenSSL::HMAC.digest('sha1', $access_key_secret, policy_encode)
hs = Digest::MD5.hexdigest(h)
sign_result = Base64.strict_encode64(h).strip()
token_dict = {}
token_dict['ossAccessKeyId'] = $access_key_id
token_dict['host'] = $host
token_dict['policy'] = policy_encode
token_dict['signature'] = sign_result
token_dict['expire'] = expire_syncpoint
token_dict['dir'] = $upload_dir
result = hash_to_jason(token_dict)
result
end
set :bind, $server_ip
set :port, $server_port
get '/get_post_signature_for_oss_upload' do
token = get_token()
puts "Token: #{token}"
token
end
get '/*' do
puts "********************* GET "
send_file File.join(settings.public_folder, 'index.html')
end
end
if ARGV.length == 1
$server_port = ARGV[0]
elsif ARGV.length == 2
$server_ip = ARGV[0]
$server_port = ARGV[1]
end
$server_ip = "0.0.0.0"
$server_port = 8000
puts "App server is running on: http://#{$server_ip}:#{$server_port}"
set :bind, $server_ip
set :port, $server_port
get '/get_sts_token_for_oss_upload' do
token = get_sts_token_for_oss_upload()
response = {
"AccessKeyId" => token["Credentials"]["AccessKeyId"],
"AccessKeySecret" => token["Credentials"]["AccessKeySecret"],
"SecurityToken" => token["Credentials"]["SecurityToken"]
}
response.to_json
end
get '/*' do
puts "********************* GET "
send_file File.join(settings.public_folder, 'index.html')
end
C#
using Microsoft.AspNetCore.Builder;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.AspNetCore.Http;
using System.IO;
using System.Collections.Generic;
using System;
using System.Globalization;
using System.Text;
using System.Security.Cryptography;
using Newtonsoft.Json;
using Microsoft.AspNetCore.Http.Extensions;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
namespace YourNamespace
{
public class Program
{
private ILogger<Program> _logger;
// Configure the ALIBABA_CLOUD_ACCESS_KEY_ID environment variable.
public string AccessKeyId { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_ID");
// Configure the ALIBABA_CLOUD_ACCESS_KEY_SECRET environment variable.
public string AccessKeySecret { get; set; } = Environment.GetEnvironmentVariable("ALIBABA_CLOUD_ACCESS_KEY_SECRET");
// The host format is bucketname.endpoint. Replace <YOUR-BUCKET> with your bucket name. Replace <YOUR-ENDPOINT> with the OSS endpoint, such as oss-cn-hangzhou.aliyuncs.com.
public string Host { get; set; } = "<YOUR-BUCKET>.<YOUR-ENDPOINT>";
// Specify the prefix for files to upload to OSS.
public string UploadDir { get; set; } = "user-dir-prefix/";
// Specify the expiration time in seconds.
public int ExpireTime { get; set; } = 3600;
public class PolicyConfig
{
public string expiration { get; set; }
public List<List<object>> conditions { get; set; }
}
public class PolicyToken
{
public string Accessid { get; set; }
public string Policy { get; set; }
public string Signature { get; set; }
public string Dir { get; set; }
public string Host { get; set; }
public string Expire { get; set; }
}
public static void Main(string[] args)
{
var builder = WebApplication.CreateBuilder(args);
var app = builder.Build();
builder.Logging.AddConsole();
var logger = builder.Services.BuildServiceProvider().GetRequiredService<ILogger<Program>>();
app.UseStaticFiles();
app.MapGet("/", async (context) =>
{
var filePath = Path.Combine(Directory.GetCurrentDirectory(), "templates/index.html");
var htmlContent = await File.ReadAllTextAsync(filePath);
await context.Response.WriteAsync(htmlContent);
logger.LogInformation("GET request to root path");
});
app.MapGet("/get_post_signature_for_oss_upload", async (context) =>
{
var program = new Program(logger);
var token = program.GetPolicyToken();
logger.LogInformation($"Token: {token}");
context.Response.ContentType = "application/json";
await context.Response.WriteAsync(token);
});
app.Run();
}
public Program(ILogger<Program> logger)
{
_logger = logger;
}
private string ToUnixTime(DateTime dateTime)
{
return ((DateTimeOffset)dateTime).ToUnixTimeSeconds().ToString();
}
private string GetPolicyToken()
{
var expireDateTime = DateTime.Now.AddSeconds(ExpireTime);
var config = new PolicyConfig
{
expiration = FormatIso8601Date(expireDateTime),
conditions = new List<List<object>>()
};
config.conditions.Add(new List<object>
{
"content-length-range", 0, 1048576000
});
var policy = JsonConvert.SerializeObject(config);
var policyBase64 = EncodeBase64("utf-8", policy);
var signature = ComputeSignature(AccessKeySecret, policyBase64);
var policyToken = new PolicyToken
{
Accessid = AccessKeyId,
Host = Host,
Policy = policyBase64,
Signature = signature,
Expire = ToUnixTime(expireDateTime),
Dir = UploadDir
};
return JsonConvert.SerializeObject(policyToken);
}
private string FormatIso8601Date(DateTime dtime)
{
return dtime.ToUniversalTime().ToString("yyyy-MM-dd'T'HH:mm:ss.fff'Z'",
CultureInfo.CurrentCulture);
}
private string EncodeBase64(string codeType, string code)
{
string encode = "";
byte[] bytes = Encoding.GetEncoding(codeType).GetBytes(code);
try
{
encode = Convert.ToBase64String(bytes);
}
catch
{
encode = code;
}
return encode;
}
private string ComputeSignature(string key, string data)
{
using (var algorithm = new HMACSHA1(Encoding.UTF8.GetBytes(key)))
{
return Convert.ToBase64String(algorithm.ComputeHash(Encoding.UTF8.GetBytes(data)));
}
}
}
}
