Overview

This document provides an overview of SDK code samples related to generating pre-signed object URLs.

Note：

• You are advised to use a temporary key to generate a pre-signed URL for the security of your requests such as uploads and downloads. When you apply for a temporary key, follow the Principle of Least Privilege to avoid leaking resources besides your buckets and objects.
• If you need to use a permanent key to generate a pre-signed URL, you are advised to limit the permission of the permanent key to uploads and downloads only to avoid risks.
• For more information about how to get a temporary key, please see Generating and Using Temporary Keys.

SDK API References

For the parameters and method description of all the APIs in the SDK, see API Documentation.

Generating a Pre-Signed Object URL

Sample code 1. Generate a pre-signed URL

try
{
 PreSignatureStruct preSignatureStruct = new PreSignatureStruct();
 // For details about how to get the APPID, visit https://console.cloud.tencent.com/developer.
 preSignatureStruct.appid = "1250000000";
 // Bucket region. For the abbreviations of COS regions, visit https://intl.cloud.tencent.com/zh/document/product/436/6224.
 preSignatureStruct.region = "COS_REGION"; 
 // Bucket name in the format of `BucketName-APPID`. You can get APPID by referring to https://console.cloud.tencent.com/developer.
 preSignatureStruct.bucket = "examplebucket-1250000000";
 preSignatureStruct.key = "exampleobject"; // Object key
 preSignatureStruct.httpMethod = "GET"; // HTTP request method
 preSignatureStruct.isHttps = true; // Generate an HTTPS request URL
 preSignatureStruct.signDurationSecond = 600; // Request signature duration is 600s
 preSignatureStruct.headers = null;// Header in the signature that needs to be verified
 preSignatureStruct.queryParameters = null; // URL request parameters in the signature that need to be verified
  string requestSignURL = cosXml.GenerateSignURL(preSignatureStruct); 
  // Pre-signed URL for download request (signed URL calculated with the permanent key method)
 string localDir = System.IO.Path.GetTempPath();// Local file directory
 string localFileName = "my-local-temp-file"; // Filename of the local file
 GetObjectRequest request = new GetObjectRequest(null, null, localDir, localFileName);
 // Set the pre-signed URL for download requests
 request.RequestURLWithSign = requestSignURL;
 // Set the progress callback
 request.SetCosProgressCallback(delegate (long completed, long total)
 {
   Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
 });
 // Execute the request
 GetObjectResult result = cosXml.GetObject(request);
 // Request succeeded
 Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
 // Request failed
 Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
 // Request failed
 Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

Note：

For the complete sample, go to GitHub.

Sample code 2. Generate a pre-signed upload URL

try
{
 PreSignatureStruct preSignatureStruct = new PreSignatureStruct();
 // For details about how to get the APPID, visit https://console.cloud.tencent.com/developer.
 preSignatureStruct.appid = "1250000000";
 // Bucket region. For the abbreviations of COS regions, visit https://intl.cloud.tencent.com/zh/document/product/436/6224.
 preSignatureStruct.region = "COS_REGION";
 // Bucket name in the format of `BucketName-APPID`. You can get APPID by referring to https://console.cloud.tencent.com/developer.
 preSignatureStruct.bucket = "examplebucket-1250000000";
 preSignatureStruct.key = "exampleobject"; // Object key
 preSignatureStruct.httpMethod = "PUT"; // HTTP request method
 preSignatureStruct.isHttps = true; // Generate an HTTPS request URL
 preSignatureStruct.signDurationSecond = 600; // Request signature duration is 600s
 preSignatureStruct.headers = null;// Header in the signature that needs to be verified
 preSignatureStruct.queryParameters = null; // URL request parameters in the signature that need to be verified
  // Pre-signed URL for upload (signed URL calculated with the permanent key method)
 string requestSignURL = cosXml.GenerateSignURL(preSignatureStruct);
  string srcPath = @"temp-source-file";// Absolute path of the local file
 PutObjectRequest request = new PutObjectRequest(null, null, srcPath);
 // Set the pre-signed URL for the upload request
 request.RequestURLWithSign = requestSignURL;
 // Set the progress callback
 request.SetCosProgressCallback(delegate (long completed, long total)
 {
   Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
 });
 // Execute the request
 PutObjectResult result = cosXml.PutObject(request);
 // Request succeeded
 Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
 // Request failed
 Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
 // Request failed
 Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

Note：

For the complete sample, go to GitHub.

Sample code 3. Generate a pre-signed URL with Host in the signature

try
{
 PreSignatureStruct preSignatureStruct = new PreSignatureStruct();
 // For details about how to get the APPID, visit https://console.cloud.tencent.com/developer.
 preSignatureStruct.appid = "1250000000";
 // Bucket region. For the abbreviations of COS regions, visit https://intl.cloud.tencent.com/zh/document/product/436/6224.
 preSignatureStruct.region = "COS_REGION"; 
 // Bucket name in the format of `BucketName-APPID`. You can get APPID by referring to https://console.cloud.tencent.com/developer.
 preSignatureStruct.bucket = "examplebucket-1250000000";
 preSignatureStruct.key = "exampleobject"; // Object key
 preSignatureStruct.httpMethod = "GET"; // HTTP request method
 preSignatureStruct.isHttps = true; // Generate an HTTPS request URL
 preSignatureStruct.signDurationSecond = 600; // Request signature duration is 600s
 preSignatureStruct.signHost = true; // Whether to include `Host` in the request signature. It is recommended to include `Host` in the signature to avoid unauthorized requests. Note that if `Host` is included in the signature, the `Host` request header must also be carried in the actual request.
 preSignatureStruct.headers = null;// Header in the signature that needs to be verified
 preSignatureStruct.queryParameters = null; // URL request parameters in the signature that need to be verified
  string requestSignURL = cosXml.GenerateSignURL(preSignatureStruct); 
 Console.WriteLine("requestUrl is:" + requestSignURL);
  // Pre-signed URL for download request (signed URL calculated with the permanent key method)
 string localDir = System.IO.Path.GetTempPath();// Local file directory
 string localFileName = "my-local-temp-file"; // Filename of the local file
 GetObjectRequest request = new GetObjectRequest(null, null, localDir, localFileName);
 // Set the pre-signed URL for download requests
 request.RequestURLWithSign = requestSignURL;
 // Set the progress callback
 request.SetCosProgressCallback(delegate (long completed, long total)
 {
   Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
 });
 // Execute the request
 GetObjectResult result = cosXml.GetObject(request);
 // Request succeeded
 Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
 // Request failed
 Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
 // Request failed
 Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}

Sample code 4. Generate a pre-signed URL with request parameters in the signature

try
{
 PreSignatureStruct preSignatureStruct = new PreSignatureStruct();
 // For details about how to get the APPID, visit https://console.cloud.tencent.com/developer.
 preSignatureStruct.appid = "1250000000";
 // Bucket region. For the abbreviations of COS regions, visit https://intl.cloud.tencent.com/zh/document/product/436/6224.
 preSignatureStruct.region = "COS_REGION"; 
 // Bucket name in the format of `BucketName-APPID`. You can get APPID by referring to https://console.cloud.tencent.com/developer.
 preSignatureStruct.bucket = "examplebucket-1250000000";
 preSignatureStruct.key = "exampleobject"; // Object key
 preSignatureStruct.httpMethod = "GET"; // HTTP request method
 preSignatureStruct.isHttps = true; // Generate an HTTPS request URL
 preSignatureStruct.signDurationSecond = 600; // Request signature duration is 600s
 preSignatureStruct.signHost = true; // Whether to include `Host` in the request signature. It is recommended to include `Host` in the signature to avoid unauthorized requests. Note that if `Host` is included in the signature, the `Host` request header must also be carried in the actual request.
 preSignatureStruct.headers = null;// Headers in the signature that need to be verified
 string ci_params = "imageMogr2/thumbnail/!50p";
 preSignatureStruct.queryParameters = new Dictionary<string, string>(); // Request parameters in the URL in the signature that need to be verified. Take a CI image processing request as an example.
 preSignatureStruct.queryParameters.Add(ci_params, null);
  string requestSignURL = cosXml.GenerateSignURL(preSignatureStruct); 
 Console.WriteLine("requestUrl is:" + requestSignURL);
  // Pre-signed URL for download request (signed URL calculated with the permanent key method)
 string localDir = System.IO.Path.GetTempPath();// Local file directory
 string localFileName = "my-local-temp-file"; // Filename of the local file
 GetObjectRequest request = new GetObjectRequest(null, null, localDir, localFileName);
 // Set the pre-signed URL for download requests
 request.RequestURLWithSign = requestSignURL;
 // Set the progress callback
 request.SetCosProgressCallback(delegate (long completed, long total)
 {
   Console.WriteLine(String.Format("progress = {0:##.##}%", completed * 100.0 / total));
 });
 // Execute the request
 GetObjectResult result = cosXml.GetObject(request);
 // Request succeeded
 Console.WriteLine(result.GetResultInfo());
}
catch (COSXML.CosException.CosClientException clientEx)
{
 // Request failed
 Console.WriteLine("CosClientException: " + clientEx);
}
catch (COSXML.CosException.CosServerException serverEx)
{
 // Request failed
 Console.WriteLine("CosServerException: " + serverEx.GetInfo());
}