(C++) Generate an AWS (S3) Pre-Signed URL to Download File

Demonstrates how to generate a pre-signed URL to download a file from the Amazon S3 service.

Note: This example requires Chilkat v11.0.0 or greater.

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#include <CkHttp.h>

void ChilkatSample(void)
    {
    bool success = false;

    // This example assumes the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    CkHttp http;

    http.put_AwsAccessKey("AWS_ACCESS_KEY");
    http.put_AwsSecretKey("AWS_SECRET_KEY");

    // Make sure to set your AWS region correctly
    http.put_AwsRegion("us-east-1");

    const char *bucketName = "chilkat100";
    const char *objectName = "starfish/starfish.jpg";
    const char *localFilePath = "qa_output/starfish.jpg";
    const char *awsService = "s3";

    // The signed URL will be valid for this number of seconds:
    int numSecondsValid = 86400;

    // Choose between a URL beginning with "http://" or "https://"...
    bool bUseHttps = false;

    // Generate the pre-signed URL
    const char *preSignedUrl = http.s3_GenPresignedUrl("GET",bUseHttps,bucketName,objectName,numSecondsValid,awsService);
    if (http.get_LastMethodSuccess() == false) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    // The following URL can be copy-and-pasted into a browser..
    std::cout << "Pre-Signed AWS S3 URL: " << preSignedUrl << "\r\n";

    // Here's an example of a pre-signed URL. 
    // This URL will only work within 1 day (86400 seconds) after the time this example was published.
    // 
    //     http://chilkat100.s3.amazonaws.com/starfish/starfish.jpg?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Credential=16QXXDGY83AJJR6RVQ02%2F20170111%2Fus-west-2%2Fs3%2Faws4_request&X-Amz-Date=20170111T161959Z&X-Amz-Expires=86400&X-Amz-SignedHeaders=host&X-Amz-Signature=72bf4fd9a15d7bbcdd313a3318d937a778905f62a3fbff9b789d8dc28acd9232

    // Now try to do an HTTP Download using the signed URL.
    success = http.Download(preSignedUrl,"c:/temp/qa_output/starfish.jpg");
    if (success == false) {
        std::cout << http.lastErrorText() << "\r\n";
        return;
    }

    std::cout << "Success." << "\r\n";
    }