S3 PHP Example (without an SDK)

s3_example.php

<?php

class S3 {

    private $key = 'ABC123';
    private $secret = 'lolftw';
    private $region = 'us-west-2';
    private $bucket = 'examplebucket';
    private $host = 's3.amazonaws.com';

    public function uploadFile($file_path) {

        $default_timezone = date_default_timezone_get();
        date_default_timezone_set('UTC');

        $file_contents = file_get_contents($file_path);
        $file_name = basename($file_path);
        $hashed_payload = hash('sha256', $file_contents);

        $date_full = date('D, d M Y H:i:s \G\M\T'); // @todo don't force GMT!
        $date_time = date('Ymd\THisZ'); // @todo don't force Z!
        $date = date('Ymd');

        // Set headers.
        $headers = array(
            'Host' => $this->bucket . '.' . $this->host,
            'Content-Type' => mime_content_type($file_name),
            'x-amz-content-sha256' => $hashed_payload,
            'x-amz-date' => $date_full,
        );
        ksort($headers);
        $signed_headers_string = strtolower(implode(';', array_keys($headers)));

        // Build canonical request.
        $canonical_request = "PUT\n"; // HTTP Method
        $canonical_request .= '/' . urlencode($file_name) . "\n"; // Canonical URI
        $canonical_request .= "\n"; // CanonicalQueryString
        foreach ($headers as $header => $value) {
            $canonical_request .= strtolower($header) . ':' . trim($value) . "\n";
        }
        $canonical_request .= "\n";
        $canonical_request .= $signed_headers_string . "\n"; // SignedHeaders
        $canonical_request .= $hashed_payload; // HashedPayload
        print "\n\nCanonical Request:\n" . $canonical_request;

        // Build string to sign.
        $string_to_sign = "AWS4-HMAC-SHA256\n";
        $string_to_sign .= $date_full . "\n";
        $string_to_sign .= $date . '/' . $this->region . "/s3/aws4_request\n";
        $string_to_sign .= hash('sha256', $canonical_request);
        print "\n\nString to Sign:\n" . $string_to_sign;

        // Calculate signature.
        $signature_date = hash_hmac('sha256', $date, 'AWS4' . $this->secret, true);
        $signature_region = hash_hmac('sha256', $this->region, $signature_date, true);
        $signature_service = hash_hmac('sha256', 's3', $signature_region, true);
        $signature_request = hash_hmac('sha256', 'aws4_request', $signature_service, true);
        $signature = hash_hmac('sha256', $string_to_sign, $signature_request);

        // Calculate final `Authorization` header.
        $headers['Authorization'] = 'AWS4-HMAC-SHA256 Credential=' . $this->key . '/' . $date . '/' . $this->region . '/s3/aws4_request,';
        $headers['Authorization'] .= 'SignedHeaders=' . $signed_headers_string . ',';
        $headers['Authorization'] .= 'Signature=' . $signature;
        print "\n\nAuthorization:\n" . $headers['Authorization'];

        // Convert headers to key:value strings.
        $curl_headers = array();
        foreach ($headers as $header => $value) {
            $curl_headers[] = "{$header}:{$value}";
        }

        // Init curl.
        $curl = curl_init();
        $url = 'https://' . $this->bucket . '.' . $this->host . '/' bu. $file_name;
        curl_setopt($curl, CURLOPT_URL, $url);
        curl_setopt($curl, CURLOPT_VERBOSE, 1);
        curl_setopt($curl, CURLOPT_CUSTOMREQUEST, 'PUT');
        curl_setopt($curl, CURLINFO_HEADER_OUT, true);
        curl_setopt($curl, CURLOPT_HEADER, true);
        curl_setopt($curl, CURLOPT_HTTPHEADER, $curl_headers);
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
        curl_setopt($curl, CURLOPT_FOLLOWLOCATION, true);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $file_contents);

        // Run request.
        if ($result = curl_exec($curl)) {

            print "\n\nSuccess!\n";
            $curl_info = curl_getinfo($curl, CURLINFO_HTTP_CODE);
            print_r($curl_info);
            print_r($result);

            print "\n\nHeaders sent:\n";
            $headers_sent = curl_getinfo($curl, CURLINFO_HEADER_OUT);
            print_r($headers_sent);
        }
        else {
            print "\n\nError!\n";
            print_r(array(
                'code' => curl_errno($curl),
                'message' => curl_error($curl),
            ));
        }

        @curl_close($curl);

        date_default_timezone_set($default_timezone);
    }
}

$foo = new S3();
$foo->uploadFile(__DIR__ . '/test.txt');