How to get timestamp and Signature for Amazon Api

Question

I'm looking at reading Amazon Api . But not able to read the api as a url and getting the following message "invalid timestamp or signature". How to get values for both the fields.

Answer 1

Try to follow the instructions and format here: http://docs.aws.amazon.com/AWSECommerceService/latest/DG/rest-signature.html

The signature is especially the difficult part as it has to be calculated and encoded. "Calculate an RFC 2104-compliant HMAC with the SHA256 hash algorithm using the string above with our "dummy" Secret Access Key: 1234567890. For more information about this step, see documentation and code samples for your programming language."

The timestamp is generally in this format: UTC time 2009-01-01T12:00:00Z

I would try this api signed requests helper: http://aws.amazon.com/code/Product-Advertising-API/2609

Answer 2

Here I am the providing the code for signing the request .

$param = array();
$param['AWSAccessKeyId']   = USER_AWS_ACCESS_KEY_ID; 
$param['Action']           = 'GetFeedSubmissionList'; 
$param['SellerId']         = USER_MERCHANT_ID; 
$param['SignatureMethod']  = 'HmacSHA256'; 
$param['SignatureVersion'] = '2'; 
$param['Timestamp']        = gmdate("Y-m-d\TH:i:s.\\0\\0\\0\\Z", time()); 
$param['Version']          = '2009-01-01'; 
$param['MarketplaceId']    = USER_MARKETPLACE_ID;  

$url = array();
foreach ($param as $key => $val){

 $key = str_replace("%7E", "~", rawurlencode($key));
 $val = str_replace("%7E", "~", rawurlencode($val));

 $url[] = "{$key}={$val}";
}

sort($url);

$arr   = implode('&', $url);

$sign  = 'GET' . "\n";
$sign .= str_replace("https://","",USER_AMAZON_URL) . "\n";
$sign .= '/' . "\n";
$sign .= $arr;

$signature = hash_hmac("sha256", $sign, USER_AWS_SECRET_ACCESS_KEY, true);
$signature = urlencode(base64_encode($signature));

$link  = USER_AMAZON_URL."?";
$link .= $arr . "&Signature=" . $signature;

$data = file_get_contents($link);