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javascriptamazon-web-servicescryptojs

using cryptojs to generate RFC 2104-compliant HMAC with SHA256 algorithm

im am following this amazon documentation in an attempt to find the algorithm to generate a signature in javascript. I cannot seem to get it to work.

// html
// <head>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/core.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/sha256.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/crypto-js/3.1.9-1/hmac.min.js"></script>
// body (javascript)
var test_string = "GET\nwebservices.amazon.com\n/onca/xml\nAWSAccessKeyId=AKIAIOSFODNN7EXAMPLE&AssociateTag=mytag-20&ItemId=0679722769&Operation=ItemLookup&ResponseGroup=Images%2CItemAttributes%2COffers%2CReviews&Service=AWSECommerceService&Timestamp=2014-08-18T12%3A00%3A00Z&Version=2013-08-01"

var signature2 = CryptoJS.HmacSHA256(test_string, "1234567890");
console.log(signature2.toString());

I amd getting 8fb6d93342d767d797799aee4ea5a6d8322f0d8554537c313cfa69fa25f1cd07

I should be getting j7bZM0LXZ9eXeZruTqWm2DIvDYVUU3wxPPpp+iXxzQc=

Hmmm anyone knows whats wrong?

Solution

  • There's nothing wrong, it's just that the string you got represents an array of bytes (with their hex representation). So all you need to do is Base 64 encode this array of bytes and you will get the exact same result. Checkout it out here, paste your hex represented byte array and base 64 encode it: http://tomeko.net/online_tools/hex_to_base64.php?lang=en

    As far as how this can be done, well, you may have a look at this question or this one.

    UPDATE:

    As pointed out in the comments it seems that there's a built-in way in cryptojs to convert directly to base64:

    console.log(signature2.toString(CryptoJS.enc.Base64));