[erlang-questions] Amazon API -- Lookup by ISBN

Wed Apr 8 22:47:02 CEST 2015


I'm striving to look up books in Amazon's db by ISBN. At first blush it looks easy enough:


But the last item, Signature, baffles me. Procedure here:


I'm fine with this until I hit step 4: 

-- Sort parameter/value pairs by byte value --- I can see how to do this manually, but don't know how put Erlang to the task

And I'm really stumped when I hit step 8:

-- Calculate an RFC 2104-compliant HMAC with the SHA256 hash algorithm

Any help? Better yet, does anyone have actual code to make such requests they're willing to share?

NOTE: Dave Thomas solved this problem way back in 2007. But looks like Amazon has changed their request format:


Many thanks,



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