Something sticks out like a sore thumb in that API. Where's the param signing with a secret key?
Using an HTTPS connection is all well and good, but it is not enough. HTTPS is susceptible to man in the middle attacks [1], and securing the params with a pre-shared secret key is essential.
The extra cost in 'complexity' is really far outweighed by the (warranted) extra security.
ssltrip requires a valid root ca, or an ssl library that doesn't check the signing chain. After using it though, the parameters are unencrypted and so can simply be sniffed.
Are you attempting to reencrypt the parameters with another key? If so then why run that through https?
I think they are talking about generating a hash from all of the parameters in the request + a secret, pre-shared key. Doing so prevents MITM attacks from changing the parameters.
IIRC, Amazon does this (among many others).
Either I put my secret key in the javascript and initiate the request in the browser (thus leaking my secret key), or I accept the inputs onto my server and forward the request to Pin, thus increasing PCI compliance burden because now sensitive data is passing through my server.
I'd like this more if it functioned closer to Braintree's transparent redirect. https://www.braintreepayments.com/developers/api-overview No sensitive data ever touches my servers (customer's POST goes to Braintree, and then they redirect to my server with a query string token that I use to validate the tx with Braintree).
I suspect very little if they don't also have your 'secret' API key. I guess they could request a single-use token for a card, but I don't think they could then do anything with it.