The reader starts life with a unique 128-bit key, and then, each time a card is read, a counter increments.
In DUKPT (Derived Unique Key Per Transaction), a new key is derived for every transaction, so that no key can be used twice (thus preventing replay attacks). In most credit-card scenarios throughout the industry, the reader encrypts sensitive card data using a one-time key that’s unique to the transaction. It can be a little tricky to decrypt such data, not because of the decryption operation itself, but because of how keys are generated and used. Such data is typically encrypted either with AES, or with Triple DES encryption (although ID TECH also supports other algorithms as well). A common request we get from customers is “How can I decrypt the track data coming from my reader?” (referring to credit-card track information that might occur in magstripe data, or might be part of an EMV tag). All the logic is contained in a single page (there are no server-side bits), which means you can download the HTML file and inspect the logic right in your browser (using, for example, Chrome’s excellent developer tools).Īs you can see from the screenshot above, the top button of the Encrypt/Decrypt Tool exposes a dropdown menu showing some of the things you can do with the tool. The Encrypt/Decrypt Tool is a powerful, self-contained single-page HTML app with a native JavaScript implementation of AES encryption, Triple DES, DUKPT key derivation, SHA hashing, HMAC, and much more. I’d be remiss if I didn’t also encourage you to try our Encrypt/Decrypt Tool, which you can load in your browser by clicking this link. In recent posts, I talked about Parsomatic, our free data parser (implemented as a web form), and UDemo, the Universal SDK test app that works with all of our non-legacy products (implemented in C# for Windows). ID TECH makes available a number of excellent free utilities for anyone involved in developing payment apps using our products. Tools for Payment Device Integration: Encrypt/Decrypt Tool
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