Inspirated

Recently I’ve been reading through these excellent books in my spare time:

• Understanding Cryptography by Christof Paar
• Practical Common Lisp by Peter Seibel (also available as a free eBook)

To ramp-up on both subjects with one shot I wrote an implementation of Elliptic Curve Crypto in Lisp. So far, it does EC versions of Diffie-Hellman, ElGamal and DSA. Some rudimentary testing was performed using the NIST-P192 curve and its corresponding ECDSA test vectors.

The package is available at GitHub in the krkhan/cl-ecc repository. Here’s a quick snippet of what the code looks like:

(defconstant *p17-curve*
  (make-instance
    'Curve
    :a 2
    :b 2
    :p 17
    :g (make-instance
         'Point
         :x 5
         :y 1)
    :n 19))

And an ECDSA with this curve:

(def-positive-test test-ecdsa ()
  (let* ((c *p17-curve*)
         (bob-priv 3)
         (bob-pub (ecdh-gen-pub c bob-priv))
         (msghash 8)
         (k 7)
         (sig (ecdsa-gen-sig c msghash bob-priv k)))
    (assert (sig-equalp sig (make-instance 'ECDSASig :r 0 :s 12)))
    (ecdsa-verify-sig c msghash sig bob-pub)))

As a disclaimer — even though I know no one would be stupid enough to do so — please do not use this code in a production environment. It was written for recreational purposes by a hobbyist who is bad with cryptography and even worse with Lisp. On the other hand, if you have any suggestions/patches, feel free to create an issue/pull-request on GitHub.