[Haskell-cafe] ANN: nonce package

Felipe Lessa felipe.lessa at gmail.com
Fri May 22 23:06:18 UTC 2015


(Please forgive me if you received multiple copies of this e-mail.)

Hello,

The nonce package [1] contains functions to easily generate
cryptographic nonces for many situations.  Some places where these
generated nonces can be used include:

  - Password recovery e-mail tokens.

  - XSRF protection tokens.

  - Session IDs sent on cookies.

  - Initialization vectors.

It uses an AES CPRNG periodically reseeded from /dev/urandom (or
equivalent).  It has no frills, no knobs, so it's hard to misuse.  It's
been available for an year but I just realized I've never properly
announced it.

Regrettably, I've seen many uses of the random package (System.Random)
when generating nonces.  It's a bad choice: it is not a
cryptographically secure PRNG, contains low entropy (64-bit state), and
its default usage is seeded predictably (using a constant seed).  Please
avoid using the random package for generating nonces at all costs.  In
its stead, use the nonce package or something similar.

Cheers,

[1] http://hackage.haskell.org/package/nonce

-- 
Felipe.

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