Crypto-API, MonadCryptoRandom, DRBG

November 2, 2010

Announcing a new version of crypto-api and the first release of both
DRBG and MonadCryptoRandom. Links can be found at the end of the e-mail
along with acknowledgments.


Crypto-api, a generic interface for cryptographic algorithms, has hit
version 0.2. Notable additions include:

If you use cryptographic operations then crypto-api is here to give you
an easy implementation and algorithm independent interface.

  • The “OS-independent” random source (System.Crypto.Random) now works on
    Windows. (thanks Stuart Dootson)

  • No more MonoLocalBinds or ScopedTypeVariables, GHC < 6.12 should now

  • No more “instance Monad Either” what-so-ever. It got in the way other
    other instances more than being helpful.

  • The order of arguments are swapped in CryptoRandomGen so it fits
    standard convention.

  • Build deps updated so GHC-7 works (Paulo Tanimoto)

If you maintain block ciphers, hashes, asymmetric ciphers, stream
ciphers, or random number generators then I encourage you to make an
instance for the matching Crypto-API class. Also, make use of the
testing infrastructure provided if possible. AES, SHA*, and Twofish
have lots of known-answer tests and a simple module for parsing NIST
test files is also included.


Much like MonadRandom, this has a class for random value generation
(CRandom), a class for monadic operation (MonadCryptoRandom), a
transformer (CRandT), and instances to make all this useful. The main
difference between MonadCryptoRandom from MonadRandom is the use of
CryptoRandomGen instead of RandomGen and the possibility for failure by
way of MonadError.


DRBG, a cryptographically secure pseudo random number generator based on
the NIST SP 800-90 standard, is now on hackage. This uses the
crypto-api CryptoMonadRandom class and cryptohash >= 0.6.1.


Incidently, pureMD5’s deps have been bumped to use the new crypto-api.

Future Work

Once we have a cryptocipher like package with BlockCipher instance for
AES, I imagine DRBG will include cipher-based bit generators. Aside
from that, more testing is certainly an order.


Just so there’s no confusion about my part in all this.

  1. Crypto-API: I started discussion and hacked up the code for this interface (and that’s all it is, an interface for algorithm producers and algorithm consumers to meet in the middle)
  2. MonadCryptoRandom: This is just a rip-off of the motivating idea behind MonadRandom but it allows failure. I tried to match even the names as closely as was sensible (CRand instead of Rand, etc).
  3. DRBG: Its a translation of a NIST spec. I never thought I’d do translator work, but here I am doing English to Haskell transcription.



Home: None, will share home and bug tracker with crypto-api

Home: None, will share home and bug tracker with crypto-api

Thanks go to Vincent Hanquez for his cryptohash package including
crypto-api instances, Stuart Dootson for getting the Windows code in
System.Crypto.Random working, Paulo Tanimoto for pointing out/patching
an issue with GHC-7

Ben Boeckel – I haven’t forgot about your patch but it seems
cabal/hackage rejects such a .cabal file. I’ll have to investigate or
talk to Duncan.

2 Responses to “Crypto-API, MonadCryptoRandom, DRBG”

  1. Shae Erisson Says:

    Please add a package constraint, DRBG requires
    transformers >=


  2. tommd Says:

    I won’t be adding this constraint. As we both acknowledged on IRC, the transformers issue is due to some sort of broken dep between MTL-2 and Transformers. I’ll let them work things out.

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