This module is the convenience interface for the DRBG (NIST standardized
number-theoretically secure random number generator). Everything is setup
for using the crypto-api
CryptoRandomGen type class. For example,
to seed a new generator with the system secure random (
and generate some bytes (stepping the generator along the way) one would do:
gen <- newGenIO :: IO HashDRBG let Right (randomBytes, newGen) = genBytes 1024 gen
Selecting the underlying hash algorithm is supporting using *DRBGWith types:
gen <- newGenIO :: IO (HmacDRBGWith SHA224)
gen <- newGenIO :: IO (GenBuffered (GenAutoReseed (GenXor AesCntDRBG (HashDRBGWith SHA384)) HmacDRBG))
- type HmacDRBG = State SHA512
- type HashDRBG = State SHA512
- type HmacDRBGWith = State
- type HashDRBGWith = State
- data GenXor a b
- data GenAutoReseed a b
- newGenAutoReseed :: (CryptoRandomGen a, CryptoRandomGen b) => ByteString -> Int -> Either GenError (GenAutoReseed a b)
- newGenAutoReseedIO :: (CryptoRandomGen a, CryptoRandomGen b) => Int -> IO (Either GenError (GenAutoReseed a b))
- data GenBuffered g
- module Crypto.Random
The HMAC DRBG state (of kind * -> *) allowing selection of the underlying hash algorithm (SHA1, SHA224 ... SHA512)
The Hash DRBG state (of kind * -> *) allowing selection of the underlying hash algorithm.
g :: GenXor a b generates bytes with sub-generators a and b
and exclusive-or's the outputs to produce the resulting bytes.
g :: GenAutoReseed a b is a generator of type a that gets
automatically reseeded by generator b upon every 32kB generated.
reseed g ent will reseed both the component generators by
breaking ent up into two parts determined by the genSeedLength of each generator.
genBytes will generate the requested bytes with generator
a and reseed
b if there has been 32KB of generated data since the last reseed.
Note a request for > 32KB of data will be filled in one request to generator
a is reseeded by
genBytesWithEntropy is lifted into the same call for generator
it will still reseed from generator
b if the limit is hit.
Reseed interval: If generator
a needs a
genSeedLength a = a' and generator B
needs reseeded every
2^b bytes then a
GenAutoReseed a b will need reseeded every
2^15 * (2^b / a') bytes. For the common values of
a' = 128 and
2^b = 2^48 this
means reseeding every 2^56 byte. For the example numbers this translates to
about 200 years of continually generating random values at a rate of 10MB/s.
newGenAutoReseed bs i creates a new
GenAutoReseed with a custom interval
i bytes using the provided entropy in
This is for extremely long running uses of
that can't explicitly reseed as often as a single underlying generator
would need (usually every 2^48 bytes).
newGenAutoReseedIO (2^48) :: IO (Either GenError (GenAutoReseed HashDRBG HashDRBG))
Will last for
2^48 * 2^41 bytes of randomly generated data. That's
2^49 terabytes of random values (128 byte reseeds every 2^48 bytes generated).
g :: GenBuffered a is a generator of type
a that attempts to
maintain a buffer of random values size >= 1MB and <= 5MB at any time.