cryptonite-0.9: Cryptography Primitives sink

License | BSD-style
Maintainer | Vincent Hanquez <vincent@snarc.org>
Stability | experimental
Portability | Good
Safe Haskell | None
Language | Haskell2010

Crypto.Number.ModArithmetic

Contents

- exponentiation
- inverse computing

Description

Synopsis

- expSafe :: Integer -> Integer -> Integer -> Integer
- expFast :: Integer -> Integer -> Integer -> Integer
- inverse :: Integer -> Integer -> Maybe Integer
- inverseCoprimes :: Integer -> Integer -> Integer

# exponentiation

expSafe

Arguments

:: Integer | base
-> Integer | exponant
-> Integer | modulo
-> Integer | result

Compute the modular exponentiation of base^exponant using algorithms design to avoid side channels and timing measurement

Modulo need to be odd otherwise the normal fast modular exponentiation is used.

When used with integer-simple, this function is not different from expFast, and thus provide the same unstudied and dubious timing and side channels claims.

with GHC 7.10, the powModSecInteger is missing from integer-gmp (which is now integer-gmp2), so is has the same security as old ghc version.

expFast

Arguments

:: Integer | base
-> Integer | exponant
-> Integer | modulo
-> Integer | result

Compute the modular exponentiation of base^exponant using the fastest algorithm without any consideration for hiding parameters.

Use this function when all the parameters are public, otherwise `expSafe` should be prefered.

# inverse computing

inverse :: Integer -> Integer -> Maybe Integer

inverse computes the modular inverse as in g^(-1) mod m

inverseCoprimes :: Integer -> Integer -> Integer

Compute the modular inverse of 2 coprime numbers. This is equivalent to inverse except that the result is known to exists.

if the numbers are not defined as coprime, this function will raise a CoprimesAssertionError.