codex-storage
/
constantine
mirror of https://github.com/codex-storage/constantine.git
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

Implement to Montgomery domain conversion

This commit is contained in:
mratsim 2018-12-02 19:28:42 +01:00
parent 22d8bc218d
commit 27e2d2d2bc
3 changed files with 13 additions and 5 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
README.md
View File

@ -6,8 +6,9 @@
[![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT) [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](https://opensource.org/licenses/MIT)
![Stability: experimental](https://img.shields.io/badge/stability-experimental-orange.svg) ![Stability: experimental](https://img.shields.io/badge/stability-experimental-orange.svg)
This library provides constant time finite field primitives. This library provides constant time finite field primitives for implementation of elliptic curve cryptography.
The main use will be for implementation of elliptic curve cryptography
Warning ⚠️: The library is in development state.
## Installation ## Installation

4
constantine/field_fp.nim
View File

@ -160,14 +160,14 @@ template scaleadd_impl(a: var Fp, c: Limb) =
sub(a, Fp.P, tooBig) sub(a, Fp.P, tooBig)
func scaleadd*(a: var Fp, c: Limb) = func scaleadd*(a: var Fp, c: Limb) =
## Scale-accumulate ## Scale-accumulate modulo P
## ##
## With a word W = 2^LimbBitSize and a field Fp ## With a word W = 2^LimbBitSize and a field Fp
## Does a <- a * W + c (mod p) ## Does a <- a * W + c (mod p)
scaleadd_impl(a, c) scaleadd_impl(a, c)
func scaleadd*(a: var Fp, c: static Limb) = func scaleadd*(a: var Fp, c: static Limb) =
## Scale-accumulate ## Scale-accumulate modulo P
## ##
## With a word W = 2^LimbBitSize and a field Fp ## With a word W = 2^LimbBitSize and a field Fp
## Does a <- a * W + c (mod p) ## Does a <- a * W + c (mod p)

9
constantine/montgomery.nim
View File

@ -69,5 +69,12 @@ func montyMagic*(M: static BigInt): static Limb =
for _ in static(0 ..< k): for _ in static(0 ..< k):
result *= 2 + M * result # x' = x(2 + ax) (`+` to avoid negating at the end) result *= 2 + M * result # x' = x(2 + ax) (`+` to avoid negating at the end)
# func toMonty*[P: static BigInt](a: Fp[P], montyMagic: Limb): Montgomery[P] = func toMonty*[P: static BigInt](a: Fp[P]): Montgomery[P] =
## Convert a big integer over Fp to it's montgomery representation
## over Fp.
## i.e. Does "a * (2^LimbSize)^W (mod p), where W is the number
## of words needed to represent p in base 2^LimbSize
result = a
for i in static(countdown(P.limbs.high, 0)):
scaleadd(result, 0)