53 lines
1.9 KiB
Nim
53 lines
1.9 KiB
Nim
# Constantine
|
|
# Copyright (c) 2018-2019 Status Research & Development GmbH
|
|
# Copyright (c) 2020-Present Mamy André-Ratsimbazafy
|
|
# Licensed and distributed under either of
|
|
# * MIT license (license terms in the root directory or at http://opensource.org/licenses/MIT).
|
|
# * Apache v2 license (license terms in the root directory or at http://www.apache.org/licenses/LICENSE-2.0).
|
|
# at your option. This file may not be copied, modified, or distributed except according to those terms.
|
|
|
|
import
|
|
# Internals
|
|
../../../constantine/math/arithmetic,
|
|
../../../constantine/math/io/io_bigints
|
|
|
|
# Support files for testing Elliptic Curve arithmetic
|
|
# ------------------------------------------------------------------------------
|
|
|
|
iterator unpack(scalarByte: byte): bool =
|
|
yield bool((scalarByte and 0b10000000) shr 7)
|
|
yield bool((scalarByte and 0b01000000) shr 6)
|
|
yield bool((scalarByte and 0b00100000) shr 5)
|
|
yield bool((scalarByte and 0b00010000) shr 4)
|
|
yield bool((scalarByte and 0b00001000) shr 3)
|
|
yield bool((scalarByte and 0b00000100) shr 2)
|
|
yield bool((scalarByte and 0b00000010) shr 1)
|
|
yield bool( scalarByte and 0b00000001)
|
|
|
|
func unsafe_ECmul_double_add*[EC](
|
|
P: var EC,
|
|
scalar: BigInt,
|
|
) =
|
|
## **Unsafe** Elliptic Curve Scalar Multiplication
|
|
##
|
|
## P <- [k] P
|
|
##
|
|
## This uses the double-and-add algorithm to verify the constant-time production implementation
|
|
## This is UNSAFE to use in production and only intended for testing purposes.
|
|
##
|
|
## This is highly VULNERABLE to timing attacks and power analysis attacks
|
|
var scalarCanonical: array[(scalar.bits+7) div 8, byte]
|
|
scalarCanonical.marshal(scalar, bigEndian)
|
|
|
|
var t0{.noInit.}, t1{.noInit.}: typeof(P)
|
|
t0.setInf()
|
|
t1.setInf()
|
|
for scalarByte in scalarCanonical:
|
|
for bit in unpack(scalarByte):
|
|
t1.double(t0)
|
|
if bit:
|
|
t0.sum(t1, P)
|
|
else:
|
|
t0 = t1
|
|
P = t0
|