92 lines
2.4 KiB
Nim
92 lines
2.4 KiB
Nim
## Nim-Libp2p
|
|
## Copyright (c) 2020 Status Research & Development GmbH
|
|
## Licensed under either of
|
|
## * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
|
|
## * MIT license ([LICENSE-MIT](LICENSE-MIT))
|
|
## at your option.
|
|
## This file may not be copied, modified, or distributed except according to
|
|
## those terms.
|
|
|
|
## This module integrates BearSSL Cyrve25519 mul and mulgen
|
|
##
|
|
## This module uses unmodified parts of code from
|
|
## BearSSL library <https://bearssl.org/>
|
|
## Copyright(C) 2018 Thomas Pornin <pornin@bolet.org>.
|
|
|
|
# RFC @ https://tools.ietf.org/html/rfc7748
|
|
|
|
{.push raises: [Defect].}
|
|
|
|
import bearssl
|
|
import stew/results
|
|
export results
|
|
|
|
const
|
|
Curve25519KeySize* = 32
|
|
|
|
type
|
|
Curve25519* = object
|
|
Curve25519Key* = array[Curve25519KeySize, byte]
|
|
pcuchar = ptr cuchar
|
|
Curve25519Error* = enum
|
|
Curver25519GenError
|
|
|
|
proc intoCurve25519Key*(s: openarray[byte]): Curve25519Key =
|
|
assert s.len == Curve25519KeySize
|
|
copyMem(addr result[0], unsafeaddr s[0], Curve25519KeySize)
|
|
|
|
proc getBytes*(key: Curve25519Key): seq[byte] = @key
|
|
|
|
proc byteswap(buf: var Curve25519Key) {.inline.} =
|
|
for i in 0..<16:
|
|
let
|
|
x = buf[i]
|
|
buf[i] = buf[31 - i]
|
|
buf[31 - i] = x
|
|
|
|
proc mul*(_: type[Curve25519], point: var Curve25519Key, multiplier: Curve25519Key) =
|
|
let defaultBrEc = brEcGetDefault()
|
|
|
|
# multiplier needs to be big-endian
|
|
var
|
|
multiplierBs = multiplier
|
|
multiplierBs.byteswap()
|
|
let
|
|
res = defaultBrEc.mul(
|
|
cast[pcuchar](addr point[0]),
|
|
Curve25519KeySize,
|
|
cast[pcuchar](addr multiplierBs[0]),
|
|
Curve25519KeySize,
|
|
EC_curve25519)
|
|
assert res == 1
|
|
|
|
proc mulgen(_: type[Curve25519], dst: var Curve25519Key, point: Curve25519Key) =
|
|
let defaultBrEc = brEcGetDefault()
|
|
|
|
var
|
|
rpoint = point
|
|
rpoint.byteswap()
|
|
|
|
let
|
|
size = defaultBrEc.mulgen(
|
|
cast[pcuchar](addr dst[0]),
|
|
cast[pcuchar](addr rpoint[0]),
|
|
Curve25519KeySize,
|
|
EC_curve25519)
|
|
|
|
assert size == Curve25519KeySize
|
|
|
|
proc public*(private: Curve25519Key): Curve25519Key =
|
|
Curve25519.mulgen(result, private)
|
|
|
|
proc random*(_: type[Curve25519Key], rng: var BrHmacDrbgContext): Curve25519Key =
|
|
var res: Curve25519Key
|
|
let defaultBrEc = brEcGetDefault()
|
|
let len = brEcKeygen(
|
|
addr rng.vtable, defaultBrEc, nil, addr res[0], EC_curve25519)
|
|
# Per bearssl documentation, the keygen only fails if the curve is
|
|
# unrecognised -
|
|
doAssert len == Curve25519KeySize, "Could not generate curve"
|
|
|
|
res
|