91 lines
2.6 KiB
Nim

import
constantine/math/arithmetic,
constantine/math/io/io_fields,
constantine/math/io/io_bigints,
constantine/named/algebras
#-------------------------------------------------------------------------------
#
# Note: Because of a historical accident, there are unfortunately TWO different sets
# of "standard" parameters, which is obviously bad for cross-project compatibility.
#
# the switchover happened at 2023/06/23 in the commit
# <https://github.com/HorizenLabs/poseidon2/commit/bb476b9ca38198cf5092487283c8b8c5d4317c4e>
#
# You can use this type to select between the two. The default is the "old" set.
#
type Flavour* = enum
HorizenLabsOld # the "old" round constants
HorizenLabsNew # the "new" round constants
type SpongeInput* = enum
ByteString # the input of the hash is a sequence of bytes
FieldElements # the input of the hash is a sequence of BN254 field elements
#-------------------------------------------------------------------------------
type B* = BigInt[254]
type F* = Fr[BN254_Snarks]
type S* = (F,F,F)
#-------------------------------------------------------------------------------
func getZero*() : F =
var z : F
setZero(z)
return z
#-------------------------------------------------------------------------------
const zero* : F = getZero()
const one* : F = fromHex(F,"0x01") # note: `fromUint()` does not work at compile time
const two* : F = fromHex(F,"0x02")
const twoToThe64* : F = fromHex(F,"0x10000000000000000")
#-------------------------------------------------------------------------------
func hexToF*(s : string, endian: static Endianness = bigEndian) : F =
let bigint = B.fromHex(s, endian)
return F.fromBig(bigint)
func arrayFromHex*[N](
inp: array[N, string],
endian: static Endianness = bigEndian) : array[N, F] =
var tmp : array[N, F]
for i in low(inp)..high(inp):
tmp[i] = hexToF(inp[i], endian)
return tmp
#-------------------------------------------------------------------------------
func `+`*(x, y: F): F = ( var z: F = x ; z += y ; return z )
func `-`*(x, y: F): F = ( var z: F = x ; z -= y ; return z )
func `*`*(x, y: F): F = ( var z: F = x ; z *= y ; return z )
func `==`*(a, b: F): bool =
bool(arithmetic.`==`(a, b))
func sqr*(x : F): F =
var y = x
y.square()
return y
#-------------------------------------------------------------------------------
func fastPow*(base: F, expo: B): F =
var s : F = base
var a : F = one
var e : B = expo
for i in 0..<254:
if bool(isOdd(e)):
a *= s
s.square()
e.div2()
return a
#-------------------------------------------------------------------------------