122 lines
4.4 KiB
Nim

# sponge construction for linear hashing.
#
# we recommend to use rate=8
# (note that we have the state width fixed to t=12)
#
# we use the 10* padding strategy (that is, always append an 1, and append
# as many zeros as required so that the final length is divisible by the rate)
# both when hashing bytes and when hashing field elements
#import std/assertions # on 1.6.18 with an M2 i got "cannot open file: std/assertions" ....
import ./types
import ./goldilocks
import ./permutation
#import ./io
#-------------------------------------------------------------------------------
# "import std/assertions" does not work
# i got the error: "cannot open file: std/assertions"
proc fakeAssert( cond: bool, msg: string ) =
if not cond:
raise newException(AssertionDefect, msg)
#-------------------------------------------------------------------------------
type
Sponge*[T: static typedesc, rate: static int] = object
state: F12
lenModRate: uint
func numberOfBits(T: static typedesc): int =
if T is F: return 63
if T is byte: return 8
if T is bool: return 1
fakeAssert( false , "unsupported input type for sponge construction" )
func initialize[T: static typedesc, rate: static int](sponge: var Sponge[T,rate]) =
fakeAssert( rate >= 1 and rate <= 8 , "with t=12, rate must be at most 8 (and positive)" )
let nbits = numberOfBits(T)
let IV = toF( 0x10000*uint64(nbits) + 0x100*12 + uint64(rate) ) # domain separation IV := (65536*nbits + 256*t + r)
sponge.state[8] = IV;
#---------------------------------------
func extractDigestF4[T: static typedesc, rate: static int](sponge: var Sponge[T,rate]) : F4 =
var digest : F4
for i in 0..<4: digest[i] = sponge.state[i]
return digest
func extractDigest[T: static typedesc, rate: static int](sponge: var Sponge[T,rate]) : Digest =
return toDigest(sponge.extractDigestF4())
#---------------------------------------
func update*[rate: static int](sponge: var Sponge[typedesc[F],rate], x: F) =
sponge.state[sponge.lenModRate] += x
sponge.lenModRate = (sponge.lenModRate + 1) mod rate
if (sponge.lenModRate == 0):
permInPlaceF12( sponge.state );
func finish*[T: static typedesc, rate:static int](sponge: var Sponge[T,rate]): Digest =
# padding
sponge.update(one)
while( sponge.lenModRate != 0):
sponge.update(zero)
return sponge.extractDigest()
#-------------------------------------------------------------------------------
# # _: type Sponge,
#func init*( _: type Sponge, T: static typedesc, rate: static int = 8): Sponge[T,rate] =
# when (rate < 1 or rate > 8):
# {.error: "only rates between 1 and 8 are supported".}
# var sponge: Sponge[T,rate]
# initialize[T,rate](sponge)
# return sponge
func newSponge*[T: static typedesc, rate: static int = 8](): Sponge[T,rate] =
when (rate < 1 or rate > 8):
{.error: "only rates between 1 and 8 are supported".}
var sponge: Sponge[T,rate]
initialize[T,rate](sponge)
return sponge
#---------------------------------------
# digest a sequence of field elements
func digestNim*(rate: static int = 8, elements: openArray[F]): Digest =
var sponge : Sponge[typedesc[F],rate] = newSponge[typedesc[F],rate]()
for element in elements:
sponge.update(element)
return sponge.finish()
# # digest a sequence of bytes
#func digestNim*(rate: static int = 8, bytes: openArray[byte],): F =
# var sponge = Sponge.init(nbits=8, rate)
# for element in bytes.elements(F):
# sponge.update(element)
# return sponge.finish()
#---------------------------------------
proc digestFeltsRawC(rate: int, len: int, input: ptr UncheckedArray[F ], hash: var F4) {. header: "../cbits/goldilocks.h", importc: "goldilocks_poseidon2_felts_digest", cdecl .}
proc digestBytesRawC(rate: int, len: int, input: ptr UncheckedArray[byte], hash: var F4) {. header: "../cbits/goldilocks.h", importc: "goldilocks_poseidon2_bytes_digest", cdecl .}
func digestFeltsC*(rate: static int = 8, felts: openArray[F]): Digest =
var digest : F4
let input = cast[ptr UncheckedArray[F]]( felts.unsafeAddr )
digestFeltsRawC(rate, felts.len, input, digest)
return toDigest(digest)
func digestBytesC*(rate: static int = 8, bytes: openArray[byte]): Digest =
var digest : F4
let input = cast[ptr UncheckedArray[byte]]( bytes.unsafeAddr )
digestBytesRawC(rate, bytes.len, input, digest)
return toDigest(digest)
#-------------------------------------------------------------------------------