codex-storage/nim-poseidon2
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Only support unmarshalling of little-endian bytes

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Big-endian bytes had weird padding; 0's to the right,
then a single 0 to the left.
This commit is contained in:
Mark Spanbroek 2023-11-02 09:00:03 +01:00 committed by markspanbroek
parent 10b4a3659a
commit 03ed357ca4
3 changed files with 21 additions and 53 deletions
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2
poseidon2.nim
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@ -98,4 +98,4 @@ func merkleRoot*(xs: openArray[F]) : F =
return merkleRoot(ys)
func merkleRoot*(bytes: openArray[byte]): F =
merkleRoot(seq[F].unmarshal(bytes, littleEndian))
merkleRoot(seq[F].unmarshal(bytes))

24
poseidon2/io.nim
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@ -2,32 +2,20 @@ import ./types
import constantine/math/arithmetic
import constantine/math/io/io_bigints
func padRight(source: openArray[byte], endian: static Endianness): array[32, byte] =
assert source.len <= 31
when endian == littleEndian:
copyMem(addr result[0], unsafeAddr source[0], source.len)
when endian == bigEndian:
copyMem(addr result[1], unsafeAddr source[0], source.len)
func unmarshal*(
_: type F,
bytes: openArray[byte],
endian: static Endianness): F =
func unmarshal*(_: type F, bytes: openArray[byte]): F =
assert bytes.len <= 31
let padded = bytes.padRight(endian)
let bigint = B.unmarshal(padded, endian)
var padded: array[32, byte]
copyMem(addr padded[0], unsafeAddr bytes[0], bytes.len)
let bigint = B.unmarshal(padded, littleEndian)
return F.fromBig(bigint)
func unmarshal*(
_: type seq[F],
bytes: openArray[byte],
endian: static Endianness): seq[F] =
func unmarshal*(_: type seq[F], bytes: openArray[byte]): seq[F] =
const chunkLen = 31
var elements: seq[F]
var chunkStart = 0
while chunkStart < bytes.len:
let chunkEnd = min(chunkStart + 31, bytes.len)
let element = F.unmarshal(bytes.toOpenArray(chunkStart, chunkEnd - 1), endian)
let element = F.unmarshal(bytes.toOpenArray(chunkStart, chunkEnd - 1))
elements.add(element)
chunkStart += chunkLen
return elements

36
tests/poseidon2/testIo.nim
View File

@ -7,49 +7,29 @@ import poseidon2/io
suite "unmarshalling":
test "converts big endian bytes into field elements":
let bytes = toSeq 1'u8..31'u8
let paddedTo32 = @[0x00'u8] & bytes # most significant byte is not used
let expected = F.fromBig(B.unmarshal(paddedTo32, bigEndian))
let unmarshalled = F.unmarshal(bytes, bigEndian)
check bool(unmarshalled == expected)
test "converts little endian bytes into field elements":
let bytes = toSeq 1'u8..31'u8
let paddedTo32 = bytes & @[0x00'u8] # most significant byte is not used
let paddedTo32 = bytes & @[0'u8] # most significant byte is not used
let expected = F.fromBig(B.unmarshal(paddedTo32, littleEndian))
let unmarshalled = F.unmarshal(bytes, littleEndian)
check bool(unmarshalled == expected)
test "pads big endian bytes to the right with 0's":
let bytes = @[0x12'u8, 0x34, 0x56]
let paddedTo31 = bytes & 0x00'u8.repeat(31 - bytes.len)
let paddedTo32 = @[0x00'u8] & paddedTo31 # most significant byte is not used
let expected = F.fromBig(B.unmarshal(paddedTo32, bigEndian))
let unmarshalled = F.unmarshal(bytes, bigEndian)
let unmarshalled = F.unmarshal(bytes)
check bool(unmarshalled == expected)
test "pads little endian bytes to the right with 0's":
let bytes = @[0x56'u8, 0x34, 0x12]
let paddedTo31 = bytes & 0x00'u8.repeat(31 - bytes.len)
let paddedTo32 = paddedTo31 & @[0x00'u8] # most significant byte is not used
let paddedTo32 = bytes & 0'u8.repeat(32 - bytes.len)
let expected = F.fromBig(B.unmarshal(paddedTo32, littleEndian))
let unmarshalled = F.unmarshal(bytes, littleEndian)
let unmarshalled = F.unmarshal(bytes)
check bool(unmarshalled == expected)
test "converts every 31 bytes into a field element":
template checkConversion(endian) =
let bytes = toSeq 1'u8..80'u8
let padded = bytes & 0'u8.repeat(93 - bytes.len)
let expected1 = F.fromBig(B.unmarshal(padded[ 0..<31], endian))
let expected2 = F.fromBig(B.unmarshal(padded[31..<62], endian))
let expected3 = F.fromBig(B.unmarshal(padded[62..<93], endian))
let elements = seq[F].unmarshal(bytes, endian)
let expected1 = F.fromBig(B.unmarshal(padded[ 0..<31] & @[0'u8], littleEndian))
let expected2 = F.fromBig(B.unmarshal(padded[31..<62] & @[0'u8], littleEndian))
let expected3 = F.fromBig(B.unmarshal(padded[62..<93] & @[0'u8], littleEndian))
let elements = seq[F].unmarshal(bytes)
check elements.len == 3
check bool(elements[0] == expected1)
check bool(elements[1] == expected2)
check bool(elements[2] == expected3)
checkConversion(littleEndian)
checkConversion(bigEndian)