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cleanup leftover from BN curve inversion

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Mamy André-Ratsimbazafy 2020-09-27 17:39:45 +02:00
parent 8a456b84db
commit 48bab72d1f
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1 changed files with 0 additions and 29 deletions
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constantine/config/precompute.nim
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@ -458,35 +458,6 @@ func toCanonicalIntRepr*[bits: static int](
## (octet-string) ## (octet-string)
result.exportRawUint(a, bigEndian) result.exportRawUint(a, bigEndian)
func bn_6u_minus_1_BE*[bits: static int](
u: BigInt[bits]
): array[(bits+7+3) div 8, byte] {.noInit.} =
## For a BN curve
## Precompute 6u-1 (for Little Fermat inversion)
## and store it in canonical integer representation
# TODO: optimize output size
# each extra 0-bit is an extra useless squaring for a public exponent
# For example, for BN254-Snarks, u = 0x44E992B44A6909F1 (63-bit)
# and 6u+1 is 65-bit (not 66 as inferred)
# Zero-extend "u"
var u_ext: BigInt[bits+3]
for i in 0 ..< u.limbs.len:
u_ext.limbs[i] = u.limbs[i]
# Addition chain to u -> 6u
discard u_ext.dbl() # u_ext = 2u
let u_ext2 = u_ext # u_ext2 = 2u
discard u_ext.dbl() # u_ext = 4u
discard u_ext.cadd(u_ext2, true) # u_ext = 6u
# Sustract 1
discard u_ext.sub(1)
# Export
result.exportRawUint(u_ext, bigEndian)
# ############################################################ # ############################################################
# #
# Compile-time Conversion to Montgomery domain # Compile-time Conversion to Montgomery domain