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align compression func with doc description #1

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align compression func with doc description #1

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042ad35
align compression func with doc description
Sep 30, 2020
496458f
fix compress data type
Oct 8, 2020
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10 changes: 5 additions & 5 deletions ethsnarks/jubjub.py
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Original file line number Diff line number Diff line change
Expand Up @@ -68,7 +68,7 @@

def is_negative(v):
assert isinstance(v, FQ)
return v.n < (-v).n
return v.n > (-v).n


class AbstractCurveOps(object):
Expand Down Expand Up @@ -160,7 +160,7 @@ def from_y(cls, y, sign=None):
x = xsq.sqrt()
if sign is not None:
# Used for compress & decompress
if (x.n & 1) != sign:
if is_negative(x) ^ (sign != 0):
x = -x
else:
if is_negative(x):
Expand Down Expand Up @@ -235,9 +235,9 @@ def __hash__(self):
return hash((self.x, self.y))

def compress(self):
x = self.x.n
x = self.x
y = self.y.n
return int.to_bytes(y | ((x&1) << 255), 32, "little")
return int.to_bytes(y | (is_negative(x) << 255), 32, "little")

@classmethod
def decompress(cls, point):
Expand Down Expand Up @@ -684,4 +684,4 @@ def mult_naf_lut(point, scalar, width=2):
p = w[k_i]
if p is not None:
a = a.add(p)
return a
return a