def boscoster_robust2(data):
while True:
index1 = 0
for i in range(len(data)):
if data[i][0] > data[index1][0]:
index1 = i
index2 = 0
if index2 == index1:
index2 = 1
for i in range(len(data)):
if i != index1:
if data[i][0] > data[index2][0]:
index2 = i
if data[index2][0] == 0:
return ed25519.multiply(data[index1][0], data[index1][1])
# handle pathological inputs where s1 > 2s2
# replace (s1,P1) with (s1/2,2*P1)
tail_point = ed25519.Z # handles odd scalars
while data[index1][0] > 2 * data[index2][0]:
# if s1 is odd, add (1,P1) at the end of the heap
if (data[index1][0] % 2) == 1:
tail_point = ed25519.add(tail_point, data[index1][1])
data[index1][0] = long(data[index1][0] / 2)
data[index1][1] = ed25519.add(data[index1][1], data[index1][1])
if tail_point != ed25519.Z:
data.append([1, tail_point])
data[index2][1] = ed25519.add(data[index2][1], data[index1][1])
data[index1][0] = (data[index1][0] -
data[index2][0]) % ed25519.l # scalar subtraction
def boscosterheap_robust2(data):
data = [[-datum[0], datum[1]]
for datum in data] # to form a descending heap
heapq.heapify(data)
while len(data) > 1:
item1 = heapq.heappop(data)
item2 = heapq.heappop(data)
s1, p1 = -item1[0], item1[1]
s2, p2 = -item2[0], item2[1]
# handle pathological inputs where s1 > 2s2
# replace (s1,P1) with (s1/2,2*P1)
tail_point = ed25519.Z # handles odd scalars
while s1 > 2 * s2:
# if s1 is odd, add (1,P1) at the end of the heap
if (s1 % 2) == 1:
tail_point = ed25519.add(tail_point, p1)
s1 = long(s1 / 2)
p1 = ed25519.add(p1, p1)
if tail_point != ed25519.Z:
heapq.heappush(data, [-1, tail_point])
p2 = ed25519.add(p1, p2)
s1 = (s1 - s2) % ed25519.l # scalar subtraction
if s1 > 0L:
heapq.heappush(data, [-s1, p1])
heapq.heappush(data, [-s2, p2])
result = heapq.heappop(data)
return ed25519.multiply(-result[0], result[1])
def boscosterheap(data):
data = [[-datum[0], datum[1]]
for datum in data] # to form a descending heap
heapq.heapify(data)
while len(data) > 1:
item1 = heapq.heappop(data)
item2 = heapq.heappop(data)
s1, p1 = -item1[0], item1[1]
s2, p2 = -item2[0], item2[1]
p2 = ed25519.add(p1, p2)
s1 = (s1 - s2) % ed25519.l # scalar subtraction
if s1 > 0L:
heapq.heappush(data, [-s1, p1])
heapq.heappush(data, [-s2, p2])
result = heapq.heappop(data)
return ed25519.multiply(-result[0], result[1])
def boscoster(data):
while True:
index1 = 0
for i in range(len(data)):
if data[i][0] > data[index1][0]:
index1 = i
index2 = 0
if index2 == index1:
index2 = 1
for i in range(len(data)):
if i != index1:
if data[i][0] > data[index2][0]:
index2 = i
if data[index2][0] == 0:
return ed25519.multiply(data[index1][0], data[index1][1])
data[index2][1] = ed25519.add(data[index2][1], data[index1][1])
data[index1][0] = (data[index1][0] -
data[index2][0]) % ed25519.l # scalar subtraction
def basic(data):
result = ed25519.Z # zero point
for datum in data:
result = ed25519.add(result, ed25519.multiply(datum[0], datum[1]))
return result