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alex-retrieval/pir/pir_Supreme.py

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Python
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2019-11-14 11:43:44 +01:00
import random
import math
n = 8
k = 3
x = "11110101"
def findS():
for s_candidate in range(k, n+1):
binom = math.factorial(s_candidate) / ( math.factorial(k-1) * (math.factorial(s_candidate - (k-1))) )
if binom >= n:
return s_candidate
s = findS()
def makeOneSeq(seq):
ones_remainding_counter = k - 1
while ones_remainding_counter != 0:
rand_idx = random.randint(0, s - 1)
if seq[rand_idx] == "0":
seq_temp = list(seq)
seq_temp[rand_idx] = "1"
seq = "".join(seq_temp)
ones_remainding_counter -= 1
return seq
def makeSequences():
sequnces = [ "0"*s for j in range(n) ]
for i, seq in enumerate(sequnces):
candidate = makeOneSeq(seq)
while( candidate in sequnces):
candidate = makeOneSeq(seq)
sequnces[i] = candidate
sequnces.sort()
return sequnces
sequnces = makeSequences()
#print(sequnces)
def user_send(rands, i):
gs = [[rands[l] * z + int(i[l]) for l in range(0, s)] for z in range(1, k+1)]
return gs
def servers_comp(gs):
Fs = []
for g in gs:
F = 0
for j in range(0, n):
f = 1
j_bitstring = sequnces[j]
for l in range(s):
if int(j_bitstring[l]) == 1:
f *= g[l]
F += f * int(x[j])
Fs.append(F)
return Fs
def poly_interpolation(x, Fs):
add_product = 0
for i in range(0, k):
mult_product = 1
for j in range(0, k):
if j != i:
mult_product *= (x - (j+1))/((i+1) - (j+1))
add_product += mult_product * Fs[i]
return int(add_product)
def protocol(i):
rands = [random.randint(1,20) for r in range(s)]
gs = user_send(rands, i)
Fs = servers_comp(gs)
F0 = poly_interpolation(0, Fs)
# print(F0)
return F0
for i in range(n):
i_bitstring = sequnces[i]
F0 = protocol(i_bitstring)
assert (F0 == int(x[i]))