Ring-Learning-With-Errors.py

import numpy as np
import sys

def gen_poly(n,q):
    global xN_1
    l = 0 #Gamma Distribution Location (Mean "center" of dist.)
    poly = np.floor(np.random.normal(l,size=(n)))
    while (len(poly) != n):
        poly = np.floor(np.random.normal(l,size=(n)))
        poly = np.floor(p.polydiv(poly,xN_1)[1]%q)
    return poly

q=13

A = [4,1,11,10]
sA = [6,9,11,11]
eA =[0,-1,1,1]

n=4

print(A,sA,eA)

xN_1 = [1] + [0] * (n-1) + [1]

print(xN_1)

A = np.floor(np.polydiv(A,xN_1)[1])

bA = np.polymul(A,sA)%q
bA = np.floor(np.polydiv(bA,xN_1)[1])

bA = np.polyadd(bA,eA)%q
bA = np.floor(np.polydiv(bA,xN_1)[1])

print("Print output\n",bA)

xN_1 = [1] + [0] * (n-1) + [1]

A = np.floor(np.polydiv(A,xN_1)[1])

bA = np.polymul(A,sA)%q
bA = np.floor(np.polydiv(sA,xN_1)[1])
bA = np.polyadd(bA,eA)%q

sB = gen_poly(n,q)
eB = gen_poly(n,q)

bB = np.polymul(A,sB)%q
bB = np.floor(np.polydiv(sB,xN_1)[1])
bB = np.polyadd(bB,eB)%q

sharedAlice = np.floor(np.polymul(sA,bB)%q)
sharedAlice = np.floor(np.polydiv(sharedAlice,xN_1)[1])%q 
sharedBob = np.floor(np.polymul(sB,bA)%q)
sharedBob = np.floor(np.polydiv(sharedBob,xN_1)[1])%q

# Public key and LWE