def encrypt(pb, msg):
#generate a prime
msg = int(msg)
r = pb.n - 1
while (math.gcd(r, pb.n) != 1):
r += 1
cipher = modOp.expoMod(r, pb.n, pb.n2)
cipher = cipher * (modOp.expoMod(pb.g, msg, pb.n2))
cipher = cipher % pb.n2
return cipher
def generateKeypair(bits, k=128):
p = rabinMiller.generatePrime(bits, k)
q = rabinMiller.generatePrime(bits, k)
while (p == q):
q = rabinMiller.generatePrime(bits, k)
p, q = 463, 487 # why?
n = p * q
phi = (p - 1) * (q - 1)
l = phi // math.gcd(p - 1, q - 1)
g = n + 1
n2 = n * n
while (math.gcd(modOp.expoMod(g, l, n2), n) != 1):
g += 1
#Inverse mod
mu = modOp.expoMod(L(modOp.expoMod(g, l, n2), n), phi - 1, n)
return PrivateKey(l, mu), PublicKey(n, g)
def homomorphicDivision(pb, c, p):
pdash = modOp.invMod(p, pb.n)
return modOp.expoMod(c, pdash, pb.n2)
# pr,pb = generateKeypair(9)
# print(repr(pb),repr(pr))
# enc = encrypt(pb,140)
# dec = decrypt(pr,pb,enc)
# print(dec)
# print("encoding",enc)
# enc5 = encrypt(pb,184)
# bb = homomorphicMul(pb, enc, 2)
# print(decrypt(pr, pb, bb))
# val = modOp.invMod(enc,pb.n2)
# val = (val*enc5)%pb.n2
# print(decrypt(pr,pb,val))
# print("Res : ",homomorphicAddP(pb,encrypt(pb,3),3))
# print(decrypt(pr,pb,homomorphicMul(pb,encrypt(pb,3),3)))
def homomorphicMul(pb, c, p):
return modOp.expoMod(c, p, pb.n2)
def homomorphicAddP(pb, c, p):
return (c * modOp.expoMod(pb.g, p, pb.n2)) % pb.n2
def decrypt(pr, pb, c):
c = int(c)
m = L(modOp.expoMod(c, pr.l, pb.n2), pb.n) * pr.mu
m = m % pb.n
return m