def primeTest(n):
q = n - 1
k = 0
# Find k, q, satisfied 2^k * q = n - 1
while q % 2 == 0:
k += 1
q /= 2
a = random.randint(2, n - 2);
# If a^q mod n= 1, n maybe is a prime number
if fastExpMod(a, q, n) == 1:
return "inconclusive"
# If there exists j satisfy a ^ ((2 ^ j) * q) mod n == n-1, n maybe is a prime number
for j in range(0, k):
if fastExpMod(a, (2 ** j) * q, n) == n - 1:
return "inconclusive"
# a is not a prime number
return "composite"
def decryption(C, d, n):
# RSA M = C^d mod n
return fastExpMod(C, d, n)
def encryption(M, e, n):
# RSA C = M^e mod n
return fastExpMod(M, e, n)
