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services/phew/Pailier.py

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+from Crypto.Util.number import *
+from math import lcm
+import random
+
+class pailier:
+    def __init__(self):
+        self.primes = [getPrime(512) for _ in range(2)]
+        self.n = 1
+        self.phi = 1
+        self.mul = 1
+        for i in range(2):
+            self.n  *= self.primes[i]
+            self.phi *= (self.primes[i] - 1)  
+        self.n2 = self.n * self.n
+        self.g = [pow(random.randrange(1, self.n2), self.primes[i], self.n2) for i in range(2)]
+        for x in self.g:
+            self.mul = (self.mul * x) % self.n2
+        self.miu = inverse(self.L(pow(self.mul, self.phi, self.n2)), self.n)
+        self.alpha = [None, None]
+        for idx in range(2):
+            while True:
+                a = random.randrange(2, self.n - 1)
+                if GCD(a, self.n) == 1:
+                    self.alpha[idx] = a
+                    break
+        self.beta  = [random.randrange(0, self.n), random.randrange(0, self.n)]
+
+    def L(self, val):
+        return (val - 1) // self.n
+
+    def pubkey(self):
+        return (self.n, self.g)
+
+    def encrypt(self, msg: int) -> int:
+        r  = random.randrange(0, self.n - 1)
+        gb = self.g[random.randrange(0, 2)]
+        gm = pow(gb, msg, self.n2)
+        rn = pow(r, self.n, self.n2)
+        return (gm * rn) % self.n2
+
+    def decrypt(self, ct: int) -> int:
+        raw = self.L(pow(ct, self.phi, self.n2)) % self.n
+        raw = (raw * self.miu) % self.n
+        t = pow(ct % self.n, (self.n - 1) // 2, self.n) if (self.n % 2 == 1) else 0
+        idx = 0 if t == 1 else 1
+        return (self.alpha[idx] * raw + self.beta[idx]) % self.n
+