laokoon

LaokoonHaxorcist/crypto_psa_games/server.py

@@ -0,0 +1,58 @@
+from Crypto.Util.number import bytes_to_long, getPrime, GCD
+from Crypto.Util.Padding import pad
+# from secret import FLAG
+
+WELCOME = '''Welcome to my custom PSA cryptosystem! 
+In this cryptosystem, the message is PKCS#7 padded and then encrypted with RSA.
+They say padding makes encryption more secure, right? ;)'''
+
+MENU = '''
+[1] Encrypt the flag
+[2] Exit
+'''
+
+
+class PSA:
+
+    def __init__(self):
+        self.bit_size = 512
+        self.e = 11
+
+    def gen_modulus(self):
+        while True:
+            p = getPrime(self.bit_size // 2)
+            q = getPrime(self.bit_size // 2)
+            if GCD(self.e, (p - 1) * (q - 1)) == 1:
+                break
+        return p * q
+
+    def encrypt(self, msg):
+        m = bytes_to_long(pad(msg, 16))
+        n = self.gen_modulus()
+        c = pow(m, self.e, n)
+        return c, n
+
+
+def main():
+    psa = PSA()
+    print(WELCOME)
+    while True:
+        try:
+            print(MENU)
+            opt = input('> ')
+            if opt == '1':
+                enc, modulus = psa.encrypt(b'FLAG')
+                print(f"\n{hex(enc)}\n{hex(modulus)}")
+            elif opt == '2':
+                print('Bye.')
+                exit(1)
+            else:
+                print('\nInvalid option!')
+        except:
+            print('\n\nSomething went wrong.')
+            exit(1)
+
+
+if __name__ == '__main__':
+    # main()
+    print(0x65c96a10a5553c2eb1b05ac1369a777089841005b055cbf8dcafc41fd1d11b0a0306b820cbc742796318694b9fdf145214ef3a2385984daa0d6d5ba87bdce687)