From cd683fdf17bf50f0704f14dda2d8b2261bfcc5a9 Mon Sep 17 00:00:00 2001 From: Roman Hergenreder Date: Mon, 17 Dec 2018 09:04:15 +0100 Subject: [PATCH] Day 17 --- Day 17/FasterKeyExchange.py | 76 +++++++++++++++++++++++++++++++++++++ Day 17/decode.py | 43 +++++++++++++++++++++ 2 files changed, 119 insertions(+) create mode 100644 Day 17/FasterKeyExchange.py create mode 100644 Day 17/decode.py diff --git a/Day 17/FasterKeyExchange.py b/Day 17/FasterKeyExchange.py new file mode 100644 index 0000000..39ace78 --- /dev/null +++ b/Day 17/FasterKeyExchange.py @@ -0,0 +1,76 @@ +import secrets +import hashlib +from base64 import b64encode +from Crypto.Cipher import AES +from Crypto.Util.Padding import pad + +g = 3 +p = 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 + +class Server(): + def __init__(self, port=3331): + self.port = port + self.fKE = FasterKeyExchange(g, p) + self.y_server = self.fKE.calculate_y() + self.y_client = 0 + self.IV = "d724c349c2b28831" + self.key = "313371337" + + def print_banner(self): + print(" ---_ ......._-_--.") + print(" (|\ / / /| \ \\") + print(" / / .' -=-' `.") + print(" / / .' )") + print(" _/ / .' _.) /") + print(" / o o _.-' / .'") + print(" \ _.-' / .'*|") + print(" \______.-'// .'.' \*|") + print(" \| \ | // .'.' _ |*|") + print(" ` \|// .'.'_ _ _|*|") + print(" . .// .'.' | _ _ \*|") + print(" \`-|\_/ / \ _ _ \*\\") + print(" `/'\__/ \ _ _ \*\\") + print(" /^| \ _ _ \*") + print(" ' ` \ _ _ \\") + print(" \_") + print("Challenge by pyth0n33. Have fun!") + + def run(self): + self.print_banner() + input("Enter to start") + print("\x1b[2J\x1b[H") + print("Here's my y={0}\n\n".format(self.y_server)) + self.y_client = int(input("Now give me your y please: ")) + self.key = str(self.fKE.calculate_key(self.y_client)) + self.iv = self.key[0:16] + self.encrypt() + + def encrypt(self): + key = bytes(hashlib.md5(bytes(self.key, "utf-8")).hexdigest(), "utf-8") + cipher = AES.new(key, AES.MODE_CBC, iv=bytes(self.iv, "utf-8")) + cipher_text_bytes = cipher.encrypt(pad(b"The Advanced Encryption Standard (AES), also known by its original name Rijndael, is a specification for the encryption of electronic data established by the U.S. National Institute of Standards and Technology (NIST) in 2001.", AES.block_size)) + print(b64encode(cipher_text_bytes)) + +class FasterKeyExchange(): + def __init__(self, g, p): + self.g = g + self.p = p + self.x = self.get_random_x() + + def get_random_x(self): + return secrets.SystemRandom().randint(g, p-2) + + def calculate_y(self): + return (self.g * self.x) % self.p + + def calculate_key(self, y): + return (y * self.x) % self.p + +if __name__ == "__main__": + server = Server() + server.run() + + + + + diff --git a/Day 17/decode.py b/Day 17/decode.py new file mode 100644 index 0000000..182fae0 --- /dev/null +++ b/Day 17/decode.py @@ -0,0 +1,43 @@ +#!/usr/bin/python + +import base64 +import hashlib +from Crypto import Random +from Crypto.Cipher import AES + +def linear_diophantine_equation(a, b): + if b > a: + return linear_diophantine_equation(b, a) + + if b == 0: + return a, 1, 0 + + d, x, y = linear_diophantine_equation(b, a % b) + return (d, y, x - (a // b) * y) + +a = 17577019968135092891915317246036083578063875217491307011102321322815719709605741738459191569497548099944025771002530369133716621942963853230082186943938164591230020725702755002287589522851172217336150522367152517270250629688405924844750026155547199020780202996200555426652190631837288299999083335649923708175859594750237448640513280683859296367607523542293538555215282798100455110266565881599829107971869244773384413618546118850868579583095489023778055976570366853411496753062216229293710557686212314300848121614558806328788578096144576605248971916454783615989429937555579437307320472405217413938048149254574677430624 + +b = 15228628318558071728245462802366236848375416102820239825350329247148900182647243994904519787528142824353837070194785550898962097219309344881183948914850354340893035399529028331238911753358245357848436203268982345430735846016484221944423499956958406189854969330305125479065873712331269870135028162018087451460656203085824963123310757985362748654204595136594184636862693563510767025800252822776154986386637346156842972134635578534633722315375292616298410141343725683471387328655106920310236007034951004329720717533666052625540760911360823548318810161367913281234234193760867208897459774865037319252137821553407707977377 + +g = 3 +p = 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 + +message = "jqMYIn4fzSqzIXArwJm/kPitNhf4lwhL0yPRKpF+NYXyPmhoEwNG/k2L5vCZqFWNPvTzisnu93/8uK/PZnnCGg==" +messageDecoded = base64.b64decode(message) + +def test_x(x): + return (g * x) % p == a + +# (g * x) % p = a +# (g * x) - (k * p) = a + +x = linear_diophantine_equation(g, p)[2] * a +key = str((b * x) % p) +iv = key[0:16] + +# Decrypt +key = bytes(hashlib.md5(bytes(key, "utf-8")).hexdigest(), "utf-8") +cipher = AES.new(key, AES.MODE_CBC, iv=bytes(iv, "utf-8")) +plain_text_bytes = cipher.decrypt(messageDecoded) +plain_text = plain_text_bytes.decode("utf-8") +print(plain_text)