From 39e5df2cfb004431e70bb6e03208dbd59383027b Mon Sep 17 00:00:00 2001
From: Robert Bendun <robert@bendun.cc>
Date: Wed, 17 Apr 2024 21:36:12 +0200
Subject: [PATCH] still not working lol

---
 main.py  | 76 +++++++++++++++++++++++++++++---------------------------
 utils.py | 35 --------------------------
 2 files changed, 40 insertions(+), 71 deletions(-)
 delete mode 100644 utils.py

diff --git a/main.py b/main.py
index 519c5ca..26ed21e 100644
--- a/main.py
+++ b/main.py
@@ -1,44 +1,48 @@
-from utils import generate_secret, coin_toss, H
-from utils import prime
-from utils import encrypt, decrypt
-from Crypto.Math.Numbers import Integer
+import ecpy.curves as curves
+import secrets
+import pickle
+import Crypto.Random
+import Crypto.Cipher.AES
+import Crypto.Protocol.KDF
 
-def alice_1():
-	g = Integer(2)
-	a = generate_secret()
-	A_secret = pow(g, Integer(int.from_bytes(a)), prime)
-	return A_secret, a
+m0 = b"alice"
+m1 = b"bob"
+c = False
 
-def bob_1(A_secret):
-	g = Integer(2)
-	b = generate_secret()
-	B_secret = pow(g, Integer.from_bytes(b), prime)
-	coin = coin_toss()
-	if coin:
-		B_secret = A_secret * B_secret
-	return B_secret, b, coin 
+q = 224
+curve = curves.Curve.get_curve('NIST-P224')
+g = curve.generator
 
-def alice_2(A_secret, B_secret, a, m0, m1):
-	a = int.from_bytes(a)
-	k0 = H(str(pow(int(B_secret), a, prime)).encode())
-	k1 = H(str(pow((B_secret // A_secret), a, prime)).encode())
-	# Nonce at this point is generated by AES built-in method, not by scrypt
-	e0, e1 = encrypt(k0, m0.encode()), encrypt(k1, m1.encode())
-	return *e0, *e1
+def H(p: curves.Point) -> bytes:
+    secret = pickle.dumps((p.x, p.y), protocol=4)
+    salt = Crypto.Random.get_random_bytes(16)
+    key = Crypto.Protocol.KDF.scrypt(secret, salt, 16, N=2**14, r=8, p=1)
+    return key[:32] # first 32 bytes of generated key
 
-def bob_2(A_secret, b, c, e0, e1, n0, n1):
-	kc = H(str(pow(int(A_secret), int.from_bytes(b), prime)).encode())
-	if c:
-		return decrypt(e1, n1, kc)
-	else:
-		return decrypt(e0, n0, kc)
+def E(key: bytes, message: bytes) -> tuple[bytes, bytes]:
+    cipher = Crypto.Cipher.AES.new(key, Crypto.Cipher.AES.MODE_CTR)
+    ct = cipher.encrypt(message)
+    return (ct, cipher.nonce)
 
-m0, m1 = "alice", "bob"
+def D(key: bytes, encrypted_with_nonce: tuple[bytes, bytes]) -> bytes:
+    ct, nonce = encrypted_with_nonce
+    cipher = Crypto.Cipher.AES.new(key, Crypto.Cipher.AES.MODE_CTR, nonce=nonce)
+    return cipher.decrypt(ct)
 
-A, a = alice_1()
-B, b, c = bob_1(A)
-e0, n0, e1, n1 = alice_2(A, B, a, m0, m1)
-result = bob_2(A, b, c, e0, e1, n0, n1)
+a = 1 + secrets.randbelow(q)
+b = 1 + secrets.randbelow(q)
 
+A = curve.mul_point(a, g)
+
+B = curve.mul_point(b, g)
+if c:
+    B = curve.add_point(A, B)
+
+k0 = H(curve.mul_point(a, B))
+k1 = H(curve.mul_point(a, curve.sub_point(B, A)))
+e0 = E(k0, m0)
+e1 = E(k1, m1)
+
+kc = H(curve.mul_point(b, A))
+print(D(kc, e1 if c else e0))
 
-print(result.decode())
diff --git a/utils.py b/utils.py
deleted file mode 100644
index 4ba2bf0..0000000
--- a/utils.py
+++ /dev/null
@@ -1,35 +0,0 @@
-from Crypto.PublicKey import ECC
-from Crypto.Protocol.KDF import scrypt
-from Crypto.Random import get_random_bytes
-from Crypto.Cipher import AES
-from secrets import randbelow
-
-prime = 0xffffffffffffffffffffffffffffffff000000000000000000000001
-
-def generate_secret(c = 0):
-	# 'DER' format for byte output
-        return ECC.generate(curve='NIST P-224').export_key(format='DER')
-
-def H(secret):
-	# secret should be bytearray[], pref. from generate_secret() function
-	salt = get_random_bytes(16)
-	key = scrypt(bytes(secret), salt, 16, N=2**14, r=8, p=1)
-	return key[:32] # first 32 bytes of generated key
-
-def coin_toss():
-	x = randbelow(2 ** 64)
-	if x & 1:
-		return False
-	else:
-		return True
-
-def encrypt(key, data):
-	cipher = AES.new(key, AES.MODE_CTR)
-	ct = cipher.encrypt(data)
-	nonce = cipher.nonce
-	return ct, nonce
-
-def decrypt(ct, nonce, key):
-	cipher = AES.new(key, AES.MODE_CTR, nonce=nonce)
-	pt = cipher.decrypt(ct)
-	return pt