Alice og Bob.

__main__.py

@@ -1,3 +1,3 @@
-from .week4 import main
+from .week6 import main
 
 main()

week6.py

@@ -0,0 +1,100 @@
+from __future__ import annotations
+
+import hashlib
+import itertools
+import random
+import secrets
+from typing import List
+
+from week1 import BloodType
+
+
+def sha256(b: bytes) -> bytes:
+    return hashlib.sha256(b).digest()
+
+
+def rand_bytes():
+    return secrets.SystemRandom().getrandbits(128).to_bytes(16, "big")
+
+
+def xor_bytes(a: bytes, b: bytes, k=256) -> bytes:
+    return (int.from_bytes(a, "big") ^ int.from_bytes(b, "big")).to_bytes(k, "big")
+
+
+class Gate:
+    def __init__(self, left: Gate, right: Gate, index: int) -> None:
+        self.left = left
+        self.right = right
+        self.i = index
+        self.k = {
+            0: rand_bytes(),
+            1: rand_bytes()
+        }
+        self.output = None
+
+        c_prime = {}
+        for a, b in itertools.product((0, 1), repeat=2):
+            c_prime[(a, b)] = xor_bytes(
+                sha256(self.left.k[a] + self.right.k[b] + self.i.to_bytes(1, "big")),
+                self.k[not a * b] + bytes(128 // 8)
+            )
+        pi = list(itertools.product((0, 1), repeat=2))
+        random.shuffle(pi)
+        self.c = {i: c_prime[p]
+                  for i, p in enumerate(pi)}
+
+
+class InputWire:
+    def __init__(self, index) -> None:
+        self.i = index
+        self.k = {
+            0: rand_bytes(),
+            1: rand_bytes()
+        }
+        self.output = None
+
+
+class Circuit:
+    def __init__(self, input_wires: List[InputWire], gates: List[Gate]) -> None:
+        self.input_wires = input_wires
+        self.gates = gates
+
+    def evaluate(self, x: List[bytes]) -> bytes:
+        for i, xi in enumerate(x):
+            self.input_wires[i].output = xi
+
+        for gate in self.gates:
+            for j in range(4):
+                xor = xor_bytes(
+                    sha256(gate.left.output + gate.right.output + gate.i),
+                    gate.c[j]
+                )
+                k_prime, tau = xor[:16], xor[16:]
+                if tau == bytes(16):
+                    gate.output = k_prime
+
+        return self.gates[-1].output
+
+
+def encode(e: List[InputWire], x: List[int]) -> List[bytes]:
+    return [e[i].k[xi]
+            for i, xi in enumerate(x)]
+
+
+class Alice:
+    pass
+
+
+class Bob:
+    pass
+
+
+def run(donor: BloodType, recipient: BloodType):
+    m1 = Alice.choose(x)
+    m2 = Bob.transfer(y, m2)
+    z = Alice.retrieve(m2)
+    return z
+
+
+def main():
+    run(donor=BloodType.A_NEGATIVE, recipient=BloodType.B_POSITIVE)