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CS1032/lecture-2023-11-23/crypt.py

@@ -0,0 +1,17 @@
+from hashlib import sha256
+from itertools import cycle
+import base64
+
+def crypt(msg: bytes, key: str) -> bytes:
+	key_h = sha256()
+	key_h.update(key.encode('utf8'))
+	key = key_h.digest()
+
+	return bytes(p ^ k for (p, k) in zip(msg, cycle(key)))
+
+def encrypt(msg: str, key: str) -> str:
+	return base64.b64encode(crypt(bytes(msg, 'utf8'), key)).decode('utf8')
+
+def decrypt(msg: str, key: str) -> str:
+	return crypt(base64.b64decode(msg), key).decode('utf8')
+