From 209ca55ada97dd1a546bc0b1f05e740c968b4a0d Mon Sep 17 00:00:00 2001
From: Abel Stuker <stukerabel@gmail.com>
Date: Mon, 25 Nov 2024 22:30:51 +0100
Subject: [PATCH] feat: add magic-byte challenge

---
 magic-byte/README.md            | 14 ++++++++++++++
 magic-byte/SOLUTION.md          | 15 +++++++++++++++
 magic-byte/create_magic_byte.py | 33 +++++++++++++++++++++++++++++++++
 magic-byte/magic_byte.txt       |  1 +
 4 files changed, 63 insertions(+)
 create mode 100644 magic-byte/README.md
 create mode 100644 magic-byte/SOLUTION.md
 create mode 100644 magic-byte/create_magic_byte.py
 create mode 100644 magic-byte/magic_byte.txt

diff --git a/magic-byte/README.md b/magic-byte/README.md
new file mode 100644
index 0000000..952a8fc
--- /dev/null
+++ b/magic-byte/README.md
@@ -0,0 +1,14 @@
+# Magic Byte
+
+## Text
+
+Hi! I encrypted my flag with some awesome magic. ... Lore ... Lore ...
+Figure it out :)
+
+## Files
+
+magic_byte.txt
+
+## How to Deploy
+
+N/A
diff --git a/magic-byte/SOLUTION.md b/magic-byte/SOLUTION.md
new file mode 100644
index 0000000..829bc16
--- /dev/null
+++ b/magic-byte/SOLUTION.md
@@ -0,0 +1,15 @@
+## Difficulty
+
+Easy, because it is easy.
+
+## Category
+
+Crypto
+
+## How To Solve
+
+Just bruteforce the magic byte, xoring the ciphertext with the byte.
+
+## Flag
+
+IGCTF{hello_flag!}
diff --git a/magic-byte/create_magic_byte.py b/magic-byte/create_magic_byte.py
new file mode 100644
index 0000000..25598f4
--- /dev/null
+++ b/magic-byte/create_magic_byte.py
@@ -0,0 +1,33 @@
+magic = 0xCC
+flag = "IGCTF{hello_flag!}"
+
+def xor_string_with_byte(input_str, xor_byte):
+    # Convert the input string to bytes
+    input_bytes = input_str.encode()
+
+    # XOR each byte in the string with the given byte
+    xor_result = bytes([b ^ xor_byte for b in input_bytes])
+
+    # Convert the XOR result to a hex string
+    hex_result = xor_result.hex()
+
+    return hex_result
+
+def reverse_xor(hex_str, xor_byte):
+    # Convert the hex string back to bytes
+    xor_bytes = bytes.fromhex(hex_str)
+
+    # XOR each byte in the result with the same XOR byte
+    original_bytes = bytes([b ^ xor_byte for b in xor_bytes])
+
+    # Convert the result back to the original string
+    original_str = original_bytes.decode()
+
+    return original_str
+
+
+result = xor_string_with_byte(flag, magic)
+print(result)
+
+original = reverse_xor(result, magic)
+print(original)
diff --git a/magic-byte/magic_byte.txt b/magic-byte/magic_byte.txt
new file mode 100644
index 0000000..3eab51a
--- /dev/null
+++ b/magic-byte/magic_byte.txt
@@ -0,0 +1 @@
+flag: 858b8f988ab7a4a9a0a0a393aaa0adabedb1
\ No newline at end of file