ONcE upon a TIME there was a PAD...

Challenge description

The SFL team is using an encryption service to encrypt their files.

You've stolen two files from the SFL team. Unfortunately the files are encrypted. Can you finde a way to decrpyt them?

Hint 1: VGhlIGVuY3J5cHRpb24gaXMgZmluZSwgeW91IG5lZWQgdG8gdW5kbyB0aGUgZW5jcnlwdGlvbi4=

Files:

bitmapenc.jpg
flagenc.jpg

Solution

The files bit_map_enc.jpg and flag_enc.jpg have been encrypted using the OneTimePad Algorithm and the same key. So the files are generated as follows: \[ bitmapenc.jpg = bitmap.jpg \oplus key \] and \[ flagenc.jpg = flag.jpg \oplus key \]

We can now xor the two file with each other to produce the following new file: \[solution.jpg = bitmapenc.jpg \oplus flagenc.jpg = bitmap.jpg \oplus key \oplus flag.jpg \oplus key =^1 flag.jpg \oplus bit-map.jpg \] (1) The keys (the encryption) get lost because \( flag \oplus flag = 0 \) and \( anyvalue \oplus 0 = anyvalue \).

The new file does now displays as: solution.jpg