I have encrypted some text but it seems I have lost the key! Can you find it?  
[yors-truly.py](https://github.com/Nightxade/ctf-writeups/blob/master/assets/CTFs/Wolv-CTF-2024/beginner/yors-truly.py)  
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We're provided a Python source file:  
```pyimport base64
plaintext = "A string of text can be encrypted by applying the bitwise XOR operator to every character using a given key"key = "" # I have lost the key!
def byte_xor(ba1, ba2):    return bytes([_a ^ _b for _a, _b in zip(ba1, ba2)])
ciphertext_b64 = base64.b64encode(byte_xor(key.encode(), plaintext.encode()))
ciphertext_decoded = base64.b64decode("NkMHEgkxXjV/BlN/ElUKMVZQEzFtGzpsVTgGDw==")
print(ciphertext_decoded)```
Note that XOR is a reversible operation, since `a ^ a = 0` and XOR is associative and commutative.  
Therefore, to recover the key, it we can simply XOR the plaintet and the ciphertext. See below:  
$$plaintext=pt$$  $$ciphertext=ct$$  $$ct=pt \oplus key$$  $$ct \oplus pt = pt \oplus key \oplus pt = key$$  
Therefore, here is the solve script:  
```pyimport base64
plaintext = "A string of text can be encrypted by applying the bitwise XOR operator to every character using a given key"key = "" # I have lost the key!
def byte_xor(ba1, ba2):    return bytes([_a ^ _b for _a, _b in zip(ba1, ba2)])
ciphertext_b64 = base64.b64encode(byte_xor(key.encode(), plaintext.encode()))
ciphertext_decoded = base64.b64decode("NkMHEgkxXjV/BlN/ElUKMVZQEzFtGzpsVTgGDw==")
print(byte_xor(plaintext.encode(), ciphertext_decoded))```
Run the script to get the flag!  
    wctf{X0R_i5_f0rEv3r_My_L0Ve}