# 1337UP LIVE CTF 2023
## Keyless
> My friend made a new encryption algorithm. Apparently it's so advanced, you don't even need a key!> > Author: CryptoCat> > [`keyless.zip`](https://raw.githubusercontent.com/D13David/ctf-writeups/main/1337uplive/crypto/keyless/keyless.zip)
Tags: _crypto_
## SolutionWe get the following `python` code:
```pythondef encrypt(message):    encrypted_message = ""    for char in message:        a = (ord(char) * 2) + 10        b = (a ^ 42) + 5        c = (b * 3) - 7        encrypted_char = c ^ 23        encrypted_message += chr(encrypted_char)    return encrypted_message
flag = "INTIGRITI{REDACTED}"encrypted_flag = encrypt(flag)
with open("flag.txt.enc", "w") as file:    file.write(encrypted_flag)```
All steps can be reversed quite easily, so we write a script to do so, and get the flag.
```pythonflag = open("flag.txt.enc", "r").read()
def decrypt(message):    result = ""    for char in message:        char = ord(char) ^ 23        char = (char + 7) // 3        char = (char - 5) ^ 42        char = (char - 10) // 2        result += chr(char)    return result
print(decrypt(flag))```
Flag `INTIGRITI{m4yb3_4_k3y_w0uld_b3_b3773r_4f73r_4ll}`