Redpwn 2020 Crypto - base646464




Encoding something multiple times makes it exponentially more secure!


Lets take a look at generate.js, which reads

const btoa = str => Buffer.from(str).toString('base64');

const fs = require("fs");
const flag = fs.readFileSync("flag.txt", "utf8").trim();

let ret = flag;
for(let i = 0; i < 25; i++) ret = btoa(ret);

fs.writeFileSync("cipher.txt", ret);

The function btoa is basically string to its base64 encoding.
The flag is encoded repetitively 25 times in a for loop.
We just need to base64 decode it 25 times and we will get the flag.

from base64 import b64decode

with open('cipher.txt','r') as cipher_file:
    data =

for i in range(25):
    data = b64decode(data)


A cool sarcasm on bad crypto challenges in CTFs :)


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