Repetitions writeup - Pico CTF ( General skills )

Solution -

Step 1: Download challenge files - Begin by downloading the enc_flag file provided by the challenge. After downloading, take a quick look at the content of the file. You can use the cat command to display its contents: cat enc_flag

After examining the file, it appears to be a Base64 encoded value. Base64 encoding is often used to represent binary data in an ASCII string format, and it’s easy to decode using simple command-line tools.

Step 2: Decode the Base64 Content - The next step is to decode the file’s content using the base64 utility. The command for decoding a Base64 string is as follows: cat enc_flag | base64 -d

Step 3: Repeated Decoding - The challenge name, "Repetitions", hints that we will need to repeat the decoding process multiple times. After each decode, the result is still encoded in Base64, requiring further decoding.

Continue to decode the file until you finally reach a human-readable flag. It took me 6 rounds of decoding to reveal the correct flag.

Here’s the final command used to decode the flag after all repetitions: cat enc_flag | base64 -d | base64 -d | base64 -d | base64 -d | base64 -d | base64 -d

After the sixth decoding step, the hidden flag is revealed!