Description
A certificate signing request file hides the flag. Treat it as Base64 PEM data and decode the contents to recover the string.
Download the CSR and strip the PEM header/footer.
Base64-decode the body to inspect the DER contents. The flag appears near the top.
wget https://artifacts.picoctf.net/c/422/readmycert.csr
cat readmycert.csr
grep -v '-----' readmycert.csr | base64 --decode
Solution
- Step 1Decode the PEMEither pipe the middle lines through base64 --decode or drop them into CyberChef. The decoded ASN.1 text includes picoCTF{...}.
- Step 2Copy the flagExtract the picoCTF string from the decoded output and submit.
Flag
picoCTF{read_mycert...b0}
No openssl tooling is required; basic Base64 decoding reveals the answer.