100 points
Category: Cryptography
Tags : #certificate #base64
How about we take you on an adventure on exploring certificate signing requests Take a look at this CSR file.
Dumping the contents of the readmycert.cer file yields :
-----BEGIN CERTIFICATE REQUEST-----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-----END CERTIFICATE REQUEST-----
Looks base64 encoded, running through an online base64 decoder, the flag is found in amongst the decoded output :
picoCTF{........redacted........}
Flag value redacted for the purposes of this write up.