“23 minutes later bkcrack spit out the key to the ALLBAS.ZIP file and was able to decrypt it.”
Tim Jenkin built the encryption for the ANC’s Operation Vula, zipped the source with a password when he left the UK in 1991, and forgot the password. ZipCrypto from that era falls to a known plaintext attack if you can predict 12 bytes. Graham-Cumming guessed a filename and the open source bkcrack did the rest. Code that protected an underground network against apartheid lost to PKZIP’s own weak crypto.