2025found by harvest
Blue Arena
2 challenges with 2 published solutions between them. No writeups were ever filed against this event's listing, so its solutions were found in public repositories instead. Each link is pinned to the commit it was read from.
The event listingCryptography1
Recover a plaintext or a key from something that was supposed to protect it. In practice: identify the scheme, find the parameter the author got wrong, exploit it.
Solve it with:Cipher identifier and automatic decoderVigenere cipher solver with automatic key recoveryRSA decryption and attack runnerWiener’s attack on small RSA private exponentsIn-browser hash cracker with rule transformsLearn: Classical ciphers and frequency analysisLearn: RSA and the parameters that break it
Corrupted Caesar
1 official solutionAlso written up in: sajjadium/ctf-archives
Reverse engineering1
Work out what a compiled program does without its source, then work backwards from the check to the input that passes it.
Solve it with:Strings extractor for binaries and blobsWebAssembly disassemblerJava .class disassemblerPython .pyc bytecode disassemblerLearn: Binary exploitation
Obelisk of B Forbidden Cipher
1 official solutionAlso written up in: sajjadium/ctf-archives