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2020from public repositories

Hc0n 2020

7 challenges with 7 published solutions between them. CTFtime has no listing for this event at all, so nothing built on CTFtime can show what it was made of. These writeups were found in public repositories instead. Each link is pinned to the commit it was read from.

Where these writeups live

Uncategorised4

The upstream scoreboard did not say, so neither do we.

Solve it with:Cipher identifier and automatic decoderLearn: Recognising encodings

Cryptography1

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

Misc1

Everything that fits no other box: esolangs, puzzles, scripting exercises, and the jail escapes that have not yet earned their own category.

Solve it with:Brainfuck and esolang decoderCipher identifier and automatic decoderRegex tester with match offsets and capture groupsLearn: Recognising encodings

Steganography1

Find the payload hidden inside a carrier that looks ordinary. Bit planes, appended data, metadata, and audio spectrograms.

Solve it with:LSB steganography extractorPNG chunk analyzerAudio spectrogram and SSTV decoderZero-width character and text steganography decoderLearn: Steganography

Other 2020 events