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HTB Cyber Apocalypse 2021 - PhaseStream4 | Crypto
PhaseStream4 The aliens saw us break PhaseStream 3 and have proposed a quick fix to protect their new cipher. Downloadable: output.txt Given Script from Crypto.Cipher import AES from Crypto.Util import Counter import os KEY = os.urandom(16) def encrypt(plaintext): cipher = AES.new(KEY, AES.MODE_CTR, counter=Counter.new(128)) ciphertext = cipher.encrypt(plaintext) return ciphertext.hex() with open('test_quote.txt',...
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HTB Cyber Apocalypse 2021 - PhaseStream3 | Crypto
PhaseStream3 The aliens have learned the stupidity of their misunderstanding of Kerckhoffs’s principle. Now they’re going to use a well-known stream cipher (AES in CTR mode) with a strong key. And they’ll happily give us poor humans the source because they’re so confident it’s secure! Downloadable: ciphertext.txt Given Script from...
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HTB Cyber Apocalypse 2021 - PhaseStream 2 | Crypto
PhaseStream 2 The aliens have learned of a new concept called “security by obscurity”. Fortunately for us they think it is a great idea and not a description of a common mistake. We’ve intercepted some alien comms and think they are XORing flags with a single-byte key and hiding the...