Caesar / ROT13 Cipher
Work with the classical ciphers that still show up in CTF challenges, puzzle malware and basic obfuscation: Caesar, ROT13, Atbash and Vigenere. None of them provide real security -- which is exactly why they are the best way to learn what modern cryptography had to fix.
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Why learn broken ciphers
- They make the core ideas concrete: key space, frequency analysis, brute force and key reuse.
- They still appear in the wild as light obfuscation in scripts, malware strings and CTF challenges.
- Every weakness here motivated a real fix -- randomised keys, large key spaces, and authenticated modern encryption such as AES-GCM.
Security note
Never protect real data with these ciphers. For genuine confidentiality use vetted modern cryptography such as AES-GCM or a maintained library, and keep the keys out of your source code.
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