Spark & Anvil Privacy
An older teen at a cipher wheel turning tokens into scrambled ones

Ages 15–18 · Grades 9–12 · Cryptography

VaultForge

Every secret code has a logic you can reason your way into. Here you read a real scrambled message, predict what it says, and crack it — no jargon, no lectures, nothing sent anywhere. White-hat only: these are the historical ciphers that teach the math behind modern crypto.

Open the Cipher Lab Mixed practice

Most popular

Cipher Wheel Map plain tokens to scrambled ones. Encrypt Lock a message with a key. Crack It Find the pattern to open the lock. Teach Explain a cipher to a peer. Exchange Agree on a secret in public — the math that runs the padlock.

The Cipher Lab ★ the main event

Read a real scrambled message — a Caesar shift, a Vigenère keyword, a frequency puzzle, the clock math behind a shift — predict what it says or which technique cracks it, then see the worked-out decryption and why the method works. A pure engine decrypts each one, so the answer is exact. Once you see why every classical cipher eventually breaks, the Exchange surface shows the public-key idea that fixed it — agreeing on a shared secret in the open.

Open the Cipher Lab →

Who you’ll meet

Not mascots — everyday code-breakers, each one showing a single cryptography idea in action. You’ll run into them in the Cipher Lab.

  • Cassia — slides the alphabet a fixed number of places (the Caesar shift)
  • Freya — reverses a known shift to recover the message
  • Pax — finds the key from a single matched letter (breaking the shift)
  • Sela — cycles through a keyword so each letter shifts differently (Vigenère)
  • Hana — shows how a longer keyword hides letter patterns
  • Mox — counts letters to break a cipher — frequency analysis
  • Vesna — does the clock math behind every shift (modular arithmetic)
  • Kai — maps the most common letter back to E to find the key
  • Ivo — shows why a 25-key cipher can’t protect anything real
  • Sen — the mentor — sets a goal, cracks alongside you, guides reflection

Check what you know

Sixteen short kits — from "what is a cipher?" to substitution, Vigenère, frequency analysis, hashing, and public-key ideas — anchored to computer-science security standards. Hints when you want them; your progress stays on this device.

1. What Is Encryption? Encode vs encrypt; confidentiality · 25 questions 2. The Caesar Shift Shift cipher; the key · 25 questions 3. Substitution & Frequency Analysis Monoalphabetic substitution; frequency analysis · 25 questions 4. The Vigenère Cipher Polyalphabetic; keyword · 25 questions 5. Modular Arithmetic The clock math behind ciphers · 25 questions 6. Transposition Ciphers Reorder, don't replace · 25 questions 7. The Key & Kerckhoffs's Principle The key vs the algorithm · 25 questions 8. Symmetric vs Asymmetric Shared key vs key pair · 25 questions 9. The Public-Key Handshake Locked-box exchange; public/private keys · 25 questions 10. Hashing & Integrity One-way functions; fingerprints; integrity · 25 questions 11. Steganography Hidden in plain sight · 25 questions 12. Known-Plaintext & Crib Attacks Crib / pattern attacks · 25 questions 13. Passwords & Entropy Strength, entropy, reuse · 25 questions 14. Phishing & Social Engineering Recognize the fake (defensive) · 25 questions 15. Forensics Lite Find the flag in the data · 25 questions 16. Capture-the-Flag Capstone Multi-stage CTF · 25 questions

How it works

VaultForge is written to trust you — it’s about the reasoning, not memorizing terms, and a wrong prediction is just a place to learn. These are historical, breakable ciphers taught for understanding, never to defeat real security. Your progress is saved only on this device: no accounts, nothing sent anywhere.

Mixed practice — revisit what you've learned A short round that shuffles questions across the kits you've played, brought back when they're ready to review (spaced out so it sticks).

More ways to play

Vault Run How It Was Breached Daily Puzzle Rated Ladder