Math Engine Cipher turns mathematical constants into encryption keys.

Enter any expression — π, √2·1337/π, e, φ, or a compound formula — and the resulting digits become a rolling key stream that encrypts your text character by character. Every letter gets a different shift value, making the cipher far stronger than a simple Caesar shift. Numbers, spaces, and special characters remain unchanged.

HOW IT WORKS
• The built-in engine computes any expression to up to 500 decimal digits — fully offline
• The digits form a rolling key stream
• Each letter in your text is shifted by the next key value
• Use the same expression and settings to decrypt

FEATURES
• Offline math engine — no internet required, no API key needed
• Wolfram Alpha integration — optional, for advanced expressions not supported locally
• Manual key mode — enter digits directly if preferred
• Configurable start position and digits-per-shift
• Key-stream preview so you know exactly what key is used
• Biometric app lock — protect the app with Face ID, fingerprint, or device PIN
• One-tap share for encrypted or decrypted results
• Dark, minimal interface

EXAMPLE USE CASE — GEOCACHING PUZZLE CACHE
Math Engine Cipher is a perfect tool for creating mystery caches or puzzle challenges:

1. Encrypt your final coordinates or a clue using a mathematical expression — e.g. sqrt(2)*1337/pi
2. Publish the encrypted text along with a hint pointing to the expression
3. Solvers enter the expression in the app and decrypt the message to find the next step

The key is not a password — it is a mathematical formula. Solvers who figure out the right expression get the reward. Those who don't, see only noise.

OFFLINE MATH ENGINE
The built-in engine uses GMP and MPFR — the same arbitrary-precision libraries used by professional computer algebra systems. It is IEEE 754-2008 compliant and produces bit-identical results to Wolfram Alpha at any precision. No query is ever sent to a server.

OPTIONAL WOLFRAM ALPHA INTEGRATION
For expressions beyond the local whitelist (integrals, special functions, symbolic results), you can supply your own Wolfram Alpha API key. The key is stored in the system keychain — never in plain text.

To get a free API key:
1. Go to wolframalpha.com/api
2. Click "Get an API Key" and create a free account
3. Select the free "Non-commercial" plan (2,000 queries/month)
4. Copy your App ID and paste it into the app settings

PRIVACY
In local mode, the app makes zero network requests. There is no account, no analytics, and no telemetry. The optional biometric lock ensures the app content is never visible without authentication.

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Math Engine Cipher is designed for puzzle makers, geocachers, educators, and anyone who appreciates the beauty of mathematics.

DISCLAIMER
Math Engine Cipher implements a polyalphabetic substitution cipher. It is intended for puzzles, games, and personal experimentation — not as a replacement for professional cryptographic tools. For protecting highly sensitive data, use dedicated encryption software with proven security standards (e.g. AES-256).