NazoRaku - Cipher Puzzles

A puzzle game where you UNDERSTAND ciphers by solving them - not by reading about them. From the Caesar cipher to RSA and hashing, crack classic and modern ciphers one stage at a time, and the way each cipher works clicks into place. Work out the key from a clue and enter it, spot letters with frequency analysis, reverse-look up a grid - relive that "aha" moment of decryption again and again. [ 9 ciphers, 57 puzzles ] Classic ciphers - free, 40 puzzles - Caesar (10) - Shift letters; work out the shift from the crib and enter it - Vigenere (10) - Polyalphabetic with a keyword; guess the key - Substitution (8) - One-to-one swap; crack it with frequency analysis - Transposition (6) - See through the reordering - Polybius Square (6) - Letters to numbers via a 5x5 grid; reverse-look up Modern ciphers - 17 puzzles - XOR (6, free) - Exclusive OR; XOR with the key to recover the text - Public-Key, simplified RSA (4, Modern Cipher Pack) - Work out the number locked with the public key - Hash Function (4, Modern Cipher Pack) - Feel one-wayness; find an input that collides to the same output - Block Cipher, AES-style (3, Modern Cipher Pack) - Step through add-key, substitute, and permute, one move at a time [ Features ] - Explanation right after you solve - history, real-world usage, weaknesses, and the bridge to modern tech - Staged hints - the first level is free; reveal more step by step when stuck (keeps the "I solved it" feeling) - No ads at all while you are solving a puzzle - designed to preserve focus - Achievement badges and stats (including your daily solving streak) - iPhone and iPad - Japanese and English (UI, puzzle text, and hints; follows the device language) - Ciphertext shown in an easy-to-read monospaced font [ Who is this for ] - Anyone who loves puzzles and riddles - Students and engineers curious about cryptography and security - People who want quick brain-training in spare moments [ Part of the Raku Series ] The third information-systems title of the Raku Series. Knowledge from ARURAKU (algorithms) and DATARAKU (data structures) pays off in NazoRaku's decryption - hashing and modular exponentiation tie ciphers back to the fundamentals. [ Pricing ] Free to play. All 40 classic-cipher puzzles and the 6 XOR puzzles are free. In-app purchases: hint tickets (1 or a 10-pack), Remove Ads, the Modern Cipher Pack (unlocks public-key, hash, and block ciphers), and an all-in-one Premium (remove ads + all stages + unlimited hints). Non-consumable purchases can be restored from "Restore" in Settings / Store (hint tickets are consumable and cannot be restored). [ Ads ] To keep the app free, ads are shown at the bottom of screens such as Home and the stage list. No ads are shown on the screen where you solve puzzles. On first launch, the app asks whether ads tailored to your interests (personalized ads) may be shown. You can change this anytime from "Ad Settings" in Settings / Store.