Five ciphers work perfectly for kids, notes to friends, escape room puzzles, and treasure hunts — no computer needed.
1. A1Z26 (Number Substitution)
Replace each letter with its position in the alphabet: A=1, B=2, C=3, … Z=26.
| Letter | A | B | C | D | E | H | L | O | R | W |
|---|---|---|---|---|---|---|---|---|---|---|
| Number | 1 | 2 | 3 | 4 | 5 | 8 | 12 | 15 | 18 | 23 |
“HELLO” → 8-5-12-12-15
“WORLD” → 23-15-18-12-4
Separate groups with hyphens to avoid ambiguity (12 could be L, or 1 followed by 2 = AB). The letter-to-number cipher tool does this instantly for any phrase.
2. Caesar Cipher (Shift Cipher)
Shift every letter forward in the alphabet by the same number. With shift 3 (the shift Julius Caesar used), A becomes D, B becomes E, Z wraps to C.
Cipher wheel method:
- Write the alphabet on a large circle of paper.
- Write the alphabet on a smaller circle.
- Pin the small circle to the large one with a brass fastener.
- Rotate the inner circle by your chosen shift.
- Read off pairs: inner letter = plaintext, outer letter = ciphertext.
“MEET ME AT NOON” with shift 3 → “PHHW PH DW QRRQ”
The full mechanics are at Caesar Cipher Explained.
3. Reverse Alphabet (Atbash)
Map every letter to its mirror image: A becomes Z, B becomes Y, C becomes X, and so on. This is called the Atbash cipher; it appears in the Hebrew Bible in the book of Jeremiah.
| Plain | A | B | C | D | E | F | G | H | I | J |
|---|---|---|---|---|---|---|---|---|---|---|
| Cipher | Z | Y | X | W | V | U | T | S | R | Q |
“HELLO” → SVOOL
“SECRET” → HVXIVG
Atbash is its own inverse — encode the ciphertext and you get the plaintext back, because the mirror flips twice.
4. Rail Fence Cipher
Write your message in a zig-zag across two rows, then read each row left to right.
Message: MEET ME AT THE PARK (removing spaces: MEETMEATTHEPARK)
Write alternating letters on two rails:
- Rail 1: M E M A T E A K (positions 1,3,5,7,9,11,13,15)
- Rail 2: E T E T H P R (positions 2,4,6,8,10,12,14)
Read Rail 1 then Rail 2: MEEMAATEAK + ETETHPR = MEEMATEAK ETETHPR
The exact output depends on how you count positions; the key idea is reading off rows separately and re-interleaving them to decode.
5. Pig Latin (Sound-Based, Not Technically a Cipher)
For younger children who are not ready for alphabet manipulation, Pig Latin adds a sound-based layer to English. Move consonants at the start of a word to the end and add “ay”: “hello” becomes “ello-hay”, “secret” becomes “ecret-say”. It is not a cipher in the technical sense — it is just English with rearranged sounds — but children find it fun and it builds awareness of letter patterns.
Making Cipher Challenges
To create a puzzle for a friend or escape room:
- Pick a cipher and a key (for Caesar, a shift number; for A1Z26, the method alone is the key).
- Write a short message (under 20 words for beginners).
- Encode it and give a hint — the name of the cipher is usually enough.
- Leave the decoder (a cipher wheel or the alphabet strip) nearby for younger players.
See Code vs. Cipher to understand the distinction between the two kinds of secret communication, or use the Caesar cipher tool to encode any message digitally.