Why Caesar Cipher?
The Caesar cipher shifts each letter by a fixed number of positions in the alphabet. It's ideal for puzzle creators because:
- Accessible — Most cachers recognise it instantly
- Flexible difficulty — Vary from easy (ROT13) to trickier shifts
- Thematic potential — The shift number can tie into your cache theme
- Quick to solve — Respectful of solvers' time
Step 1: Prepare Your Message
Decide what you want to encode. For geocaching puzzles, this is typically:
- The final coordinates
- A hint leading to the next stage
- A word that completes a formula
Example plaintext:
NORTH FIFTY ONE DEGREES
Tip: Spell out numbers to make the cipher more interesting and avoid confusion with coordinates that mix letters and digits.
Step 2: Choose Your Shift Value
The shift value determines how many positions each letter moves. Consider these approaches:
ROT13 (Shift 13)
The most common choice. Self-reversing, so encoding and decoding use the same operation.
Thematic Shift
Use a number meaningful to your cache: founding year, local landmark height, historical date.
Hidden in Plain Sight
Put the shift value in your cache description as a seemingly random number.
Example: If your cache is about Julius Caesar's invasion of Britain in 55 BC, use shift 5 (from 55) and mention the date in your description.
Step 3: Encode Your Message
Use our Caesar Cipher tool to encode your message. Here's an example with shift 7:
Plaintext:
NORTH FIFTY ONE DEGREES
Ciphertext (shift 7):
UVYAO MPMAF VUL KLNYLLZ
Step 4: Add Hints and Context
A good puzzle doesn't just present encoded text—it guides solvers to the solution. Consider:
- Title hints: "Caesar's Secret" or "Shift Your Thinking"
- Description clues: Reference Roman history or famous quotes about shifting
- Visual hints: Include an image of Caesar or Roman numerals
- Shift clue: "The answer lies 7 steps ahead" or embed the number subtly
Example cache description excerpt:
"Julius Caesar was known for his secret messages. In 55 BC, his legions crossed the channel. Perhaps you too need to take a few steps forward to find what you seek..."
Difficulty Variations
Easy (D1-D1.5)
- • Use ROT13 (most solvers try this first)
- • State clearly it's a Caesar cipher
- • Preserve spaces and punctuation
Medium (D2-D2.5)
- • Use a non-standard shift (not 13)
- • Hint at the shift value thematically
- • Remove spaces from ciphertext
Hard (D3+)
- • Don't identify the cipher type
- • Use multiple Caesar ciphers with different shifts
- • Combine with another encoding (e.g., Caesar then A1Z26)
Complete Example Puzzle
Cache Title: "Et Tu, Brute?"
The title references Shakespeare's Julius Caesar, hinting at the cipher type.
Cache description excerpt:
"On the Ides of March, 44 BC, everything changed. The great leader fell, but his methods of secret communication live on. Take 3 steps back in time to find your destination."
KLOQE CEBKQ QEOBB ABDOBBP
Solution:
"Take 3 steps back" = shift of -3 (or 23)
Decodes to: NORTH FRONT THREE DEGREES
Pro Tips
- Test your puzzle. Have a friend solve it before publishing. What seems obvious to you might not be to others.
- Verify the decoded coordinates. Double-check that decoding produces valid coordinates pointing to your cache location.
- Provide a checker. Use a coordinate checker so solvers can verify their answer before heading out.
- Consider mobile solvers. Many cachers solve puzzles on phones— ensure your text is easily copyable.