ROT5 (digits)
ROT5 (digits). A classical cipher, computed on your device.
Runs on your device. The file is never uploaded.
ROT5 (digits) adds five to every digit in your text, wrapping 0 round to 5 and 5 round to 0, and rewrites nothing else. The regex it runs matches the ten digits and no other character. Words, punctuation and letters therefore stay as readable as they were, which leaves the numbers hidden from a glance and from nothing more.
Questions
What does ROT5 change?
Digits only. Each digit moves five places, so 0 becomes 5 and 5 becomes 0. Letters and punctuation are untouched, which is why it is normally used beside ROT13 rather than on its own.
How do I undo it?
Run it again. Five places twice over ten digits returns the original, so ROT5 is its own inverse and has no key.
Why would I use it?
To obscure a number from a casual glance, for example an answer or a score in a forum post. It provides no protection beyond that.
Can I combine it with ROT13?
Yes. Run ROT13 for the letters and ROT5 for the digits over the same text. That pairing is what people usually mean by ROT18.