I need to visually encrypt (make the information uninterpretable by a non-prepared human) a natural number (known to be below some
x) representing it as a much bigger, seemingly (for an unprepared observer) random (so just
a+x doesn't work) natural number and then decrypt it back.
a = the source value 0 < a < x b = the encrypted value x < b < y y = 2147483647
UPDATE: @chris-taylor has answered the question, but more answers are still welcome. For example (my dilettantish expectations on fancy math suggest it can be possible and easy for math geeks) it would be cool to have a simple formula (without a huge key mapping) to solve the task beating the law of b2(a2) being always greater or always smaller than b1(a1) when a1 < a2. But this is not necessary, I am just curious.