Affine Cipher

The Affine cipher is a monoalphabetic substitution cipher and it can be the exact same as a standard Caesarian shift when "a" is 1. Mathematically, it is represented as e(x) = (ax + b) mod m. Decryption is a slightly different formula, d(x) = a-1(x - b) mod m.

To encode something, you need to pick the "a" and it must be coprime with the length of the alphabet. To make this easier, I have the (+) and (-) buttons to change the A to the next higher or lower coprime number.

a: -


This is your encoded or decoded text:

December was once the tenth month in the calendar. It used to have only 30 days, but Numa Pompilius, the second king of Rome circa 700 BC, changed the number of days in the month to 29. Julius Caesar changed it to 31 in 46 BC. Tyler Akins! <>
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