Affine Cipher Encrypt

Problem

Encrypt uppercase text with an affine cipher: E(x) = (a * x + b) mod 26, where x is the letter index A=0. Return the uppercase ciphertext.

Hint

With a = 1 the affine cipher reduces to a Caesar shift.

case 1

in: ["ABC",1,1]

expected: "BCD"

case 2

in: ["HELLO",1,3]

expected: "KHOOR"

case 3

in: ["ABC",5,8]

expected: "INS"

case 4

in: ["XYZ",1,1]

expected: "YZA"

case 5

in: ["SECRET",7,3]

expected: "ZFRSFG"

Starter codePython

def affine_encrypt(text, a, b):
    # Your code here
    pass

5 test cases · run your code against them in the editor