Homework for TransUnion internship - Caesar cipher

Caesar cipher Wiki

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Idea

Shift letters by value x in ascii code space.

Encryption

En(x) = ((x + n) - first_letter_ascii_code)mod26 + first_letter_ascii_code Where:

• x - letter ascii code.
• n - shift value
• first_letter_ascii_code - either 65(A) or 97(a). This is determined by if the letter is lower or upper case.

Decryption

En(x) = ((x - n) - first_letter_ascii_code)mod26 + first_letter_ascii_code

Example

text - defend the east wall of the castle

shift - 1

encrypted - efgfoe uif fbtu xbmm pg uif dbtumf