Golang : Rot13 and Rot5 algorithms example

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Continuing from our previous ROT47 tutorial, we will now learn how to implement the ROT13 + ROT5 algorithms. ROT13 basically rotates a character by 13 places, ‘A’ to ‘N’, ‘B’ to ‘M’ and so on. The ROT5, rotates the digits: ‘0’ to ‘5’, ‘1’ to ‘6’ and so on.

ROT13 is often combined with ROT5, which is used to encode and decode digits i.e. 0-9 and sometimes is also known as ROT18. The following is an implementation done in Golang.

Here you go!

`````` package main

import (
"fmt"
"unicode"
)

// rot13(alphabets) + rot5(numeric)
func rot13rot5(input string) string {

var result []rune
rot5map := map[rune]rune{'0': '5', '1': '6', '2': '7', '3': '8', '4': '9', '5': '0', '6': '1', '7': '2', '8': '3', '9': '4'}

for _, i := range input {
switch {
case !unicode.IsLetter(i) && !unicode.IsNumber(i):
result = append(result, i)
case i >= 'A' && i <= 'Z':
result = append(result, 'A'+(i-'A'+13)%26)
case i >= 'a' && i <= 'z':
result = append(result, 'a'+(i-'a'+13)%26)
case i >= '0' && i <= '9':
result = append(result, rot5map[i])
case unicode.IsSpace(i):
result = append(result, ' ')
}
}
return fmt.Sprintf(string(result[:]))
}

func main() {
text := "ROT18 = ROT13+ROT5. The ROT13 (Caesar cipher by 13 chars) is often combined with ROT5. ROT13 to handle alphabets and ROT5 to handle digits."
fmt.Println(text)
fmt.Println(rot13rot5(text))

fmt.Println("Invertible test:")
fmt.Println(rot13rot5(rot13rot5(text)))
}
``````

Output:

ROT18 = ROT13+ROT5. The ROT13 (Caesar cipher by 13 chars) is often combined with ROT5. ROT13 to handle alphabets and ROT5 to handle digits.

EBG63 = EBG68+EBG0. Gur EBG68 (Pnrfne pvcure ol 68 punef) vf bsgra pbzovarq jvgu EBG0. EBG68 gb unaqyr nycunorgf naq EBG0 gb unaqyr qvtvgf.

Invertible test:

ROT18 = ROT13+ROT5. The ROT13 (Caesar cipher by 13 chars) is often combined with ROT5. ROT13 to handle alphabets and ROT5 to handle digits.

Happy coding!

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