Cifra de césar

main.go

package main

import (
	"fmt"
	"strings"
)

func main() {
	var input string
	fmt.Println("Insira o texto")
	fmt.Scan(&input)
	encryptedString := encrypt(strings.ToLower(input))
	fmt.Println(encryptedString)
	fmt.Println(decrypt(encryptedString))
}

func encrypt(plainText string) string {
	var encodedString []rune
	for _, value := range plainText {
		if rune(value) == 122 {
			encodedString = append(encodedString, rune('a')+2)
		} else {
			encodedString = append(encodedString, value+3)
		}
	}

	return string(encodedString)
}

func decrypt(encodedString string) string {
	var plainText []rune
	for _, value := range encodedString {
		if rune(value) == 97 {
			plainText = append(plainText, rune('z')-2)
		} else {
			plainText = append(plainText, value-3)
		}
	}
	return string(plainText)
}