95 lines
2.1 KiB
Go
95 lines
2.1 KiB
Go
package main
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import (
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"flag"
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"io/ioutil"
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"log"
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"os"
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"regexp"
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"strings"
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"unicode"
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)
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const lettersInTheAlphabet = 26
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const startUpperCase = 65
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const endUpperCase = startUpperCase + lettersInTheAlphabet
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const startLowerCase = 97
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const endLowerCase = startLowerCase + lettersInTheAlphabet
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type keyLetter struct {
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upperCase string
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position int32
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}
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func parseArguments() (string, string) {
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var inputKey string
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var inputFile string
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flag.StringVar(&inputKey, "k", "", "Specify key word.")
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flag.StringVar(&inputFile, "f", "", "Specify file to encrypt.")
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flag.Parse()
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return inputKey, inputFile
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}
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func readFile(relativePath string) string {
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content, err := ioutil.ReadFile(relativePath)
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if err != nil {
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log.Fatalln(err)
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}
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return string(content)
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}
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func writeFile(relativePath string, message string) {
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file, err := os.Create(relativePath)
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if err != nil {
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log.Fatalln(err)
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}
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defer file.Close()
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file.WriteString(message)
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}
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func validateKeyWord(inputKey string) string {
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reg, err := regexp.Compile("[^a-zA-Z]+")
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if err != nil {
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log.Fatalln(err)
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}
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processedString := reg.ReplaceAllString(inputKey, "")
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return strings.ToUpper(processedString)
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}
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func initKeyWord(key string) []keyLetter {
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var keyWord []keyLetter
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for _, letter := range key {
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keyWord = append(keyWord, keyLetter{
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upperCase: string(letter),
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position: letter - 'A',
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})
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}
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return keyWord
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}
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func encryptMessage(keyWord []keyLetter, message string) string {
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encrypted := ""
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index := 0
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for _, letter := range message {
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if !unicode.IsLetter(letter) {
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encrypted += string(letter)
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} else {
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keyWordIndex := index % len(keyWord)
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newLetter := letter + keyWord[keyWordIndex].position
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if (unicode.IsLower(letter) && newLetter >= endLowerCase) ||
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(unicode.IsUpper(letter) && newLetter >= endUpperCase) {
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newLetter -= lettersInTheAlphabet
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}
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encrypted += string(newLetter)
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index += 1
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}
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}
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return encrypted
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}
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func main() {
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inputKey, inputFile := parseArguments()
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message := readFile(inputFile)
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keyWord := initKeyWord(validateKeyWord(inputKey))
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writeFile("output.txt", encryptMessage(keyWord, message))
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}
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