func TestFrequencyAttack(t *testing.T) {
const (
charset = "abcdefghijklmnopqrstuvwxyz"
)
message, err := ioutil.ReadFile(os.Getenv("GOPATH") + "src/github.com/karlek/tombraid/message.txt")
csLen := len(charset)
for i := 0; i < csLen; i++ {
cipher, err := broken.Caesar(charset, message, i)
if err != nil {
return err
}
chars := frequency.EnglishAnalysis(cipher)
if err != nil {
return err
}
guesses, err := FrequencyAttack(chars, charset, cipher)
if err != nil {
return t.Errorf("FrequencyAttack(%v, %v, %v, %v) = %v, want %v\n\n", chars, charset, cipher, unciphered, message)
}
for _, unciphered := range guesses {
if unciphered == message {
return nil
}
}
}
}
func FrequencyAttack(chars []string, charset, cipher string) (guesses []string, err error) {
//
for _, commonChar := range frequency.Top3 {
for _, char := range chars {
pos := strings.Index(charset, char)
if pos == -1 {
return nil, errorsutil.Errorf("Character `%c` is not present in charset: `%s`", char, charset)
}
commonCharPos := strings.Index(charset, commonChar)
if commonCharPos == -1 {
return nil, errorsutil.Errorf("Character `%c` is not present in charset: `%s`", commonChar, charset)
}
unwindBy := commonCharPos - pos
unciphered, err := broken.Caesar(charset, cipher, unwindBy)
if err != nil {
return nil, err
}
guesses = append(guesses, unciphered)
}
}
return guesses, nil
}
func breakCaesar() (err error) {
buf, err := ioutil.ReadFile(os.Getenv("GOPATH") + "/src/github.com/karlek/tombraid/message.txt")
if err != nil {
return err
}
message := string(buf)
csLen := len(charset)
isFreqBroken := false
isBruteBroken := false
for i := 0; i < csLen; i++ {
cipher, err := broken.Caesar(charset, message, i)
if err != nil {
return err
}
commonChars := frequency.EnglishAnalysis(cipher)
freqGuesses, err := caesar.FrequencyAttack(commonChars, charset, cipher)
if err != nil {
return err
}
bruteGuesses, err := caesar.BruteAttack(charset, cipher)
if err != nil {
return err
}
for _, guess := range freqGuesses {
if guess == message {
isFreqBroken = true
}
}
for _, guess := range bruteGuesses {
if guess == message {
isBruteBroken = true
}
}
}
switch {
case isFreqBroken && isBruteBroken:
fmt.Println("All attacks successful!")
case isFreqBroken:
fmt.Println("Only frequency attack worked!")
case isBruteBroken:
fmt.Println("Only brute force attack worked!")
default:
fmt.Println("No attack broke the cipher!")
}
return nil
}
// Preforms a brute force attack by shifting the cipher foreach
// character in the charset
func BruteAttack(charset, cipher string) (guesses []string, err error) {
csLen := len(charset)
for i := 0; i < csLen; i++ {
newCipher, err := broken.Caesar(charset, cipher, i)
if err != nil {
return nil, err
}
guesses = append(guesses, newCipher)
}
return guesses, nil
}