func SpatialEntropy(match match.Match, turns int, shiftCount int) float64 {
var s, d float64
if match.DictionaryName == "qwerty" || match.DictionaryName == "dvorak" {
//todo: verify qwerty and dvorak have the same length and degree
s = float64(len(adjacency.BuildQwerty().Graph))
d = adjacency.BuildQwerty().CalculateAvgDegree()
} else {
s = float64(KEYPAD_STARTING_POSITIONS)
d = KEYPAD_AVG_DEGREE
}
possibilities := float64(0)
length := float64(len(match.Token))
//TODO: Should this be <= or just < ?
//Estimate the number of possible patterns w/ length L or less with t turns or less
for i := float64(2); i <= length+1; i++ {
possibleTurns := math.Min(float64(turns), i-1)
for j := float64(1); j <= possibleTurns+1; j++ {
x := zxcvbn_math.NChoseK(i-1, j-1) * s * math.Pow(d, j)
possibilities += x
}
}
entropy := math.Log2(possibilities)
//add extra entropu for shifted keys. ( % instead of 5 A instead of a)
//Math is similar to extra entropy for uppercase letters in dictionary matches.
if S := float64(shiftCount); S > float64(0) {
possibilities = float64(0)
U := length - S
for i := float64(0); i < math.Min(S, U)+1; i++ {
possibilities += zxcvbn_math.NChoseK(S+U, i)
}
entropy += math.Log2(possibilities)
}
return entropy
}
func extraUpperCaseEntropy(match match.Match) float64 {
word := match.Token
allLower := true
for _, char := range word {
if unicode.IsUpper(char) {
allLower = false
break
}
}
if allLower {
return float64(0)
}
//a capitalized word is the most common capitalization scheme,
//so it only doubles the search space (uncapitalized + capitalized): 1 extra bit of entropy.
//allcaps and end-capitalized are common enough too, underestimate as 1 extra bit to be safe.
for _, regex := range []string{START_UPPER, END_UPPER, ALL_UPPER} {
matcher := regexp.MustCompile(regex)
if matcher.MatchString(word) {
return float64(1)
}
}
//Otherwise calculate the number of ways to capitalize U+L uppercase+lowercase letters with U uppercase letters or
//less. Or, if there's more uppercase than lower (for e.g. PASSwORD), the number of ways to lowercase U+L letters
//with L lowercase letters or less.
countUpper, countLower := float64(0), float64(0)
for _, char := range word {
if unicode.IsUpper(char) {
countUpper++
} else if unicode.IsLower(char) {
countLower++
}
}
totalLenght := countLower + countUpper
var possibililities float64
for i := float64(0); i <= math.Min(countUpper, countLower); i++ {
possibililities += float64(zxcvbn_math.NChoseK(totalLenght, i))
}
if possibililities < 1 {
return float64(1)
}
return float64(math.Log2(possibililities))
}
func ExtraLeetEntropy(match match.Match, password string) float64 {
var subsitutions float64
var unsub float64
subPassword := password[match.I:match.J]
for index, char := range subPassword {
if string(char) != string(match.Token[index]) {
subsitutions++
} else {
//TODO: Make this only true for 1337 chars that are not subs?
unsub++
}
}
var possibilities float64
for i := float64(0); i <= math.Min(subsitutions, unsub)+1; i++ {
possibilities += zxcvbn_math.NChoseK(subsitutions+unsub, i)
}
if possibilities <= 1 {
return float64(1)
}
return math.Log2(possibilities)
}
