mirror of
https://github.com/superseriousbusiness/gotosocial.git
synced 2025-10-29 19:52:24 -05:00
98263a7de6* start fixing up tests * fix up tests + automate with drone * fiddle with linting * messing about with drone.yml * some more fiddling * hmmm * add cache * add vendor directory * verbose * ci updates * update some little things * update sig
39 lines
868 B
Go
39 lines
868 B
Go
package passwordvalidator
|
|
|
|
import (
|
|
"math"
|
|
)
|
|
|
|
// GetEntropy returns the entropy in bits for the given password
|
|
// See the ReadMe for more information
|
|
func GetEntropy(password string) float64 {
|
|
return getEntropy(password)
|
|
}
|
|
|
|
func getEntropy(password string) float64 {
|
|
base := getBase(password)
|
|
length := getLength(password)
|
|
|
|
// calculate log2(base^length)
|
|
return logPow(float64(base), length, 2)
|
|
}
|
|
|
|
func logX(base, n float64) float64 {
|
|
if base == 0 {
|
|
return 0
|
|
}
|
|
// change of base formulae
|
|
return math.Log2(n) / math.Log2(base)
|
|
}
|
|
|
|
// logPow calculates log_base(x^y)
|
|
// without leaving logspace for each multiplication step
|
|
// this makes it take less space in memory
|
|
func logPow(expBase float64, pow int, logBase float64) float64 {
|
|
// logb (MN) = logb M + logb N
|
|
total := 0.0
|
|
for i := 0; i < pow; i++ {
|
|
total += logX(logBase, expBase)
|
|
}
|
|
return total
|
|
}
|