scsusers/password.go

package scsusers

import (
	"crypto/rand"
	"encoding/base32"
	mr "math/rand"
	"time"
	"unicode"
)

func flipCoin() bool {
	r := mr.New(mr.NewSource(time.Now().UnixNano()))
	return r.Intn(3) == 1
}

func scrambleCase(in []byte) []byte {
	var out []byte
	for _, x := range string(in) {
		if unicode.IsUpper(x) && flipCoin() {
			out = append(out, byte(unicode.ToLower(x)))
		} else {
			out = append(out, byte(x))
		}
	}
	return out
}

func randBytes(n int) []byte {
	randomBytes := make([]byte, 32)
	_, err := rand.Read(randomBytes)
	if err != nil {
		panic(err)
	}
	return []byte(base32.StdEncoding.EncodeToString(randomBytes)[:n])
}

func generatePassword(n int) []byte {
	for {
		p := scrambleCase(randBytes(16))
		if hasDigit(p) && hasUppercase(p) && hasLowercase(p) {
			return p
		}
	}

}

func hasDigit(in []byte) bool {
	for _, x := range string(in) {
		if unicode.IsDigit(x) {
			return true
		}
	}
	return false
}

func hasUppercase(in []byte) bool {
	for _, x := range string(in) {
		if unicode.IsUpper(x) {
			return true
		}
	}
	return false
}

func hasLowercase(in []byte) bool {
	for _, x := range string(in) {
		if unicode.IsLower(x) {
			return true
		}
	}
	return false
}