Allow configuration of #digit + period

[evandrix]

Some RFC6238 TOTP implementations use digits other than 6, or periods other than 30s e.g. Fortinet uses 60s

[moldabekov]

@evandrix thanks for feedback, I will dig into.

[evandrix]

np, i wrote this Go implementation, adapted from yours, https://github.com/pcarrier/gauth, as well as the dependency of that https://github.com/creachadair/otp

"${HOME}/.gauth" format: <Name><SPACE><Num_Digits><SPACE><Period><SPACE><Base32-secret>

main.go

package main

import (
    "log"
    "os"
    "fmt"
    "time"
    "path"
    "bytes"
    "strings"
    "strconv"
    "os/user"
    "io/ioutil"
    "encoding/csv"
    "text/tabwriter"
    "github.com/creachadair/otp"
)

func main() {
    usr,err := user.Current()
    if err != nil {log.Fatal(err)}

    cfg_fp := path.Join(usr.HomeDir,".gauth")
    cfg_data,err := ioutil.ReadFile(cfg_fp)
    if err != nil {log.Fatal(err)}

    cfg_rdr := csv.NewReader(bytes.NewReader(cfg_data))
    cfg_rdr.Comma = ' '
    cfg,err := cfg_rdr.ReadAll()
    if err != nil {log.Fatal(err)}

    tw := tabwriter.NewWriter(os.Stdout,0,2,1,' ',0)
    for _,record := range cfg {
        name,ndigit_s,period_s,secret := record[0],record[1],record[2],record[3]
        if ndigit,err:=strconv.Atoi(ndigit_s); err==nil {
            if period,err:=strconv.Atoi(period_s); err==nil {
                var cfg otp.Config
                cfg.Digits = ndigit
                cfg.TimeStep = otp.TimeWindow(period)
                cfg.ParseKey(secret)

                time := time.Now().Unix()
                period_int64,err := strconv.ParseInt(period_s,10,64)
                if err != nil {log.Fatal(err)}

                fmt.Fprintf(tw,"%s\t%s\t[%-*s]\n",name,cfg.TOTP(),period-1,strings.Repeat("=",int(time%period_int64)))
            }
        }
    }
    tw.Flush()
}

[moldabekov]

@evandrix oh, nice! Could you please make a PR then?