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Add compatibility for totp codes with different intervals #7

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Add compatibility for totp codes with different intervals #7

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2694554
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gergesh Feb 9, 2018
02a1be2
Features are complete, codes don't generate properly.
gergesh Feb 9, 2018
dbaf46b
Fixed small mistake, done
gergesh Feb 9, 2018
36d9698
Remove debug print
gergesh Feb 9, 2018
a1bd091
gofmt'ed
gergesh Feb 10, 2018
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44 changes: 31 additions & 13 deletions main.go
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Original file line number Diff line number Diff line change
Expand Up @@ -90,11 +90,13 @@ var (
flag7 = flag.Bool("7", false, "generate 7-digit code")
flag8 = flag.Bool("8", false, "generate 8-digit code")
flagClip = flag.Bool("clip", false, "copy code to the clipboard")
flag10 = flag.Bool("10", false, "use a 10-second interval")
flag20 = flag.Bool("20", false, "use a 20-second interval")
)

func usage() {
fmt.Fprintf(os.Stderr, "usage:\n")
fmt.Fprintf(os.Stderr, "\t2fa -add [-7] [-8] [-hotp] keyname\n")
fmt.Fprintf(os.Stderr, "\t2fa -add [-7] [-8] [-10] [-20] [-hotp] keyname\n")
fmt.Fprintf(os.Stderr, "\t2fa -list\n")
fmt.Fprintf(os.Stderr, "\t2fa [-clip] keyname\n")
os.Exit(2)
Expand Down Expand Up @@ -146,9 +148,10 @@ type Keychain struct {
}

type Key struct {
raw []byte
digits int
offset int // offset of counter
raw []byte
digits int
offset int // offset of counter
interval int // interval of generation
}

const counterLen = 20
Expand Down Expand Up @@ -176,19 +179,23 @@ func readKeychain(file string) *Keychain {
if len(f) == 1 && len(f[0]) == 0 {
continue
}
if len(f) >= 3 && len(f[1]) == 1 && '6' <= f[1][0] && f[1][0] <= '8' {
if len(f) >= 4 && len(f[1]) == 1 && '6' <= f[1][0] && f[1][0] <= '8' && len(f[2]) == 2 {
var k Key
name := string(f[0])
k.digits = int(f[1][0] - '0')
raw, err := decodeKey(string(f[2]))
k.interval, err = strconv.Atoi(string(f[2]))
if err != nil {
log.Fatal(err)
}
raw, err := decodeKey(string(f[3]))
if err == nil {
k.raw = raw
if len(f) == 3 {
if len(f) == 4 {
c.keys[name] = k
continue
}
if len(f) == 4 && len(f[3]) == counterLen {
_, err := strconv.ParseUint(string(f[3]), 10, 64)
if len(f) == 5 && len(f[4]) == counterLen {
_, err := strconv.ParseUint(string(f[4]), 10, 64)
if err == nil {
// Valid counter.
k.offset = offset - counterLen
Expand Down Expand Up @@ -235,6 +242,16 @@ func (c *Keychain) add(name string) {
size = 8
}

latency := 30
if *flag10 {
latency = 10
if *flag20 {
log.Fatalf("cannot use -10 and -20 together")
}
} else if *flag20 {
latency = 20
}

fmt.Fprintf(os.Stderr, "2fa key for %s: ", name)
text, err := bufio.NewReader(os.Stdin).ReadString('\n')
if err != nil {
Expand All @@ -246,10 +263,11 @@ func (c *Keychain) add(name string) {
log.Fatalf("invalid key: %v", err)
}

line := fmt.Sprintf("%s %d %s", name, size, text)
line := fmt.Sprintf("%s %d %d %s", name, size, latency, text)
if *flagHotp {
line += " " + strings.Repeat("0", 20)
}

line += "\n"

f, err := os.OpenFile(c.file, os.O_CREATE|os.O_RDWR|os.O_APPEND, 0600)
Expand Down Expand Up @@ -291,7 +309,7 @@ func (c *Keychain) code(name string) string {
}
} else {
// Time-based key.
code = totp(k.raw, time.Now(), k.digits)
code = totp(k.raw, time.Now(), k.digits, k.interval)
}
return fmt.Sprintf("%0*d", k.digits, code)
}
Expand Down Expand Up @@ -340,6 +358,6 @@ func hotp(key []byte, counter uint64, digits int) int {
return int(v % d)
}

func totp(key []byte, t time.Time, digits int) int {
return hotp(key, uint64(t.UnixNano())/30e9, digits)
func totp(key []byte, t time.Time, digits int, latency int) int {
return hotp(key, uint64(t.UnixNano())/(uint64(latency)*10e8), digits)
}