From 5bc8ff087a723deb1d4ae38eb8db11c57e11a77d Mon Sep 17 00:00:00 2001
From: Pierre Carrier <pierre@gcarrier.fr>
Date: Thu, 14 Nov 2013 02:29:27 -0800
Subject: [PATCH] Support for "irregular" secret lengths
I realized whilst turning 2FA for Dropbox that they use a secret length
that's not a multiplier of 8, which breaks Go's base32 decoder.
---
gauth.go | 24 +++++++++++++++++-------
1 file changed, 17 insertions(+), 7 deletions(-)
diff --git a/gauth.go b/gauth.go
index 059e334..a2038bd 100644
--- a/gauth.go
+++ b/gauth.go
@@ -16,13 +16,22 @@ import (
)
func TimeStamp() (int64, int) {
- time := time.Now().Unix()
- return time / 30, int(time % 30);
+ time := time.Now().Unix()
+ return time / 30, int(time % 30)
+}
+
+func normalizeSecret(sec string) string {
+ noPadding := strings.ToUpper(strings.Replace(sec, " ", "", -1))
+ padLength := 8 - (len(noPadding) % 8)
+ if padLength < 8 {
+ return noPadding + strings.Repeat("=", padLength)
+ } else {
+ return noPadding
+ }
}
func AuthCode(sec string, ts int64) (string, error) {
- normalizedSec := strings.ToUpper(strings.Replace(sec, " ", "", -1))
- key, err := base32.StdEncoding.DecodeString(normalizedSec)
+ key, err := base32.StdEncoding.DecodeString(sec)
if err != nil {
return "", err
}
@@ -77,12 +86,13 @@ func main() {
prevTS := currentTS - 1
nextTS := currentTS + 1
- fmt.Println(" prev curr next");
- for name, secret := range cfg {
+ fmt.Println(" prev curr next")
+ for name, rawSecret := range cfg {
+ secret := normalizeSecret(rawSecret)
prevToken := authCodeOrDie(secret, prevTS)
currentToken := authCodeOrDie(secret, currentTS)
nextToken := authCodeOrDie(secret, nextTS)
fmt.Printf("%-10s %s %s %s\n", name, prevToken, currentToken, nextToken)
}
- fmt.Printf("[%-29s]\n", strings.Repeat("=", progress));
+ fmt.Printf("[%-29s]\n", strings.Repeat("=", progress))
}