init

totp.go

@@ -0,0 +1,30 @@
+// Time-based One-time Password
+package main
+
+import (
+	"crypto/hmac"
+	"crypto/sha256"
+	"encoding/binary"
+)
+
+const TOTPStep = 30 // 30s
+func GenTOTP(user string, password string, ts int64) uint64 {
+	step := ts / TOTPStep
+	mac := hmac.New(sha256.New, []byte(user+password))
+	b := make([]byte, 8)
+	binary.LittleEndian.PutUint64(b, uint64(step))
+	mac.Write(b)
+	num := binary.LittleEndian.Uint64(mac.Sum(nil)[:8])
+	// fmt.Printf("%x\n", mac.Sum(nil))
+	return num
+}
+
+func VerifyTOTP(code uint64, user string, password string, ts int64) bool {
+	if code == 0 {
+		return false
+	}
+	if code == GenTOTP(user, password, ts) || code == GenTOTP(user, password, ts-TOTPStep) || code == GenTOTP(user, password, ts+TOTPStep) {
+		return true
+	}
+	return false
+}