redegsigned OTP page and show next TOTP code

2026-09-25 06:18:09 +05:00
parent fbedc631c5
commit 369c6e4a37
7 changed files with 258 additions and 65 deletions
@@ -9,10 +9,11 @@ object Totp {
    /**
     * Generate a 6-digit TOTP code from a Base32-encoded secret (RFC 6238 / RFC 4226).
     * Uses HmacSHA1, 30-second window, 6 digits — matching standard authenticator apps.
+     * [periodOffset] shifts the time window, e.g. 1 yields the next code.
     */
-    fun generate(base32Secret: String, digits: Int = 6, periodSeconds: Long = 30): String {
+    fun generate(base32Secret: String, digits: Int = 6, periodSeconds: Long = 30, periodOffset: Long = 0): String {
        val key = base32Decode(base32Secret.uppercase().replace(" ", "").replace("-", ""))
-        val counter = System.currentTimeMillis() / 1000L / periodSeconds
+        val counter = System.currentTimeMillis() / 1000L / periodSeconds + periodOffset
        val otp = hotp(key, counter, digits)
        return otp.toString().padStart(digits, '0')
    }