---
title: "Your Cab Driver Knows Your PIN"
date: "2026-07-04"
summary: The static 4-digit OTPs used for ride bookings could become a reused PIN across sensitive services, and anyone who has shared a cab with you already knows it.
description: Ride-booking apps use the same static OTP for every trip. For younger users growing up with UPI and mobile banking, this memorable 4-digit code risks becoming a default PIN for bank accounts, phone locks, and more.
toc: false
readTime: true
autonumber: true
math: false
tags: ["thinking out loud", "security"]
showTags: true
hideBackToTop: false
---

> [!NOTE]
> A local LLM was used to rephrase this content.

Many services today ask for a 4-digit or 6-digit PIN. Think of ATMs, UPI apps, mobile banking apps, phone lock screens, and even your Windows login. Plenty of people use the exact same PIN everywhere, just for convenience. You might carefully cover the keypad at the ATM, but how often have you said your PIN out loud to an auto or cab driver while booking a ride?

Older users often pick PINs from numbers they already know by heart. For example, the last four digits of their parent's bike or car registration number, or the last four digits printed on their debit card. They have no shortage of familiar numbers to fall back on.

Younger users, who are growing up with UPI and mobile banking, won't have the same luxury. They will start using UPI and ride booking apps like Rapido and Namma Yatri at a young age, often for trips to school, college, or the mall. The first 4-digit numbers they will punch in every day will be the static OTPs for ride bookings. Since this code will stay the same for every ride, in every city, across their entire life, it will quickly become a number they know by heart. And because it will always be 4 digits, they might unconsciously start treating it like a permanent PIN, reusing it for their bank account, phone lock, or UPI app.

This will be risky. Anyone who has ever ridden in their cab, autorickshaw, or bike taxi will have likely seen or heard that code. If someone shoulder-surfs it, hears it over a phone call, or sees it in a screenshot, they might guess the PINs the user has set for more sensitive services.
