WiFi is a group of wireless network protocols based on the IEEE 802.11 standard. WiFi is an ubiquitous wireless standard employed in laptops, mobile phones and IoT devices.

High level Architecture

A WiFi device typically connects to an access point (AP) or a wireless router to access the internet. Each 802.11 capable device has a 48-bit link layer Media access control (MAC) address. This MAC address serves as a unique WiFi device identifier.

Similarly, every AP has a unique Service Set Identifier (SSID) and is the network’s name. A WiFi device connects to a specific AP using the SSID and it’s password.

Frame types

802.11…

Cryptography relies heavily on confidentiality of its private keys . A HSM (Hardware security module) is a physical computing hardware used for secure key storage, key management and cryptographic operations.

HSM vendors have designed HSM in various form factors ranging from nano-form with USB interface, network appliance, PCI extension card, to HSM cloud as a service.

Applications and use-cases

• Public key infrastructure: HSM are used to securely store Certificate authority (CA) private key and also sign certificates.
• Web servers and clients (browsers) use Transport layer security (TLS) to form a secure channel called HTTPS. …

As a runner, I want to make contactless payments using my smartwatch so that I can purchase a drink after my run without carrying a wallet or my smartphone.

I can do this today as various wearable vendors offer smartwatches with contactless payment capabilities. However to perform user authentication, the user has to unlock their smartwatch through a passcode or an unlock pattern. However passcodes/lock patterns can be guessed (by others) and are inconvenient to enter on a smartwatch.

A more convenient and secure way for wearables to perform user authentication is to use fingerprint sensors to enroll and verify…

Let’ say you (a payer) want to make a contactless payment using a NFC enabled smartphone. The diagram below gives a high level overview. There are multiple steps happening under the hood.

Step 1: Payer unlocks the phone and sends the token

First the digital wallet performs user authentication. The customer must unlock it’s smartphone using a fingerprint or entering its pin code. Then (S)he must enable NFC and bring her phone in close proximity (4 cm) to POS terminal. Finally, Google Pay sends the payment token over NFC to the merchant POS.

During the card registration with Android Smartphone, Google Pay stores your (credit/debit) card information in it’s cloud…

RSA is a public-key cryptographic system first published in 1977. RSA security relies on the difficulty of factoring the product of two large prime numbers.

RSA use cases

• TLS Authentication: Server and Client can use RSA to perform server authentication and optional client authentication.
• An entity can sign a message with its RSA private key. Anyone with entity’s public key can run a signature verification algorithm to confirm that the message came from the entity.
• RSA can be used to communicate symmetric keys (used for data encryption-decryption) between two parties.

RSA key generation overview

• For a key length of k bits, Find two distinct random prime numbers…

The other day I was waiting for a bus to drop my kids at school in Cambridge, UK. On that day, there was a 10–15 passengers who wanted to board the bus. Some of the passengers already had their tickets on on their mobile app or in a printed paper. As these passengers boarded the bus, the driver visually inspected their tickets. The other passengers bought the tickets using contactless cards or cash. The ticket machine printed a paper ticket for these passengers for this and later bus trips. …

Did you know that 2.6 billion people used digital wallets in 2020 globally? I learned about this statistic when switching to a digital wallet.

I have used traditional leather wallets for more than a decade in various cities: Berlin, Lahore, Trondheim, and Cambridge. I keep my credit card(s), driving license, etcetera in it.

Just recently, I started using a digital wallet Google Pay. A digital wallet is an app on a smartphone/wearable that enables contactless payment. Google Pay is straightforward to install. First, I scanned my credit card with my mobile camera. Google Pay stores my credit card number, CVC…

Unlike Norway, my apartment in the UK has a gas stove. But do you know the origin of this gas? My kitchen stove could be running on Norwegian gas, flowing through a 1,166 km pipeline in the North sea. Or, my house heating may be using Qatari LNG gas transported via gigantic tankers to the UK. Conversely, my kid’s hot water shower may be utilizing a local gas source — gas originating from the UK continental shelf.

Similarly, the UK generates electricity from various sources. Its five main sources are renewables, gas, nuclear, biomass, and coal. Total electricity generated in…