Cost-Effective Secure Authentication for Accessory Ecosystems and Disposable Applications

Read on if you are interested in authenticating a single accessory, creating a regulated ecosystem of electronic accessories or dealing with counterfeiting of disposables. This blog post reviews how our new economical secure authentication ICs offer the security features to meet the goals of your threat model.

Cost Optimized Secure Authentication ICs for Disposable and Accessory Ecosystems

Every day, secure authentication processes are happening around you, whether you realize it or not. For example, when you're using sending emails, plugging your phone into its charger or printing documents, authentication is occurring behind the scenes.

In this blog post, we will review how our new cost-effective secure authentication ICs will help you meet the goals of your threat model by providing valuable security features.

Why Accessory/Disposable Authentication?

There are several notable reasons why authentication is essential for disposable and accessory ecosystems. The first purpose is safety—although sometimes components may run a dangerous function, authentication can prove that the system is genuine and works safely. Another reason authentication is necessary is interoperability. Everything in the ecosystem must be able to communicate with each other for it to work; on a related note, ecosystem control is a critical reason for authentication to ensure that all parts within the system deliver the same user experience whether they come from your brand or a third party. An uptick in counterfeits in recent years has created a need to protect against them and establish verification in your system, which is another reason why authentication is necessary. User experience is also a cause for authentication. Through the IP in your firmware, you can supply and maintain a unique experience for each user. All these aspects will have consequences for revenue protection and the reputation of your brand.

Market Segments for Accessory/Disposable

Accessory/disposable technologies cover a multitude of market segments. In the medical field, these products are found in the form of items such as cables, breathing tubes, sensors, cartridges and patches. The consumer segment sees products for cosmetics, e-cigarette and printing, as well as fragrance and Qi® 1.3 wireless charging, both of which are also found with automotive products. Other automotive products include original equipment manufacturer (OEM) or third-party electronic cards and electric vehicle batteries. Industrial accessory/disposable products include third-party accessories, maintenance service and OEM ecosystem control. In the E-mobility market segment, you will note E-bike electronic cards, battery swapping and battery authentication. For data center products, you can find technologies related to OEM or third-party card authentication for cryptographically controlled manufacturing. Accessory/disposable ecosystems are everywhere, and we must provide authentication for products in all market segments.

High-Level Portfolio

We offer several high-level security products in our authentication portfolio. Among our silicon products, we offer CryptoAuthentication™ (ATECC608) devices, CryptoAutomotive™ (TA100) security ICs, Trusted Platform Module (TPM)(ATTPM20P) and Platform Root of Trust. For onboarding, we offer our Trust Platform which includes Trust&GO, TrustFLEX and TrustCUSTOM. The three tiers allow you to leverage our Microchip Secure Provisioning Service and select your secure authentication IC, choose which credentials you want to provision and select the Minimum Orderable Quantity (MOQ) that will best suit your needs. The platform will support you through your entire process—from prototype all the way to production.

How Does Secure Authentication Work?

A secure authentication IC is a companion device to any microcontroller (MCU). It functions like a vault that protects secrets.

Secrets (keys, certificates and data) are provisioned into the secure boundary of the device during manufacturing at Microchip secured factories. The secrets are protected from being exposed and are managed by Microchip’s secure provisioning process.

Figure 1: Secure Authentication Process

The host MCU sends a random challenge to the secure authentication IC that will host the secret keys and have a crypto engine. The random challenge is fed into the crypto engine with the key to build the response.

Expanding Portfolio

Figure 2: Microchip Portfolio

We have recently added several new solutions to our portfolio. In the automotive market, we launched the TA010. For accessories and disposables, check out our new ECC204 along with the SHA104/SHA105, SHA106 and ECC206.

The idea behind these new devices was to provide minimum viable cryptographic accelerators along with keeping a small memory real estate to keep the cost optimized. So for algorithms such as ECDSA sign, HMAC/SHA256 are the only ones supported by the devices listed above. For a more complete set of accelerators, the TA100 and ATECC608 are the devices to look at.

Symmetric Authentication

Symmetric authentication refers to the simplest type of authentication, requiring only one secret key for the host to authenticate the client (disposable/accessories).

Figure 3: Basic Symmetric Authentication Principle

We will use a simplistic approach to explain. In this example, we are looking at a brain sensor and host. There is a secure system on both sides—here, we have SHA105 on the left and SHA104 on the right. The host sends a challenge to the sensor to run the SHA256 algorithm to create the digest or response. This uses a symmetric key on both sides. The response from the accessory/disposable then goes back to the host to compare to make sure both responses are identical to receive the information from the sensor.

A more elegant way to achieve this is to use symmetry key diversification. This provides a unique symmetric key for each single accessory/disposable, thus reducing the risk of counterfeiting every key and exposing the whole system.

Asymmetric Authentication

Asymmetric authentication, also called public-key cryptography, uses two types of keys (public and private key pairs) to authenticate.

Figure 4: Asymmetric Authentication

In this scenario, we can assume certification has been established between the customer and device (similar to what the Qi 1.3 standard does, for example), and we are now looking at the embedded system and how the challenge response is happening. We have a signer public key in the host and a device public key and signature in the accessory. The signature is the output of the ECDSA sign operation performed on the random challenge by the private key. The device public key is verified by the signer public key and the device public key verifies the signature. Then, the system can continue its operations and accept further information.

Figure 5: Asymmetric Authentication with Root Public Key

This scenario is a bit more complex as we now add a root or OEM public key. We need to verify each stage public key from the signer public key by the root to the device public key by the signer public key as well as verify that the signature is legitimate. Once the system acknowledges the signature as correct, it can move forward.

Parasitic Power: From 3-Pin to 2-Pin

Parasitic power is crucial when limiting the number of pins in a package. We added an integrated capacitor in front of the device which can hold enough energy to run the authentication computation and provide that response; this capacitor enabled us to go from 3-pin to 2-pin. One pin has the data and power where communications and supply take place, while the second pin is your ground. Reducing the number of pins eliminates the need for PCB in a disposable, thus lowering the system level cost and streamlining implementation.

Secure Key Provisioning Service

Microchip is equipped with a hardware security module (HSM) in our factories. This setup is where the cryptographic operations take place between the customer and the device. We can take on numerous projects from various customers and provision keys and other data that needs to be kept confidential. The Trust Platform will give you an overview of available options.

Trust Platform Design Suite

Our DM320118 is the base kit to help you get started, as it can be used with the Trust Platform Design Suite (TPDS) and other software tools. Be sure to check which add-on boards are right for you. Alternatively, socket add-on boards are also available. The TPDS provides access to use case tutorials for symmetric and asymmetric authentication as well as Qi 1.3. It also provides C-code examples, configurators for the selected secure authentication IC and the necessary utilities to onboard in the Microchip Secure Provisioning Service.

Final Thoughts

Our portfolio consistently gives you easier access to secure authentication, quick development with simple toolsets and simpler flows leveraging e-commerce stores. Our products are fitted for mass market with low MoQ including provisioning and architecture agnostic with CryptoAuthLib.

Be sure to watch our Design Week 2023 session for a deeper look at secure authentication. For more information, please visit our secure authentication web page.

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