IoT Security - Zign 200

The number of devices, machines, or sensors linked over open communication networks on the internet of things (IoT) has exploded. Every device represents a potential entry point for malicious intrusion – into the device itself, or its network.

Cryptographic keys are needed to verify a device’s identity, secure communication between devices, and encrypt sensitive data at rest as well as in transit. Zign® 200 is a secure key generation, management, and storage solution for any IoT device. A software-based solution, Zign is the only hardware entropy source currently available that doesn’t have to be loaded at silicon fabrication.

The Zign 200 API enables IoT developers to generate cryptographic keys securely and to perform other symmetric key functions. It can also be integrated as a trust anchor for Mbed TLS, OpenSSL, wolfSSL, and other libraries, extending the chain of trust beyond just a single device.

Secure Vault with SRAM PUF

Device makers need a way to protect keys and other secret material. This is typically done by encrypting or wrapping them with other keys. But how do you protect the encryption root key? How to keep secrets secret?

Zign 200 uses inherently random SRAM start-up values as a PUF from which the root key is generated. The root key is never stored and is only available (in volatile memory) when needed. This means the key is never present in persistent memory – not even when the chip is powered down – which raises the security significantly and eliminates the need for OTP or other secure memory.

Zign 200 offers functions to wrap and manage secret keys and data which then can be stored in unprotected memory or can be securely transmitted over the network. A potentially unlimited number of keys can be derived from the root key by using the NIST-compliant key-derivation function. Zign 200 also offers random values, generated by a NIST 800-90A/B-compliant
random number generator and a collision-free unique device identity (UID). All Zign features are accessed by the host software via the API.

Operating Ranges

SRAM PUF responses have been qualified for use with the Zign X00 series in a wide range of operational environments,  over years of field operation:

• All major fabs from 0.35 μm to 5 nm
• Temperature range from -55°C to 150°C [-67°F to 300°F]
• Voltage supply variation +/- 20%
• Lifetime > 25 years

Zign 200 is delivered as a library compiled for a specific target chip, along with API specifications and user manual. The solution is available in off-the-shelf configurations with size ranging between 10.3 kB and 11 kB.