AN 556: Using the Design Security Features in Intel FPGAs

ID 683269
Date 5/21/2021
Document Table of Contents
Give Feedback

Non-Volatile and Volatile Key Storage

Intel FPGAs offer both volatile and non-volatile key storage. The volatile key storage registers are reprogrammable and erasable. The contents of the key registers are retained between power-cycles with a coin-cell battery. Non-volatile key registers are fuse-based and are one-time programmable.

Note: Examples of lithium coin-cell type batteries that are used for volatile key storage purposes are BR1220 (–30°C to 80°C) and BR2477A (–40°C to 125°C).
Table 5.  Volatile and Non-Volatile Key Comparison
Option Volatile Key Non-Volatile Key
Key Length 256 bits 256 bits
Key Programmability Reprogrammable and erasable key One-time programmable key
External Battery Required Not required
Key Programming Method 3 On-board Both on-board and off-board 4
Design Protection 5 Secure against copying, reverse engineering, and tampering
3 Key programming is carried out through JTAG interface. You need to use valid MSEL pin settings for the JTAG interface.
4 Programming the non-volatile key fuses uses the standard voltage sources used by the FPGA during normal operation. No additional voltage rails are necessary for programming non-volatile key.
5 Volatile key tamper-protection is only available for Arria® II, Arria® V, Cyclone® V, Stratix® V, Intel® Arria® 10, and Intel® Cyclone® 10 GX devices.