In-System Programming (ISP) of Actel’s Low-Power Flash Devices Using FlashPro3
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particularly suitable for applications where device updates must be transmitted over an unsecured
network such as the Internet. The embedded AES decryption core can prevent sensitive data from
encrypt FPGA core programming data and/or FlashROM programming data in the Actel tools. The
low-power flash devices also decrypt with a single 128-bit AES Key. In addition, low-power flash
devices support a Message Authentication Code (MAC) for authentication of the encrypted
bitstream on-chip. This allows the encrypted bitstream to be authenticated and prevents erroneous
data from being programmed into the device. The FPGA core, FlashROM, and Flash Memory Blocks
(FBs), in Fusion only, can be updated independently using a programming file that is AES-encrypted
(cipher text) or uses plain text.
Security in ARM-Enabled Low-Power Flash Devices
There are slight differences between the regular flash device and the ARM-enabled flash devices,
which have the M1 and M7 prefix.
The AES key is used by Actel and pre-programmed into the device to protect the ARM IP. As a
result, the design will be encrypted along with the ARM IP, according to the details below.
CoreMP7 Device Security
ARM7 (M7-enabled) devices are shipped with the following security features:
FPGA Array enabled for AES encrypted programming and verification
FlashROM enabled for plaintext read and write
Cortex-M1 Device Security
Cortex-M1–enabled devices are shipped with the following security features:
FPGA Array enabled for AES-encrypted programming and verification
FlashROM enabled for AES-encrypted write and verify
Fusion Embedded Flash Memory enabled for AES encrypted write.
Figure 16-1 AES-128 Security Features
Actel Designer
Software
Programming
File Generation
with AES
Encryption
Flash Device
Decrypted
Bitstream
MAC
Validation
AES
Decryption
FPGA Core,
FlashROM,
FBs
Transmit Medium /
Public Network
Encrypted Bistream
User Encryption AES Key