LPC55S69 : Encrypt flash on fly, min write chunk

[EugeneHiihtaja]

Hello !

In UM I can see :

"

LPC55S6x devices offer support for real-time encryption and decryption for on-chip flash
using the PRINCE encryption algorithm. Compared to AES, PRINCE is fast because it
can decrypt and encrypt without adding extra latency. PRINCE operates as data is read or
written, without the need to first store data in RAM and then encrypt or decrypt to another
space. It operates on a block size of 64-bits with a 128-bit key.

"

What is minimal data chunk what I can write to flash memory at once ?

8 byte block what is also 8 byte boundary aligned ?

What are constrains if PRINCE block is not used on certain 8KB flash block ?

Regards,

Eugene

[xiangjun_rong]

Hi, Eugene,

As you know that the Prince module writes flash using the api function in ROM(IAP), when the PRINCE module is enabled, the data saved in flash is encrypted although the flash program function write sdata in plain text.

Because the flash page size is 512, so the flash-program should write flash in 512 bytes as chuck.

For the Prince module, the minimum sub-region size is 8K bytes, so the constrains if PRINCE block is not used or used must be in 8K bytes boundary.

Hope it can help you

BR

XiangJun Rong