Zeroization of nvRAM

[Anonymous]

I consider using nvRAM in the same manner as you would use the BBRAM of an FPGA or SoC. These internal BBRAMs are used for a semi-non-volatile RAM as in having a particular focus on effective zeroization. I have not been able to find information on the effectiveness of zeroization on nvRAMs.

Specifically, I seek more information on how convenient it is to perform zeroization commands on Cypress nvRAMs, i.e. writing '0's and verifying this afterwards. My intention is to store a key used for encrypting very sensitive data. This key must there be easy to erase at any moment.

Any help is very much appreciated!

Thanks.

[PradiptaB_11]

Hi,

The write and read operations on a nvSRAM cell (Volatile + Non Volatile Cell) will be the same as on a SRAM cell. Initially whatever is written to the device is stored in the volatile SRAM cell. Afterwards by means of a store operation it is transferred to the non volatile section. Once stored it can be recalled to the volatile section as and when required. You can refer the datasheet for nvSRAM for more information on the store and recall operations.

As such there is no erase operation for the nvSRAM just as there is none for the SRAM. When power is cut off the data will be lost from the volatile section and cannot be retrieved back as in SRAM. For the non volatile section for a erase like operation you need to write all zeroes to the memory and perform a store operation.Then the previous data is erased from both the volatile and non volatile section of the memory.This can be verified also by performing the recall operation later.

I hope this answers yours query. Let us know for any further concerns.

Thanks and Regards,

Pradipta.

[Anonymous]

Hi Pradipta,

Thanks. So This doesn't really meet my requirements as there is considerable overhead in order to erase content, having to power up, write '0's, store content to the non-volatile section and read back to confirm.

Could you recommend any other solutions? I suppose for this purpose, conventional BBSRAM might be optimal. I basically only need space for storing a 256 bit key.

Cheers.

[PradiptaB_11 · Accepted solution]

Hi,

If the focus is on effective zeroization then you can go with any external or internal battery backed SRAM ( You can check the SRAM portfolio from Cypress), as this application does not necessarily require you to retain the data, rather you want to erase the key once it is utilized.

Thanks and Regards,

Pradipta.