topic Re: PRNG support in HSE for S32G3 in S32G

PRNG support in HSE for S32G3

Suresh_iast_332 — Tue, 08 Oct 2024 09:23:00 GMT

In HSE user manual of S32G3, Random Number Generation class DRG3, DRG4 and PTG3 uses the TRNG

is the PRNG is supported in HSE for s32G3?

if yes, may I know which HSE service API is responsible to generate the PRNG?

Regards,

Suresh

Re: PRNG support in HSE for S32G3

alejandro_e — Thu, 10 Oct 2024 04:18:02 GMT

Hello @Suresh_iast_332,

Sorry for the late response, the teams bandwidth is limited at the moment.

About your questions, the HSE does not support PRNG, since the aim of that module is crypto and secure operations it only supports TRNG.

Let me know if this information was useful or if you have more questions.

Re: PRNG support in HSE for S32G3

Suresh_iast_332 — Tue, 15 Oct 2024 05:32:51 GMT

Thanks for response @alejandro_e , is there any demo code or example code on HSE for Random number generation

Re: PRNG support in HSE for S32G3

alejandro_e — Tue, 15 Oct 2024 17:41:38 GMT

Hello @Suresh_iast_332,

Yes there is a demo application with the RNG HSE functionalities. You should be able to download it from the NXP flexnet page, the same page from which you downloaded the HSE firmware, please follow these steps:

- Sign in to your NXP account (NXP Semiconductors)

- Click on My NXP Account (top-right) and click on Software Licensing and Support under the Licensing section within the window it opens.

- This will redirect you to another page. In this new page, select the option View Accounts under the Software accounts section.

- This will again redirect you to another page. On this page, you should see an Automotive SW – S32G Standard Software option, click on it.

- now you should be able to see the Automotive SW - S32G - HSE Firmware option, click on it.

- Now you should be able to see all the HSE versions available, click on HSE FW 0.2.51.0 SR STANDARD Release for S32G3.

- accept the Software Terms and Conditions, now you should be able to see all the files related to that HSE release, you should be able to see the executable HSE_DEMOAPP_S32G3XX_0_2_51_0_D2404.exe, download and install this package, by default it will be installed in your NXP folder (C:\NXP\HSE_DEMOAPP_S32G3XX_0_2_51_0)

- Once installed you can open import the project from the S32 Design Studio, use the following path C:\NXP\HSE_DEMOAPP_S32G3XX_0_2_51_0\demo_app\projects\S32DS\HSE_DEMO_S32G2XX

- In the main file (located in src\services\src) you will see a function call for void HSE_Crypto(void) inside this function you can see a call to static void HSE_GetRng_Example(void) there you can see how to use the RNG functionality of the HSE.

Please follow the HSE_DEMOAPP_S32G3XX_0_2_51_0_ReadMe.pdf located directly on the installation path of the HSE, there you will see the instructions on how to compile and execute the HSE demo app.

Let me know if this information was useful

Re: PRNG support in HSE for S32G3

Suresh_iast_332 — Thu, 24 Oct 2024 08:51:34 GMT

Hello @alejandro_e,

Thanks for response.

1) As per your input I have downloaded the HSE_DEMOAPP_S32G3XX_0_2_51_0_D2404.exe and installed I can see the HSE_GetRng_Example API in hse_crypto.c file, which uses the HSE_RNG_CLASS_DRG3 for Random number generation. This means the deterministic random number generation or Pseudo random number generation via HSE is same which uses HSE_RNG_CLASS_DRG3 or HSE_RNG_CLASS_DRG4?

2) How the seed is generated for HSE_RNG_CLASS_DRG3 and HSE_RNG_CLASS_DRG4, from the example directly calling the GetRngNum API by passing HSE_RNG_CLASS_DRG3 without any entropy or seed.

a. So HSE_RNG_CLASS_DRG3 uses entropy generated by TRNG implicit and user no need pass or call TRNG API to generate entropy?

b. ForHSE_RNG_CLASS_DRG3 how the seed or reseeding done, is it on every invoke of GetRngNum API or is there any other mechanism?

c. If we want to reseed the DRG for certain count of Random number generation ( eg. 10 or 20 random numbers via DRG) then where and how we could reseed the HSE_RNG_CLASS_DRG3 and HSE_RNG_CLASS_DRG4?

d. From the HSE service API reference manual we are not able to find the API for generating Random Number using TRNG. could please let us know which API can be used for Random number generation using TRNG?

Best Regards

Suresh

Re: PRNG support in HSE for S32G3

alejandro_e — Thu, 24 Oct 2024 21:24:25 GMT

Hello @Suresh_iast_332,

Here are the answers to your questions:

1 - The HSE_RNG_CLASS_X defines the reseeding of the of the RNG module as explained in the HSE Service API Reference Manual [page 251, 0.2.51.0] that you can find in your installation path, for me it is C:/NXP/HSE_FW_S32G3XX_0_2_51_0/docs/HSE_FW_H_S32G3XX_0.2.51.0_Service_API_Reference_Manual.pdf:

2 - for the entropy/seed you can see the following at the end of the same page of the API reference manual:

2a - Yes, exactly.

2b - the HSE_RNG_CLASS_DRG3 does not do a reseeding on each call, as you can see above.

2c - if you need to reseed the TRNG module every X number of calls, you will need to implement your own control flow. For example, if you want to reseed every 10 calls, you can call the TRNG functionality with HSE_RNG_CLASS_DRG3 9 times and on the 10th time you use HSE_RNG_CLASS_DRG4 to generete a reseed, so the next 9 calls have a different seed, and you repeat the flow again.

Depending on your performance requirements you can use HSE_RNG_CLASS_DRG4 or HSE_RNG_CLASS_PTG3.

2d - As I mentioned before and as shown in the last image, the HSE always provides TRNG functionality, therefore it does not provide PRNG.

Let me know if this information solves your question.

Re: PRNG support in HSE for S32G3

Suresh_iast_332 — Fri, 25 Oct 2024 07:40:58 GMT

Hello @alejandro_e ,

Thanks for your quick response.

I am adding some more quires related to my previous question

1. We want to generate non-deterministic random number using TRNG so which class from HSE API service reference manual we can use?
2.We want to generate deterministic random number using PRNG so which class from HSE API service reference manual we can use?
3.if we want to use seed form TRNG for PRNG, then can we first call TRNG HSE API for random number generation and then call PRNG HSE API for deterministic random number generation

4. From above classes to achieve point 3 can we have the following
a. can we call HSE API GetRngNum with HSE_RNG_CLASS_DRG4 (Non-Deterministic) for TRNG and then call GetRngNum with HSE_RNG_CLASS_DRG3 (Deterministic) for PRNG?
b. can we achieve generating deterministic random number (PRNG) via HSE or is there is any other option/API to generate PRNG?

Re: PRNG support in HSE for S32G3

alejandro_e — Fri, 25 Oct 2024 16:49:34 GMT

Hello @Suresh_iast_332,

Here are the answers to your questions:

1 - I can recommend using HSE_RNG_CLASS_DRG4 or HSE_RNG_CLASS_DRG4 depending on your security and performance requirements.

2 - The closes to PRNG functionality could be using HSE_RNG_CLASS_DRG3:

where prediction resistance means [page 23-24, https://nvlpubs.nist.gov/nistpubs/SpecialPublications/NIST.SP.800-90Ar1.pdf]:

3/4 - The HSE does not directly give the PRNG functionality, furthermore you cannot access the seed used internally by the HSE. One thing you could do is implement you own PRNG algorithm for example https://en.wikipedia.org/wiki/Counter-based_random_number_generator#Squares_RNG for which you can find source code here: https://github.com/FlorisSteenkamp/squares-rng, there you can see there is a C implementation in the readme. Please consider that this code is not provided by NXP and therefore we do not provide support or any kind of license or warranty. With that said, what you could do is use a random number generated by HSE (for example using HSE_RNG_CLASS_PTG3 to have the highest level of entropy) as the seed for your PRNG algorithm. As I mentioned, the code I shared and the example of the implementation are not provided by NXP and therefore we won't be able to give you any support.

Let me know if this information answers your questions.

Re: PRNG support in HSE for S32G3

alejandro_e — Thu, 14 Nov 2024 23:50:53 GMT

Hello @Suresh_iast_332,

I want to correct a mistake. This won't change anything in your implementation and most of the explanation stills holds valid, it is just a concept clarification.

The service ID HSE_SRV_ID_GET_RANDOM_NUM is used to generate PRNG. The parameter of this service is struct hseGetRandomNumSrv_t, which contains the type hseRngClass_t as a member. The type hseRngClass_t is used to specify the DRGN (Deterministic Random Number Generator) class: DRG3, DRG4 and PTG3. The DRNG is also known as PRNG. In other words, the HSE service HSE_SRV_ID_GET_RANDOM_NUM is used to generate PRGN.

The TRNG generated by HSE cannot be used by the host, instead it is used by the DRNG as a seed. More information about HSE RNG service is described in chapter 7.5 of HSE Firmware Reference manual [HSE_H/M Firmware Reference Manual, Rev.2.5, 10/2024], this document is in the secure file section of the S32G3, you may need to request access to get this file, for this please contact your FAE/NXP representative.

Best regards,

Alejandro

Re: PRNG support in HSE for S32G3

kavyapk — Fri, 15 Nov 2024 07:19:15 GMT

Hello Team,

Could you please clarify the below points regarding reseeding

1.Can we do reseeding for PRNG via TRNG for a particular condition like reseeding shall happen after every 10 call.

2.If not what NXP is suggesting for a conditional reseeding.

Thank you

Re: PRNG support in HSE for S32G3

alejandro_e — Fri, 15 Nov 2024 23:05:28 GMT

Hello @kavyapk,

As mentioned in one of my previous replies you need to implement your own logic to reseed every X number of calls, for example:

you can call the PRNG functionality with HSE_RNG_CLASS_DRG3 9 times and on the 10th time you use HSE_RNG_CLASS_DRG4 (this class generated reseeding on each service call) and generate a reseed, so the next 9 calls have a different seed, and you repeat the flow again.

As mentioned, most of the explanation in this post still holds valid after my clarification, it is just a concept change, but the implementation suggestions are still correct.

Best regards,

Alejandro

Re: PRNG support in HSE for S32G3

Suresh_iast_332 — Fri, 22 Nov 2024 05:53:25 GMT

Hello @alejandro_e

Thanks for your previous response.

As per response TRNG cannot be used by the Host instead it is used by the DRNG as a seed. So, is this the same implementation for the premium package or do we have option to use TRNG at the host for random number generation?

Best Regards,

Suresh

Re: PRNG support in HSE for S32G3

alejandro_e — Fri, 22 Nov 2024 18:35:03 GMT

Hello @Suresh_iast_332,

The premium package is a version created with each clients requirements, therefore there is not a unique premium package. You will need to speak with your FAE/NXP representative to determine which functionalities can be enabled/customized.

Let me know if you have more questions regarding this topic.

Best regards,

Alejandro