topic Re: Encrypted Key (KEK) injection in Secure Authentication

Encrypted Key (KEK) injection

psvz — Mon, 26 Dec 2022 17:17:12 GMT

I couldn't find source code for function Se05x_API_WriteSymmKey()

Could you please confirm that key decryption and persistence is handled atomically inside SE050, so that decrypted key is never transmitted back to the host?

I can see from the source code that only symmetric keys can be injected with KEK. Could you please confirm requirements for KEK itself - is it only AES? DES? Could it be asymmetric? It would help if you had some example code...

Thank you.

Re: Encrypted Key (KEK) injection

Kan_Li — Tue, 27 Dec 2022 03:22:50 GMT

Hi @psvz ,

Are you going to inject a symmetric key for both Encryption and Decryption? If so , please kindly refer to the demo in "simw-top\sss\ex\symmetric\ex_sss_symmetric.c" for details.

For symmetric keys, read back is not possible.

Have a great day,
Kan

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Re: Encrypted Key (KEK) injection

psvz — Tue, 27 Dec 2022 11:42:07 GMT

@Kan_Li - the example simw-top\sss\ex\symmetric\ex_sss_symmetric.c does NOT use KEK, so it is not helpful. Let's discuss all the questions because it is a deal-breaker for me:

1/ where is the source code for function Se05x_API_WriteSymmKey()?

2/ when injecting with KEK (no examples available) - could you please confirm that key decryption and persistence is handled atomically inside SE050, so that decrypted key is never transmitted back to the host?

3/ What type of key (AES, DES, RSA, EC) can SE050 use as KEK (not documented)?

If you could please answer each question or point me out to NXP product folks who could help?

Thank you.

Re: Encrypted Key (KEK) injection

Kan_Li — Wed, 28 Dec 2022 03:11:36 GMT

Hi @psvz ,

Please kindly refer to the following for details.

1/ where is the source code for function Se05x_API_WriteSymmKey()?

-Please refer to \simw-top\hostlib\hostLib\se05x_03_xx_xx\se05x_APDU_impl.h for details.

- Yes, they are handled automatically inside the SE.

3/ What type of key (AES, DES, RSA, EC) can SE050 use as KEK (not documented)?

-The key type is defined in https://www.rfc-editor.org/rfc/rfc3394 .

Please kindly refer to https://www.nxp.com/docs/en/application-note/AN12413.pdf for more details.

Hope that helps,

Have a great day,
Kan

Re: Encrypted Key (KEK) injection

psvz — Wed, 28 Dec 2022 13:47:27 GMT

@Kan_Li - Kan, this is very very VERY helpful!!! You've made my day - Thanks a lot!