Hi Experts,

I have some questions about crypto persisten keys.

1. psa_open_key() is removed in psa crypto spec,so it is impossible to import a persistent key into key slot with key_id,which means encrypt/decrypt data directly with a persistent key is not allowed,these persistent keys can only be

used to derive volatile keys which will be used for encryption/decryption, I am not sure if I understand correctly.

2. Besides,HUK can be used to derive the other crypto keys,such as ps crypto key.HUK may be stored in OTP area of MCU(without crypto element such as cc312),then what's intended flow to derive crypto keys from HUK via calling PSA crypto service?There is no reference implementation in tf-m code.

tfm_plat_get_huk_derived_key(){

get HUK from OTP
||
||
\/
how to derive crypto key from HUK with calling crypto service?
}

3. BTW,HUK has a persistent key id TFM_CRYPTO_KEY_ID_HUK defined in tfm_crypto_defs.h,but I haven't seen any reference to this macro. What's the intended use of this key id?And what's the key owner of HUK?

Best Regards,
Poppy Wu

Macronix Microelectronics (Suzhou) Co.,Ltd
http://www.mxic.com.cn

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