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SubjectRe: [PATCH v4 4/5] crypto: caam - add in-kernel interface for blob generator
Hello Jarkko,

On 05.12.21 01:18, Jarkko Sakkinen wrote:
> On Mon, Oct 11, 2021 at 12:02:37PM +0200, Ahmad Fatoum wrote:
>> The CAAM can be used to protect user-defined data across system reboot:
>> - When the system is fused and boots into secure state, the master
>> key is a unique never-disclosed device-specific key
>> - random key is encrypted by key derived from master key
>> - data is encrypted using the random key
>> - encrypted data and its encrypted random key are stored alongside
>> - This blob can now be safely stored in non-volatile memory
>> On next power-on:
>> - blob is loaded into CAAM
>> - CAAM writes decrypted data either into memory or key register
>> Add functions to realize encrypting and decrypting into memory alongside
>> the CAAM driver.
>> They will be used in a later commit as a source for the trusted key
>> seal/unseal mechanism.
>> Reviewed-by: David Gstir <>
>> Tested-By: Tim Harvey <>
>> Signed-off-by: Steffen Trumtrar <>
>> Signed-off-by: Ahmad Fatoum <>
> What is CAAM? This is missing.

That's Crypto Accelerator on NXP SoCs. There is a description in the cover
letter and in the follow-up patch wiring this into the new trusted key
source. I didn't elaborate on this here as this patch touches
drivers/crypto/caam and I assumed familiarity.

For v5, I can add some extra info:

"The NXP Cryptographic Acceleration and Assurance Module (CAAM)
can be used to protect user-defined data across system reboot..."

Sounds good? Does the last patch in the series look ok to you?


> /Jarkko

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