Re: [RFC PATCH 1/2] crypto: Allow working with key references

[Richard Weinberger]

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> Von: "Herbert Xu" <herbert@xxxxxxxxxxxxxxxxxxx>
> An: "richard" <richard@xxxxxx>
> CC: "Linux Crypto Mailing List" <linux-crypto@xxxxxxxxxxxxxxx>, linux-arm-kernel@xxxxxxxxxxxxxxxxxxx, "linux-kernel"
> <linux-kernel@xxxxxxxxxxxxxxx>, linux-imx@xxxxxxx, festevam@xxxxxxxxx, "kernel" <kernel@xxxxxxxxxxxxxx>, "Sascha Hauer"
> <s.hauer@xxxxxxxxxxxxxx>, shawnguo@xxxxxxxxxx, davem@xxxxxxxxxxxxx, "david" <david@xxxxxxxxxxxxx>
> Gesendet: Donnerstag, 30. Mai 2019 04:33:57
> Betreff: Re: [RFC PATCH 1/2] crypto: Allow working with key references

> On Thu, May 30, 2019 at 12:48:43AM +0200, Richard Weinberger wrote:
>> Some crypto accelerators allow working with secure or hidden keys.
>> This keys are not exposed to Linux nor main memory. To use them
>> for a crypto operation they are referenced with a device specific id.
>> 
>> This patch adds a new flag, CRYPTO_TFM_REQ_REF_KEY.
>> If this flag is set, crypto drivers should tread the key as
>> specified via setkey as reference and not as regular key.
>> Since we reuse the key data structure such a reference is limited
>> by the key size of the chiper and is chip specific.
>> 
>> TODO: If the cipher implementation or the driver does not
>> support reference keys, we need a way to detect this an fail
>> upon setkey.
>> How should the driver indicate that it supports this feature?
>> 
>> Signed-off-by: Richard Weinberger <richard@xxxxxx>
> 
> We already have existing drivers doing this.  Please have a look
> at how they're doing it and use the same paradigm.  You can grep
> for paes under drivers/crypto.

Thanks for the pointer.
So the preferred way is defining a new crypto algorithm prefixed with
"p" and reusing setkey to provide the key reference.

Thanks,
//richard