Re: [dpdk-dev] [PATCH] cryptodev: formalize key wrap method in API

[Akhil Goyal <gakhil@marvell.com>]

> Hi Akhil
> 
> From: Akhil Goyal
> > Hi Matan,
> >
> > > The Key Wrap approach is used by applications in order to protect keys
> > > located in untrusted storage or transmitted over untrusted
> > > communications networks. The constructions are typically built from
> > > standard primitives such as block ciphers and cryptographic hash
> > > functions.
> > >
> > > The Key Wrap method and its parameters are a secret between the keys
> > > provider and the device, means that the device is preconfigured for
> > > this method using very secured way.
> > >
> > > The key wrap method may change the key length and layout.
> > >
> > > Add a description for the cipher transformation key to allow wrapped
> > > key to be forwarded by the same API.
> > >
> > > Signed-off-by: Matan Azrad <matan@nvidia.com>
> > > ---
> >
> > How will the driver gets notified whether the key is wrapped or not?
> > The driver would expect the keys are as per the capabilities exposed.
> > If it does not check as per the capabilities, how will it identify a bad Key len
> and
> > the wrapped key length?
> 
> As I wrote, the device is preconfigured to the key wrapping mode in very
> secured way.
> No one knows this secret except the device and the key provider (outside the
> crypto lib and dpdk application).
> The driver may know something but not necessarily.
> If the device validation to the key is failed, the driver will return an error to
> the app.
> 
Shouldn't this be a capability/feature flag whether it can be supported by the underlying
Driver or not?

I am not saying that the driver should know the details of the wrapping mode.
But it can be asked, whether it support this wrapping mode or not?


> 
> > >  lib/librte_cryptodev/rte_crypto_sym.h | 7 +++++++
> > >  1 file changed, 7 insertions(+)
> > >
> > > diff --git a/lib/librte_cryptodev/rte_crypto_sym.h
> > > b/lib/librte_cryptodev/rte_crypto_sym.h
> > > index 5973e31..6aca2c7 100644
> > > --- a/lib/librte_cryptodev/rte_crypto_sym.h
> > > +++ b/lib/librte_cryptodev/rte_crypto_sym.h
> > > @@ -200,6 +200,13 @@ struct rte_crypto_cipher_xform {
> > >               uint16_t length;        /**< key length in bytes */
> > >       } key;
> > >       /**< Cipher key
> > > +      * The original key data may be provided wrapped (encrypted)
> > > + using
> > > a key
> > > +      * wrap algorithm such as AES key wrap (from rfc3394) or other.
> > > + In
> > > such
> > > +      * case, the wrapping details is a secret between the key provider and
> > > +      * the device. Such key wrapping may increase the length of the
> > > provided
> > > +      * key beyond the advertised supported key size. Hence it is the
> > > +      * responsibility of the driver/device to validate the length of the
> > > +      * provided key.
> > >        *
> > >        * For the RTE_CRYPTO_CIPHER_AES_F8 mode of operation, key.data
> > > will
> > >        * point to a concatenation of the AES encryption key followed
> > > by a
> > > --
> > > 1.8.3.1