[dpdk-dev] [PATCH] cryptodev: support multiple cipher block sizes

Matan Azrad matan at nvidia.com
Mon Feb 8 14:36:58 CET 2021


Hi Kuztal

From: Kusztal, ArkadiuszX
> Hi Matan,
> 
> Few comments/questions inline with [Arek]
> 
> > -----Original Message-----
> > From: dev <dev-bounces at dpdk.org> On Behalf Of Matan Azrad
> > Sent: Thursday, February 4, 2021 3:34 PM
> > To: dev at dpdk.org
> > Cc: akhil.goyal at nxp.com; Doherty, Declan <declan.doherty at intel.com>;
> > Somalapuram Amaranath <asomalap at amd.com>; Ruifeng Wang
> > <ruifeng.wang at arm.com>; Ajit Khaparde <ajit.khaparde at broadcom.com>;
> > Anoob Joseph <anoobj at marvell.com>; Zhang, Roy Fan
> > <roy.fan.zhang at intel.com>; Griffin, John <john.griffin at intel.com>; De
> > Lara Guarch, Pablo <pablo.de.lara.guarch at intel.com>; Michael Shamis
> > <michaelsh at marvell.com>; Nagadheeraj Rottela
> > <rnagadheeraj at marvell.com>; Ankur Dwivedi <adwivedi at marvell.com>;
> > Gagandeep Singh <g.singh at nxp.com>; Jay Zhou <jianjay.zhou at huawei.com>
> > Subject: [dpdk-dev] [PATCH] cryptodev: support multiple cipher block
> > sizes
> >
> > In cryptography, a block cipher is a deterministic algorithm operating
> > on fixed- length groups of bits, called blocks.
> >
> > A block cipher consists of two paired algorithms, one for encryption
> > and the other for decryption. Both algorithms accept two inputs:
> > an input block of size n bits and a key of size k bits; and both yield
> > an n-bit output block. The decryption algorithm is defined to be the
> > inverse function of the encryption.
> >
> > Some cipher algorithms support multiple block sizes, e.g. AES-XTS
> > supports any block size in range [16B, 2^24B], in this case, A
> > plain-text data, divided into N amount of n-bits blocks, which is
> > encrypted to the same data size, cipher-text, must be decrypted in the
> > same division of N amount of n-bits blocks in order to get the same plain-text
> data.
> [Arek] - Except that the last data block does not need to be n-bit long, beside
> that and lack of chaining it makes XTS no different to any other block cipher
> mode of operation.
> Block size itself for XTS-AES is always 16 bytes in the first place which is AES
> constraint.
> 2^20 * 16B -> 2^24B constraint from IEEE 1619-2017, SP800-38E is data unit
> length that contains "data unit in bytes/ 16" AES blocks where last one can be
> incomplete.
> 
> >
> > The current cryptodev API doesn't allow the user to select a specific
> > block size supported by the devices In addition, there is no
> > definition how the IV is detected per block when single operation includes
> more than one block.
> 
> [Arek] - Do you mean tweak increment per data unit? Like one op as a data
> stream (multiple data units) and tweak incremented by pmd?

It can be defined differently per algorithm.
I know from AES-XTS standard that the tweak should be incremented by 1 per data-unit.
So, yes, here, the driver\device should take care for the incrementation.
  

> 
> >
> > That causes applications to use single operation per block even though
> > all the data is continuous in memory what reduces datapath performance.
> >
> > Add a new feature flag to support multiple block sizes, called
> > RTE_CRYPTODEV_FF_CIPHER_MULITPLE_BLOCKS.
> > Add a new field in cipher capability, called bsf - block size flags,
> > where the devices can report the range of the supported block sizes.
> > Add a new cipher transformation field, called block_size, where the
> > user can select one block size from the supported range.
> >
> > All the new fields do not change the size of their structures.
> >
> > Using flags to report the supported block sizes capability allows the
> > devices to report a range simply as same as the user to read it simply.
> > Also, thus sizes are usually common and probably will be shared
> > between the devices.
> >
> > Signed-off-by: Matan Azrad <matan at nvidia.com>
> > ---
> >  lib/librte_cryptodev/rte_crypto_sym.h | 12 ++++++++++++
> > lib/librte_cryptodev/rte_cryptodev.h  | 23 ++++++++++++++++++++++-
> >  2 files changed, 34 insertions(+), 1 deletion(-)
> >
> > diff --git a/lib/librte_cryptodev/rte_crypto_sym.h
> > b/lib/librte_cryptodev/rte_crypto_sym.h
> > index 9d572ec..9a1215d 100644
> > --- a/lib/librte_cryptodev/rte_crypto_sym.h
> > +++ b/lib/librte_cryptodev/rte_crypto_sym.h
> > @@ -265,6 +265,18 @@ struct rte_crypto_cipher_xform {
> >                * which can be in the range 7 to 13 inclusive.
> >                */
> >       } iv;   /**< Initialisation vector parameters */
> > +
> > +     uint32_t block_size;
> > +     /**< When RTE_CRYPTODEV_FF_CIPHER_MULITPLE_BLOCKS is
> > reported, this is
> > +      * the block size of the algorithm, otherwise or when the value is 0,
> > +      * use the default block size provided in the capability.
> > +      * The value should be in the range defined by the bsf field in the
> > +      * cipher capability.
> 
> [Arek] - nowadays algorithms rather don't have different block sizes, though I
> see people set this field even for stream ciphers.
> If such algorithm would happen it probably could just get a suffix in
> crypto_cipher_enum. Otherwise some fixed size array could be added.

First, if no different block size per algorithm, why do we need this parameter at all?

Second,
Cipher block defined to be like this D(E(b)) = b
D: decryption function
E: encryption function
P: plain-text block data.

In case of AES-XTS the cipher block size is the data-unit size.
There is a big range of optional data, see in standard.


> > +      *
> > +      * - For AES-XTS it is the size of data-unit, from IEEE Std 1619-2007.
> > +      * For-each data-unit in the operation, the tweak(IV) value is
> > +      * assigned consecutively starting from the operation assigned tweak.
> > +      */
> [Arek] - if data unit would be session value (key scope in xts naming) where the
> number of units would be taken from, sym_op->len ?

Yes, it is already defined there that it must be multiple of block size(data-unit in AES-XTS case).

> (For standard storage example: data unit size -> logical block size, sym_op->len
> -> range of consecutive logical blocks.) If so it probably could be session-less op
> as this cipher key would be unusable after it.
> 

Can be session and session-less modes.

If the user want to operate on different groups of blocks in the same stream
he can use the same session(key) with different ops.

Am I missing here?

> >  };
> >
> >  /** Symmetric Authentication / Hash Algorithms diff --git
> > a/lib/librte_cryptodev/rte_cryptodev.h
> > b/lib/librte_cryptodev/rte_cryptodev.h
> > index ae34f33..60ba839 100644
> > --- a/lib/librte_cryptodev/rte_cryptodev.h
> > +++ b/lib/librte_cryptodev/rte_cryptodev.h
> > @@ -96,6 +96,19 @@ struct rte_crypto_param_range {  };
> >
> >  /**
> > + * Crypto device supported block size flags for cipher algorithms
> > + * Each flag represents single or range of supported block sizes  */
> > +#define RTE_CRYPTO_CIPHER_BSF_ALL 0x1
> > +/* All the sizes from the algorithm standard */ #define
> > +RTE_CRYPTO_CIPHER_BSF_512_BYTES 0x2 #define
> > +RTE_CRYPTO_CIPHER_BSF_520_BYTES 0x4 #define
> > +RTE_CRYPTO_CIPHER_BSF_4048_BYTES 0x8 #define
> > +RTE_CRYPTO_CIPHER_BSF_4096_BYTES 0x10 #define
> > +RTE_CRYPTO_CIPHER_BSF_4160_BYTES 0x20 #define
> > +RTE_CRYPTO_CIPHER_BSF_1M_BYTES 0x40
> [Arek] - when adding constants source should be attached as well.
> > +
> > +/**
> >   * Symmetric Crypto Capability
> >   */
> >  struct rte_cryptodev_symmetric_capability { @@ -122,11 +135,19 @@
> > struct rte_cryptodev_symmetric_capability {
> >                       enum rte_crypto_cipher_algorithm algo;
> >                       /**< cipher algorithm */
> >                       uint16_t block_size;
> > -                     /**< algorithm block size */
> > +                     /**<
> > +                      * algorithm block size
> > +                      * For algorithms support more than single block size,
> > +                      * this is the default block size supported by the
> > +                      * driver, all the supported sizes are reflected in the
> > +                      * bsf field.
> > +                      */
> >                       struct rte_crypto_param_range key_size;
> >                       /**< cipher key size range */
> >                       struct rte_crypto_param_range iv_size;
> >                       /**< Initialisation vector data size range */
> > +                     uint32_t bsf;
> > +                     /**< Block size flags */
> >               } cipher;
> >               /**< Symmetric Cipher transform capabilities */
> >               struct {
> > --
> > 1.8.3.1



More information about the dev mailing list