IV generation in cryptographic driver in AEAD

IV generation in cryptographic driver in AEAD

[Denis B]

Hello,

In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
versions prior to 4.2 the cryptographic driver is expected to generate
an IV.

What if my driver is unable to generate an IV?

Thanks,
Dennis.

Re: IV generation in cryptographic driver in AEAD

[Catalin Vasile]

Inline comments.

________________________________________
From: linux-crypto-owner@vger.kernel.org <linux-crypto-owner@vger.kernel.org> on behalf of Denis B <begun.denis@gmail.com>
Sent: Wednesday, May 18, 2016 3:06 PM
To: linux-crypto@vger.kernel.org
Subject: IV generation in cryptographic driver in AEAD

Hello,

In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
versions prior to 4.2 the cryptographic driver is expected to generate
an IV.

What if my driver is unable to generate an IV?
[Catalin Vasile]
Simple: You do not implement the givcrypt() primitive. The kernel will generate the IV in software and then call your encrypt() primitive.

Thanks,
Dennis.
--
To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: IV generation in cryptographic driver in AEAD

[Denis B]

Forgive my dumbness, but in:

      .cra_type = &crypto_aead_type,
      .cra_u = {
            .aead = {
                .setkey = pp_crypto_aead_setkey,
                .setauthsize = pp_crypto_aead_setauthsize,
                .decrypt = pp_crypto_aead_dec,
                .encrypt = pp_crypto_aead_enc,
                .givencrypt = pp_crypto_aead_genivencrypt,
                .givdecrypt = pp_crypto_aead_genivdecrypt,
                .ivsize = AES_BLOCK_SIZE,
                .maxauthsize = SHA256_DIGEST_SIZE,
            },
      },

Just delete the givencrypt and givdecrypt lines (or set to NULL)?

On Wed, May 18, 2016 at 4:56 PM, Catalin Vasile <cata.vasile@nxp.com> wrote:
> Inline comments.
>
> ________________________________________
> From: linux-crypto-owner@vger.kernel.org <linux-crypto-owner@vger.kernel.org> on behalf of Denis B <begun.denis@gmail.com>
> Sent: Wednesday, May 18, 2016 3:06 PM
> To: linux-crypto@vger.kernel.org
> Subject: IV generation in cryptographic driver in AEAD
>
> Hello,
>
> In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
> versions prior to 4.2 the cryptographic driver is expected to generate
> an IV.
>
> What if my driver is unable to generate an IV?
> [Catalin Vasile]
> Simple: You do not implement the givcrypt() primitive. The kernel will generate the IV in software and then call your encrypt() primitive.
>
> Thanks,
> Dennis.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: IV generation in cryptographic driver in AEAD

[Herbert Xu]

Denis B <begun.denis@gmail.com> wrote:
> Forgive my dumbness, but in:
> 
>      .cra_type = &crypto_aead_type,
>      .cra_u = {
>            .aead = {
>                .setkey = pp_crypto_aead_setkey,
>                .setauthsize = pp_crypto_aead_setauthsize,
>                .decrypt = pp_crypto_aead_dec,
>                .encrypt = pp_crypto_aead_enc,
>                .givencrypt = pp_crypto_aead_genivencrypt,
>                .givdecrypt = pp_crypto_aead_genivdecrypt,
>                .ivsize = AES_BLOCK_SIZE,
>                .maxauthsize = SHA256_DIGEST_SIZE,
>            },
>      },
> 
> Just delete the givencrypt and givdecrypt lines (or set to NULL)?

You also need to set your cra_type to nivaead.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: IV generation in cryptographic driver in AEAD

[Catalin Vasile]

Inline comments

________________________________________
From: Denis B <begun.denis@gmail.com>
Sent: Wednesday, May 18, 2016 5:21 PM
To: Catalin Vasile
Cc: linux-crypto@vger.kernel.org
Subject: Re: IV generation in cryptographic driver in AEAD

Forgive my dumbness, but in:

      .cra_type = &crypto_aead_type,
      .cra_u = {
            .aead = {
                .setkey = pp_crypto_aead_setkey,
                .setauthsize = pp_crypto_aead_setauthsize,
                .decrypt = pp_crypto_aead_dec,
                .encrypt = pp_crypto_aead_enc,
                .givencrypt = pp_crypto_aead_genivencrypt,
                .givdecrypt = pp_crypto_aead_genivdecrypt,
                .ivsize = AES_BLOCK_SIZE,
                .maxauthsize = SHA256_DIGEST_SIZE,
            },
      },

Just delete the givencrypt and givdecrypt lines (or set to NULL)?
[Catalin Vasile]
You need to set it to NULL. If your struct is declared globally, the parts
that load your code will be set any uninitialized struct elements to NULL.

On Wed, May 18, 2016 at 4:56 PM, Catalin Vasile <cata.vasile@nxp.com> wrote:
> Inline comments.
>
> ________________________________________
> From: linux-crypto-owner@vger.kernel.org <linux-crypto-owner@vger.kernel.org> on behalf of Denis B <begun.denis@gmail.com>
> Sent: Wednesday, May 18, 2016 3:06 PM
> To: linux-crypto@vger.kernel.org
> Subject: IV generation in cryptographic driver in AEAD
>
> Hello,
>
> In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
> versions prior to 4.2 the cryptographic driver is expected to generate
> an IV.
>
> What if my driver is unable to generate an IV?
> [Catalin Vasile]
> Simple: You do not implement the givcrypt() primitive. The kernel will generate the IV in software and then call your encrypt() primitive.
>
> Thanks,
> Dennis.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: IV generation in cryptographic driver in AEAD

[Denis B]

My algs struct now looks like this:

static struct crypto_alg pp_crypto_algs[] = {
   {
      .cra_name = "authenc(hmac(sha256),cbc(aes))",
      .cra_driver_name = "pp_crypto_cbc_hmac_sha256",
      .cra_priority = 1, /**TODO set to highest values after
implementing encrypt decrypt functions */
      .cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC,
      .cra_blocksize = AES_BLOCK_SIZE,
      .cra_ctxsize = sizeof(struct pp_crypto_aead_ctx),
      .cra_type = &crypto_nivaead_type,
      .cra_u = {
            .aead = {
                .setkey = pp_crypto_aead_setkey,
                .setauthsize = pp_crypto_aead_setauthsize,
                .decrypt = pp_crypto_aead_dec,
                .encrypt = pp_crypto_aead_enc,
                .givencrypt = NULL,
                .givdecrypt = NULL,
                .ivsize = AES_BLOCK_SIZE,
                .maxauthsize = SHA256_DIGEST_SIZE,
            },
      },
      .cra_init = pp_crypto_aead_sha256_init,
      .cra_exit = pp_crypto_aead_exit,
      .cra_module = THIS_MODULE,
   },
   {
      .cra_name = "authenc(hmac(sha512),cbc(aes))",
      .cra_driver_name = "pp_crypto_cbc_hmac_sha512",
      .cra_priority = 1, /**TODO set to highest values after
implementing encrypt decrypt functions */
      .cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC,
      .cra_blocksize = AES_BLOCK_SIZE,
      .cra_ctxsize = sizeof(struct pp_crypto_aead_ctx),
      .cra_type = &crypto_nivaead_type,
      .cra_u = {
            .aead = {
                .setkey = pp_crypto_aead_setkey,
                .decrypt = pp_crypto_aead_dec,
                .encrypt = pp_crypto_aead_enc,
                .givencrypt = NULL,
                .givdecrypt = NULL,
                .ivsize = AES_BLOCK_SIZE,
                .maxauthsize = SHA512_DIGEST_SIZE,
            },
      },
      .cra_init = pp_crypto_aead_sha512_init,
      .cra_exit = pp_crypto_aead_exit,
      .cra_module = THIS_MODULE,
   }
};

I issue a ping and see esp_output() getting called. After that, I'm
used to seeing pp_crypto_givaead_enc() in my driver called. Now I see:

ping: sendto: Function not implemented


Please note that I am working with kernel 3.12, where in esp4.c line
266 we have:

err = crypto_aead_givencrypt(req);

On Thu, May 19, 2016 at 9:44 AM, Catalin Vasile <cata.vasile@nxp.com> wrote:
> Inline comments
>
> ________________________________________
> From: Denis B <begun.denis@gmail.com>
> Sent: Wednesday, May 18, 2016 5:21 PM
> To: Catalin Vasile
> Cc: linux-crypto@vger.kernel.org
> Subject: Re: IV generation in cryptographic driver in AEAD
>
> Forgive my dumbness, but in:
>
>       .cra_type = &crypto_aead_type,
>       .cra_u = {
>             .aead = {
>                 .setkey = pp_crypto_aead_setkey,
>                 .setauthsize = pp_crypto_aead_setauthsize,
>                 .decrypt = pp_crypto_aead_dec,
>                 .encrypt = pp_crypto_aead_enc,
>                 .givencrypt = pp_crypto_aead_genivencrypt,
>                 .givdecrypt = pp_crypto_aead_genivdecrypt,
>                 .ivsize = AES_BLOCK_SIZE,
>                 .maxauthsize = SHA256_DIGEST_SIZE,
>             },
>       },
>
> Just delete the givencrypt and givdecrypt lines (or set to NULL)?
> [Catalin Vasile]
> You need to set it to NULL. If your struct is declared globally, the parts
> that load your code will be set any uninitialized struct elements to NULL.
>
> On Wed, May 18, 2016 at 4:56 PM, Catalin Vasile <cata.vasile@nxp.com> wrote:
>> Inline comments.
>>
>> ________________________________________
>> From: linux-crypto-owner@vger.kernel.org <linux-crypto-owner@vger.kernel.org> on behalf of Denis B <begun.denis@gmail.com>
>> Sent: Wednesday, May 18, 2016 3:06 PM
>> To: linux-crypto@vger.kernel.org
>> Subject: IV generation in cryptographic driver in AEAD
>>
>> Hello,
>>
>> In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
>> versions prior to 4.2 the cryptographic driver is expected to generate
>> an IV.
>>
>> What if my driver is unable to generate an IV?
>> [Catalin Vasile]
>> Simple: You do not implement the givcrypt() primitive. The kernel will generate the IV in software and then call your encrypt() primitive.
>>
>> Thanks,
>> Dennis.
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: IV generation in cryptographic driver in AEAD

[Herbert Xu]

Denis B <begun.denis@gmail.com> wrote:
> My algs struct now looks like this:
> 
> static struct crypto_alg pp_crypto_algs[] = {
>   {
>      .cra_name = "authenc(hmac(sha256),cbc(aes))",
>      .cra_driver_name = "pp_crypto_cbc_hmac_sha256",
>      .cra_priority = 1, /**TODO set to highest values after
> implementing encrypt decrypt functions */
>      .cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC,
>      .cra_blocksize = AES_BLOCK_SIZE,
>      .cra_ctxsize = sizeof(struct pp_crypto_aead_ctx),
>      .cra_type = &crypto_nivaead_type,
>      .cra_u = {
>            .aead = {
>                .setkey = pp_crypto_aead_setkey,
>                .setauthsize = pp_crypto_aead_setauthsize,
>                .decrypt = pp_crypto_aead_dec,
>                .encrypt = pp_crypto_aead_enc,
>                .givencrypt = NULL,
>                .givdecrypt = NULL,
>                .ivsize = AES_BLOCK_SIZE,
>                .maxauthsize = SHA256_DIGEST_SIZE,

You also need to set geniv to "eseqiv".

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: IV generation in cryptographic driver in AEAD

[Gary R Hook]

On 05/19/2016 11:19 PM, Herbert Xu wrote:
> Denis B <begun.denis@gmail.com> wrote:
>> My algs struct now looks like this:
>>
>> static struct crypto_alg pp_crypto_algs[] = {
>>    {
>>       .cra_name = "authenc(hmac(sha256),cbc(aes))",
>>       .cra_driver_name = "pp_crypto_cbc_hmac_sha256",
>>       .cra_priority = 1, /**TODO set to highest values after
>> implementing encrypt decrypt functions */
>>       .cra_flags = CRYPTO_ALG_TYPE_AEAD | CRYPTO_ALG_ASYNC,
>>       .cra_blocksize = AES_BLOCK_SIZE,
>>       .cra_ctxsize = sizeof(struct pp_crypto_aead_ctx),
>>       .cra_type = &crypto_nivaead_type,
>>       .cra_u = {
>>             .aead = {
>>                 .setkey = pp_crypto_aead_setkey,
>>                 .setauthsize = pp_crypto_aead_setauthsize,
>>                 .decrypt = pp_crypto_aead_dec,
>>                 .encrypt = pp_crypto_aead_enc,
>>                 .givencrypt = NULL,
>>                 .givdecrypt = NULL,
>>                 .ivsize = AES_BLOCK_SIZE,
>>                 .maxauthsize = SHA256_DIGEST_SIZE,
>
> You also need to set geniv to "eseqiv".

I just gotta ask. Forgive my ignorance.

Why is (or should) setting geniv (be) required?

crypto_givcipher_default() appears to call crypto_default_geniv() if the 
geniv member
is NULL. That function returns "eseqiv" or "chainiv" (under certain 
conditions). If an
implementation isn't generating its own IVs, shouldn't the default 
happen anyway? Or is
this more a matter of populating the structure with known, intentional 
values?

Thank you for any illumination provided.

Gary

Re: IV generation in cryptographic driver in AEAD

[Herbert Xu]

On Fri, May 20, 2016 at 10:50:38AM -0500, Gary R Hook wrote:
>
> Why is (or should) setting geniv (be) required?
> 
> crypto_givcipher_default() appears to call crypto_default_geniv() if
> the geniv member
> is NULL. That function returns "eseqiv" or "chainiv" (under certain
> conditions). If an
> implementation isn't generating its own IVs, shouldn't the default
> happen anyway? Or is
> this more a matter of populating the structure with known,
> intentional values?
> 
> Thank you for any illumination provided.

In the upstream kernel AEAD geniv has been completely phased out
and no longer exists.  Denis is working on an old kernel that still
has it.

We haven't yet phased it out for skcipher but I'm working on it.

Cheers,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

Re: IV generation in cryptographic driver in AEAD

[Gary R Hook]

On 05/20/2016 06:31 PM, Herbert Xu wrote:
> On Fri, May 20, 2016 at 10:50:38AM -0500, Gary R Hook wrote:
>>
>> Why is (or should) setting geniv (be) required?
>>
>> crypto_givcipher_default() appears to call crypto_default_geniv() if
>> the geniv member
>> is NULL. That function returns "eseqiv" or "chainiv" (under certain
>> conditions). If an
>> implementation isn't generating its own IVs, shouldn't the default
>> happen anyway? Or is
>> this more a matter of populating the structure with known,
>> intentional values?
>>
>> Thank you for any illumination provided.
>
> In the upstream kernel AEAD geniv has been completely phased out
> and no longer exists.  Denis is working on an old kernel that still
> has it.
>
> We haven't yet phased it out for skcipher but I'm working on it.

...and there was light.

Thank you; very helpful.

(I'll work harder on my line wraps... If someone knows how to get 
Thunderbird
to do it for me, I'd love to know.)

Re: IV generation in cryptographic driver in AEAD

[Stephan Mueller]

Am Mittwoch, 18. Mai 2016, 15:06:19 schrieb Denis B:

Hi Denis,

> Hello,
> 
> In AEAD mode (or in any case, in IPSec ESP IPv4 – esp4.c), in kernel
> versions prior to 4.2 the cryptographic driver is expected to generate
> an IV.

The driver is not expected to generate the IV. Please see the ASCII art at 
[1]. The IV generation is done with the seqiv component. So, you driver can 
implement all of the logic of GCM, but pull the IV generation from the C 
implementation provided by the kernel crypto API.

[1] http://www.chronox.de/crypto-API/ch02s07.html
> 
> What if my driver is unable to generate an IV?
> 
> Thanks,
> Dennis.
> --
> To unsubscribe from this list: send the line "unsubscribe linux-crypto" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html


Ciao
Stephan