linux-kernel - Re: [PATCH v3] crypto: des3_ede: permit weak keys unless REQ_WEAK

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Message-ID: <20081206201720.GA18783@localhost.localdomain>
Date:	Sat, 6 Dec 2008 15:17:20 -0500
From:	Neil Horman <nhorman@...driver.com>
To:	Jarod Wilson <jarod@...hat.com>
Cc:	Herbert Xu <herbert@...dor.apana.org.au>,
	linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3] crypto: des3_ede: permit weak keys unless
	REQ_WEAK_KEY set

On Sat, Dec 06, 2008 at 12:39:38AM -0500, Jarod Wilson wrote:
> Jarod Wilson wrote:
>> While its a slightly insane to bypass the key1 == key2 ||
>> key2 == key3 check in triple-des, since it reduces it to the
>> same strength as des, some folks do need to do this from time
>> to time for backwards compatibility with des.
>>
>> My own case is FIPS CAVS test vectors. Many triple-des test
>> vectors use a single key, replicated 3x. In order to get the
>> expected results, des3_ede_setkey() needs to honor the weak
>> key flag.
>
> v2: make CRYPTO_TFM_REQ_WEAK_KEY flag usage consistent w/rest
> of crypto subsystem, per comments from Herbert in Red Hat
> bugzilla #474394.
>
> v3: set more appropriate RES flag, also per Herbert.
>
> Signed-off-by: Jarod Wilson <jarod@...hat.com>
>
> ---
>  crypto/des_generic.c |    5 +++--
>  1 files changed, 3 insertions(+), 2 deletions(-)
>
> diff --git a/crypto/des_generic.c b/crypto/des_generic.c
> index 5d0e458..5bd3ee3 100644
> --- a/crypto/des_generic.c
> +++ b/crypto/des_generic.c
> @@ -868,9 +868,10 @@ static int des3_ede_setkey(struct crypto_tfm *tfm, 
> const u8 *key,
>  	u32 *flags = &tfm->crt_flags;
>
>  	if (unlikely(!((K[0] ^ K[2]) | (K[1] ^ K[3])) ||
> -		     !((K[2] ^ K[4]) | (K[3] ^ K[5]))))
> +		     !((K[2] ^ K[4]) | (K[3] ^ K[5]))) &&
> +		     (*flags & CRYPTO_TFM_REQ_WEAK_KEY))
>  	{
> -		*flags |= CRYPTO_TFM_RES_BAD_KEY_SCHED;
> +		*flags |= CRYPTO_TFM_RES_WEAK_KEY;
>  		return -EINVAL;
>  	}
>
>
Looks good to me.  Thanks Jarod!
Acked-by: Neil Horman <nhorman@...driver.com>
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