On Wed, Nov 23, 2011 at 8:08 AM, Steffen Klassert
<steffen.klassert@xxxxxxxxxxx> wrote:
> Hi.
>
> On Wed, Nov 23, 2011 at 12:00:29AM +0200, Kasatkin, Dmitry wrote:
>> Hi,
>>
>> I have noticed very odd behavior with hmac calculation on my dual
>> core, 4 HTs PC.
>> I am using async hash API to to calculate hmac over the page.
>> I am using "hmac(sha1)" and the same key to calculate different pages.
>>
>> I have a work queue, which calculates the hmac like...
>>
>> int()
>> {
>> tfm = crypto_alloc_ahash(...);
>> }
>>
>> work_task()
>> {
>> crypto_ahash_setkey(tfm, key, keylen);
>> crypto_ahash_digest(req);
>> }
>>
>> HMAC result "sometimes" is incorrect.
>
> Looks like a race. HMAC precalculates the hash of the ipaded/opaded key
> and saves this hash on the transform. So the setkey method should be used
> just once in the initialization path.
>
>>
>> But when I move crypto_ahash_setkey() do the initialization code then
>> HMAC result is always correct...
>> (key is the same, so I can initialize it only once)
>>
>> int()
>> {
>> tfm = crypto_alloc_ahash(...);
>> crypto_ahash_setkey(tfm, key, keylen);
>> }
>
> That's how it should be. And in this case it works, as you
> already noticed :)
>
>
Thanks...
See my another reply...
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