On Wed, 19 Aug 2009 13:19:54 +0200 "CEVAN Ondrej" <Ondrej.CEVAN@xxxxxxxxxxxxxx> wrote: > Hello everybody, > > according to the function call in drivers/crypto/talitos.c (Linux version > 2.6.29) in function ipsec_esp(): > > /*hmac data*/ > map_single_talitos_ptr(dev, &desc->ptr[1], sg_virt(areq->src) - > sg_virt(areq->assoc), sg_virt(areq->assoc), 0, DMA_TO_DEVICE); > > if initialization vector (IV) should be included for HMAC computation, it > must be in the memory after the associated data (ASSOC) and after ASSOC and > IV the areq->src data must follow. Thus in memory it should look like: > +---------+------+-------------------------+ > | ASSOC | IV | DATA to encrypt/decrypt | > +---------+------+-------------------------+ > > Is my assumption right? Well my code is working but I want to ask you if it yes, I recently posted a patch to change the above (assoc - src) pointer math, to an (assoclen + ivsize) calculation. > is really a requirement that is hopefully somewhere specified. Where could I > find such information? My searching in Documentation dir and Google was > without success. it's specified in the code :) It's a requirement for IPSec ESP, of which a good guide can be found here: http://unixwiz.net/techtips/iguide-ipsec.html > Also, how does it work when I do not want to use ASSOC but still the IV > should be included in HMAC computation? Is it then intended that the pointer > areq->assoc points on the IV? Or am I not in the right ballpark? yes, I imagine the request would come in with its 'assoc' pointer equal to its 'giv'. For an authenc request for IPsec ESP, req->assoc points to the ESP header (SPI+seq.num), req->giv points after the ESP header to the IV, and req->src points to the data to be ciphered (which directly follows the IV). Kim -- To unsubscribe from this list: send the line "unsubscribe linux-crypto" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
