On Wed, Jan 18, 2012 at 2:26 PM, David Howells <dhowells@xxxxxxxxxx> wrote: > Kasatkin, Dmitry <dmitry.kasatkin@xxxxxxxxx> wrote: > >> It would also nice to have an API to supply pre-computed data hash. For >> example IMA uses the same functionality to compute the hash of the file >> content, and then, based on security.ima type decided either verify it using >> just hash, or use digital signature. We could pass a hash as data. But may >> be we do not want to have extra operation and compute hash over hash. > > If I understand you correctly, you'd like to have the option to do the hashing > externally to this API? Would you supply the completed hash or just a hash > with the data in it, and require this API to complete it (ie. chuck metadata > into it)? > I meant just a hash of data.. Right, I remember, PGP finalizes hash with some additional metadata pgp_pkey_digest_signature() seems does it... > I don't think it should be hard. I could add an alternative to > verify_sig_add_data() perhaps. Either that or one function that does the lot > and takes the precomputed hash as input. There would be no need for the split > into four functions (begin, add_data, end, cancel) in such a case. The reason > for the split is so that the caller can invoke add_data several times with > non-contiguous bits of data. > Yes. it is clear... Would it be possible to have pass data (uncompleted) hash? > It might even make sense to expose the crypto hash object for direct access > rather than use add_data - but that then makes it hard to use crypto hardware > where you would just shovel the raw data into it and it does all the hashing > and cryptography in a black box. > > David > -- > 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 -- 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
