I assume you're talking about the |return_size| indirection here. I think you will see much more of them as soon as the asymmetric algorithms start to show up, as they should naturally contain get_params functionality for the numbers of the key objects. For the moment being, we aren't seeing much of that kind of functionality.
Cheers, Richard On Wed, 05 Jun 2019 02:50:07 +0200, Dr Paul Dale wrote: > > > I thought the references were to allow const arrays of OSSL_PARAM to be > viable. > > A quick check through the code reveals these in test and doc only. There are > two instances of > OSSL_PARAM arrays being declared in evp, both add the pointed to variable > after creation, both > only have two elements (the integer and the terminator) and both are stack > allocated. I.e. there > is currently is no example of the use case for which the indirection is > present :( > > Pauli > -- > Dr Paul Dale | Cryptographer | Network Security & Encryption > Phone +61 7 3031 7217 > Oracle Australia > > On 5 Jun 2019, at 10:31 am, SHANE LONTIS <shane.lon...@oracle.com> wrote: > > I presume the reference approach was used to solve the issue of who > actually owns/free's the > data. > > On 5 Jun 2019, at 9:18 am, Dr Paul Dale <paul.d...@oracle.com> wrote: > > Shane’s major complaints are about the indirection the OSSL_PARAM > structure forces ― for > integers and return lengths and the necessity of allocating > additional memory in parallel > with the OSSL_PARAM. > > The extra indirection was intended to support const arrays of > OSSL_PARAM, which turn out > to be a rarity because they aren’t thread safe. With most OSSL_PARAM > structure being > dynamically created, the need for the indirection seems redundant. > E.g. could the return > length be moved into OSSL_PARAM? I think so. > > Moving integral values into the structure is more difficult because > BIGNUMs will always > need to be references. Allocating additional memory will still be > required. I’ve got > three obvious solutions: > > 1. include a void * in the OSSL_PARAM structure that needs to be > freed when the structure > is destroyed or > 2. have a block of data in the OSSL_PARAM structure that can be used > for native types > (OSSL_UNION_ALIGN works perfectly for this) or > 3. add a flag field to the OSSL_PARAM to indicate that the referenced > value needs to be > freed. > > The memory allocation comes to the for when reading e.g. a file and > extracting data ― > either the reader needs a lot of local variables to hold everything > or it has to allocated > for each. The file’s data is transient in memory. > > For the most part, the receiver side APIs seem reasonable. It is the > owning side that has > the complications. > > I think I might be able come up with some owner side routines that > assist here but > allowing changes to the params structure would be far easier. > > I kind of like using the OSSL_PARAM arrays as a replacement for > string ctrl functions if > not ctrl as well (subject to backward compatibility concerns). > > Pauli > -- > Dr Paul Dale | Cryptographer | Network Security & Encryption > Phone +61 7 3031 7217 > Oracle Australia > > On 4 Jun 2019, at 11:26 pm, Richard Levitte <levi...@openssl.org> > wrote: > > On Tue, 04 Jun 2019 14:57:00 +0200, > Salz, Rich wrote: > > Part of the idea was that this would be a means of > communication > > between application and provider, just like controls are > with > libcrypto sub-systems. > > I can probably find the email thread (or maybe it was a GitHub > comment on my proposal for params), where you said, quite > definitively, that this was *not* a general-purpose mechanism > but > rather a way to expose the necessary internals for opaque > objects > like RSA keys. > > Either I misunderstood what you said at the time, or you > misunderstood > what I said... there's definitely a disconnect here somewhere. > > What I wonder is why it should be exclusively only one of those > options? > > Either way, the OSSL_PARAM is defined publically and openly (i.e. > non-opaque), and we currently have the following functions in the > public API: > > EVP_MD_CTX_set_params > EVP_MD_CTX_get_params > OSSL_PROVIDER_get_params > > I fully expect that more will come. I have a branch where I've > EVP_MAC_CTX_set_params, for example, and I wouldn't be surprised > if > EVP_CIPHER_CTX_set_params and EVP_CIPHER_CTX_get_params appear > before > long (I'm actually rather surprised they haven't already), and I'm > absolutely sure we will see similar functions for asymmetric > algorithms. > > What changed your mind? > > Perhaps not surprisingly, I agree with Shane's assessment and > am > strongly opposed to the project foisting this on everyone at > this > time. @DavidBen, your thoughts? > > Maybe we're reading differently, I didn't see Shane being opposed > to > parameter passing in this way per se, just the exact form of the > OSSL_PARAM structure, which is different. > > Cheers, > Richard > > -- > Richard Levitte levi...@openssl.org > OpenSSL Project http://www.openssl.org/~levitte/ > > -- Richard Levitte levi...@openssl.org OpenSSL Project http://www.openssl.org/~levitte/
