Store Mgmt and keys loading ( keyform ENG )

Antonio Santagiuliana santantonioswap at gmail.com
Fri Oct 8 08:34:33 UTC 2021


Could I ask you what is the best way to let the Openssl carry on in the
case I can't pass the private key from my store manager load() function as
key is offloaded in secure hw?
I have set RSA_FLAG_EXT_PKEY in RSA_METHOD but if I don't call the callback
function from my Store Mgmt's load() where I get the uri ( the callback
func is ossl_store_handle_load_result() ) I get error "could not read the
private key".
If instead I call the callback func , I don't know how to fill in its
params , as I don't have the private key. What should I put in the params
to let the rest of call chain ( I am on the dgst command ) not caring about
private key but carry on with operation?or can I avoid calling the callback?
Thank you

On Thu, 7 Oct 2021, 09:47 Antonio Santagiuliana, <santantonioswap at gmail.com>
wrote:

> It is because of prototypes of methods..
>
> On Thu, 7 Oct 2021, 08:49 Antonio Santagiuliana, <
> santantonioswap at gmail.com> wrote:
>
>> Hello,
>> just continuing on this..
>> I defined my store mgmt as :
>> static const OSSL_ALGORITHM test_store[] = {
>> { "handle", "provider=test", mystore_functions},
>> {NULL, NULL, NULL}
>> };
>>
>> echo "test" | LD_LIBRARY_PATH=.    apps/openssl  dgst
>> --provider-path=./providers --provider=test  --sign handle:1 -out
>> messa.encrypted.bin
>>
>> Could not open file or uri for loading private key from handle:1
>>
>> C0628C24787F0000:error:16000069:STORE
>> routines:ossl_store_get0_loader_int:unregistered
>> scheme:crypto/store/store_register.c:237:scheme=file
>>
>> C0628C24787F0000:error:1608010C:STORE
>> routines:inner_loader_fetch:unsupported:crypto/store/store_meth.c:356:No
>> store loader found. For standard store loaders you need at least one
>> of the default or base providers available. Did you forget to load
>> them? Info: Global default library context, Scheme (file : 0),
>> Properties (<null>)
>>
>> C0628C24787F0000:error:16000069:STORE
>> routines:ossl_store_get0_loader_int:unregistered
>> scheme:crypto/store/store_register.c:237:scheme=handle
>>
>> 1) It firstly looks for a provider for scheme file: and it doesn't
>> find as I haven't set up any store mgmt for file: .
>>
>> 2) It looks like on second attempt it tries to look for handle: but it
>> finds it not registered. What does this error mean ? Does it look for
>> registered uri schemes online ? if that is the case how can this works
>> instead : https://github.com/tpm2-software/tpm2-openssl ? They use
>> handle: scheme as well.
>>
>> Does this mean it's a problem of the methods I registered for the
>> store or is something related to the uri scheme I am using ?
>> Sorry but I couldn't find more info on this in the sources/docs .
>>
>>
>> thank you
>>
>>
>>
>> On Mon, Oct 4, 2021 at 4:52 PM Antonio Santagiuliana
>> <santantonioswap at gmail.com> wrote:
>> >
>> > OK, thank you very much for your comments, that's clear.
>> >
>> > On Mon, 4 Oct 2021, 15:45 Tomas Mraz, <tomas at openssl.org> wrote:
>> >>
>> >> No, that's wrong. The dgst and other apps in OpenSSL-3.0 were already
>> >> modified to use OSSL_STORE API to load keys. So you do not need to
>> >> specify keyform=ENGINE if your key is provided by a provider that
>> >> supports the STORE functionality for some special URL scheme. You just
>> >> specify the right URL with that scheme to reference the key in the
>> >> provider.
>> >>
>> >> Of course third party applications need to be modified to call
>> >> OSSL_STORE API in a similar way how the openssl application does it.
>> >>
>> >> Tomas
>> >>
>> >> On Mon, 2021-10-04 at 15:39 +0100, Antonio Santagiuliana wrote:
>> >> > Thank you for your comment.
>> >> > Am I wrong then in saying that dgst and possibly other apps are not
>> >> > ready to be used with providers  rather than engines in the case you
>> >> > need keyform=ENGINE ?
>> >> >
>> >> >
>> >> > On Mon, 4 Oct 2021, 14:13 Tomas Mraz, <tomas at openssl.org> wrote:
>> >> > > You would have to implement a STORE provider that handles your
>> >> > > special
>> >> > > url scheme and then the keys would be referenced by the
>> >> > > yourscheme://any-identifier-you-have. Of course the application
>> >> > > (i.e.,
>> >> > > the openssl application which already does this) would have to use
>> >> > > the
>> >> > > OSSL_STORE API to load the keys and not directly the OSSL_DECODER
>> >> > > API
>> >> > > or the d2i/PEM_read APIs.
>> >> > >
>> >> > > Tomas
>> >> > >
>> >> > > On Mon, 2021-10-04 at 13:56 +0100, Antonio Santagiuliana wrote:
>> >> > > > I checked the sources, I found that keyform cannot be set to
>> >> > > > ENGINE
>> >> > > > if engine is not specified in the command options, this is in the
>> >> > > > function make_engine_url() called from load_key() when
>> >> > > > format==FORMAT_ENGINE.
>> >> > > > I am not specifying engine in the dgst command options as I am
>> >> > > using
>> >> > > > a  provider.
>> >> > > > I would like to achieve the same as FORMAT_ENGINE does, but with
>> >> > > > provider.
>> >> > > >
>> >> > > >
>> >> > > > On Mon, 4 Oct 2021, 12:12 Antonio Santagiuliana,
>> >> > > > <santantonioswap at gmail.com> wrote:
>> >> > > > > Hello,
>> >> > > > > I am doing my own provider starting from the default provider's
>> >> > > > > code.
>> >> > > > > I have now a question, I am seeing the STOREMGMT operation is
>> >> > > > > required to interpret the URI of input private key,  I would
>> >> > > > > like
>> >> > > > > that the string passed by the user for input key is not
>> >> > > > > interpret
>> >> > > > > as file to open but just my provider should save the string
>> >> > > > > value
>> >> > > > > to be used later .This is  when invoking command options such
>> >> > > > > as
>> >> > > > > dgst sign -in "text" -keyform ENG.
>> >> > > > > With engines' architecture this is possible by passing option -
>> >> > > > > keyform ENG to dgst command. The string in that case is not
>> >> > > > > interpreted as a file path and just passed through.
>> >> > > > > There was engine_set_load_privkey_function that was getting
>> >> > > > > this
>> >> > > > > string.
>> >> > > > > How can I achieve this now with the provider architecture ? If
>> >> > > > > I
>> >> > > > > pass -keyform ENG to dgst command together with --provider , it
>> >> > > > > says "no engine specified to load private key" Should I use
>> >> > > > > OSSL_FUNC_store_load_fn and OSSL_FUNC_store_open_fn ? .
>> >> > > > > Also, at low level I am using RSA_FLAG_EXT_PKEY flag set as I
>> >> > > don't
>> >> > > > > have a real private key info to load and use from a Filesystem.
>> >> > > > > Is there anything to set in the KEYMGMT too ? I can see there
>> >> > > > > is
>> >> > > a
>> >> > > > > flag OSSL_KEYMGMT_SELECT_PRIVATE_KEY indicating the private key
>> >> > > > > data in a key object should be considered. Not really sure if
>> >> > > this
>> >> > > > > is something I should set or not and how this keymgmt operation
>> >> > > > > relates with storemgmt operation.
>> >> > > > >
>> >> > > > > thank you if you can send some comment on this.
>> >> > > > >
>> >> > >
>> >>
>> >> --
>> >> Tomáš Mráz
>> >> No matter how far down the wrong road you've gone, turn back.
>> >>                                               Turkish proverb
>> >> [You'll know whether the road is wrong if you carefully listen to your
>> >> conscience.]
>> >>
>> >>
>>
>
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