[tpm2] Re: Are there any help documents/sites on writing an ESAPI program.

[Roberts, William C <william.c.roberts at intel.com>]

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The Esys integration tests are also super helpful:
https://github.com/tpm2-software/tpm2-tss/blob/master/test/integration/esys-ecdh-zgen.int.c


> -----Original Message-----
> From: Roberts, William C
> Sent: Thursday, April 30, 2020 10:44 AM
> To: 'Steven Clark' <davolfman(a)gmail.com>; tpm2 <tpm2(a)lists.01.org>
> Subject: RE: [tpm2] Are there any help documents/sites on writing an ESAPI
> program.
> 
> The tools themselves are real world examples.
> 
> You shouldn't go digging into the ESYS_CONTEXT or TCTI_CONTEXT but the
> structure parameters And returns to ESYS calls you can. Its set up where you can't
> go structure digging and compile with the include directory includes
> (https://github.com/tpm2-software/tpm2-tss/tree/master/include/tss2).
> If you add includes from the project that exist elsewhere you're doing it wrong.
> 
> Now for the ZGen code, we actually want to add it to tools. Its actually on the
> short list of commands To add, see bug: https://github.com/tpm2-
> software/tpm2-tools/issues/877
> 
> The reason we didn't add it yet, is we didn't know exactly how it works and to
> test it. Imran and I Actually have a meeting with someone way more
> knowledgeable on ECC to help us along. We would Love, even just sample code
> to help us out, or if you created the tool even better. Anything you can Share
> back is a win.
> 
> 
> Now for taking the training wheels off, Esys_Initialize(), you can leave off the tcti
> and abi pointers by passing NULL. That should just get you a context with the
> TPM and away you go. Here is a very simple program to start
> With:
> https://gist.github.com/williamcroberts/66a7dab3adfb973fbae3219954535009
> 
> You can alter that by changing the template and making an EC key to play with, or
> have it pass in blobs from tpm2_create tool. Tpm2_create tool has the output
> options -u and -r that you can pass along, and load those up by:
> 1. Desterilizing with libmu (offhand I think the calls will be
> Tss2_MU_TPM2B_PRIVATE_Unmarshal and
> Tss2_MU_TPM2B_PUBLIC_Unmarshal) 2. Calling Esys_Load() and getting the
> ESYS_TR handle to pass to the zgen routine
> 
> 
> 
> > -----Original Message-----
> > From: Steven Clark [mailto:davolfman(a)gmail.com]
> > Sent: Wednesday, April 29, 2020 7:51 PM
> > To: tpm2 <tpm2(a)lists.01.org>
> > Subject: [tpm2] Are there any help documents/sites on writing an ESAPI
> > program.
> >
> > I need to perform a command that doesn't have a tools executable yet
> > (TPM2_ECDH_ZGen) and on a persistent object handle that won't be
> > compatible with the on-disk key-databases of FAPI or PKCS#11.  So that
> > means I need to write my own code in C, and that code needs to use the ESAPI.
> >
> > I've had a lot of lead time to see this coming so I've done a few little
> experiments.
> > They have not improved my confidence in my understanding of the API.
> > For example I'm still not sure which structures I'm supposed to access
> > directly and which ones are supposed to be manipulated using functions.
> >
> > The Specs are either long and theoretical or dry and terse.  And both
> > the tests for TSS and the source files for Tools make use of internal
> > abstraction layers.  I'm having trouble getting a whole-process
> > picture.  Are there any resources out there to help me get my sea-legs on ESAPI
> code?