Re: [Trustedjava-support] error tpm emulator

[Martin P. <Mar...@ia...>]

Hi...

patrizia cellesi wrote:
> i have a problem: i have done an interation between a client and a privacy CA
> using your example in the JTSS package. The only difference is that the client
> and the PCA are not in the same project, but i've realized the PCA as a servlet
> to simulate a real communication. the client and the Pca use the TSS stack. i
> have create a context in the client and in the pca, but when i do the
> context.connect() in the pca it gives me the follow error (i use the tpm emulator):

> 13:03:27:284 [WARN] TcTddlLinux::open (-1): Unable to open TPM device file /dev/tpm.
> Reason: /dev/tpm (Device or resource busy)

The TPM chip (/dev/tpm) can only be accessed by one TSS at a time. The TSS design
calls for one system-wide TSS running, multiplexing application accesses.

If you want to simulate a PrivacyCA setup with both client and server on
the same machine, this is doable.
The client gets to run the TSS and access the TPM.
The server side of a PrivacyCA does not need a TPM, only some crypto helper
routines from the TSS top level.

Take a closer look at PrivacyCA.java from JTpmTools, lines 117-

  // context for crypto operations in verify
  // NOTE: IAIK jTSS context does not need to be connected to a TPM
  context_ = new TcTssLocalCallFactory().newContextObject();

A context is created to get access to some helper functions, but never connected
on the server side, thus no TPM is needed. This trick works only on jTSS.


HTH

-- 
Martin Pirker
IAIK, TU Graz