Tadd,

The TPM doesn’t care what values are hashed into TPM_CHOSENID_HASH, but if you 
require interoperability with a TCG-compliant privacy CA then the privacyCA 
value should be a marshaled TPM_PUBKEY structure.  Part 2 2.1 Representation of 
Information describes the basic rules for marshaling and Part 2 10.5 TPM_PUBKEY 
describes this structure.

An easier reference for the marshaling code is the TrouSerS source 
(https://sourceforge.net/projects/trousers/files/trousers/).  See 
src/tspi/tspi_aik.c:Tspi_TPM_CollateIdentityRequest() which shows how to 
compute the ChosenID hash.

Phil

> On Apr 7, 2016, at 6:11 AM, Ken Goldman <[email protected]> wrote:
> 
> On 4/6/2016 9:32 PM, Tadd Seiff wrote:
>> Hi all,
>> 
>> I need help understanding the TPM_CHOSENID_HASH structure in the TPM
>> spec, section 12.4 in the structures document for 1.2.  It says:
>> 
>> TPM_CHOSENID_HASH = SHA(identityLabel || privacyCA)
>> 
>> 1.) What does the || notation suggest here?  Concatenation? Or'ing?
> 
> From Part 1:
> 
> "Throughout all parts of the specification the characters x1 || x2 imply 
> the concatenation of x1 and x2."
> 
>> 2.) The privacyCA element is actually a structure, so, what do I do with
>> that?  Just use the whole structure as a byte array?
> 
> The way I read Part 3 15.1 TPM_MakeIdentity, the TPM doesn't care.  The 
> actual value is between you and the privacy CA.
> 
> I'm not an expert at this section.  Let's see what others say.
> 
> 
> 
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