Re: [PATCH RESEND] docs: update trusted-encrypted.rst

[Coly Li]

On 2020/8/17 01:08, James Bottomley wrote:
> On Mon, 2020-08-17 at 01:01 +0800, Coly Li wrote:
>> On 2020/8/17 00:06, Stefan Berger wrote:
>>> On 8/15/20 3:51 AM, Coly Li wrote:
> [...]
>>>>     Usage::
>>>> @@ -115,7 +114,7 @@ append 'keyhandle=0x81000001' to statements
>>>> between quotes, such as
>>>
>>>
>>> A note in this file states this:
>>>
>>> Note: When using a TPM 2.0 with a persistent key with handle
>>> 0x81000001, append 'keyhandle=0x81000001' to statements between
>>> quotes, such as "new 32 keyhandle=0x81000001".
>>>
>>> Now if someone was (still) interested in TPM 1.2 then the below
>>> changes you are proposing wouldn't work for them. Maybe you should
>>> adapt the note to state that these keyhandle=... should be removed
>>> for the TPM 1.2 case.
>>>
>>
>> I agree. Indeed I have no idea why number 0x81000001 is used, and I
>> don't have practice experience with TPM 1.2. Now the purpose of this
>> patch accomplished: experts response and confirm my guess :-)
> 
> It was the conventional persistent value for the RSA 2048 version of
> the primary storage seed.  Originally the PC spec required the
> manufacturer provision this on all TPM 2.0 based PC class systems. 
> Unfortunately in spite of it being in the Windows Hardware guide no
> manufacturer ever did, meaning you either have to create it yourself or
> do something different.  Because of usability problems, every consumer
> of TPM key function has opted to do something different, namely derive
> the EC primary if no parent is specified.

Aha, thanks for the hint :-)

My motivation is for the NVDIMM security with TPM 2.0 chip on x86 server
(Lenovo SR650). To automatically load a trusted key, I encounter the
outdated command line in trusted-encrypted.rst. From your response, it
seems 0x81000001 is still a working value that I can recommend to other
people who want to encrypt/decrypt their NVDIMM banks.

Coly Li