[tpm2] Re: Remote Attestation With Tpm2 Tools

[tpm2] Re: Remote Attestation With Tpm2 Tools

[Steffen Schwebel]

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Hello,

not something I can help you with I'm afraid.
Just wondering if you know about keylime project https://keylime.dev/

They seem to be the guys to ask in regards to remote attestation.

regards,
Steffen

On 9/6/20 7:54 AM, Hanson Char wrote:
> I just managed to get the 3 scripts provided at
>
>   https://tpm2-software.github.io/2020/06/12/Remote-Attestation-With-tpm2-tools.html#scripts-for-implementation-of-the-simple-attestation-framework
>
> to work with the latest tpm2-tss (built from the latest master
> branches) in Ubuntu 20.04 (x86-64 with Infineon TPM SLB9670) so I
> thought I would share some of what I've found.
>
> 1. For the Infineon TPM device SLB9670, I realized the version of the
> TPM firmware needed to be upgraded (e.g. to the latest version
> 7.85.4555.0).  The tpm2_create command in the script would fail when
> executed against the TPM firmware version 7.63.3353.0.
>
> 2. The three scripts need to be in their individual directories.  For
> example:
>
>     ├── DN
>     │   └── device_node.sh
>     ├── PCA
>     │   └── private_ca.sh
>     └── SP
>         └── service_provider.sh
>
> 3. I needed to modify the specific golden PCR value, and the location
> of pcr.bin in service_provider.sh.  In particular:
>
> diff --git a/SP/service_provider.sh b/SP/service_provider.sh
> index a0b40ec..b6433d6 100755
> --- a/SP/service_provider.sh
> +++ b/SP/service_provider.sh
> @@ -13,7 +13,8 @@ device_service_request=0
>
>  # Attestation Data
>  GOLDEN_PCR_SELECTION="sha1:0,1,2+sha256:0,1,2"
> -GOLDEN_PCR="59bf9091f4cbbd2a8796bfe086a501c57226c42739dcf8ad323e7493ad51e38f"
> +#
> GOLDEN_PCR="59bf9091f4cbbd2a8796bfe086a501c57226c42739dcf8ad323e7493ad51e38f"
> +GOLDEN_PCR="c7b544e0359614c896ed32b0fd7fad43c32ba7e19d4b613cdbda162f784b5781"
>
>  # Service Data
>  SERVICE_CONTENT="Hello world!"
> @@ -175,7 +176,7 @@ system_software_state_validation() {
>     software_status_string="Attestation quote signature validation"
>     tpm2_checkquote --public d_s_service_aik.pub  --qualification
> "$NONCE" \
>     --message attestation_quote.dat --signature
> attestation_quote.signature \
> -   --pcr pcr.bin -Q
> +   --pcr ../DN/pcr.bin -Q
>     retval=$?
>     rm -f attestation_quote.signature
>     if [ $retval == 1 ];then
>
> Hope this helps anyone who may try to run the scripts.
>
> Meanwhile, I wonder how the sequence diagram and the scripts may
> differ when privacy is not a concern; and would appreciate any
> pointers or hints.
>
> Regards,
> Hanson
>
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[tpm2] Re: Remote Attestation With Tpm2 Tools

[Roberts, William C]

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> -----Original Message-----
> From: Hanson Char <hanson.char(a)gmail.com>
> Sent: Sunday, September 6, 2020 12:55 AM
> To: tpm2(a)lists.01.org
> Subject: [tpm2] Remote Attestation With Tpm2 Tools
> 
> I just managed to get the 3 scripts provided at
> 
>   https://tpm2-software.github.io/2020/06/12/Remote-Attestation-With-tpm2-
> tools.html#scripts-for-implementation-of-the-simple-attestation-framework
> 
> to work with the latest tpm2-tss (built from the latest master branches) in
> Ubuntu 20.04 (x86-64 with Infineon TPM SLB9670) so I thought I would share
> some of what I've found.
> 
> 1. For the Infineon TPM device SLB9670, I realized the version of the TPM
> firmware needed to be upgraded (e.g. to the latest version 7.85.4555.0).  The
> tpm2_create command in the script would fail when executed against the TPM
> firmware version 7.63.3353.0.
> 
> 2. The three scripts need to be in their individual directories.  For example:
> 
>     ├── DN
>     │   └── device_node.sh
>     ├── PCA
>     │   └── private_ca.sh
>     └── SP
>         └── service_provider.sh
> 
> 
> 3. I needed to modify the specific golden PCR value, and the location of pcr.bin in
> service_provider.sh.  In particular:
> 
> diff --git a/SP/service_provider.sh b/SP/service_provider.sh index
> a0b40ec..b6433d6 100755
> --- a/SP/service_provider.sh
> +++ b/SP/service_provider.sh
> @@ -13,7 +13,8 @@ device_service_request=0
> 
>  # Attestation Data
>  GOLDEN_PCR_SELECTION="sha1:0,1,2+sha256:0,1,2"
> -
> GOLDEN_PCR="59bf9091f4cbbd2a8796bfe086a501c57226c42739dcf8ad323e7493a
> d51e38f"
> +#
> GOLDEN_PCR="59bf9091f4cbbd2a8796bfe086a501c57226c42739dcf8ad323e7493a
> d51e38f"
> +GOLDEN_PCR="c7b544e0359614c896ed32b0fd7fad43c32ba7e19d4b613cdbda16
> 2f784b5781"
> 
>  # Service Data
>  SERVICE_CONTENT="Hello world!"
> @@ -175,7 +176,7 @@ system_software_state_validation() {
>     software_status_string="Attestation quote signature validation"
>     tpm2_checkquote --public d_s_service_aik.pub  --qualification "$NONCE" \
>     --message attestation_quote.dat --signature attestation_quote.signature \
> -   --pcr pcr.bin -Q
> +   --pcr ../DN/pcr.bin -Q
>     retval=$?
>     rm -f attestation_quote.signature
>     if [ $retval == 1 ];then
> 
> 
> 
> Hope this helps anyone who may try to run the scripts.
> 
> Meanwhile, I wonder how the sequence diagram and the scripts may differ when
> privacy is not a concern; and would appreciate any pointers or hints.

Yeah you can skip the whole makecredential and activate credential parts, and you could just
sign the quote with a fixed AIK (Attestation Identity Key). That would remove annonimity, but
you would know that key is the TPM by:
1. Knowing on the server side receiving the quote that this public key is valid known to a TPM.
2. Using TPM2_Cerfify to certify that the key with name X is loaded into the TPM, and you trust
     Its parents and that name. The name of the signing key for the quote is in the attestation data.
     So you could certify the key is in the TPM using the certify command and another known public key,
     Like the endorsement key, and then verify the public structure is consistent with your expected
     template through the name.

    1 is the easier solution.

> 
> Regards,
> Hanson