[tpm2] Re: Is the tpm2_create command safe against sniffing attacks?

[Joseph Lee (ZeronsoftN) <joseph at zeronsoftn.com>]

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Hi Dimi,

Sorry to bother you. By installing the latest version of tpm2-tools, 
encrypted communication is possible.
Seal/unseal was possible as shown below.

But I have one question. How can I detect if a MITM attack occurs during 
the seal/unseal process? After establishing a session, is there any way 
to get the EK certificate of that session?
It seems that the tpm2_getekcertificate command can only get 
certificates created via the createek command. I'd like to know if the 
TPM I've made a session with is genuine.

Seal:
 > tpm2_createprimary -c prim.ctx
 > tpm2_startauthsession --hmac-session -c prim.ctx -S sess.ctx
 > tpm2_create -Q -g sha256 -u seal.pub -r seal.priv -i temp.key -C 
prim.ctx -S sess.ctx
 > tpm2_load -Q -C prim.ctx -u seal.pub -r seal.priv -n seal.name -c 
seal.ctx
 > tpm2_evictcontrol -C o -c seal.ctx 0x81010001
 > tpm2_flushcontext sess.ctx

Unseal:
 > tpm2_startauthsession --hmac-session -c prim.ctx -S sess.ctx
 > tpm2_unseal -c seal.ctx -S sess.ctx -o out.key
 > tpm2_flushcontext sess.ctx

Thanks & Regards,
Joseph

------ Original Message ------
보낸 사람: "Joseph Lee (ZeronsoftN)" <joseph(a)zeronsoftn.com>
받는 사람: "Dimitar Tomov" <dimi(a)designfirst.ee>; "tpm2(a)lists.01.org" 
<tpm2(a)lists.01.org>
보낸 날짜: 2021-08-02 오전 6:27:36
제목: [tpm2] Re: Is the tpm2_create command safe against sniffing attacks?

>Hi Dimi,
>
>Thank you for your kind answer. Looking at the link you gave, I think I 
>can get more ideas.
>
>I've been trying session encryption via tpm2-tools all weekend.
>But I haven't found a way to create an encrypted session in tpm2-tools 
>yet. Maybe tpm2-tools doesn't support encrypted sessions?
>
>If this is clear, I will implement parameter encryption through 
>tpm2-tools with referring to wolfTPM.
>
>Thanks & Regards,
>Joseph
>
>------ Original Message ------
>보낸 사람: "Dimitar Tomov" <dimi(a)designfirst.ee>
>받는 사람: "tpm2(a)lists.01.org" <tpm2(a)lists.01.org>; "Joseph Lee 
>(ZeronsoftN)" <joseph(a)zeronsoftn.com>
>보낸 날짜: 2021-08-02 오전 4:33:02
>제목: [tpm2] Re: Is the tpm2_create command safe against sniffing 
>attacks?
>
>>Hi Joseph,
>>
>>TPM 2.0 offers Parameter Encryption capability and HMAC sessions as 
>>measures against Man-in-the-middle attacks
>>
>>Examples in wolfTPM demonstrate how to enable Parameter Encryption
>>
>>  
>>https://github.com/wolfSSL/wolfTPM/blob/b0a65e44b8a25be88b2f9ff4e35fbf08360e5d01/examples/nvram/store.c#L121
>>
>>There is also Keygen , Key import and Key loading examples with 
>>Parameter Encryption
>>
>>https://github.com/wolfSSL/wolfTPM/blob/b0a65e44b8a25be88b2f9ff4e35fbf08360e5d01/examples/nvram/store.c#L121
>>
>>Last week we discussed the Dolos Group story about a stolen laptop 
>>with TPM https://developers.tpm.dev/posts/15883726
>>
>>If Parameter Encryption and HMAC session have been used, this story 
>>would have developed differently.
>>
>>Hope this helps.
>>
>>Dimi
>>--
>>Founder of TPM.dev
>>
>>--------------------------------------------------------------------------------
>>From: Joseph Lee (ZeronsoftN) <joseph(a)zeronsoftncom 
>><mailto:joseph(a)zeronsoftn.com>>
>>Sent: Saturday, July 31, 2021 2:09 AM
>>To:tpm2(a)lists.01.org <tpm2(a)lists.01.org>
>>Subject: [tpm2] Is the tpm2_create command safe against sniffing 
>>attacks?
>>
>>Hello,
>>
>>https://pulsesecurity.co.nz/articles/TPM-sniffing
>>In this article, can see that communication with the TPM is vulnerable 
>>to sniffing if not careful.
>>
>>https://tpm2-software.github.io/2020/04/13/Disk-Encryption.html
>>Is the disk encryption described in tpm2-software's blog safe against 
>>these attacks?
>>
>>tpm2_createprimary -Q -C o -c prim.ctx
>>dd if=/dev/urandom bs=1 count=32 status=none | tpm2_create -Q -g 
>>sha256 -u seal.pub -r seal.priv -i- -C prim.ctx
>>tpm2_load -Q -C prim.ctx -u seal.pub -r seal.priv -n seal.name -c 
>>seal.ctx
>>tpm2_evictcontrol -C o -c seal.ctx 0x81010001
>>
>>My question is:
>>     1. Is there a tool in linux that can sniff communication with the 
>>current system's TPM?
>>     2. How to encrypt communications if the methods described above 
>>are not secure?
>>         It seems that encryption is possible through 
>>tpm2_startauthsession , but I do not know how to apply it to 
>>tpm2_create . (The -S option simply did not work.)
>>
>>Thank you.
>>
>>
>>
>>
>
>
>

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