A User Centric Security Model for Tamper-Resistant Devices

7.4 Application Binding Protocol Local
7.4.2 Protocol Description
The aim of the Application-Binding Protocol Local (ABPL) is to facilitate both the
client and server applications on the same device to authenticate each other and verify their
current states to be secure. The ABPL also enables applications to establish the application
binding for future communications. The ABPL message description is as below:
ABPL-1. CL : IMA CL = e KCL−T EM
(CL i ||SE i ||N CL )
CL → F : CL i ||SE i ||Sign CL (CL i ||SE i ||N CL ||IMA CL )||CertS CL
The request message contains the identities of the client and server applications together
with a random number generated by the CL. In addition, the client application creates an
IMA message (section 7.3.2) for the T EM. The client application signs the message and
appends its certicate.
ABPL-2. F → SE : CL i ||SE i ||Sign CL (CL i ||SE i ||N CL ||IMA CL )||CertS CL
The rewall F receives the application-binding request and it will query the SE. If the
server application wants to proceed with the ABPL, it forwards the message; otherwise, it
registers an exception.
ABPL-3. SE : IMA SE = e KSE−T EM
(SE i ||CL i ||N SE )
SE → T EM : CL i ||SE i ||IMA CL ||IMA SE
The SE veries the client's signature. If successful, it generates an IMA message for the
CL. The SE then sends the message to the T EM that contains the identities and IMA
messages of both the CL and SE.
ABPL-4. T EM → SL : V RE CL = e KCL−T EM
(h(SE)||K t SE−CL ||N CL + 1)
T EM → SE : V RE SE = e KSE−T EM
(h(CL)||K t SE−CL ||N SE + 1)
The T EM veries the IMA messages from both the CL and SE. Then it will calculate
the hash value of the SE, encrypt it with the shared key K CL−T EM and send it to the CL.
Similarly, the TEM will calculate the hash value of the CL, encrypt it with the shared
key K SE−T EM and send it to the SE. The encrypted messages also contain a session key
generated by the T EM; this key is valid only during the ABPL run.
ABPL-5. SE : skm = e K t
SE−CL
(e SE−CL ||N CL + 2||N SE )
SE : au = e KSE−CL (AP ||OR||N CL ||N SE )
SE : tc = Sign SE (SE i ||CL i ||N SE ||au)
SE → CL : SE i ||CL i ||IMA CL ||skm||tc||CertS SE
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