A User Centric Security Model for Tamper-Resistant Devices

7.6 Application Binding Protocol Distributed
this process will be simple as SCA already trusts that particular evaluation laboratory.
Otherwise, it will request the CAMS to traverse the certicate chain to nd out whether
the SCA's evaluation laboratory is part of that certicate chain. Even if this fails, the SCA
can request its card manufacturer to decide whether it should proceed with the binding
or not depending upon the provided certicate. Therefore, only if SCA can successfully
ascertain the validity of the certicate provider of the SCB's certicate will it proceed
with the protocol.
PBP-5. SCA : cfa = h(g r SCB||g r SCA||N SCB ||N SCA )
SCA : V al SCA = Sign SCA (cfa||SCA i ||SCB i ||U i )
SCA : mE = e kSCA−SCB (V R||V al SCA ||CertS SCA )
SCA → SCB : mE||f mkSCA−SCB (mE)
In response, the SCA will proceed with a platform assurance and validation mechanism
(section 4.4). On successful completion, the SCA will generate a message V al SCA . In the
message V al SCA , the SCA appends identities of both smart cards and user along with cfa.
The signed message (V al SCA ) is appended by the certicate and encrypted and MACed
by the session keys.
The SCB veries the SCA's signature and then validates the CertS SCA . To verify the
certicate chain, the SCB will iteratively employ a similar procedure to SCA discussed
as part of the message four. The SCB will also verify the identity of the user of the SCA.
The SCB will record whether the user's identity is the same for both smart cards or not.
This information will be used by applications to decide whether they would like to establish
a communication link with an application installed on a dierent user's smart card.
PBP-6. SCB : V al SCB = Sign SCB (cfb||SCA||SCB||U i )
SCB : mE = e kSCA−SCB (V al SCB )
SCB → SCA : mE||f mkSCA−SCB (mE)
The SCB will initiate the platform assurance and validation mechanism which generates
the hash value of the critical components of the SCB. It will append the Die-Hellman
exponentials, random numbers and identities of communicating smart cards and the current
owner of the SCB. The entire message is signed by the SCB then encrypted and MACed
by the session keys.
7.6 Application Binding Protocol Distributed
The Application Binding Protocol Distributed (ABPD) is similar the ABP that we
discussed in section 7.4. The subtle dierence between these two protocols is that the
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