A User Centric Security Model for Tamper-Resistant Devices

6.2 Secure Channel Protocols
Notation Description
g r X
Denotes the Die-Hellman exponential generated by the entity X with
random number r X . We use this notation to represent the g r X
mod p,
where g and p are system parameters that are represented by the Die-
Hellman group selected by the entity X. For further discussion please
refer to [132, 146, 181]
K Denotes the shared secret generated by the communicating entities using
the Die-Hellman scheme. Keys for application download and session
keys are generated from this shared secret.
ek X−Y Denotes the session encryption key shared between entities X and Y to
be used with a symmetric algorithm.
mk X−Y Denotes the session MAC key shared between entities X and Y.
h(Z) Represents the result of generating a hash of data Z by a hash function
(e.g. SHA256 [147]).
U Cre User authentication credential (e.g. login and password) associated with
a particular SP.
X Sup Denotes the supported features of entity X that include Die-Hellman
groups [148], user authentication mechanisms (i.e. login/password), symmetric
and signature algorithms.
AU X A signed message from an entity X that authenticates it to other entities.
SI Session cookie generated by the respective SP. It indicates the session
information and facilitates protection against DoS attacks, possibly along
with providing the facility of protocol session resumption.
V R Validation request sent by an SP to a smart card. In response, the smart
card provides the security and reliability assurance to the SP.
ADP The Application Download Protocol (ADP) will include appropriate parameters
for the application download protocol, which in the context of
this thesis is the GlobalPlatform application download process based on
the symmetric key cryptosystem (e.g. SCP03) [170].
ALP The Application Lease Policy (ALP) species the minimum security, reliability
and operational requirements imposed by the SP on a smart
card. The ALP also includes the relevant application's details that include
application size and functionality support requirements.
hs & hp hs is a hash message generated by the SC on data including its identity,
generated Die-Hellman exponentials and random numbers. Similarly,
hp is generated by the SP. Both these messages aim to avoid a man-inthe-middle
attack on the proposed protocols.
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