A User Centric Security Model for Tamper-Resistant Devices

A.3 Aziz-Die (AD) Protocol
on the public keys generated by both communicating entities. The public key, encrypted
signature and the certicate for the SP is sent to the SC. The certicate is sent in
plaintext; therefore, in this protocol there is no privacy protection for the SP (i.e. which
is not necessary to have as most of the servers have public addresses: Internet addresses).
The SC will generate the shared secret key similar to the SP (in previous message). The
SC will decrypt the signature and then verify the signature on the public keys generated
by the both SP and SC. This is to avoid man-in-the-middle attack.
STS-3. SC → SP : e kSC−SP (Sign SC (g SP ||g SC )||CertS SC )
The SC will sign the public keys generated by the SC and SP then append the certicate.
The entire message is then encrypted by the shared secret key k SC−SP . This message
provides mutual entity authentication, and mutual explicit key authentication along with
preventing the man-in-the-middle attack.
A.3 Aziz-Die (AD) Protocol
The AD protocol was proposed for the wireless local area networks [175] and unlike STS
it does not rely on the Die-Hellman exponentials to generate the shared secretes.
AD-1. SC → SP : CertE SC ||CertS SC ||N SC
The AD protocol is started by the SC that generates a random number N SC , append it
with the SC encryption key pair certicate.
AD-2. SP → SC : zV SC (N SP )||CertE SP ||CertS SP ||Sign SP (zV SC (N SP )||N SC )
On receiving the rst message, the SP will generate a random number N SP and encrypt
it with the SC's public key. It then appends the signature key pair certicate along with
a signed message that includes the encrypted random number of the SP along with the
random number sent by the SC.
AD-3. SC → SP : zV SP (r
SC ′ )||Sign SC(zV SP (r
SC ′ )||zV SC(N SP ))
SC, SP : k SC−SP = r
SC ′ + N SP
The SC, on receiving the second message will rst decrypt the SP's random number and
then veries the signature. Subsequently, the SC generates another random number r
SC.
′
Now the SC can now generate the shared key k SC−SP by adding the r
SC ′ with the SP's
random number.
The SC will encrypt the r ′ SC
with the public key of the SP and generate a signature on
the encrypted random numbers from SC and SP. On receipt, the SP can also generate
the shared secret k SC−SP as the SC has generated it.
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