A User Centric Security Model for Tamper-Resistant Devices

B.7 Platform Binding Protocol
B.7 Platform Binding Protocol
The Casper script in this section corresponds to the Platform Binding Protocol (PBP)
described in section 7.5.
#Free variables
datatype Field = Gen | Exp(Field, Num) unwinding 2
halfkeySP, halfkeyTPM, sessionKey : Field
SP, TPM : Agent
ns, nt, nm, scos, app : Nonce
s, t : Num
VKey: Agent -> PublicKey
SKey: Agent -> SecretKey
EKey: Agent -> PublicKey
DKey: Agent -> SecretKey
InverseKeys = (sessionKey, sessionKey), (VKey, SKey),(EKey, DKey), (Exp, Exp), (Gen,
Gen)
#Protocol description
0. -> SP : TPM
1. SP -> TPM : SP, VKey(SP)
2. TPM -> SP : {TPM, SP, nt}{VKey(SP)}
2a. TPM -> SP : {Exp(Gen, t) % halfkeyTPM}{VKey(SP)}
3. SP -> TPM : {SP, TPM, ns}{EKey(TPM)}
3a. SP -> TPM : {Exp(Gen, s) % halfkeySP}{EKey(TPM)}
4. TPM -> SP : {TPM, SP, {scos (+) ns}{SKey(TPM)}}{sessionKey}
5. SP -> TPM : {SP, TPM, nt}{sessionKey}
6. TPM -> SP : {TPM, SP, {app (+) ns}{SKey(TPM)}}{sessionKey}
#Actual variables
SerPro, TruPlaMan, MAppl : Agent
Nsp, Ntpm, Nm : Nonce
SCOS, APP : Nonce
S, T, M : Num
SCOperatingSys, SApplication : Nonce
#Processes
INITIATOR(SP, TPM, ns, s, app, scos) knows SKey(SP), DKey(SP), VKey, EKey
RESPONDER(TPM, SP, nt, t, scos, app) knows SKey(TPM), DKey(TPM), VKey, EKey
#System
INITIATOR(SerPro, TruPlaMan, Nsp, S, APP, SCOS)
RESPONDER(TruPlaMan, SerPro, Ntpm, T, SCOS, APP)
#Functions
symbolic VKey, SKey, EKey, DKey
#Intruder Information
Intruder = MAppl
IntruderKnowledge = {SerPro, TruPlaMan, MAppl, MAppl, Nm, DKey(MAppl),SKey(MAppl),
VKey, EKey, M}
#Specification
StrongSecret(SP, sessionKey, [TPM])
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