78 lines
1.7 KiB
C++
78 lines
1.7 KiB
C++
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/** HEADDOC
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* @protocol Station-to-Station Protocol (STS)
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* @reference Diffie W., van Oorschot P. C., and Wiener M. J.,
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* Authentication and authenticated key exchange,
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* Boyd C. and Mathuria A., Protocols for Authentication and
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* Key Agreement
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* @description STS adds a diGital signaure to the exchanged messages to
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* provide authentication for the Diffie-Hellman protocol. In
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* addition, the shared secret is used to provide further
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* assurances.
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* @variant Variant using MACs
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**/
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#define __STS__
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#ifndef __ORACLE__
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#include "common.h"
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#endif
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/**
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* This role serves as an "oracle" to ensure the executability of the
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* protocol by taking care of the problems that arise from our way of
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* modelling Diffie-Hellman keys.
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*/
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protocol @executability(O) {
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#define Gi g(i)
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#define Gr g(r)
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role O {
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var i, r: Nonce;
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// msg 2
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recv_!O1( O, O, MAC(Zr, g(r), Gi) );
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send_!O2( O, O, MAC(Zi, g(r), Gi) );
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// msg 3
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recv_!O3( O, O, MAC(Zi, Gi, g(r)) );
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send_!O4( O, O, MAC(Zr, Gi, g(r)) );
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}
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#undef Gi
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#undef Gr
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}
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// It is not specified how the session key is derived from the ephemeral DH
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// secret Z; we use KDF(Z).
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protocol sts-mac(I, R)
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{
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role I {
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fresh i: Nonce;
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var Gr: Ticket;
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send_1( I, R, g(i) );
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recv_!2( R, I, Gr, {Gr, g(i)}sk(R), MAC(Zi, Gr, g(i)) );
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send_!3( I, R, {g(i), Gr}sk(I), MAC(Zi, g(i), Gr) );
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/* SECURITY CLAIMS */
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claim( I, SKR, SKi );
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claim( I, Alive );
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claim( I, Weakagree );
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}
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role R {
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fresh r: Nonce;
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var Gi: Ticket;
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recv_1( I, R, Gi );
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send_!2( R, I, Gi, {g(r), Gi}sk(R), MAC(Zr, g(r), Gi) );
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recv_!3( I, R, {Gi, g(r)}sk(I), MAC(Zr, Gi, g(r)) );
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/* SECURITY CLAIMS */
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claim( R, SKR, SKr );
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claim( R, Alive );
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claim( R, Weakagree );
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}
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}
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