69 lines
1.7 KiB
Plaintext
69 lines
1.7 KiB
Plaintext
# BAN concrete Andrew Secure RPC
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#
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# Modelled after the description in the SPORE library
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# http://www.lsv.ens-cachan.fr/spore/andrewBAN2.html
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#
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# Note:
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# The shared key between I and R is modelled as k(I,R) currently
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# there is no way to express that this key is equal to k(R,I)
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# In order to overcome this a 'dummy' role X has been hadded that recrypts
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# a given term crypted with k(I,R) with k(R,I)
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#
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# Note:
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# Read 4 by the Initatior has been placed after the synchronisation claim
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# as it allows trivial synchronisation attacks otherwise (the message is
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# completely fresh and can therefore always be replaced by an arbitrary value
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# created by the intruder) which are not considered in SPORE
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#
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usertype SessionKey;
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const Fresh: Function;
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const Compromised: Function;
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protocol @swapkey(X)
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{
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# Protocol added to work around the symmetry problems where k(I,R) != k(R,I)
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role X
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{
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var I,R: Agent;
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var T:Ticket;
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read_!X1(X,X,I,R,{T}k(I,R));
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send_!X2(X,X,{T}k(R,I));
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}
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}
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protocol andrew-Concrete(I,R)
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{
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role I
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{
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fresh ni: Nonce;
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var nr: Nonce;
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var kir: SessionKey;
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send_1(I,R, I,ni );
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read_2(R,I, {ni,kir}k(I,R) );
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send_3(I,R, {ni}kir);
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claim_I1(I,Secret,kir);
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claim_I2(I,Nisynch);
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claim_I3(I,Empty,(Fresh,kir));
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read_6(R,I, nr);
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}
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role R
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{
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var ni: Nonce;
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fresh nr: Nonce;
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fresh kir: SessionKey;
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read_1(I,R, I,ni );
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send_2(R,I, {ni,kir}k(I,R) );
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read_3(I,R, {ni}kir);
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send_6(R,I, nr);
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claim_R1(R,Secret,kir);
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claim_R2(R,Nisynch);
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claim_R3(R,Empty,(Fresh,kir));
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}
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}
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