usertype SessionKey; const pk: Function; secret sk: Function; secret k: Function; inversekeys (pk,sk); protocol andrewBan(I,R) { role I { const ni: Nonce; var nr: Nonce; var kir: SessionKey; send_1(I,R, I,ni ); read_2(R,I, {ni,kir,I}k(I,R) ); send_3(I,R, {ni}kir ); read_4(R,I, nr ); claim_5(I,Nisynch); claim_6(I,Secret, kir); claim_7(I,Secret, k(I,R)); } role R { var ni: Nonce; const nr: Nonce; const kir: SessionKey; read_1(I,R, I,ni ); send_2(R,I, {ni,kir,I}k(I,R) ); read_3(I,R, {ni}kir ); send_4(R,I, nr ); claim_8(R,Nisynch); claim_9(R,Secret, kir); claim_10(R,Secret, k(I,R)); } } const Alice,Bob,Eve: Agent; untrusted Eve; const ne: Nonce; const kee: SessionKey; compromised sk(Eve); run andrewBan.I(Agent,Agent); run andrewBan.R(Agent,Agent); run andrewBan.I(Agent,Agent); run andrewBan.R(Agent,Agent);