70 lines
1.7 KiB
Plaintext
70 lines
1.7 KiB
Plaintext
# Lowe's fixed version of Needham Schroeder Public Key
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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/nspkLowe.html
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#
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#
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# Note:
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# The modelling in SPORE includes a server to distribute the public keys
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# of the agents, this is not necessary and it allows for attacks against
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# synchronisation and agreement, because the keys that the server sends
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# out can be replayed.
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const pk: Function;
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secret sk: Function;
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inversekeys(pk,sk);
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protocol needhamschroederpkLowe(I,R,S)
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{
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role I
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{
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const Ni: Nonce;
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var Nr: Nonce;
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send_1(I,S, (I,R));
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read_2(S,I, {pk(R), R}sk(S));
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send_3(I,R,{Ni,I}pk(R));
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read_6(R,I, {Ni,Nr,R}pk(I));
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send_7(I,R, {Nr}pk(R));
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claim_I1(I,Secret,Ni);
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claim_I2(I,Secret,Nr);
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}
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role R
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{
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const Nr: Nonce;
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var Ni: Nonce;
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read_3(I,R,{Ni,I}pk(R));
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send_4(R,S,(R,I));
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read_5(S,R,{pk(I),I}sk(S));
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send_6(R,I,{Ni,Nr,R}pk(I));
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read_7(I,R,{Nr}pk(R));
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claim_R1(R,Secret,Nr);
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claim_R2(R,Secret,Ni);
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}
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role S
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{
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read_1(I,S,(I,R));
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send_2(S,I,{pk(R),R}sk(S));
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read_4(R,S,(R,I));
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send_5(S,R,{pk(I),I}sk(S));
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}
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}
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const Alice,Bob,Simon,Eve: Agent;
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untrusted Eve;
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const ne: Nonce;
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compromised sk(Eve);
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# General scenario, 2 parallel runs of the protocol
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run needhamschroederpkLowe.I(Agent,Agent,Simon);
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run needhamschroederpkLowe.S(Agent,Agent,Simon);
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run needhamschroederpkLowe.R(Agent,Agent,Simon);
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run needhamschroederpkLowe.I(Agent,Agent,Simon);
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run needhamschroederpkLowe.R(Agent,Agent,Simon);
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run needhamschroederpkLowe.S(Agent,Agent,Simon);
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