67 lines
1.5 KiB
Plaintext
67 lines
1.5 KiB
Plaintext
# Amended Needham Schroeder Symmetric Key
|
|
#
|
|
# Modelled after the description in the SPORE library
|
|
# http://www.lsv.ens-cachan.fr/spore/nssk_amended.html
|
|
#
|
|
#
|
|
# Note:
|
|
# According to SPORE there are no attacks on this protocol, scyther
|
|
# finds one however. This has to be investigated further.
|
|
|
|
|
|
|
|
# Model dec that is invertible by inc
|
|
const dec,inc: Function;
|
|
inversekeys(dec,inc);
|
|
usertype SessionKey;
|
|
const Fresh: Function;
|
|
const Compromised: Function;
|
|
|
|
protocol needhamschroedersk-amend(I,R,S)
|
|
{
|
|
role I
|
|
{
|
|
fresh Ni: Nonce;
|
|
var Nr: Nonce;
|
|
var Kir: SessionKey;
|
|
var T,T2: Ticket;
|
|
|
|
send_1(I,R,I);
|
|
read_2(R,I,T);
|
|
send_3(I,S,(I,R,Ni,T));
|
|
read_4(S,I, {Ni,R,Kir,T2}k(I,S));
|
|
send_5(I,R,T2);
|
|
read_6(R,I,{Nr}Kir);
|
|
send_7(I,R,{{Nr}dec}Kir);
|
|
|
|
claim_I2(I,Secret,Kir);
|
|
claim_I3(I,Nisynch);
|
|
claim_I4(I,Empty,(Fresh,Kir));
|
|
}
|
|
|
|
role R
|
|
{
|
|
fresh Nr: Nonce;
|
|
var Kir: SessionKey;
|
|
|
|
read_1(I,R,I);
|
|
send_2(R,I,{I,Nr}k(R,S));
|
|
read_5(I,R,{Kir,Nr,I}k(R,S));
|
|
send_6(R,I,{Nr}Kir);
|
|
read_7(I,R,{{Nr}dec}Kir);
|
|
claim_R1(R,Secret,Nr);
|
|
claim_R3(R,Nisynch);
|
|
claim_R4(R,Empty,(Fresh,Kir));
|
|
}
|
|
|
|
role S
|
|
{
|
|
var Ni,Nr: Nonce;
|
|
fresh Kir: SessionKey;
|
|
read_3(I,S,(I,R,Ni,{I,Nr}k(R,S)));
|
|
send_4(S,I,{Ni,R,Kir,{Kir,Nr,I}k(R,S)}k(I,S));
|
|
}
|
|
|
|
}
|
|
|