Efficient and Secure Biometric-Based User Authenticated Key Agreement Scheme with Anonymity

Box 2

Role specification in HLPSL for the server .

role server (Ui,Sj: agent,

    SKuisj: symmetric_key,

    H  : hash_func,

    Snd,Rcv: channel(dy))

played_by Sj

def=

 local State  : nat,

    IDi, PWi, RPWi, BIOi, X, Ai, Bi, Ci, R1, Di, Ei, Fi, R2, Gi, Vi  : text

 const user_server_r1, server_user_r2,

    subs1, subs2  : protocol_id

 init State 0

 transition

%%%%% Registration phase

 1. State = 0 Rcv(IDi.H(PWi.H(BIOi)) _SKuisj)

   State＇ 1 secret(, subs1, Sj)

     secret(, subs2, Ui)

     Snd(xor(H(xor(IDi, X)), H(IDi.H(PWi.H(BIOi)))).xor(H(xor(IDi, X).H(PWi.H(BIOi))), X) _SKuisj)

%%%%% Login phase

 2. State = 1 Rcv(xor(H(H(xor(IDi, X)).H(PWi.H(BIOi))), X).xor(IDi, R1＇).xor(IDi, H(H(xor(IDi,

X)).RPWi＇)).H(IDi.R1＇.H(xor(IDi, X))))

%%%%% Verification phase

   State＇ 2 R2＇ new()

    IDi＇ xor(xor(IDi, H(H(xor(IDi, X)).RPWi＇)), Ci＇, X)

    R1＇ xor(xor(IDi, R1＇), IDi)

    Fi＇ H(IDi.R1＇.H(xor(IDi, X)))

    Gi＇ xor(R2＇, H(R1＇.H(IDi.R1＇.Ai＇)))

    Vi＇ H(H(R1＇.R2＇.H(xor(IDi, X)).IDi).R1＇.R2＇)

    Snd(Gi＇.Vi＇)

    witness(Sj, Ui, server_user_r2, R2＇)

    request(Ui, Sj, user_server_r1, R1＇)

end role