normal : simi-fuctional :. normal : simi-fuctional :
Post on 12-Jan-2016
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Normal:
Simi-fuctional:
Normal:
Simi-fuctional:
• Gamereal:Real security game
• Gamerestrictedrestricted:
Real security game except that the attacker cannot ask for keys for identities which are equal to the challenge identity modulo p2.
• Gamek:This is like the restricted security game, except that the ciphertext given to the attacker is semi-functional and the first k keys are sem
i- functional. The rest of the keys are normal.
• Gamefinal:same as Gameq except that the ciphertext is a semi-functional encrypt
ion of a random message, not one of the two messages requested by the attacker.
• Gamereal Gamerestrictedrestricted
C B A
g, X1X2, X3, Y2Y3, TPK = {N,u=ga,g,h=gb,e(g,g)α}
K1=grX3t K2=gα(uIDh)rX3
t`
ID
(M0,M1,ID*)
C0=Mβe(g,g)αs, C1=((uID*h)s), C2=gs
• Gamerestrictedrestricted Game00
C B A
g, X3, T
PK = {N,u=ga,g,h=gb,e(g,g)α}
K1=grX3t K2=gα(uIDh)rX3
t`
ID
(M0,M1,ID*)
C0=Mβe(T,g)αs, C1=TaID*+b, C2=T
β`
b`
• Gamek-1k-1 Gamek
C B Ag, X1X2, X3, Y2Y3, T
PK = {N,u=ga,g,h=gb,e(g,g)α}
if i>k K1=griX3ti K2=gα(uIDih)riX3
ti`
IDi
(M0,M1,ID*)
C0=Mβe(X1X2,g)αs, C1=(X1X2)aID*+b, C2=X1X2
β`b`
if i>k K1=gri(Y2Y3)ti K2=gα(uIDih)ri(Y2Y3)ti`
if i=k K1=T K2=gαTaIDk+bX3ti`
• Gameq Gamefinalfinal
C B A
g, gαX2, X3, gsY2, Z2, TPK = {N,u=ga,g,h=gb,e(g,g)α=e(gαX2,g)}
K1=gr Z2θX3
t K2=gα(uIDh)rZ2θ`X3
t`
ID
(M0,M1,ID*)
C0=MβT, C1=(gsY2)aID*+b, C2=gsY2
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