For the biometric authentication protocols illustrated in the figure, note that the biometric capture device is authenticated in the case of a static biometric but not authenticated for a dynamic biometric. Explain why authentication is useful in the case of a stable biometric but not needed in the case of dynamic biometric.

Client U, user Host Client ransmission Host -1 r. h(). fO } | h0,f(), functions -|r, h(), f)} | random hO, fO, functions P' passwordfr,h(P)- r. return of r password to passcode via token lfr. h(W) turn of r if fr', h(P) yeso yeso fir, h(P(U)) then yes else no for, h(WU)) then yes else no (a) Protocol for a password (b) Protocol for a token Client Host Transmission Client U, user Transmission Host r. random number ,random sequence challenge EO. function r, random number EO, function | {r, E()} { r, x, E()) *- B' BT, biometric D' biometric device! E(r', D. BT- E-Er, P. BT)- r', P'. BT) ifr=r, and D'=D and BT" BT(U) then yes else no r, return of r r. return of r extract B from BS) If r' = rand x' =x and B' = B(U) then yes else no yeso yes|no (c) Protocol for static biometric (d) Protocol for dynamic biometric Client U, user Host Client ransmission Host -1 r. h(). fO } | h0,f(), functions -|r, h(), f)} | random hO, fO, functions P' passwordfr,h(P)- r. return of r password to passcode via token lfr. h(W) turn of r if fr', h(P) yeso yeso fir, h(P(U)) then yes else no for, h(WU)) then yes else no (a) Protocol for a password (b) Protocol for a token Client Host Transmission Client U, user Transmission Host r. random number ,random sequence challenge EO. function r, random number EO, function | {r, E()} { r, x, E()) *- B' BT, biometric D' biometric device! E(r', D. BT- E-Er, P. BT)- r', P'. BT) ifr=r, and D'=D and BT" BT(U) then yes else no r, return of r r. return of r extract B from BS) If r' = rand x' =x and B' = B(U) then yes else no yeso yes|no (c) Protocol for static biometric (d) Protocol for dynamic biometric