Patient provides an EMR linked to DID to HAC

P.1 Patient $\to$ HAC : $\underset{M}{\underbrace{DID,{\left\{EMR\right\}}_k}},{\left\{H\left(M\right)\right\}}_{k_p^{-1}},{\left\{k\right\}}_{k_c}$

HAC retrieves the key k_b associated to DID from Indy

P.2 HAC $\to$ Indy : DID

P.3 Indy $\to$ HAC : DID, k_b, ${\left\{H\left(DID,k_b\right)\right\}}_{k_p^{-1}}$

Patient proves ownership of k_b via challenge/response

P.4 HAC $\to$ Patient : DID, N_c

P.5 Patient $\to$ Patient—USB : H(DID, N_c)

P.6 Patient—USB $\to$ Patient : ${\left\{H\left(DID,N_c\right)\right\}}_{k_b^{-1}}$

P.7 Patient $\to$ HAC : ${\left\{H\left(DID,N_c\right)\right\}}_{k_b^{-1}}$