256
T. Ismail et al.
Table 2. Scenario of the recovery phase
Data Requester
Data Owner
Schnorr algorithm
α = (H(R))
, s: secret key
v = α −s
1. Choose r and calculate
x = α r mod p
x
− →
2.Choose e, n (3 ≤ n ≤ 20)
e, n
← −− −
3.Calculate y = r + es mod p
Calculate F = n first bits of ID DR
Calculate Y = y
F
Y
− →
4.Calculate y = Y
F
5.Verify x
?
= H(R) y .v e mod p
Diffie Hellman algorithm
s, p, g
b
6.Calculate A = g s mod p
F 1 = premier n bits de H(R)
A 1 = A
F 1
A 1 ,p,g
−−−−→
7.Calculate B = g b mod p
B 1 = B
F 1
B 1
← − −
Calculate Ks
← −−−−−−−− →
B = B 1
F 1
8. Calculate
A = A 1
F 1
Ks = B s mod p
K s = A s mod p
9.Encryt private key PU
P U
= E Ks (PU)
P U
← −− −
10.Extract PU
PU = D Ks (P U
)
11. Recover R = D P U R (R
)
metadata. Next, the DO encrypts his private key (PU) using K s and sends the
resulted value P U
to the DR.
P U
= E Ks (P U)
(4)
T. Ismail et al.
Table 2. Scenario of the recovery phase
Data Requester
Data Owner
Schnorr algorithm
α = (H(R))
, s: secret key
v = α −s
1. Choose r and calculate
x = α r mod p
x
− →
2.Choose e, n (3 ≤ n ≤ 20)
e, n
← −− −
3.Calculate y = r + es mod p
Calculate F = n first bits of ID DR
Calculate Y = y
F
Y
− →
4.Calculate y = Y
F
5.Verify x
?
= H(R) y .v e mod p
Diffie Hellman algorithm
s, p, g
b
6.Calculate A = g s mod p
F 1 = premier n bits de H(R)
A 1 = A
F 1
A 1 ,p,g
−−−−→
7.Calculate B = g b mod p
B 1 = B
F 1
B 1
← − −
Calculate Ks
← −−−−−−−− →
B = B 1
F 1
8. Calculate
A = A 1
F 1
Ks = B s mod p
K s = A s mod p
9.Encryt private key PU
P U
= E Ks (PU)
P U
← −− −
10.Extract PU
PU = D Ks (P U
)
11. Recover R = D P U R (R
)
metadata. Next, the DO encrypts his private key (PU) using K s and sends the
resulted value P U
to the DR.
P U
= E Ks (P U)
(4)