14. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà
ïðîñòîå ÷èñëî, îáùåèçâåñòíî
Çàäàäèì ïðîèçâîëüíûé ìíîãî÷ëåí ñòåïåíè k − 1
pM
F (x) = (ak−1 x k−1 + ak−2 x k−2 + . . . + a1 x + M)
ðàçäåëÿåìûé ñåêðåò
ñëó÷àéíûå ÷èñëà, íåèçâåñòíû
M
a1 , a2 , . . . , ak−1
mod p,
15. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà
Òåïåðü âû÷èñëÿåì êîîðäèíàòû n òî÷åê:
k1 = F (1) = (ak−1 · 1k−1 + ak−2 · 1k−2 + . . . + a1 · 1 + M)
mod p
k2 = F (2) = (ak−1 · 2k−1 + ak−2 · 2k−2 + . . . + a1 · 2 + M)
mod p
...
kn = F (n) = (ak−1 · nk−1 + ak−2 · nk−2 + . . . + a1 · n + M)
mod p
16. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà
Òåïåðü âû÷èñëÿåì êîîðäèíàòû n òî÷åê:
k1 = F (1) = (ak−1 · 1k−1 + ak−2 · 1k−2 + . . . + a1 · 1 + M)
mod p
k2 = F (2) = (ak−1 · 2k−1 + ak−2 · 2k−2 + . . . + a1 · 2 + M)
mod p
...
kn = F (n) = (ak−1 · nk−1 + ak−2 · nk−2 + . . . + a1 · n + M)
(i, ki , p, k − 1)
ðàçäàåì ó÷àñòíèêàì ñõåìû
mod p
17. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà
Âîññòàíîâëåíèå êîýôôèöèåíòîâ
(èíòåðïîëÿöèîííûé ìíîãî÷ëåí Ëàãðàíæà):
F (x) =
li (x)yi
mod p
x − xj
xi − xj
mod p
i
li (x) =
i=j
(xi , yi )
êîîðäèíàòû òî÷åê ìíîãî÷ëåíà
18. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà. Ïðèìåð
Ãåíåðàöèÿ çíà÷åíèé
1. Ïóñòü M = 11, n = 5, t = 3.
19. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà. Ïðèìåð
Ãåíåðàöèÿ çíà÷åíèé
1. Ïóñòü M = 11, n = 5, t = 3.
2. Âîçüìåì p = 13. Ïîñòðîèì ìíîãî÷ëåí ñòåïåíè k − 1 = 2:
F (x) = (7x 2 + 8x + 11)
mod 13
20. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà. Ïðèìåð
Ãåíåðàöèÿ çíà÷åíèé
1. Ïóñòü M = 11, n = 5, t = 3.
2. Âîçüìåì p = 13. Ïîñòðîèì ìíîãî÷ëåí ñòåïåíè k − 1 = 2:
F (x) = (7x 2 + 8x + 11)
3.
k1 = F (1) = (7 · 12 + 8 · 1 + 11)
mod 13
mod 13 = 0
2
mod 13 = 3
2
k3 = F (3) = (7 · 3 + 8 · 3 + 11)
mod 13 = 7
k4 = F (4) = (7 · 42 + 8 · 4 + 11)
mod 13 = 12
k5 = F (5) = (7 · 52 + 8 · 5 + 11)
mod 13 = 5
k2 = F (2) = (7 · 2 + 8 · 2 + 11)
21. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà ðàçäåëåíèå ñåêðåòà Øàìèðà. Ïðèìåð
Ãåíåðàöèÿ çíà÷åíèé
1. Ïóñòü M = 11, n = 5, t = 3.
2. Âîçüìåì p = 13. Ïîñòðîèì ìíîãî÷ëåí ñòåïåíè k − 1 = 2:
F (x) = (7x 2 + 8x + 11)
3.
k1 = F (1) = (7 · 12 + 8 · 1 + 11)
mod 13
mod 13 = 0
2
mod 13 = 3
2
k3 = F (3) = (7 · 3 + 8 · 3 + 11)
mod 13 = 7
k4 = F (4) = (7 · 42 + 8 · 4 + 11)
mod 13 = 12
k5 = F (5) = (7 · 52 + 8 · 5 + 11)
mod 13 = 5
k2 = F (2) = (7 · 2 + 8 · 2 + 11)
4. Ðàñïðåäåëåíèå (i, ki , 13, 2) ïî ó÷àñòíèêàì
29. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìû, îñíîâàííûå íà ÊÒÎ. Ñõåìà ÀñìóòàÁëóìà
ñåêðåò
p ïðîñòîå ÷èñëî, áîëüøåå M
d1 , d2 , . . . , dn âçàèìíî ïðîñòûå, òàêèå, ÷òî:
M
di p
di+1 di
d1 · d2 · . . . · dt p · dn−t+2 · . . . · dn
ñëó÷àéíîå
r
M = M + rp
Äîëè ñåêðåòà {p, di , ki }, ãäå ki = M
mod di
30. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìû, îñíîâàííûå íà ðåøåíèè ñèñòåì óðàâíåíèé.
Ñõåìà Êàðíèíà Ãðèíà Õåëëìàíà
Çàäàí n + 1 âåêòîð v0, v1, . . . , vn ðàçìåðíîñòè m
Ðàíã ëþáîé ìàòðèöû, ñîñòàâëåííîé èç m âåêòîðîâ, ðàâåí
m
Âåêòîð v0 èçâåñòåí âñåì ó÷àñòíèêàì.
Ñåêðåò ïðîèçâåäåíèå u, v0
Äîëè ñåêðåòà ñêàëÿðíûå ïðîèçâåäåíèÿ
vi
u, vi
è âåêòîðû
Äëÿ âîññòàíîâëåíèÿ ñåêðåòà ïî èçâåñòíûì äîëÿì (è
íàáîðó âåêòîðîâ v1, v2, . . . , vn ) ðåøàåòñÿ ñèñòåìà èç m
óðàâíåíèé äëÿ íàõîæäåíèÿ âåêòîðà .
32. Ëåêöèÿ 10
Ñõåìû ðàçäåëåíèÿ ñåêðåòà. Æèçíåííûé öèêë êëþ÷åé
Ñõåìà Áëîìà
Ïðåäâîðèòåëüíûé ýòàï
Ñèììåòðè÷åñêàÿ ìàòðèöà D ∈ F k×k ëèáî ñåêðåòíà (åñëè
ïðåäïîëàãàåòñÿ äîáàâëåíèå ó÷àñòíèêîâ), ëèáî çàáûâàåòñÿ.
IA ñëó÷àéíûé âåêòîð äëèíû k îòêðûòûé ¾êëþ÷¿ A
gA = DIA çàêðûòûé ¾êëþ÷¿ A
Îáìåí îòêðûòûìè êëþ÷àìè ìåæäó A è B
T
T
T
T
1. SA = gA IB = (gA IB )T = (IA D T IB )T = IB DIA
T
T
T
2. SB = gB IA = (DIB )T IA = IB D T IA = IB DIA
3. SA = SB