Лекция 9 - Протоколы распределения ключей

Ëåêöèÿ 9 Ïðîòîêîëû ðàñïðåäåëåíèÿ êëþ÷åé

Ëåêöèÿ 9
Ïðîòîêîëû ðàñïðåäåëåíèÿ êëþ÷åé
Ìèõàèë Ëåîíèäîâè÷ Áóðÿêîâ

2012 ãîä



ïðîòîêîëû ïåðåäà÷è óæå ñãåíåðèðîâàííûõ êëþ÷åé;



ïðîòîêîëû ñîâìåñòíîé âûðàáîòêè îáùèõ êëþ÷åé;



ñõåìû ïðåäâàðèòåëüíîãî ðàñïðåäåëåíèÿ êëþ÷åé.



îòäåëüíûå ó÷àñòíèêè



îòäåëüíûå ó÷àñòíèêè
ãðóïïû ó÷àñòíèêîâ


Ñèììåòðè÷íîå øèôðîâàíèå. Äâóõñòîðîíèèå ïðîòîêîëû



a) A → B : EkAB (k, t, idB ), t ìåòêà âðåìåíè, idB
èäåíòèôèêàòîð B



b) A → B : k + hkAB (t, idB ) èñïîëüçîâàíèå êëþ÷åâîé
õýø-ôóíêöèè



b) A → B : k + hkAB (t, idB ) èñïîëüçîâàíèå êëþ÷åâîé
õýø-ôóíêöèè
c) äîïîëíèòåëüíàÿ àóòåíòèôèêàöèÿ:
B → A: rB ñëó÷àéíîå
A → B : EkAB (k, rB ) èëè k + hkAB (rB )


d) B → A : rB A → B : EkAB (kA , rA , rB , idB )
B → A : EkAB (kB , rA , rB , idA )
k = f (kA , kB ) âûðàáîòàííûé êëþ÷
+ âçàèìíàÿ àóòåíòèôèêàöèÿ


d) B → A : rB A → B : EkAB (kA , rA , rB , idB )
B → A : EkAB (kB , rA , rB , idA )
k = f (kA , kB ) âûðàáîòàííûé êëþ÷
+ âçàèìíàÿ àóòåíòèôèêàöèÿ
e) ïðîòîêîë Øàìèðà
EK êîììóòèðóþùåå ïðåîáðàçîâàíèå:
EK 1 (EK 2 (x)) = EK 2 (EK 1 (x)) äëÿ âñåõ k1 , k2 , x

A → B : EKA (k)
B → A : EKB (EKA (k))
A → B : DKA (EKB (EKA (k)))
+ ñîîòâåòñòâóþùèå ìåòêè âðåìåíè è èäåíòèôèêàòîðû
EK (x) = x a mod p (a îïðåäåëåòñÿ êëþ÷îì k )


Ñèììåòðè÷íîå øèôðîâàíèå. Òðåõñòîðîíèèå ïðîòîêîëû



Èñïîëüçóþò òðåòüþ äîâåðåííóþ ñòîðîíó T (Trust)



T õðàíèò êëþ÷è âñåõ àáîíåíòîâ



Ïðîòîêîë ÍèäõåìàØðåäåðà



Ïðîòîêîë ÎòâåÿÐèèñà



Ïðîòîêîë ÍüþìàíàÑòàááëáàéíà



1. Alice → Trent : A, B, RA



2. Trent → Alice :
{RA , B, K , {K , A}KB }KA



{RA , B, K , {K , A}KB }KA
3. Alice → Bob : {K , A}KB



{RA , B, K , {K , A}KB }KA
4. Bob → Alice : {RB }K



{RA , B, K , {K , A}KB }KA
4. Bob → Alice : {RB }K
5. Alice → Bob : {RB − 1}K



1. A → B : M, A, B, {NA , M, A, B}KAS



1. A → B : M, A, B, {NA , M, A, B}KAS
2. B → S : M, A, B, {NA , M, A, B}KAS , {NB , M, A, B}KBS



1. A → B : M, A, B, {NA , M, A, B}KAS
3. S → B : M, {NA , KAB }KAS , {NB , KAB }KBS



1. A → B : M, A, B, {NA , M, A, B}KAS
4. B → A : M, {NA , KAB }KAS



1. A → B : M, A, B, {NA , M, A, B}KAS
4. B → A : M, {NA , KAB }KAS

Äàííûå øàãè íå àóòåíöèôèöèðóþò B



1. A → B : A, RA



1. A → B : A, RA
2. B → T : B, RB , EB (A, RA , TB )



1. A → B : A, RA
2. B → T : B, RB , EB (A, RA , TB )
3. T → A : EA (B, RA , K , TB ), EB (A, K , TB ), RB



1. A → B : A, RA
2. B → T : B, RB , EB (A, RA , TB )
3. T → A : EA (B, RA , K , TB ), EB (A, K , TB ), RB
4. A → B : EB (A, K , TB ), EK (RB )


Àñèììåòðè÷íîå øèôðîâàíèå. Òðåõñòîðîíèèå ïðîòîêîëû



a) A → B : EB (k, t, idA )



a) A → B : EB (k, t, idA )
b) ïðîòîêîë ÍèäõåìàØðåäåðà



1. Alice → Trent : A, B



2. Trent → Alice : {KB , B}K −1
T



T

3. Alice → Bob : T , RA , AKB



T

4. Bob → Trent : B, A



T

5. Trent → Bob : {KA , A}K −1
T



T

T

6. Bob → Alice : RB , RA KA



T

T

6. Bob → Alice : RB , RA KA
7. Alice → Bob : {RB }KB


Èñïîëüçîâàíèå ÝÖÏ



a) A → B : EB (k, t, SA (idB , k, t)) øèôðîâàíèå ïîäïèñàííîãî
êëþ÷à;



êëþ÷à;
b) A → B : EB (k, t), SA (idB , k, t) øèôðîâàíèå è ïîäïèñü
êëþ÷à;



êëþ÷à;
b) A → B : EB (k, t), SA (idB , k, t) øèôðîâàíèå è ïîäïèñü
êëþ÷à;
c) A → B : t, EB (k), SA (idB , t, EB (k)) ïîäïèñü
çàøèôðîâàííîãî ñîîáùåíèÿ, . . .


Ñåðòèôèêàòû îòêðûòûõ êëþ÷åé
öèôðîâîé èëè áóìàæíûé äîêóìåíò, ïîäòâåðæäàþùèé
ñîîòâåòñòâèå ìåæäó îòêðûòûì êëþ÷îì è èíôîðìàöèåé,
èäåíòèôèöèðóþùåé âëàäåëüöà êëþ÷à.

CA = (idA , kA , t, ST (idA , kA , t))
idA èäåíòèôèêàòîð A
kA îòêðûòûé êëþ÷
t äàòà âûäà÷è, ñðîê äåéñòâèÿ
ST (idA , kA , t) ïîäïèñü äîâåðåííîãî öåíòðà (äëÿ íå¼ òàêæå
íóæåí îòêðûòûé êëþ÷ ⇒ öåïî÷êà ñåðòèôèêàòîâ)


Îòêðûòîå ðàñïðåäåëåíèå êëþ÷åé.
Ïðîòîêîë ÄèôôèÕýëëìàíà



a îáðàçóþùèé ãðóïïû áîëüøîãî ïîðÿäêà (ïàðàìåòð
ïðîòîêîëà)
A → B : ax , x ñëó÷àéíîå
B → A : ay , y ñëó÷àéíîå
k = (ax )y = (ay )x îáùèé êëþ÷



a îáðàçóþùèé ãðóïïû áîëüøîãî ïîðÿäêà (ïàðàìåòð
ïðîòîêîëà)
A → B : ax , x ñëó÷àéíîå
B → A : ay , y ñëó÷àéíîå
k = (ax )y = (ay )x îáùèé êëþ÷
Óÿçâèì ê àòàêå ¾÷åëîâåê ïîñåðåäèíå¿.



Âàðèàíò ïðîòîêîëà ñ èñïîëüçîâàíèåì ïîäïèñè:



1. A → B : ax



1. A → B : ax
2. B → A : ay , Ek (SB (ax , ay )), k îáùèé âûðàáîòàííûé êëþ÷



1. A → B : ax
2. B → A : ay , Ek (SB (ax , ay )), k îáùèé âûðàáîòàííûé êëþ÷
3. A → B : Ek (SA (ax , ay ))


Ïðîòîêîë ÌàöóìîòîÒàêàøèìèÈìàè

ZA = apA , ZB = apB îòêðûòûå êëþ÷è



A → B : ax
B → A : ay



A → B : ax
B → A : ay
y
x
k = (ay )pA ZB = (ax )pB ZA = axpB+ypA îáùèé êëþ÷

Лекция 9 - Протоколы распределения ключей

Recommended

Recommended

More Related Content

Featured

Featured (20)

Лекция 9 - Протоколы распределения ключей