Secure TriggersAriel Futoransky, Emiliano Kargieman,

Carlos Sarraute, Ariel Waissbein

Core Security Technologies

{ek,wata}@coresecurity.com

Definitions

• Let S be a secret and P={p} a family of predicates.Let p be a predicate in P

• Def: A trigger is an algorithm T(S,p) that takes any input x in {0,1}* and returns S iff p(x)=true.Else, it returns nothing.

• Def: The trigger T(S,p) is said secure if a polynomial-time attacker, given P, the sampling distribution, and arbitrary access to T(S,p), cannot learn anything about S.

Examples (1): Simple Trigger

• If the input x is equal to a private value y, then the Secret S is released.

T(S,“x=y?")

x = y? S

Examples (2): Multiple Strings Trigger

• If the input set X={x1,…,xn} includes a private set Y ={y1,…,yt}, then the Secret S is released.

T(S,“XY?")x1 ?

S……

xn

y1…

yn

Examples (3): Subsequence Trigger

• If xi1 = y1, …, xit = yt, then the secret S is released. – Where both {yj}, and {ik} are private.

T(S,“(xjk)=(yk)?")x

xi1

Examples (3): Subsequence Trigger

• If xi1 = y1, …, xit = yt, then the secret S is released. – Where both {yj}, and {ik} are private.

T(S,“(xjk)=(yk)?")x

xi1

xi2

Examples (3): Subsequence Trigger

• If xi1 = y1, …, xit = yt, then the secret S is released. – Where both {yj}, and {ik} are private.

T(S,“(xjk)=(yk)?")x

…

xit

xi1

xi2

Examples (3): Subsequence Trigger

• If xi1 = y1, …, xit = yt, then the secret S is released. – Where both {yj}, and {ik} are private.

T(S,“(xjk)=(yk)?")x

? Sy1

…

yt

=

=

x

…

xit

xi1

xi2 y2=

Applications of the triggers

• Information Warfare WormAttack

• Online automated shopping

• Other– Software protection– …

Results

• Generic definitions of security for Secure Triggers on the UCS framework

• Instantiations:• Simple triggers are secure

• Multiple strings triggers are secure

• Subsequence triggers are secure

• Paper submitted for publication,let us know if you want a copy