t-Private Systems: Unified Private Memories and Computation

A

t

-private system consists of computing logic along with ROMs to store the persistent private keys. Ishai

et al.

[4] have developed a

t

-private logic schema with zero information loss against a probing adversary with up to

t

probes per cycle. Valamehr

et al.

[12] describe memory coding schemes to protect against a physical access adversary who observes transistor level fatigue through destructive slicing of the silicon chip. The two schemes cannot be combined to build a unified

t

-private system consisting of both memory and computing logic. For instance, Valamehr coding schemes do not have an associated computing logic schema. The keys after being read from ROM first have to be decoded and then re-encoded for

t

-private logic, opening them to probing attacks. In this paper, we propose a new unified

computable

t

-private model to support both memory coding and logic coding. We develop the computing schema, logic preserving implementations of logic gates such as AND, OR and NOT, for the new computable

t

-private memories. Our computable

t

-private model takes fewer gates, less storage, fewer random bits than the existing schemes, and yet limits the adversary success probability. The memory is analyzed in the physical adversary framework of Valamehr, and computing logic is analyzed in the zero information loss framework of Ishai

et al.

[4].