We construct a stream-cipher S whose implementation is secure even if arbitrary (adversely chosen) information on the internal state of S is leaked during computation. This captures all possible side-channel attacks on S where the amount of information leaked in a given period is bounded, but overall can be arbitrary large, in particular much larger than the internal state of S. The only other ...

Distributed ledger technologies (DLT), including blockchains, combine the use of cryptography and distributed networks to achieve a novel form records creation keeping designed for tamper-resistance immutability. Over past several years, these capabilities have made DLTs, increasingly popular as general-purpose technology used recordkeeping in variety sectors industry domains, yet many open cha...

We introduce delegation schemes wherein a user may delegate certain rights to himself, but may not safely delegate these rights to others. In our motivating application, a user has a primary (long-term) key that receives some personalized access rights, yet the user may reasonably wish to delegate these rights to new secondary (short-term) keys he creates to use on his laptop when traveling, to...

We revisit the question of constructing public-key encryption and signature schemes with security in the presence of bounded leakage and tampering memory attacks. For signatures we obtain the first construction in the standard model; for public-key encryption we obtain the first construction free of pairing (avoiding non-interactive zero-knowledge proofs). Our constructions are based on generic...

Tampering attacks are cryptanalytic attacks on the implementation of cryptographic algorithms (e.g., smart cards), where an adversary introduces faults with the hope that the tampered device will reveal secret information. Inspired by the work of Ishai et al. [Eurocrypt’06], we propose a compiler that transforms any circuit into a new circuit with the same functionality, but which is resilient ...

Bent and resilient functions play significant roles in cryptography, coding theory, and combinatorics. However, the numbers of bent and resilient functions on a given number of variables are not known. Even a reasonable bound on the number of bent functions is not known and the best known bound on the number of resilient functions seems weak for functions of high orders. In this paper we presen...

In this dissertation we investigate the question of protecting cryptographic devices from tampering attacks. Traditional theoretical analysis of cryptographic devices is based on black-box models which do not take into account the attacks on the implementations, known as physical attacks. In practice such attacks can be executed easily, e.g. by heating the device, as substantiated by numerous w...

A seal is only as good as the man in whose briefcase it's carried. —KAREN SPÄRCK JONES 12.1 Introduction Many computer systems rely to some extent on secure printing, packaging, and seals to guarantee important aspects of their protection. • Many software products get some protection against forgery, using tricks such as holographic stickers that are supposed to tear when removed from the packa...

Blocks and chains are the building blocks of blockchain, which is a community network. two terms used to describe collections data information. The most fundamental need for blockchain that these postings be connected by cryptography, case here. Cryptography. entries in each block added as list grows. Although concept cryptography difficult, we have made it easier you understand. Asymmetric-key...

Anonymity is increasingly important for networked applications amidst concerns over censorship and privacy. In this paper, we describe Herbivore, a peer-to-peer, scalable, tamper-resilient communication system that provides provable anonymity and privacy. Building on dining cryptographer networks, Herbivore scales by partitioning the network into anonymizing cliques. Adversaries able to monitor...