Silvio Micali

Bio: Silvio Micali is an academic researcher from Massachusetts Institute of Technology. The author has contributed to research in topics: Common value auction & Digital signature. The author has an hindex of 84, co-authored 236 publications receiving 45550 citations. Previous affiliations of Silvio Micali include Polaroid Corporation & University of California.

Computationally Sound Proofs

Abstract: This paper puts forward a new notion of a proof based on computational complexity and explores its implications for computation at large. Computationally sound proofs provide, in a novel and meaningful framework, answers to old and new questions in complexity theory. In particular, given a random oracle or a new complexity assumption, they enable us to prove that verifying is easier than deciding for all theorems; provide a quite effective way to prove membership in computationally hard languages (such as ${\cal C}o$-$\cal N \cal P$-complete ones); and show that every computation possesses a short certificate vouching its correctness. Finally, if a special type of computationally sound proof exists, we show that Blum's notion of program checking can be meaningfully broadened so as to prove that $\cal N \cal P$-complete languages are checkable.

On-line/off-line digital signatures

Abstract: A new type of signature scheme is proposed. It consists of two phases. The first phase is performed off-line, before the message to be signed is even known. The second phase is performed on-line, once the message to be signed is known, and is supposed to be very fast. A method for constructing such on-line/off-line signature schemes is presented. The method uses one-time signature schemes, which are very fast, for the on-line signing. An ordinary signature scheme is used for the off-line stage. In a practical implementation of our scheme, we use a variant of Rabin's signature scheme (based on factoring) and DES. In the on-line phase all we use is a moderate amount of DES computation and a single modular multiplication. We stress that the costly modular exponentiation operation is performed off-line. This implementation is ideally suited for electronic wallets or smart cards.

Physically Observable Cryptography (Extended Abstract).

Abstract: Complexity-theoretic cryptography considers only abstract notions of computation, and hence cannot protect against attacks that exploit the information leakage (via electromagnetic fields, power con- sumption, etc.) inherent in the physical execution of any cryptographic al- gorithm. Such "physical observation attacks" bypass the impressive bar- rier of mathematical security erected so far, and successfully break math- ematically impregnable systems. The great practicality and the inherent availability of physical attacks threaten the very relevance of complexity- theoretic security. To respond to the present crisis, we put forward physically observable cryptography: a powerful, comprehensive, and precise model for defining and delivering cryptographic security against an adversary that has ac- cess to information leaked from the physical execution of cryptographic algorithms. Our general model allows for a variety of adversaries. In this paper, however, we focus on the strongest possible adversary, so as to capture what is cryptographically possible in the worst possible, physi- cally observable setting. In particular, we - consider an adversary that has full (and indeed adaptive) access to any leaked information; - show that some of the basic theorems and intuitions of traditional cryptography no longer hold in a physically observable setting; and - construct pseudorandom generators that are provably secure against all physical-observation attacks.

Noninteractive zero-knowledge

Abstract: This paper investigates the possibility of disposing of interaction between prover and verifier in a zero-knowledge proof if they share beforehand a short random string.Without any assumption, it i...

I and i

Abstract: There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality. Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

Handbook of Applied Cryptography

Abstract: From the Publisher: A valuable reference for the novice as well as for the expert who needs a wider scope of coverage within the area of cryptography, this book provides easy and rapid access of information and includes more than 200 algorithms and protocols; more than 200 tables and figures; more than 1,000 numbered definitions, facts, examples, notes, and remarks; and over 1,250 significant references, including brief comments on each paper.

Principles of Neural Science

Abstract: I have developed "tennis elbow" from lugging this book around the past four weeks, but it is worth the pain, the effort, and the aspirin. It is also worth the (relatively speaking) bargain price. Including appendixes, this book contains 894 pages of text. The entire panorama of the neural sciences is surveyed and examined, and it is comprehensive in its scope, from genomes to social behaviors. The editors explicitly state that the book is designed as "an introductory text for students of biology, behavior, and medicine," but it is hard to imagine any audience, interested in any fragment of neuroscience at any level of sophistication, that would not enjoy this book. The editors have done a masterful job of weaving together the biologic, the behavioral, and the clinical sciences into a single tapestry in which everyone from the molecular biologist to the practicing psychiatrist can find and appreciate his or

Identity-Based Encryption from the Weil Pairing

Abstract: We propose a fully functional identity-based encryption scheme (IBE). The scheme has chosen ciphertext security in the random oracle model assuming an elliptic curve variant of the computational Diffie-Hellman problem. Our system is based on the Weil pairing. We give precise definitions for secure identity based encryption schemes and give several applications for such systems.

Secure spread spectrum watermarking for multimedia

Abstract: This paper presents a secure (tamper-resistant) algorithm for watermarking images, and a methodology for digital watermarking that may be generalized to audio, video, and multimedia data. We advocate that a watermark should be constructed as an independent and identically distributed (i.i.d.) Gaussian random vector that is imperceptibly inserted in a spread-spectrum-like fashion into the perceptually most significant spectral components of the data. We argue that insertion of a watermark under this regime makes the watermark robust to signal processing operations (such as lossy compression, filtering, digital-analog and analog-digital conversion, requantization, etc.), and common geometric transformations (such as cropping, scaling, translation, and rotation) provided that the original image is available and that it can be successfully registered against the transformed watermarked image. In these cases, the watermark detector unambiguously identifies the owner. Further, the use of Gaussian noise, ensures strong resilience to multiple-document, or collusional, attacks. Experimental results are provided to support these claims, along with an exposition of pending open problems.