Locally computable (NC0) functions are "simple" functions for
which every bit of the output can be computed by reading a small number
of bits of their input. The study of locally computable cryptography
attempts to construct cryptographic functions that achieve this strong
notion of simplicity and simultaneously provide a high level of
security. Such constructions are highly parallelizable and they can be
realized by Boolean circuits of constant depth.
This book establishes, for the first time, the possibility of local
implementations for many basic cryptographic primitives such as one-way
functions, pseudorandom generators, encryption schemes and digital
signatures. It also extends these results to other stronger notions of
locality, and addresses a wide variety of fundamental questions about
local cryptography. The author's related thesis was honorably mentioned
(runner-up) for the ACM Dissertation Award in 2007, and this book
includes some expanded sections and proofs, and notes on recent
developments.
The book assumes only a minimal background in computational complexity
and cryptography and is therefore suitable for graduate students or
researchers in related areas who are interested in parallel
cryptography. It also introduces general techniques and tools which are
likely to interest experts in the area.