Cryptography Reference
In-Depth Information
1
Introduction and Preliminaries
It is possible to build a cabin with no foundations,
but not a lasting building.
Eng. Isidor Goldreich (1906-1995)
1.1
Introduction
The vast expansion and rigorous treatment of cryptography is one of
the major achievements of theoretical computer science. In particular,
concepts such as computational indistinguishability, pseudorandomness
and zero-knowledge interactive proofs were introduced, classical notions
such as secure encryption and unforgeable signatures were placed on
sound grounds, and new (unexpected) directions and connections were
uncovered. Indeed, modern cryptography is strongly linked to complex-
ity theory (in contrast to “classical” cryptography which is strongly
related to information theory).
Modern cryptography is concerned with the construction of infor-
mation systems that are robust against malicious attempts to make
these systems deviate from their prescribed functionality. The pre-
scribed functionality may be the private and authenticated communi-
