Prehistory of Cryptography - A Classical Introduction to Cryptography: Applications for Communications Security - page 13

which the goal is to deduce the secret key) from a decryption attack (in which the goal
is to decrypt a target ciphertext). It is thus quite important to describe the adversary
models related to every cryptographic system.

1.2.4 Cryptography from Various Perspectives

On the Government Side: The Cold War

The military success of the Allies during World War II was partly due to cryptography,
and as such, cryptography became highly estimated during the cold war. A famous
implementation was the red telephone between Moscow and Washington DC. This was
a kind of email service (not a real telephone) with encryption through a one-time pad
(see Section 1.1.4).

United States and Russia had an opposite approach of intelligence. While Russia
mainly used on-site physical agents, the United States started to develop a communi-
cation wiretapping industry. They created the NSA, the existence of which remained
secret until very recently, and developed the Echelon network. 9 Echelon is aimed at
listening to all electronic communications (telephone, radio, fax, satellite, cables, etc.),
at automatically analyzing and filtering them, and at developing virtual agents which
can trigger alerts.

Cryptography was considered as a war weapon and regulated as such: import-
export organizations, salesmen, developers, researchers, publishers were controlled by
government agencies in many countries (United States, France, etc.). Switzerland was
one of the only cryptographic paradise where one could freely set up mirror companies
for cryptographic products. In other countries, obscure agencies used to put vetoes
on some sensitive research projects (like studying data integrity control algorithms),
to lobby to forbid scientific publications (even the present textbook could have been
classified as a war weapon and the topic holder could have been prosecuted by a
military court), and to classify some patent applications. Programs were set up in
order to facilitate government inspection of private communications by key escrow (for
instance, with the US cliper chip which has now disappeared). 10 There is indeed an
equilibrium to find between individual privacy and national security, and governments
used to clearly favor the latter. The situation has become much more liberal now and
cryptography can be taught, studied, and used in private business.

On the Industry Side: Electronic Commerce

While cryptography research, development, and usage were restricted, there was a need
for communication protection in civil environments. In the seventies, banking was using
more and more electronic transactions and had to make them secure. At this time, the

9

For more references on the NSA, see Ref. [22].

10

This situation is described by Whitfield Diffie and Susan Landau in Ref. [60].