Cryptography Reference
In-Depth Information
desires for privacy, as well as business needs for the protection of commercial
secrets.
Indeed, cryptographic technology is sometimes labelled as a
dual use good
,
which means that it is considered to be a technology with the potential to be
both beneficial or harmful, depending on the perspective taken on a particular
cryptographic application.
1.1.4
The importance of security infrastructure
The security commentator Bruce Schneier wrote a topic called
Applied Crypto-
graphy
in the early 1990s. A few years later he wrote a topic on computer security
called
Secrets and Lies
. He claimed that during the writing of the second topic he
had an 'epiphany' in which he realised that all the cryptographic mechanisms in
Applied Cryptography
were almost immaterial compared to the 'real' security
problems associated with the provision of a complete information security
system. The biggest problem was not designing the cryptographic mechanisms
themselves. The real problem was making the cryptography actually work in
a practical system through the provision of an entire information security
architecture, of which cryptography was only a small, but vital, component.
This is an important issue and one that needs to be kept in mind throughout
this topic. Cryptography, just like any security technology, cannot be made to
work without having the infrastructure in place to support its implementation. By
'infrastructure' we mean the procedures, plans, policies, management, whatever
it takes, to make sure that the cryptographic mechanisms actually do the job for
which they were intended.
We will consider certain aspects of this infrastructure. However, there aremany
aspects of this infrastructure that are well beyond the scope of our discussions.
Ideally, computer operating systems should be designed and used securely,
networks should be implemented and configured securely, and entire information
systems should be planned andmanaged securely. A perfectly good cryptographic
mechanismcan fail to deliver its intended security services if any one of these other
areas of the security infrastructure fail.
This holistic attitude to information security is one that must always be kept in
mind whenever a cryptographic application is designed or used. One of the aims
of this topic is to identify which elements of this wider security infrastructure are
particularly relevant to the effectiveness of a cryptographic application.
We now consider the types of risk to which information is typically exposed. We
examine a very basic communication scenario and discuss some of the factors
