Cryptography Reference
In-Depth Information
Cryptographic
Protocols
9
We have now completed our review of the most fundamental cryptographic
primitives that make up the cryptographic toolkit. We have seen that each
primitive provides very specific security services that can be applied to data.
However, most security applications require different security services to be
applied to a variety of items of data, often integrated in a complex way. What we
must now do is examine how cryptographic primitives can be combined together
to match the security requirements of real applications. This is done by designing
cryptographic protocols.
We begin this chapter with a brief introduction to the idea of a cryptographic
protocol.We then examine and analyse some very simple cryptographic protocols.
Finally, we discuss the important class of cryptographic protocols that provide
entity authentication and key establishment.
At the end of this chapter you should be able to:
• Explain the concept of a cryptographic protocol.
• Analyse a simple cryptographic protocol.
• Appreciate the difficulty of designing a secure cryptographic protocol.
• Justify the typical properties of an authentication and key establishment
protocol.
• Appreciate the significance of the Diffie-Hellman protocol and variants of it.
• Compare the features of two authentication and key establishment protocols.
We begin by providing two different, but related, motivations for the need for
cryptographic protocols.
