Security Patterns in Practice: Designing Secure Architectures Using Software Patterns

CHAPTER 12

Patterns for Web Services Cryptography

He told me that toward 1886 he had devised a new system of enumeration and that in a very few days he had gone slightly over twenty-four thousand. He had not written it down, for what he had thought just once would not be erased. His first stimulus, I believe, had been his discontent with the fact that ‘thirty-three Uruguayans’ required two symbols and three words, rather than a single word and a single symbol. Later he applied his extravagant principle to the other numbers. In place of seven thousand thirteen, he would say (for example) Máximo Perez; in place of seven thousand fourteen, The Railway; other numbers were Luis Melián Lafinur, Olimar, sulphur, Clubs, The Whale, Gas, The Cauldron, Napoleon, Agustín Vedia. In lieu of five hundred, he would say nine. Each word had a particular sign, a species of mark; the last were very complicated…¹

Jorge Luis Borges, ‘Funes el memorioso’, http://www.literatura.us/borges/funes.html

12.1 Introduction

Information can be captured and read during its transmission. A message can also be modified or replayed. How can we protect this information from such attacks? Encryption provides message confidentiality by transforming readable data (plain text) into an unreadable format (cipher text) that can be understood only by the intended recipient after decryption, the inverse function that makes the encrypted information readable again. There are two types of encryption: symmetric and asymmetric ...