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strong at all, but it must have been indeed quite efective in the days of ancient Rome, where infor-
mation dissemination (especially of the secret sort) was slow and sometimes nonexistent.
he concept of the Caesar Cipher has been applied to a modern cryptographic algorithm called
ROT13, where the letter is substituted for another letter 13 positions ahead. ROT13 is also con-
sidered an extremely weak implementation and was mostly used in Usenet forums to propagate
inappropriate jokes and pass them of as cryptic codes.
*
Encryption became an important requirement for nations during the two world wars. he
need to send messages secretly and the need to decrypt enemy messages became an important
consideration to establish supremacy. his led to the development of the science of cryptogra-
phy on the whole. Just after World War I, Germany developed an encryption system, a machine
known as
Enigma
. he Nazis used this machine extensively in World War II. In fact, it is said that
the Allied cryptanalysts (codebreakers) were able to decrypt a large number of messages, which is
said to be one of the prime causes of an early victory for the Allies in World War II. his system
was considered secure, because the possibility of the number of keys was very large. he Enigma's
mechanism was based on a number of rotors that constituted the
Enigma machine
. he cryptog-
raphy performed by the Enigma was a simple substitution cipher, where one letter was substituted
for another, but the complexity of the Enigma was in its mechanism where each rotor would rotate
a predetermined number of times to provide the substituted letter as the constituent of the key.
For instance, if the operator pressed the button
A
on the Enigma machine (one of the letters of a
plaintext message), then the rotors would kick into action and, after a predetermined number of
turns, would probably provide
T
as one of the letters in the ciphertext. he Enigma cryptosystem
was quite successful, but one of the laws it had was that the plaintext letter itself could not come
up as part of the ciphertext, making it possible for cryptanalysts to rule out the omitted letters and
then re-create the message.
With the advent of computers, cryptography saw a great boost, as complex mathematical algo-
rithms are one of the prime elements of cryptography and computers were capable of processing
complex mathematical operations. he most well-known encryption system was a project entitled
Lucifer
, developed by IBM. his was later adopted by the National Security Agency and named
Data Encryption Standard or DES in 1976. DES has been in use ever since its inception and still
remains an extremely popular encryption algorithm for cryptographic implementations.
8.1.2 Cryptography—Terminology and Deinitions
Before we explore cryptography and its implementation for Java Web applications, it is imperative
that certain key terminologies relating to cryptography be explored to facilitate easy understand-
ing for the rest of the chapter. hey are as follows:
◾
Cryptosystem/encryption algorithm/cipher
Encryption and decryption
◾
◾
Substitution and transposition
Key and keyspace
◾
◾
Symmetric and asymmetric algorithms
◾
Initialization vector
Block and stream cipher
◾
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Article on the use of ROT13 for inappropriate jokes on Usenet forums—http://www.indopedia.org/ROT13.
html.
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