As stated, telecommunication is seen as an unreliable media for transporting secret messages. Therefore today, cryptography is needed more than ever before, especially for e-commerce.
Key cryptosystems try to provide more privacy.
symmetric-key cryptosystems:
The same key is used for both encryption and decryption. In this case the encipherer and the recipient of the message/text have to agree on a common key before the enciphering-process can start. And most of all they should trust each other. And exactly this is the main problem of this system: how to exchange the key without offering an opportunity for stealing it?
In former times messengers or pigeons were doing the exchange of those keys.
Symmetric-key systems make sense in small entities. If a lot of people are spread over a wide area and belong to the same network, distributing the keys starts getting complicated.
Today, those cryptosystems get controlled by other keys, based on highly complex mathematical algorithms.
some symmetric-key systems are:
- DES (Data Encryption Standard), the standard for credit cards
- Triple-DES, which is a variation of DES, encrypting the plaintext three times.
- IDEA (International Data Encryption Standard)
- blowfish encryption algorithm, which is said to be faster than DES and IDEA
Security and confidence are the key-words for a popular key-system: As DES and its successors have been used for so many years and by many people without having been broken, they are considered safe - safer than others, not used that frequently, no matter whether they are actually safer or not.
For further information see:
TEXTBLOCK 1/1 // URL: http://world-information.org/wio/infostructure/100437611776/100438659090
b. July 13, 1527, London, England
d. December 1608, Mortlake, Surrey
English alchemist, astrologer, and mathematician who contributed greatly to the revival of interest in mathematics in England. After lecturing and studying on the European continent between 1547 and 1550, Dee returned to England in 1551 and was granted a pension by the government. He became astrologer to the queen, Mary Tudor, and shortly thereafter was imprisoned for being a magician but was released in 1555. Dee later toured Poland and Bohemia (1583-89), giving exhibitions of magic at the courts of various princes. He became warden of Manchester College in 1595.