Key-Systems

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:
http://www.sbox.tu-graz.ac.at/home/j/jonny/projects/crypto/symmetr/content.htm

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Royal Dutch/Shell Group

One of the world's largest corporate entities in sales, consisting of companies in more than 100 countries, whose shares are owned by NV Koninklijke Nederlandsche Petroleum Maatschappij (Royal Dutch Petroleum Company Ltd.) of The Hague and by the "Shell" Transport and Trading Company, PLC, of London. Below these two parent companies are two holding companies, Shell Petroleum NV and the Shell Petroleum Company Limited, whose shares are owned 60 percent by Royal Dutch and 40 percent by "Shell" Transport and Trading. The holding companies, in turn, hold shares in and administer the subsidiary service companies and operating companies around the world, which engage in oil, petrochemical, and associated industries, from research and exploration to production and marketing. Several companies also deal in metals, nuclear energy, solar energy, coal, and consumer products.

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