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:
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Following the 1980s a sweeping restructuring of commercial media power has happened. While some firms have grown through expansion others extended through mergers and acquisitions. Examples are
In recent years those developments have led to the rise of transnational media giants, resulting in the domination of the global media system by about ten huge conglomerates. These have interests in numerous media industries, ranging from film production, magazines, newspapers, book publishing and recorded music to TV and radio channels and networks, but also include retail stores, amusement parks and digital media products.
Behind these firms are about three or four dozen smaller media companies, which primarily engage in local, national or niche markets. In short, the overwhelming majority of the world's content production facilities and distribution channels lies in the hands of approximately fifty enterprises.
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