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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- Concerning their human and financial resources commercial media and independent content provider are an extremely unequal pair. While the 1998 revenues of the world's leading media conglomerates (AOL Time Warner, Disney, Bertelsmann, Viacom and the News Corporation) amounted to US$ 91,144,000,000 provider of independent content usually act on a non-profit basis and to a considerable extent depend on donations and contributions.
Also the human resources they have at their disposal quite differ. Viacom for example employs 112,000 people. Alternative media conversely are mostly run by a small group of activists, most of them volunteers. Moreover the majority of the commercial media giants has a multitude of subsidiaries (Bertelsmann for instance has operations in 53 countries), while independent content provider in some cases do not even have proper office spaces. Asked about their offices number of square meters Frank Guerrero from RTMark comments "We have no square meters at all, because we are only on the web. I guess if you add up all of our servers and computers we would take up about one or two square meters."
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Hieroglyphs are pictures, used for writing in ancient Egypt. First of all those pictures were used for the names of kings, later more and more signs were added, until a number of 750 pictures
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