150
A
The Roman smoke signals network consisted of towers within a visible range of each other and had a total length of about 4500 kilometers. It was used for military signaling.
For a similar telegraph network in ancient Greece see
About 750
In Japan block printing is used for the first time.
868
In China the world's first dated book, the Diamond Sutra, is printed.
1041-1048
In China moveable types made from clay are invented.
1088
The first of the great medieval universities was established in Bologna. At the beginning universities predominantly offered a kind of do-it-yourself publishing service.
Books still had to be copied by hand and were so rare that a copy of a widely desired book qualified for being invited to a university. Holding a lecture equaled to reading a book aloud, like a priest read from the Bible during services. Attending a lecture equaled to copy a lecture word by word, so that you had your own copy of a book, thus enabling you to hold a lecture, too.
For further details see History of the Idea of a University,
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Here the keys for encryption and decryption differ. There needs to exist a private key, which is only known to the individual, and a public key, which is published. Every person has her or his own private key that is never published. It is used for decrypting only. Mathematically the different keys are linked to each other, still it is nearly impossible to derive the private key from the public one.
For sending a message to someone, one has to look up the other's public key and encrypt the message with it. The keyholder will use his/her private key to decrypt it. While everybody can send a message with the public key, the private key absolutely has to stay secret - and probably will.
"The best system is to use a simple, well understood algorithm which relies on the security of a key rather than the algorithm itself. This means if anybody steals a key, you could just roll another and they have to start all over." (Andrew Carol)
very famous examples for public-key systems are:
· RSA:
The RSA is probably one of the most popular public-key cryptosystems. With the help of RSA, messages can be encrypted, but also digital signatures are provided.
The mathematics behind are supposedly quite easy to understand (see:
· PGP:
PGP is a public key encryption program. Most of all it is used for e-mail encryption.
It is supposed to be quite safe - until now.
· PGPi is simply the international variation of PGP.
for further information about the RSA and other key-systems visit the RSA homepage:
or:
All of those tools, like hash functions, too, can help to enhance security and prevent crime.
They can theoretically, but sometimes they do not, as the example of the published credit card key of France in March 2000 showed.
For more information see:
Still, cryptography can help privacy.
On the other hand cryptography is only one element to assure safe transport of data. It is especially the persons using it who have to pay attention. A key that is told to others or a lost cryptographic key are the end of secrecy.
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Although the traditional media companies first steps into the digital sphere were fairly clumsy, they have quickly learned from their mistakes and continued to enlarge their Internet presence.
During the last years many of the smaller players in the field of digital media have been driven out of competition by the huge media conglomerates. This mainly is a result of the advantages that the commercial media giants have over their less powerful counterparts:
- As engagement in online activities mostly does not lead to quick profits, investors must be able to take losses, which only powerful companies are able to.
- Traditional media outlets usually have huge stocks of digital programming, which they can easily plug into the Internet at little extra cost.
- To generate audience, the big media conglomerates constantly promote their Websites and other digital media products on their traditional media holdings.
- As possessors of the hottest "brands" commercial media companies often get premier locations from browser software makers, Internet service providers, search engines and portals.
- Having the financial resources at their disposition the big media firms are aggressive investors in start-up Internet media companies.
Commercial media companies have close and long ties to advertisers, which enables them to seize most of these revenues.
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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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Visa International's over 21,000 member financial institutions have made VISA one of the world's leading full-service payment network. Visa's products and services include Visa Classic card, Visa Gold card, Visa debit cards, Visa commercial cards and the Visa Global ATM Network. VISA operates in 300 countries and territories and also provides a large consumer payments processing system.
Industrial design refers to the ornamental aspect of a useful article which may constitute of two or three-dimensional elements. To be qualified for
Copyright laws generally provide for three kinds of neighboring rights: 1) the rights of performing artists in their performances, 2) the rights of producers of phonograms in their phonograms, and 3) the rights of broadcasting organizations in their radio and television programs. Neighboring rights attempt to protect those who assist intellectual creators to communicate their message and to disseminate their works to the public at large.
The Roman smoke signals network consisted of towers within visible range of each other and had a total length of about 4500 kilometers. It was used for military signaling.
For a similar telegraph network in ancient Greece see
Also "Angelic" language. Archaic language alphabet composed of 21 letters, discovered by John Dee and his partner Edward Kelley. It has its own grammar and syntax, but only a small sample of it has ever been translated to English.