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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Starting in the mid 1990s today most traditional media can also be found online. The overwhelming majority of bigger newspapers and periodicals, but also radio and TV stations now complement their classic media formats with digital programming. For the most part they transform existing analogue information in digital form, with some additional features.
Especially the big media conglomerates, having realized the economic potential of the Internet, have started to get into the business of digital content. Not surprisingly their engagement in the virtual sphere has not brought much new concerning their programming. They offer entertainment, music, sports and some news channels. One of the reasons for this development might be, that the big commercial media companies are able to re-use already existing programming from their other ventures. Examples are
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Initially computer programmers had to write instructions in machine language. This
Expert systems are advanced computer programs that mimic the knowledge and reasoning capabilities of an expert in a particular discipline. Their creators strive to clone the expertise of one or several human specialists to develop a tool that can be used by the layman to solve difficult or ambiguous problems. Expert systems differ from conventional computer programs as they combine facts with rules that state relations between the facts to achieve a crude form of reasoning analogous to
Latitude: 47.86353, Longitude: 12.00983
RSOC - Bad Aibling is a ground station for the interception of civil and military satellite communications traffic operated by the
for more information:
Description by FAS intelligence resource program.
Description of the tasks of the Signals Intelligence Brigade.
Look at a detailed guide for military newbies at Bad Aibling.