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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Usually the subject matter of copyright is described as "literary and artistic works" - original creations in the fields of literature and arts. Such works may be expressed in words, symbols, pictures, music, three-dimensional objects, or combinations thereof. Practically all national copyright laws provide for the protection of the following types of works:
Literary works: novels, poems dramatic works and any other writings, whether published or unpublished; in most countries also computer programs and "oral works"
Musical works
Artistic works: whether two-dimensional or three-dimensional; irrespective of their content and destination
Maps and technical drawings
Photographic works: irrespective of the subject matter and the purpose for which made
Audiovisual works: irrespective of their purpose, genre, length, method employed or technical process used
Some copyright laws also provide for the protection of choreographic works, derivative works (translations, adaptions), collections (compilations) of works and mere data (data bases); collections where they, by reason of the selection and arrangement of the contents, constitute intellectual creations. Furthermore in some countries also "works of applied art" (furniture, wallpaper etc.) and computer programs (either as literary works or independently) constitute copyrightable matter.
Under certain national legislations the notion "copyright" has a wider meaning than "author's rights" and, in addition to literary and artistic works, also extends to the producers of sound recordings, the broadcasters of broadcasts and the creators of distinctive typographical arrangements of publications.
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CNN is a U.S.-TV-enterprise, probably the world's most famous one. Its name has become the symbol for the mass-media, but also the symbol of a power that can decide which news are important for the world and which are not worth talking about. Every message that is published on CNN goes around the world. The Gulf War has been the best example for this until now, when a CNN-reporter was the one person to do the countdown to a war. The moments when he stood on the roof of a hotel in Baghdad and green flashes surrounded him, went around the world.
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.