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.
TEXTBLOCK 1/1 // URL: http://world-information.org/wio/infostructure/100437611776/100438659074
b. Jan. 4, 1809, Coupvray, near Paris, France
d. Jan. 6, 1852, Paris, France
Educator who developed a system of printing and writing that is extensively used by the blind and that was named for him. Himself blind Braille became interested in a system of writing, exhibited at the school by Charles Barbier, in which a message coded in dots was embossed on cardboard. When he was 15, he worked out an adaptation, written with a simple instrument, that met the needs of the sightless. He later took this system, which consists of a six-dot code in various combinations, and adapted it to musical notation. He published treatises on his type system in 1829 and 1837.
The first of the great medieval universities was established at 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 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,