Another Question of Security

Even with the best techniques it is impossible to invent a cryptographic system that is absolutely safe/unbreakable. To decipher a text means to go through many, sometimes nearly - but never really - endless attempts. For the computers of today it might take hundreds of years or even more to go through all possibilities of codes, but still, finally the code stays breakable. The much faster quantum computers will proof that one day.
Therefore the decision to elect a certain method of enciphering finally is a matter of trust.

For the average user of computers it is rather difficult to understand or even realize the dangers and/or the technological background of electronic transmission of data. For the majority thinking about one's own necessities for encryption first of all means to trust others, the specialists, to rely on the information they provide.
The websites explaining the problems behind (and also the articles and books concerning the topic) are written by experts of course as well, very often in their typical scientific language, merely understandable for laymen. The introductions and other superficial elements of those articles can be understood, whereas the real background appears as untouchable spheres of knowledge.

The fact that dangers are hard to see through and the need for security measures appears as something most people know from media reports, leads directly to the problem of an underdeveloped democracy in the field of cryptography. Obviously the connection between cryptography and democracy is rather invisible for many people. Those mentioned media reports often specialize in talking about the work computer hackers do (sometimes being presented as criminals, sometimes as heroes) and the danger to lose control over the money drawn away from one's bank account, if someone steals the credit card number or other important financial data. The term "security", surely connected to those issues, is a completely different one from the one that is connected to privacy.
It is especially the latter that touches the main elements of democracy.

for the question of security see:
http://www-db.stanford.edu/pub/gio/CS99I/security.html

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Asymmetric or Public-Key-Cryptosystems

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: http://world.std.com/~franl/crypto/rsa-guts.html.

· 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:
http://www.rsa.com/rsalabs/faq/
http://www.rsa.com/rsalabs/faq/questions.html
or:
http://www.pgpi.org

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:
http://news.voila.fr/news/fr.misc.cryptologie

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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