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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Traditional copyright and the practice of paying
Yet again new technologies have altered the way of how (copyrighted) works are produced, copied, made obtainable and distributed. The emergence of global electronic networks and the increased availability of digitalized intellectual property confront existing copyright with a variety of questions and challenges. Although the combination of several types of works within one larger work or on one data carrier, and the digital format (although this may be a recent development it has been the object of detailed legal scrutiny), as well as networking (telephone and cable networks have been in use for a long time, although they do not permit interactivity) are nothing really new, the circumstance that recent technologies allow the presentation and storage of text, sound and visual information in digital form indeed is a novel fact. Like that the entire information can be generated, altered and used by and on one and the same device, irrespective of whether it is provided online or offline.
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Industrial design refers to the ornamental aspect of a useful article which may constitute of two or three-dimensional elements. To be qualified for
The Clipper Chip is a cryptographic device proposed by the U.S. government that purportedly intended to protect private communications while at the same time permitting government agents to obtain the "keys" upon presentation of what has been vaguely characterized as "legal authorization." The "keys" are held by two government "escrow agents" and would enable the government to access the encrypted private communication. While Clipper would be used to encrypt voice transmissions, a similar chip known as Capstone
would be used to encrypt data. The underlying cryptographic algorithm, known as Skipjack, was developed by the National Security Agency (NSA).
The U.S. Data Encryption Standard (= DES) is the most widely used encryption algorithm, especially used for protection of financial transactions. It was developed by IBM in 1971. It is a symmetric-key cryptosystem. The DES algorithm uses a 56-bit encryption key, meaning that there are 72,057,594,037,927,936 possible keys.
for more information see:
Ronald L. Rivest is Webster Professor of Electrical Engineering and Computer Science in MIT's EECS Department. He was one of three persons in a team to invent the