The
single key scheme, named the Data Encryption Standard - DES for short -was designed in 1977 as the official method for defensive unclassified computer data in agencies of the American Federal government. Its evolution began in1973 when the US National Bureau of Standards, responding to public concern about the privacy of computerized information outside military and diplomatic channels, invited the submission of data-encryption techniques as the first step towards an encryption scheme intended for public use.
The method selected by the bureau as the DES was developed by IBM researchers. During encryption, the DES algorithm divides a message into blocks of eight fonts, and then enciphers them one after another. Under control of the key, the letters and numbers of each block are scrambled no fewer than 16times, resulting in eight characters of cipher text. As good as the DES is, obsolescence will almost certainly overtake it. The life span of encryption systems tends to be short; the older and more widely used a cipher is, the higher the potential payoff if it is cracked, and the greater the likelihood that someone has succeeded. An entirely different approach to encryption, called the 2-key or public-key system, simplifies the problem of key distribution and organization. The approach to cryptography eliminates the need for subscribers to share keys that must be kept confidential. In a public-key system, each subscriber has a pair
of keys. One of them is the so-called public key, which is freely available to anyone who wishes to communicate with its owner. The other is a secret key,known only to its owner. Though either key can be used to encipher or to decipher data encrypted with its mate, in most instances, the public key is
employed for encoding, and the private key for decoding. Thus, anyone can sends secret message to anyone else by using the addressee's public key to encrypt its contents. But only the recipient of the message can make intelligence of it, since only that person has the private key.A public key cryptosystem is called the PGP, for Pretty Good Privacy.Designed by Phil Zimmerman, this program is freely distributed for the purposeof giving the public the knowledge that whatever communications they pass, they
can be sure that it is practically unbreakable.
The method selected by the bureau as the DES was developed by IBM researchers. During encryption, the DES algorithm divides a message into blocks of eight fonts, and then enciphers them one after another. Under control of the key, the letters and numbers of each block are scrambled no fewer than 16times, resulting in eight characters of cipher text. As good as the DES is, obsolescence will almost certainly overtake it. The life span of encryption systems tends to be short; the older and more widely used a cipher is, the higher the potential payoff if it is cracked, and the greater the likelihood that someone has succeeded. An entirely different approach to encryption, called the 2-key or public-key system, simplifies the problem of key distribution and organization. The approach to cryptography eliminates the need for subscribers to share keys that must be kept confidential. In a public-key system, each subscriber has a pair
of keys. One of them is the so-called public key, which is freely available to anyone who wishes to communicate with its owner. The other is a secret key,known only to its owner. Though either key can be used to encipher or to decipher data encrypted with its mate, in most instances, the public key is
employed for encoding, and the private key for decoding. Thus, anyone can sends secret message to anyone else by using the addressee's public key to encrypt its contents. But only the recipient of the message can make intelligence of it, since only that person has the private key.A public key cryptosystem is called the PGP, for Pretty Good Privacy.Designed by Phil Zimmerman, this program is freely distributed for the purposeof giving the public the knowledge that whatever communications they pass, they
can be sure that it is practically unbreakable.
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