encryption :: essays research papers

Traditional cryptography is based on the sender and pass catcher of a pass knowing and using the same secret come across the sender uses the secret nominate to encrypt the message, and the receiver uses the same secret key to decrypt the message. This method is known as secret-key cryptography. The main problem is getting the sender and receiver to agree on the secret key without anyone else finding out. If they are in separate physical locations, they must trust a courier, or a phone system, or some other transmission system to non disclose the secret key being communicated. Anyone who overhears or intercepts the key in transit can later read all messages encrypted using that key. The generation, transmission and remembering of keys is called key management all cryptosystems must deal with key management issues. Secret-key cryptography often has difficulty providing secure key management.Public-key cryptography was invented in 1976 by Whitfield Diffie and Martin Hellman in o rder to solve the key management problem. In the new system, each person gets a pair of keys, called the public key and the private key. all(prenominal) persons public key is published while the private key is kept secret. The need for sender and receiver to share secret information is eliminated all communication theory involve solely public keys, and no private key is ever transmitted or shared. No longer is it necessary to trust some communication theory channel to be secure against eavesdropping or betrayal. Anyone can send a confidential message just using public information, but it can only be decrypted with a private key that is in the sole possession of the intended recipient. Furthermore, public-key cryptography can be used for authentication (digital traces) as wellspring as for privacy (encryption). Heres how it works for encryption when Alice wishes to send a message to sorrel, she looks up Bobs public key in a directory, uses it to encrypt the message and sends it off. Bob then uses his private key to decrypt the message and read it. No one listening in can decrypt the message. Anyone can send an encrypted message to Bob but only Bob can read it. Clearly, one requirement is that no one can figure out the private key from the corresponding public key.Heres how it works for authentication Alice, to sign a message, does a computation involving both her private key and the message itself the output is called the digital signature and is attached to the message, which is then sent.