Difference (from prior major revision)
(author diff)
Changed: 30c30
Prior to this, [encryption keys]? were symmetric, and possession of the key would allow both encryption and decryption of the message. The key had to be exchanged between the communicating parties via a secure channel such as a trusted courier or face-to-face contact. This situation rapidly becomes unmanageable when the number of participants increases. In particular, a seperate key is required for each communicating pair if other parties are not to decrypt their messages.
Prior to this, [encryption keys]? were symmetric, and possession of the key would allow both encryption and decryption of the message. The key had to be exchanged between the communicating parties via a secure channel such as a trusted courier or face-to-face contact. This situation rapidly becomes unmanageable when the number of participants increases. In particular, a seperate key is required for each communicating pair if other parties are not to decrypt their messages. A system of this kind is also known as a "private key cryptosystem".
Changed: 32c32
Public key cryptography allows the key to be split into an asymmetrickey pair consisting of two separate keys. A message encrypted using one of the keys must be decrypted using the other. One of the keys can now be distributed as far as possible to allow anyone to encrypt messages for a particular key pair -- a public key. Only one key pair is now needed per receiver as possession of the public key does not compromise the security of the private key.
In public key cryptography, there are a pair of related keys, one of which is made public and used for encryption -- the public key. The private key is kept secret and used for decryption. A system of this kind is known as asymmetric. Only one key pair is now needed per receiver as possession of the public key does not compromise the security of the private key. In general the system is not reversable, i.e., a message encrypted with the private key can not be decrypted with the public key, although this is the case for RSA.
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