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Public Key Cryptography In Summary
- A public key is used to encrypt and a
separate, different private key to decrypt the
message.
- Each party involved generates a key pair.
- Each party publishes their public key.
- Each party secures their private key, which must remain
secret.
- Assuming A desires to send a message to B, it first encrypts
the message using B's public key.
- B can decrypt the message using its private key. Since no one
else knows B's private key, this is absolutely secure -- no one
else can decrypt it.
- There still remain difficult problems of authentication of
public keys, compromised keys, bogus & out of date keys.
Further, Public Key encryption is very, very slow compared to
single key systems.
- A very useful way of using public key cryptography is as a
means of distributing secret keys for conventional single key
cryptography. The most common example of this, which most of us
have probably used, is the Secure Sockets Layer
(SSL) cryptography used in the World Wide Web, see
later.
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