What are public keys and private keys in networking?

Answer

One person has answered with this: "Public and Private Keys are not usually used in networking, more common in secure financial transactions and sensitive data transfer. If you worked in a bank you have have to send a customer the public key, then the encrypted data, this enables them to read the data, it also recodes the data for extra security. a private key is similar, except more secure."

However, this does not reflect any familiarity with the topic.

Answer

Public and private keying systems are used for all sorts of secure communication systems. Every time you see a "certificate" pop up when installing software, it is using a public and private key system to verify the source of the file. Every time you set up a "secure" internet connection, or a "locked" HTML page, you're using public and private keys. Otherwise, you'd have to send your digital keys "in the clear" over the network (a bad idea) or transmit them via some other channel (such as physical paper, and the like).

A private key (a special series of numbers) is used to encrypt something that you want others to decrypt using your public key (another special series of numbers). That way they can be sure that ONLY you sent the information because otherwise the public key would not work. This is one type of "digital signature." You publish your certificate that includes your public key and recipients of email or files encrypted with your private key use the public key to decrypt them (or verify them).

Similarly, if someone wants to send you a file that they know ONLY YOU can read, they can encrypt it with your public key and only your private key will "unlock" the file.

Because public/private key systems are relatively time-consuming to run in real-time, most systems actually use a faster "symmetric" key to encrypt and decrypt files (using DES or other high-speed crypto-engines), and they only use the public/private keys to encrypt and decrypt the one-time symmetric keys, in a so-called "secure key exchange".

ANSWER

Any cryptographic system uses two keys for encryption/decryption.Public key, known to every one and a private or secret key, knowm only to the recepietn of the message.

An important element to the public key system is that the public and private keys are related in such a way that only the public key can be used to encrypt messages and only the corresponding private key can be used to decrypt them.

First answer by Roisin 17. Last edit by Harithaveni. Contributor trust: 17 [recommend contributor]. Question popularity: 22 [recommend question]