Keys are a crucial part of cryptography. They are also one of the more difficult things to control. There is often confusion as to what a key actually is. The key is not a token. It is a file on the computer used by an algorithm to encrypt/decrypt. The key doesn't do any encrypting. The algorithm encrypts.
A session key is a key which is disposed of when transmission of the data is complete. Do not take the short cut of choosing options which generate keys faster. That makes them less secure. You can choose short key sizes for data that is transient. But it is best to pick long keys and pass phrases.
A key ring is a list of public keys. Since a key is a file, you would think it should be stored on a hard drive. However you should put them on removable drives that you can physically take with you. Make sure you also backup your keys.
There is a lot more to talk about with keys. Next time I plan to cover key wrappers, escrow, services, and recovery.
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