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Loris Guerra
17,536 PointsConfusion about Shared Secret Key
In this example, if Bob and Alice agree together on a Shared-Secret-Key that they use to encrypt messages, (and this Shared-Key is also switched-changed often), how could they still decrypt all the messages using their own private key?
2 Answers
Steven Parker
231,272 PointsThey wouldn't need a private key if they do symmetric encryption.
The shared key would be the only key needed to encrypt and decrypt the messages. Changing it often prevents someone who manages to acquire it from reading their entire message history, or messages they generate in the future after the next change.
If they were using private keys, they would not use a shared key. Each of them would have a unique private key and a public key (4 keys total).
Patrick Palmowski
4,042 PointsNow I´m confused, do they use a public key now? Because why would they use a shared private key, it just has the characteristics like a public key. Am I so wrong?
Steven Parker
231,272 PointsA "private" key would not be shared. And private keys (along with pubic keys) are used in a different kind of encryption.
In the kind of encryption that this question was asking about, the shared secret key is the only key used.