Thread: Symmetrical encryption

The sender of an encoded message must also send the key to the recipient so that she can decode the message. For security reasons, never send the key along with the encoded message. If the sender can give the key to the recipient once, preferably personally, then the recipient can use this key repeatedly in future. However, for practical reasons, when the sender uses this key to exchange encoded messages with others, he is taking a risk of letting his key fall in the wrong hands. With the key, anyone can decode the entire correspondence that has been protected using the key.



If one exchanges confidential data with a number of people, he has to decide whether to use one key for all messages, thereby taking a big risk, or define several keys, which reduces the risk but increases the cost [of logistics).