What is encryption?
Encryption keys consist of a combination of letters and numbers.
The longer the key, the harder it is to figure out, e.g. a 256 bit key is more secure than a 128 bit key.
Using the same key to encrypt and decrypt creates a problem known as the key distribution problem.
In order to decrypt your ciphertext data, the receiver will need a copy of your secret key.
Sending the secret key over the internet causes a serious security risk – a hacker could intercept the key and decrypt the ciphertext data too!
Other than physically transporting the key yourself, there is a solution to the key distribution problem. It’s called asymmetric (or public key) encryption.