What is symmetric key cryptography in cryptocurrencies?

Symmetric-key cryptography in cryptocurrencies is a type of data encryption in which a single key is suitable for both encryption and decryption. In a symmetrical scheme, multiple users can use the same key. The same key is used to encrypt and decrypt the plaintext. Guessing the decryption key is almost impossible, so symmetric encryption schemes provide a high level of security and are often used in computer systems.