The symmetric key is a key-based cryptography whose algorithms use the same keys to perform encryption of plaintext and decryption of the ciphertext. These keys are shared between two parties over a secure channel. Any participant owning the shared key can perform both encryption and decryption operations on the data. A symmetric key cipher can either be stream encrypted or block encrypted.
Symmetric key cryptography doesn't play any significant role in blockchain-based applications. However, it will provide a better insight into key-based cryptography before we look into asymmetric cryptography.
