In Symmetric key cryptography same secret key is used by the sender and the receiver.
symmetric-key cryptography. An encryption system in which the sender and receiver of a message share a single, common key that is used to encrypt and decrypt the message. Contrast this with public-key cryptology, which utilizes two keys - a public key to encrypt messages and a private key to decrypt them.
Symmetric-key algorithms are algorithms for cryptography that use the same cryptographic keys for both encryption of plaintext and decryption of ciphertext. ... The keys, in practice, represent a shared secret between two or more parties that can be used to maintain a private information link.
The shared secret is either shared beforehand between the communicating parties, in which case it can also be called a pre-shared key, or it is created at the start of the communication session by using a key-agreement protocol, for instance using public-key cryptography such as Diffie-Hellman or using symmetric-key.