Embodiments of this disclosure disclose a key management method and a related device, the method including: selecting a random number and a key according to an operation instruction inputted by a user; generating a first encryption ciphertext of the key, according to the random number, the key, a first public key, and a second public key, the first public key being determined according to a point on an elliptic curve and a private key of a hardware security module (HSM), and the second public key being determined according to the point on the elliptic curve and a private key of the client; generating a symmetric key sequence according to the key and a preselected hash function; encrypting data according to the symmetric key sequence to obtain a data ciphertext; and transmitting the first encryption ciphertext and the data ciphertext to a cloud server.