Abstract: This application provides a method for saving a ciphertext and an apparatus. The method includes: obtaining an encryption instruction, where the encryption instruction instructs to encrypt a file in an external memory; obtaining an eigenvalue of a first account identifier based on the encryption instruction; encrypting a first key by using the eigenvalue of the first account identifier to generate a first ciphertext, where the first key is used to encrypt a second key, and the second key is used to encrypt a first file in the external memory; encrypting the eigenvalue of the first account identifier to generate a second ciphertext; and storing the first ciphertext and the second ciphertext in a non-erasable partition.

Abstract: A method for preparing a semi-rigid melamine foam plastic, comprising Step (1): adding a formaldehyde solution and polyvinyl alcohol (PVA) to a reactor, heating the reactor, and adding alkali; Step (2): feeding solid melamine powder and a modifier 3-aminopropyltriethoxysilane (APTES) into the reactor, raising the temperature in the reactor to 75-85° C., adjusting the pH value of the solution of material by adding acid; heating the solution of material, performing a heat preservation reaction, and then adding alkali, Step (3): feeding a predetermined amount of foaming agent, emulsifier, auxiliary agent and curing agent into a stirring reactor to obtain a mixed auxiliary agent; pumping the mixed auxiliary agent and the semi-rigid modified melamine resin into an emulsifier; placing the emulsified resin into a microwave heating chamber for microwave foaming; Step (4): cutting the semi-rigid melamine foam plastic obtained in step (3) and then drying.