Encryption method, decryption method, and related apparatus

A method, comprising:

• generating a first initial layer-3 message, wherein the first initial layer-3 message comprises a first part and a second part;
• generating a keystream for encrypting the first initial layer-3 message;
• performing an exclusive OR operation on the keystream and the first initial layer-3 message, to generate a second initial layer-3 message, wherein the second initial layer-3 message comprises an encrypted first part of the first initial layer-3 message, an unencrypted second part of the first initial layer-3 message, and an encryption indication indicating that the first part of the first initial layer-3 message is encrypted;
• and
• transmitting the second initial layer-3 message to a network device.

An apparatus comprising a processor and a non-transitory medium storing program instructions;

• wherein the instructions, when executed by the processor, cause the apparatus to:
• generate a first initial layer-3 message, wherein the first initial layer-3 message comprises a first part and a second part;
• generate a keystream for encrypting the first initial layer-3 message;
• perform an exclusive OR operation on the keystream and the first initial layer-3 message, to generate a second initial layer-3 message, wherein the second initial layer-3 message comprises an encrypted first part of the first initial layer-3 message, an unencrypted second part of the first initial layer-3 message, and an encryption indication indicating that the first part of the first initial layer-3 message is encrypted;
• and
• output the second initial layer-3 message for transmitting to a network device.