ELECTRONIC DEVICE FOR SELECTING KEY TO BE USED FOR ENCRYPTION ON BASIS OF AMOUNT OF INFORMATION OF DATA TO BE ENCRYPTED, AND OPERATION METHOD OF ELECTRONIC DEVICE

In an electronic device and an operation method of the electronic device according to various embodiments, the electronic device comprises: a user interface; a processor operatively connected to the user interface; and a memory operatively connected to the processor and including a general area and a secure area, wherein the memory is configured to store a plurality of keys for encrypting data corresponding to a user's input, and the memory may store instructions that, when executed, cause the processor to: receive the data through the user interface; non-transitorily store the received data in the general area; check the amount of information of the stored data; select at least one key from among the plurality of keys stored in the memory on the basis of at least a portion of the checked amount of information; encrypt the data by using the selected key; and transmit the encrypted data and information indicating the selected key to the secure area requiring access authority.