This disclosure relates to data encryption and decryption. In one aspect, a method includes receiving, by a second peer end computing device, first data from a first peer end computing device. The second end computing device generates a random term based on a result range pre-agreed upon with the first peer end computing device. The result range includes a minimum result value and a maximum result value. The random term is a product of a random number and an agreed upon constant. The agreed upon constant is greater than a difference between the maximum result value and the minimum result value. The second peer end computing device performs a homomorphic operation based on the first data, local private second data, and the random term to obtain an encryption result. The second peer end computing device returns the encryption result to the first peer end computing device.