Unique Encryption

A spy needs your help to encrypt a 5 letter message. To encrypt the message the following steps are need to be done: 1)Each letter of the message will be converted to it's equivalent number (i.e A=0, B=1,..Z=25) 2)98, 57, 31, 45, 46 are the 5 numbers in the key. 3)Add the equivalent number of the first letter of the message to the first number of the key, then the equivalent numbe