fe_heroes_message_xor.py

def fe_xor(string, key):
    '''Decrypts a Fire Emblem Heroes string using a specified key.'''
    if type(key) == str:
        key = map(ord, key)
    cur_k = (key[0] + key[1]) & 0xFF
    crypt = ''
    for i in range(len(string)):
        cur_k ^= key[i % len(key)]
        crypt += chr((cur_k ^ ord(string[i])) or ord(string[i]))
    return crypt