ruby, 71 bytes

Result

WA

Duration

548ms

Code [DL]

p gets.chars.each_with_index.map{ |i,c| ((i.ord+c-64)%26+65).chr }.join

stdin

KZDVLPBAPFSYSJSVXGBLKBLRCH

stdout

"LBGZQVIIYPDKFXHLOYUFFXIPBHY"

stderr

strace