Operation IDEA operates on 64-bit blocks using a 128-bit key , and consists of a series of eight identical transformations -LRB- a round , see the illustration -RRB- and an output transformation -LRB- the half-round -RRB- .

IDEA operates on 64-bit blocks , using a 128-bit key . It contains a series of eight identical transformations -LRB- rounds -RRB- and one output transformation -LRB- the half-round -RRB- .
