// subBytes rewrites each byte of the state with the S-Box. unSubBytes and subBytes are the same.
func (constr *Construction) subBytes(in gfmatrix.Row) gfmatrix.Row {
out := gfmatrix.NewRow(in.Size())
for pos := 0; pos < in.Size(); pos++ {
out[pos] = in[pos].Invert()
}
return out
}
func (constr *Construction) decrypt(in gfmatrix.Row) gfmatrix.Row {
roundKeys := constr.StretchedKey()
state := in.Add(roundConst).Add(roundKeys[10])
state = firstRound.Mul(state)
state = constr.subBytes(state)
for i := 9; i >= 1; i-- {
state = state.Add(roundConst).Add(roundKeys[i])
state = unRound.Mul(state)
state = constr.subBytes(state)
}
state = state.Add(roundKeys[0])
return state
}
func (constr *Construction) encrypt(in gfmatrix.Row) gfmatrix.Row {
roundKeys := constr.StretchedKey()
state := in.Add(roundKeys[0])
for i := 1; i <= 9; i++ {
state = constr.subBytes(state)
state = round.Mul(state)
state = state.Add(roundConst).Add(roundKeys[i])
}
state = constr.subBytes(state)
state = lastRound.Mul(state)
state = state.Add(roundConst).Add(roundKeys[10])
return state
}