local function sha256(msg)
  msg = preproc(msg, #msg)
  local H = initH256({})
  for i = 1, #msg, 64 do digestblock(msg, i, H) end
  return str2hexa(num2s(H[1], 4) .. num2s(H[2], 4) .. num2s(H[3], 4) .. num2s(H[4], 4) ..
          num2s(H[5], 4) .. num2s(H[6], 4) .. num2s(H[7], 4) .. num2s(H[8], 4))
end

function makev2address(key)
    local protein = {}
    local stick = sha256(sha256(key))
    local n = 0
    local link = 0
    local v2 = "k"
    repeat
          if n < 9 then protein[n] = string.sub(stick,0,2)
          stick = sha256(sha256(stick)) end
          n = n + 1
    until n == 9
    n = 0
    repeat
          link = tonumber(string.sub(stick,1+(2*n),2+(2*n)),16) % 9
          if string.len(protein[link]) ~= 0 then
            v2 = v2 .. makeaddressbyte(tonumber(protein[link],16))
            protein[link] = ''
            n = n + 1
          else
            stick = sha256(stick)
          end
    until n == 9
    return v2
end

print(makev2address("test"))