function SHA256(mes)
  local con = 4294967296
  local ch = {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a, 0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19}
  local k = {0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
  0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3, 0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
  0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
  0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
  0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13, 0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
  0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
  0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
  0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208, 0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2}

  local function bit(obj, bit)
    return obj%(bit*2)>=bit
  end

  local function Or(ca, cb)
    local new = 0
    for i = 0, 32 do
      new = new+((bit(ca,2^i)or bit(cb,2^i))and 2^i or 0)
    end
    return new
  end

  local function rshift(obj, times)
    times = times or 1
    return math.floor(obj*.5^times)%con
  end

  local function lshift(obj, times)
    times = times or 1
    return math.floor(obj*2^times)%con
  end

  local function rrotate(obj,times)
    times = times or 1
    return Or(rshift(obj,times),lshift(obj,32-times))
  end

  local function And(ca, cb)
    local new = 0
    for i = 0, 32 do
      new = new+((bit(ca,2^i)and bit(cb,2^i))and 2^i or 0)
    end
    return new % 2^32
  end

  local function append(cur)
    local new = ""
    for i = 1, 8 do
      local r = cur%256
      new = string.char(r)..new
      cur = (cur-r)/256
    end
    return new
  end

  local function Not(ca)
    return (2^32-1)-ca
  end

  local function xor(ca, cb)
    local new = 0
    for i = 0, 32 do
      new = new+(bit(ca,2^i)~=bit(cb,2^i)and 2^i or 0)
    end
    return new%con
  end

  mes = mes.."\128"..("\0"):rep(64-((#mes+9)%64))..append(#mes*8)

  local Chunks = {}
  for i = 1, #mes, 64 do
    table.insert(Chunks,mes:sub(i,i+63))
  end
  for _,Chunk in next,Chunks do
    local w = {}
    for i = 0, 15 do
      w[i] = (function()local n=0 for q=1,4 do n=n*256+Chunk:byte(i*4+q) end return n end)()
    end
    for i = 16, 63 do
      local s0 = xor(xor(rrotate(w[i-15],7),rrotate(w[i-15],18)),rshift(w[i-15],3))
      local s1 = xor(xor(rrotate(w[i-2],17),rrotate(w[i-2],19)),rshift(w[i-2],10))
      w[i] = (w[i-16] + s0 + w[i-7] + s1)%con
    end
    local a,b,c,d,e,f,g,h=unpack(ch)
    for i = 0, 63 do
      local s0 = xor(xor(rrotate(a,2),rrotate(a,13)),rrotate(a,22))
      local s1 = xor(xor(rrotate(e,6),rrotate(e,11)),rrotate(e,25))
      local t0 = h+s1+xor(And(e,f),And(Not(e),g))+k[i+1]+w[i]
      local t1 = s0+xor(xor(And(a,b),And(a,c)),And(b,c))
      h = g
      g = f
      f = e
      e = (d+t0)%con
      d = c
      c = b
      b = a
      a = (t0+t1)%con
    end
    ch[1]=(ch[1]+a)%con
    ch[2]=(ch[2]+b)%con
    ch[3]=(ch[3]+c)%con
    ch[4]=(ch[4]+d)%con
    ch[5]=(ch[5]+e)%con
    ch[6]=(ch[6]+f)%con
    ch[7]=(ch[7]+g)%con
    ch[8]=(ch[8]+h)%con
  end
  return ("%08x%08x%08x%08x%08x%08x%08x%08x"):format(unpack(ch))
end