[Lua工具类]Lua 中MD5的实现

最新推荐文章于 2024-08-21 08:22:12 发布

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最新推荐文章于 2024-08-21 08:22:12 发布 · 2.6k 阅读

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#lua #开发语言

这是一个关于使用Lua实现MD5哈希函数的代码，包括了MD5的基本运算和位操作，以及两个时间格式化函数。代码首先尝试导入bit库，如果导入失败则提供备用的位操作实现。MD5.update和MD5.finish分别用于更新哈希和生成最终哈希值。同时，还提供了两个时间格式化函数，FormatTime将时间转换为分钟和秒的格式，FormatTimeToHMS则输出小时、分钟和秒。

lua的MD5实现方法：

local md5 = {
  _VERSION     = "md5.lua 1.1.0",
  _DESCRIPTION = "MD5 computation in Lua (5.1-3, LuaJIT)",
  _URL         = "https://github.com/kikito/md5.lua"
}

-- bit lib implementions

local char, byte, format, rep, sub =
  string.char, string.byte, string.format, string.rep, string.sub
local bit_or, bit_and, bit_not, bit_xor, bit_rshift, bit_lshift

local ok, bit = pcall(require, 'bit')
if ok then
  bit_or, bit_and, bit_not, bit_xor, bit_rshift, bit_lshift = bit.bor, bit.band, bit.bnot, bit.bxor, bit.rshift, bit.lshift
else
  ok, bit = pcall(require, 'bit32')

  if ok then

    bit_not = bit.bnot

    local tobit = function(n)
      return n <= 0x7fffffff and n or -(bit_not(n) + 1)
    end

    local normalize = function(f)
      return function(a,b) return tobit(f(tobit(a), tobit(b))) end
    end

    bit_or, bit_and, bit_xor = normalize(bit.bor), normalize(bit.band), normalize(bit.bxor)
    bit_rshift, bit_lshift = normalize(bit.rshift), normalize(bit.lshift)

  else

    local function tbl2number(tbl)
      local result = 0
      local power = 1
      for i = 1, #tbl do
        result = result + tbl[i] * power
        power = power * 2
      end
      return result
    end

    local function expand(t1, t2)
      local big, small = t1, t2
      if(#big < #small) then
        big, small = small, big
      end
      -- expand small
      for i = #small + 1, #big do
        small[i] = 0
      end
    end

    local to_bits -- needs to be declared before bit_not

    bit_not = function(n)
      local tbl = to_bits(n)
      local size = math.max(#tbl, 32)
      for i = 1, size do
        if(tbl[i] == 1) then
          tbl[i] = 0
        else
          tbl[i] = 1
        end
      end
      return tbl2number(tbl)
    end

    -- defined as local above
    to_bits = function (n)
      if(n < 0) then
        -- negative
        return to_bits(bit_not(math.abs(n)) + 1)
      end
      -- to bits table
      local tbl = {}
      local cnt = 1
      local last
      while n > 0 do
        last      = n % 2
        tbl[cnt]  = last
        n         = (n-last)/2
        cnt       = cnt + 1
      end

      return tbl
    end

    bit_or = function(m, n)
      local tbl_m = to_bits(m)
      local tbl_n = to_bits(n)
      expand(tbl_m, tbl_n)

      local tbl = {}
      for i = 1, #tbl_m do
        if(tbl_m[i]== 0 and tbl_n[i] == 0) then
          tbl[i] = 0
        else
          tbl[i] = 1