[Sha256 with Encryption API] Lua Computercraft - Not mine

--
--  Adaptation of the Secure Hashing Algorithm (SHA-244/256)
--  Found Here: http://lua-users.org/wiki/SecureHashAlgorithm
--
--  Using an adapted version of the bit library
--  Found Here: https://bitbucket.org/Boolsheet/bslf/src/1ee664885805/bit.lua
--

local MOD = 2^32
local MODM = MOD-1

local function memoize(f)
        local mt = {}
        local t = setmetatable({}, mt)
        function mt:__index(k)
                local v = f(k)
                t[k] = v
                return v
        end
        return t
end

local function make_bitop_uncached(t, m)
        local function bitop(a, b)
                local res,p = 0,1
                while a ~= 0 and b ~= 0 do
                        local am, bm = a % m, b % m
                        res = res + t[am][bm] * p
                        a = (a - am) / m
                        b = (b - bm) / m
                        p = p*m
                end
                res = res + (a + b) * p
                return res
        end
        return bitop
end

local function make_bitop(t)
        local op1 = make_bitop_uncached(t,2^1)
        local op2 = memoize(function(a) return memoize(function(b) return op1(a, b) end) end)
        return make_bitop_uncached(op2, 2 ^ (t.n or 1))
end

local bxor1 = make_bitop({[0] = {[0] = 0,[1] = 1}, [1] = {[0] = 1, [1] = 0}, n = 4})

local function bxor(a, b, c, ...)
        local z = nil
        if b then
                a = a % MOD
                b = b % MOD
                z = bxor1(a, b)
                if c then z = bxor(z, c, ...) end
                return z
        elseif a then return a % MOD
        else return 0 end
end

local function band(a, b, c, ...)
        local z
        if b then
                a = a % MOD
                b = b % MOD
                z = ((a + b) - bxor1(a,b)) / 2
                if c then z = bit32_band(z, c, ...) end
                return z
        elseif a then return a % MOD
        else return MODM end
end

local function bnot(x) return (-1 - x) % MOD end

local function rshift1(a, disp)
        if disp < 0 then return lshift(a,-disp) end
        return math.floor(a % 2 ^ 32 / 2 ^ disp)
end

local function rshift(x, disp)
        if disp > 31 or disp < -31 then return 0 end
        return rshift1(x % MOD, disp)
end

local function lshift(a, disp)
        if disp < 0 then return rshift(a,-disp) end
        return (a * 2 ^ disp) % 2 ^ 32
end

local function rrotate(x, disp)
    x = x % MOD
    disp = disp % 32
    local low = band(x, 2 ^ disp - 1)
    return rshift(x, disp) + lshift(low, 32 - disp)
end

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 str2hexa(s)
        return (string.gsub(s, ".", function(c) return string.format("%02x", string.byte(c)) end))
end

local function num2s(l, n)
        local s = ""
        for i = 1, n do
                local rem = l % 256
                s = string.char(rem) .. s
                l = (l - rem) / 256
        end
        return s
end

local function s232num(s, i)
        local n = 0
        for i = i, i + 3 do n = n*256 + string.byte(s, i) end
        return n
end

local function preproc(msg, len)
        local extra = 64 - ((len + 9) % 64)
        len = num2s(8 * len, 8)
        msg = msg .. "\128" .. string.rep("\0", extra) .. len
        assert(#msg % 64 == 0)
        return msg
end

local function initH256(H)
        H[1] = 0x6a09e667
        H[2] = 0xbb67ae85
        H[3] = 0x3c6ef372
        H[4] = 0xa54ff53a
        H[5] = 0x510e527f
        H[6] = 0x9b05688c
        H[7] = 0x1f83d9ab
        H[8] = 0x5be0cd19
        return H
end

local function digestblock(msg, i, H)
        local w = {}
        for j = 1, 16 do w[j] = s232num(msg, i + (j - 1)*4) end
        for j = 17, 64 do
                local v = w[j - 15]
                local s0 = bxor(rrotate(v, 7), rrotate(v, 18), rshift(v, 3))
                v = w[j - 2]
                w[j] = w[j - 16] + s0 + w[j - 7] + bxor(rrotate(v, 17), rrotate(v, 19), rshift(v, 10))
        end

        local a, b, c, d, e, f, g, h = H[1], H[2], H[3], H[4], H[5], H[6], H[7], H[8]
        for i = 1, 64 do
                local s0 = bxor(rrotate(a, 2), rrotate(a, 13), rrotate(a, 22))
                local maj = bxor(band(a, b), band(a, c), band(b, c))
                local t2 = s0 + maj
                local s1 = bxor(rrotate(e, 6), rrotate(e, 11), rrotate(e, 25))
                local ch = bxor (band(e, f), band(bnot(e), g))
                local t1 = h + s1 + ch + k[i] + w[i]
                h, g, f, e, d, c, b, a = g, f, e, d + t1, c, b, a, t1 + t2
        end

        H[1] = band(H[1] + a)
        H[2] = band(H[2] + b)
        H[3] = band(H[3] + c)
        H[4] = band(H[4] + d)
        H[5] = band(H[5] + e)
        H[6] = band(H[6] + f)
        H[7] = band(H[7] + g)
        H[8] = band(H[8] + h)
end

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


local function zfill(N)
    N=string.format("%X",N)
    Zs=""
    if #N==1 then
        Zs="0"
    end
    return Zs..N
end

local function serializeImpl(t)
    local sType = type(t)
    if sType == "table" then
        local lstcnt=0
        for k,v in pairs(t) do
            lstcnt = lstcnt + 1
        end
        local result = "{"
        local aset=1
        for k,v in pairs(t) do
            if k==aset then
                result = result..serializeImpl(v)..","
                aset=aset+1
            else
                result = result..("["..serializeImpl(k).."]="..serializeImpl(v)..",")
            end
        end
        result = result.."}"
        return result
    elseif sType == "string" then
        return string.format("%q",t)
    elseif sType == "number" or sType == "boolean" or sType == "nil" then
        return tostring(t)
    elseif sType == "function" then
        local status,data=pcall(string.dump,t)
        if status then
            return 'func('..string.format("%q",data)..')'
        else
            error()
        end
    else
        error()
    end
end

local function split(T,func)
    if func then
        T=func(T)
    end
    local Out={}
    if type(T)=="table" then
        for k,v in pairs(T) do
            Out[split(k)]=split(v)
        end
    else
        Out=T
    end
    return Out
end

local function serialize( t )
    t=split(t)
    return serializeImpl( t, tTracking )
end

local function unserialize( s )
    local func, e = loadstring( "return "..s, "serialize" )
    local funcs={}
    if not func then
        return e
    end
    setfenv( func, {
        func=function(S)
            local new={}
            funcs[new]=S
            return new
        end,
    })
    return split(func(),function(val)
        if funcs[val] then
            return loadstring(funcs[val])
        else
            return val
        end
    end)
end

local function sure(N,n)
    if (l2-n)<1 then N="0" end
    return N
end

local function splitnum(S)
    Out=""
    for l1=1,#S,2 do
        l2=(#S-l1)+1
        CNum=tonumber("0x"..sure(string.sub(S,l2-1,l2-1),1) .. sure(string.sub(S,l2,l2),0))
        Out=string.char(CNum)..Out
    end
    return Out
end

local function wrap(N)
    return N-(math.floor(N/256)*256)
end

function checksum(S,num)
    local sum=0
    for char in string.gmatch(S,".") do
        for l1=1,(num or 1) do
            math.randomseed(string.byte(char)+sum)
            sum=sum+math.random(0,9999)
        end
    end
    math.randomseed(sum)
    return sum
end

local function genkey(len,psw)
    checksum(psw)
    local key={}
    local tKeys={}
    for l1=1,len do
        local num=math.random(1,len)
        while tKeys[num] do
            num=math.random(1,len)
        end
        tKeys[num]=true
        key[l1]={num,math.random(0,255)}
    end
    return key
end

function encrypt(data,psw)
    data=serialize(data)
    local chs=checksum(data)
    local key=genkey(#data,psw)
    local out={}
    local cnt=1
    for char in string.gmatch(data,".") do
        table.insert(out,key[cnt][1],zfill(wrap(string.byte(char)+key[cnt][2])),chars)
        cnt=cnt+1
    end
    return string.sub(serialize({chs,table.concat(out)}),2,-3)
end

function decrypt(data,psw)
    local oData=data
    data=unserialize("{"..data.."}")
    if type(data)~="table" then
        return oData
    end
    local chs=data[1]
    data=data[2]
    local key=genkey((#data)/2,psw)
    local sKey={}
    for k,v in pairs(key) do
        sKey[v[1]]={k,v[2]}
    end
    local str=splitnum(data)
    local cnt=1
    local out={}
    for char in string.gmatch(str,".") do
        table.insert(out,sKey[cnt][1],string.char(wrap(string.byte(char)-sKey[cnt][2])))
        cnt=cnt+1
    end
    out=table.concat(out)
    if checksum(out or "")==chs then
        return unserialize(out)
    end
    return oData,out,chs
end

function hashed_encrypt(data,salt,help)
    if(help)then write("Use decrypt to decrypt data into hash. ") end
    return encrypt(sha256(data),salt)
end