EpicLock - PC

--
--  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

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

x, y = term.getSize()

function setScreen(bColour)
    if term.isColour() then
        term.setBackgroundColour(colours[bColour])
        term.clear()
    end
end

function allColour(tColour, bColour)
    if term.isColour() then
        term.setTextColour(colours[tColour])
        term.setBackgroundColour(colours[bColour])
    else
        term.setTextColour(colours.white)
        term.setBackgroundColour(colours.black)
    end
end

function textColour(tColour)
    if term.isColour() then
        term.setTextColour(colours[tColour])
    else
        allColour("white", "black")
    end
end

function bgColour(bColour)
    if term.isColour() then
        term.setBackgroundColour(colours[bColour])
    else
        allColour("white", "black")
    end
end

function centered(str, height, tColour, bColour)
    term.setCursorPos(x / 2 - #str / 2, height)
    if tColour and bColour then
        allColour(tColour, bColour)
    elseif tColour then
        textColour(tColour)
    elseif bColour then
        bgColour(bColour)
    end
    term.write(str)
end

function left(str, height, tColour, bColour)
    term.setCursorPos(1, height)
    if tColour and bColour then
        allColour(tColour, bColour)
    elseif tColour then
        textColour(tColour)
    elseif bColour then
        bgColour(bColour)
    end
    term.write(str)
end

function right(str, height, tColour, bColour)
    term.setCursorPos(x - #str, height)
    if tColour and bColour then
        allColour(tColour, bColour)
    elseif tColour then
        textColour(tColour)
    elseif bColour then
        bgColour(bColour)
    end
    term.write(str)
end

function indented(str, indent, height, tColour, bColour)
    term.setCursorPos(indent, height)
    if tColour and bColour then
        allColour(tColour, bColour)
    elseif tColour then
        textColour(tColour)
    elseif bColour then
        bgColour(bColour)
    end
    term.write(str)
end

function clearLine(yPos, colour)
    term.setCursorPos(1, yPos)
    bgColour(colour)
    term.clearLine()
end

function checkForUsers()
    if fs.exists(".userDetails") then
        login()
    else
        register()
    end
end

function header()
    setScreen("cyan")
    for i = 1, 3 do
        clearLine(i, "blue")
    end
    indented("EpicLock", 2, 2, "lightBlue")
    bgColour("cyan")
end

function login()
    while true do
        header()
        right("Login", 2, "lightBlue", "blue")
        indented("Username: ", 2, 5, "lightBlue", "cyan")
        username = read()
        if username:len() > 0 then
            indented("Password: ", 2, 7)
            password = read("*")
            if password:len() > 0 then
                user = fs.open(".userDetails", "r")
                userUnserialized = textutils.unserialize(user.readAll())
                for k, v in pairs(userUnserialized) do
                    if v["Username"] == username and v["Password"] == sha256(password) then
                        setScreen("black")
                        left(os.version(), 1, "yellow")
                        term.setCursorPos(1, 2)
                        return
                    end
                end
            end
        end
    end
end

function register()
    while true do
        users = {}
        header()
        right("Register", 2, "lightBlue", "blue")
        indented("Username: ", 2, 5, "lightBlue", "cyan")
        username = read()
        if username:len() > 0 then
            indented("Password: ", 2, 7)
            password = read("*")
            if password:len() > 0 then
                user = fs.open(".userDetails", "w")
                users[#users + 1] = {["Username"] = username, ["Password"] = sha256(password)}
                user.write(textutils.serialize(users))
                user.close()
                login()
            end
        end
    end
end

os.pullEvent = os.pullEventRaw
checkForUsers()