LoganDark's Password System v4

-- http://www.computercraft.info/forums2/index.php?/topic/26148-logandarks-password-lock/

local pullEvent = os.pullEvent
os.pullEvent = os.pullEventRaw

local pbkdf2 -- pbkdf2(data, salt, iter, dklen)

-- credit to Anavrins (http://www.computercraft.info/forums2/index.php?/user/12870-anavrins/) for the code in the following 'do' block
do
    local mod = 2^32
    local sha_hashlen = 32
    local sha_blocksize = 64
    local band    = bit32 and bit32.band or bit.band
    local bnot    = bit32 and bit32.bnot or bit.bnot
    local bxor    = bit32 and bit32.bxor or bit.bxor
    local blshift = bit32 and bit32.lshift or bit.blshift
    local upack   = unpack
    local function rrotate(n, b)
        local s = n/(2^b)
        local f = s%1
        return (s-f) + f*mod
    end
    local function brshift(int, by) -- Thanks bit32 for bad rshift
        local s = int / (2^by)
        return s - s%1
    end
    local H = {
        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 incr(t, incr)
        if 0xFFFFFFFF - t[1] < incr then
            t[2] = t[2] + 1
            t[1] = incr - (0xFFFFFFFF - t[1]) - 1
        else t[1] = t[1] + incr
        end
        return t
    end
    local function preprocess(data)
        local len = #data

        data[#data+1] = 0x80
        while #data%64~=56 do data[#data+1] = 0 end
        local l = incr({0,0}, len*8)
        for i = 2, 1, -1 do
            data[#data+1] = band(brshift(band(l[i], 0xFF000000), 24), 0xFF)
            data[#data+1] = band(brshift(band(l[i], 0xFF0000), 16), 0xFF)
            data[#data+1] = band(brshift(band(l[i], 0xFF00), 8), 0xFF)
            data[#data+1] = band(l[i], 0xFF)
        end
        return data
    end
    local function BE_toInt(bs, i)
        return blshift((bs[i] or 0), 24) + blshift((bs[i+1] or 0), 16) + blshift((bs[i+2] or 0), 8) + (bs[i+3] or 0)
    end
    local function digestblock(data, i, C)
        local w = {}
        for j = 1, 16 do w[j] = BE_toInt(data, i+(j-1)*4) end
        for j = 17, 64 do
            local v = w[j-15]
            local s0 = bxor(bxor(rrotate(w[j-15], 7), rrotate(w[j-15], 18)), brshift(w[j-15], 3))
            local s1 = bxor(bxor(rrotate(w[j-2], 17), rrotate(w[j-2], 19)), brshift(w[j-2], 10))
            w[j] = (w[j-16] + s0 + w[j-7] + s1)%mod
        end
        local a, b, c, d, e, f, g, h = upack(C)
        for j = 1, 64 do
            local S1 = bxor(bxor(rrotate(e, 6), rrotate(e, 11)), rrotate(e, 25))
            local ch = bxor(band(e, f), band(bnot(e), g))
            local temp1 = (h + S1 + ch + K[j] + w[j])%mod
            local S0 = bxor(bxor(rrotate(a, 2), rrotate(a, 13)), rrotate(a, 22))
            local maj = bxor(bxor(band(a, b), band(a, c)), band(b, c))
            local temp2 = (S0 + maj)%mod
            h, g, f, e, d, c, b, a = g, f, e, (d+temp1)%mod, c, b, a, (temp1+temp2)%mod
        end
        C[1] = (C[1] + a)%mod
        C[2] = (C[2] + b)%mod
        C[3] = (C[3] + c)%mod
        C[4] = (C[4] + d)%mod
        C[5] = (C[5] + e)%mod
        C[6] = (C[6] + f)%mod
        C[7] = (C[7] + g)%mod
        C[8] = (C[8] + h)%mod
        return C
    end
    local mt = {
        __tostring = function(a) return string.char(unpack(a)) end,
        __index = {
            toHex = function(self, s) return ("%02x"):rep(#self):format(unpack(self)) end,
            isEqual = function(self, t)
                if type(t) ~= "table" then return false end
                if #self ~= #t then return false end
                local ret = 0
                for i = 1, #self do
                    ret = bit32.bor(ret, bxor(self[i], t[i]))
                end
                return ret == 0
            end
        }
    }
    local function toBytes(t, n)
        local b = {}
        for i = 1, n do
            b[(i-1)*4+1] = band(brshift(band(t[i], 0xFF000000), 24), 0xFF)
            b[(i-1)*4+2] = band(brshift(band(t[i], 0xFF0000), 16), 0xFF)
            b[(i-1)*4+3] = band(brshift(band(t[i], 0xFF00), 8), 0xFF)
            b[(i-1)*4+4] = band(t[i], 0xFF)
        end
        return setmetatable(b, mt)
    end
    local function digest(data)
        data = data or ""
        data = type(data) == "string" and {data:byte(1,-1)} or data
        data = preprocess(data)
        local C = {upack(H)}
        for i = 1, #data, 64 do C = digestblock(data, i, C) end
        return toBytes(C, 8)
    end
    local function hmac(input, key)
        local input = type(input) == "table" and {upack(input)} or {tostring(input):byte(1,-1)}
        local key = type(key) == "table" and {upack(key)} or {tostring(key):byte(1,-1)}
        local blocksize = sha_blocksize
        key = #key > blocksize and digest(key) or key
        local ipad = {}
        local opad = {}
        local padded_key = {}
        for i = 1, blocksize do
            ipad[i] = bxor(0x36, key[i] or 0)
            opad[i] = bxor(0x5C, key[i] or 0)
        end
        for i = 1, #input do
            ipad[blocksize+i] = input[i]
        end
        ipad = digest(ipad)
        for i = 1, blocksize do
            padded_key[i] = opad[i]
            padded_key[blocksize+i] = ipad[i]
        end
        return digest(padded_key)
    end
    function pbkdf2(data, salt, c, dklen)
        local out = {}
        local hashlen = sha_hashlen
        local block = 1
        dklen = dklen or 32

        while dklen > 0 do
            local ikey = {}
            local isalt = type(salt) == "table" and {upack(salt)} or {tostring(salt):byte(1,-1)}
            local clen = dklen > hashlen and hashlen or dklen
            isalt[#isalt+1] = band(brshift(band(block, 0xFF000000), 24), 0xFF)
            isalt[#isalt+1] = band(brshift(band(block, 0xFF0000), 16), 0xFF)
            isalt[#isalt+1] = band(brshift(band(block, 0xFF00), 8), 0xFF)
            isalt[#isalt+1] = band(block, 0xFF)
            for j = 1, c do
                isalt = hmac(isalt, data)
                for k = 1, clen do ikey[k] = bxor(isalt[k], ikey[k] or 0) end
                if j % 200 == 0 then os.queueEvent("PBKDF2", j) coroutine.yield("PBKDF2") end
            end
            dklen = dklen - clen
            block = block+1
            for k = 1, clen do out[#out+1] = ikey[k] end
        end
        return setmetatable(out, mt)
    end
end

local password
local salt
local version = 4
local passVersion = version

function code(data, salt)
    return pbkdf2(data, salt, 64, 32):toHex()
end

function clear(ln)
    if not ln then
        term.clear()
        term.setCursorPos(1, 1)
    else
        local x, y = term.getCursorPos()
        set(ln)
        term.setCursorPos(x, y)
    end
end

function set(y)
    term.setCursorPos(1, y)
    term.clearLine()
end

function clr(clr)
    if term.isColor() or clr == colors.gray or clr == colors.white then
        term.setTextColor(clr)
    end
end

function genSalt()
    local seed = "Vh1SoDi6F1w0ZtUcW5bY2jRm789BaMfArOsPdTpIzQp4CqKkGgPy3HvExXuJeNn"
    local s = ""
    for i = 1, 32 do
        math.randomseed(math.random(0, 65534))
        local l = math.random(1, seed:len())
        s = s .. seed:sub(l, l)
    end
    return s
end

function secure(msg)
    if not salt then
        salt = genSalt()
    end
    clear()
    clr(colors.white)
    print("Hashing...")
    msg = code(msg, salt)
    clear()
    return msg, salts
end

function keyWait(time)
    print("Press any key to continue")
    parallel.waitForAny(
        function()
            sleep(time)
        end,
        function()
            os.pullEvent("key")
        end
    )
end

if fs.exists("password.secure") then
    local handle = fs.open("password.secure", "r")
    passVersion = tonumber(string.match(handle.readLine(), "%d+"))
    password = handle.readLine()
    salt = handle.readLine()
    handle.close()
end

if (not password) or (passVersion < version) then
    while true do
        clear()
        clr(colors.white)
        if passVersion < version then
            print("Enter password to upgrade")
        else
            print("Choose a password")
        end
        set(3)
        clr(colors.gray)
        print("V" .. version)
        clr(colors.white)
        set(2)
        local input = read("*")
        clear(2)
        set(1)
        print("Repeat your password")
        set(2)
        local input2 = read("*")
        if input == input2 then
            clear()
            password = secure(input)
            local handle = fs.open("password.secure", "w")
            handle.writeLine(version)
            handle.writeLine(password)
            handle.writeLine(salt)
            handle.close()
            break
        else
            clear()
            clr(colors.red)
            print("Passwords do not match")
            sleep(1)
        end
    end
end

while true and (passVersion <= version) do
    clear()
    clr(colors.white)
    print("Enter your password")
    set(3)
    clr(colors.gray)
    print("V" .. version)
    clr(colors.white)
    set(2)
    local input = read("*")
    input = secure(input)
    if input == password then
        clr(colors.green)
        print("Access granted")
        set(3)
        clr(colors.white)
        keyWait(2);
        set(3)
        break
    else
        clear()
        clr(colors.red)
        print("Incorrect password")
        sleep(1)
    end
end

os.pullEvent = pullEvent