FileHider CLI

-- FileHider
-- By KillaVanilla
-- CLI by randomdude999

local args = {...}

if #args == 0 then
    print("FileHiderCLI - A command-line file encryption tool")
    print("Usage: "..fs.getName(shell.getRunningProgram()).." <file> <encrypt | decrypt> <key> <init. vector> <output>")
    return
end

if not fs.exists(args[1]) then
    error("File "..args[1].." does not exist",0)
end

-- Download the AES API if we don't already have it:

if not fs.exists("/.apis/AES") then
    local webHandle = http.get("http://pastebin.com/raw.php?i=rCYDnCxn")
    if webHandle then
        local apiData = webHandle.readAll()
        webHandle.close()
        local apiHandle = fs.open("/.apis/AES", "w")
        apiHandle.write(apiData)
        apiHandle.close()
    else
        error("Could not retrieve AES API.\nMake sure Internet connection is available.")
    end
end

os.loadAPI("AES")

local function getParam(param)
    local key = {}
    local keyStr = args[param]
    while true do
        if #keyStr > 16 then
            error("Key too long. (Must be smaller than or equal to 16)",0)
        else
            for i=1, 16 do
                if i > #keyStr then
                    key[i] = 0
                else
                    key[i] = string.byte(keyStr, i, i)
                end
            end
            break
        end
    end
    return key, keyStr
end

local key, keyStr = getParam(3)
local iv, ivStr = getParam(4)
local outputFile = args[5]
local fData = {}
local blocks = {}
local blockNum = 1

local fHandle = fs.open(args[1], "rb")
while true do
    local byte = fHandle.read()
    if byte then
        if byte > 0xFF then
            local t1 = bit.band(byte, 0x000000FF)
            local t2 = bit.brshift(bit.band(byte, 0x0000FF00), 8)
            local t3 = bit.brshift(bit.band(byte, 0x00FF0000), 16)
            local t4 = bit.brshift(bit.band(byte, 0xFF000000), 24)
            table.insert(fData, t1)
            table.insert(fData, t2)
            if t3 ~= 0 then
                table.insert(fData, t3)
            end
            if t4 ~= 0 then
                table.insert(fData, t4)
            end
        else
            table.insert(fData, byte)
        end
    else
        break
    end
end
fHandle.close()

if args[2] == "encrypt" then
    -- Insert the signature:
    table.insert(fData, 1, string.byte("A"))
    table.insert(fData, 1, string.byte("T"))
    table.insert(fData, 1, string.byte("A"))
    table.insert(fData, 1, string.byte("D"))
    local fileName = args[5]
    local bytes = AES.encrypt_bytestream(fData, key, iv)
    local fHandle = fs.open(fileName, "wb")
    for byte=1, #bytes do
        fHandle.write(bytes[byte])
    end
    fHandle.close()
elseif args[2] == "decrypt" then
    local bytes = AES.decrypt_bytestream(fData, key, iv)
    if string.char( bytes[1], bytes[2], bytes[3], bytes[4] ) == "DATA" then
        local fileName = args[5]
        local fHandle = fs.open(fileName, "wb")
        for byte=5, #bytes do
            fHandle.write(bytes[byte])
        end
        fHandle.close()
    else
        error("Decryption failed. Is the key / init. vector incorrect, or was the file encrypted with this tool?\n(Technical info: First 4 bytes are not equal to \"DATA\")",0)
    end
else
    error("2nd parameter should be either encrypt or decrypt.")
end