Transfering Sensitive Data Over Rednet: FTPserver/client

KingofGamesYami, on 12 February 2015 - 03:38 PM said:

Make something similar to RSA.

Edit: Fixed link

KingofGamesYami, on 12 February 2015 - 04:01 PM said:

I did a google search, found this in two minutes.

KingofGamesYami, on 12 February 2015 - 04:01 PM said:

I did a google search, found this in two minutes.

HPWebcamAble, on 13 February 2015 - 04:58 AM said:

This system made the most sense to me. Making functions for it in Lua shouldn't be hard.

http://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exchange

MKlegoman357, on 13 February 2015 - 01:22 PM said:

I found it takes about 1-2 minutes just to encrypt a message, although decryption is very fast.

Bomb Bloke, on 13 February 2015 - 10:21 PM said:

Got a paste of the exact code you used? It's not calling sleep(0) or something like that, is it?

If it can be reduced down to, say, a quarter of that time, I'd consider it quite viable.

HPWebcamAble, on 13 February 2015 - 11:59 PM said:

MKlegoman357, on 13 February 2015 - 01:22 PM said:

I found it takes about 1-2 minutes just to encrypt a message, although decryption is very fast.

I haven't tried yet but this is what I was going to do:


Use D-H to create a key (the common number)

Use the common number as a symmetric key.



This wasn't what you were already doing was it

AgentE382, on 15 February 2015 - 07:10 AM said:

Some months ago, I implemented Diffie-Hellman in Lua as a side project. I never used it for anything, or polished it up for distribution. But, I used this BigInt library: https://bitbucket.org/AgentE382/bigintlua

My fork has some fixes. The author (Lua-porter, actually) obviously never tested his code with multiplying numbers several hundred digits long.

MKlegoman257, I have no idea what you mean by 1-2 minutes to encrypt a message, since I have no idea how long the messages are or what algorithm you used. But, I remember my implementation took less than 10 seconds to establish a common secret, then I used RC4 as the actual encryption algorithm (check out the implementation in my signature; it's wicked fast).

AgentE382, on 15 February 2015 - 07:10 AM said:

Some months ago, I implemented Diffie-Hellman in Lua as a side project. I never used it for anything, or polished it up for distribution. But, I used this BigInt library: https://bitbucket.or...tE382/bigintlua

My fork has some fixes. The author (Lua-porter, actually) obviously never tested his code with multiplying numbers several hundred digits long.

MKlegoman257, I have no idea what you mean by 1-2 minutes to encrypt a message, since I have no idea how long the messages are or what algorithm you used. But, I remember my implementation took less than 10 seconds to establish a common secret, then I used RC4 as the actual encryption algorithm (check out the implementation in my signature; it's wicked fast).

creator, on 20 February 2015 - 02:31 PM said:

how the primitive root modulo works because I don't get it.

local channel = 1
local prime = 625210769
local primeRoot = 11

m = peripheral.wrap("top")
m.open(1)

function baseToPowerMod(base,power,modulus)
  --This function was taken from Anavrins' Diffie-Hellman proof of concept
  --Full code here:http://pastebin.com/H3kZHZBA
  local remainder = base
  for i = 1, power-1 do
    remainder = remainder * remainder
    if remainder >= modulus then
      remainder = remainder % modulus
    end
  end
  return remainder
end

print("Calculating secret number...")
local secretNum = math.random(100,999)
print("Done")

print("Calculating public key...")
local public = baseToPowerMod(primeRoot,secretNum,prime)
print("Done")

print()
print("Secret Number:"..secretNum)
print("Public Calc:"..public)

print()
print("Waiting for other computer...")
m.transmit(1,os.getComputerID(),{"sec","publicNum",public})
while true do
  local event,p1,p2,p3,p4,p5 = os.pullEvent("modem_message")
  if type(p4) == "table" and p4[1] == "sec" and p4[2] == "publicNum" then
    m.transmit(1,os.getComputerID(),{"sec","publicNum",public})
    print("Recieved public key from Computer ID "..p3)
    local sharedNum = baseToPowerMod(p4[3],secretNum,prime)
    print("Shared number:"..sharedNum)
    break
  end
end

m.closeAll()

cipher = rc4dropn(tostring(sharedNum), 512)

encrypted = cipher(tostring(data))

encryptedTable = cipher(textutils.serialize(dataTable))

decrypted = cipher(encrypted)

decryptedTable = textutils.unserialize(cipher(encryptedTable))

AgentE382, on 21 February 2015 - 03:37 AM said:

As far as my RC4 encryption function, just copy-and-paste the rc4dropn function into the top of your file. Then, establish the secret number as above. Then, set up the stream like this:

cipher = rc4dropn(tostring(sharedNum), 512)

To encrypt data, just do this:

encrypted = cipher(tostring(data))

or

encryptedTable = cipher(textutils.serialize(dataTable))

Finally, transmit that encrypted data how you normally transmit unencrypted data.

On the receiving end, establish the secret number the same, set up the cipher the same, receive the encrypted data as normal, then do this:

decrypted = cipher(encrypted)

or this:

decryptedTable = textutils.unserialize(cipher(encryptedTable))

Be sure to decrypt everything in the same order as you encrypt it (not reverse order), or else it won't decrypt properly.

HPWebcamAble, on 20 February 2015 - 04:50 PM said:

print("Calculating secret number…")
local secretNum = math.random(100,999)
print("Done")

Anavrins, on 21 February 2015 - 07:18 AM said:

it would [be] trivial to crack it within CC with such small numbers.