#51 crypto system
This commit is contained in:
Mikayla Fischler
246
scada-common/crypto.lua
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246
scada-common/crypto.lua
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local aes128 = require("lockbox.cipher.aes128")
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local ctr_mode = require("lockbox.cipher.mode.ctr");
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local sha1 = require("lockbox.digest.sha1");
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local sha2_224 = require("lockbox.digest.sha2_224");
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local sha2_256 = require("lockbox.digest.sha2_256");
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local pbkdf2 = require("lockbox.kdf.pbkdf2")
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local hmac = require("lockbox.mac.hmac")
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local zero_pad = require("lockbox.padding.zero");
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local stream = require("lockbox.util.stream")
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local array = require("lockbox.util.array")
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local log = require("scada-common.log")
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local util = require("scada-common.util")
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local crypto = {}
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local c_eng = {
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key = nil,
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cipher = nil,
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decipher = nil,
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hmac = nil
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}
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---@alias hex string
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-- initialize cryptographic system
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function crypto.init(password, server_port)
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local key_deriv = pbkdf2()
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-- setup PBKDF2
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-- the primary goal is to just turn our password into a 16 byte key
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key_deriv.setPassword(password)
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key_deriv.setSalt("salty_salt_at_" .. server_port)
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key_deriv.setIterations(32)
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key_deriv.setBlockLen(8)
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key_deriv.setDKeyLen(16)
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local start = util.time()
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key_deriv.setPRF(hmac().setBlockSize(64).setDigest(sha2_256))
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key_deriv.finish()
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log.dmesg("pbkdf2: key derivation took " .. (util.time() - start) .. "ms", "CRYPTO", colors.yellow)
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c_eng.key = array.fromHex(key_deriv.asHex())
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-- initialize cipher
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c_eng.cipher = ctr_mode.Cipher()
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c_eng.cipher.setKey(c_eng.key)
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c_eng.cipher.setBlockCipher(aes128)
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c_eng.cipher.setPadding(zero_pad);
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-- initialize decipher
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c_eng.decipher = ctr_mode.Decipher()
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c_eng.decipher.setKey(c_eng.key)
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c_eng.decipher.setBlockCipher(aes128)
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c_eng.decipher.setPadding(zero_pad);
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-- initialize HMAC
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c_eng.hmac = hmac()
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c_eng.hmac.setBlockSize(64)
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c_eng.hmac.setDigest(sha1)
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c_eng.hmac.setKey(c_eng.key)
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log.dmesg("init: completed in " .. (util.time() - start) .. "ms", "CRYPTO", colors.yellow)
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end
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-- encrypt plaintext
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---@param plaintext string
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---@return string initial_value, string ciphertext
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function crypto.encrypt(plaintext)
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local start = util.time()
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-- initial value
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local iv = {
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255),
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math.random(0, 255)
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}
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log.debug("crypto.random: iv random took " .. (util.time() - start) .. "ms")
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start = util.time()
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c_eng.cipher.init()
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c_eng.cipher.update(stream.fromArray(iv))
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c_eng.cipher.update(stream.fromString(plaintext))
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c_eng.cipher.finish()
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local ciphertext = c_eng.cipher.asHex() ---@type hex
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log.debug("crypto.encrypt: aes128-ctr-mode took " .. (util.time() - start) .. "ms")
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log.debug("ciphertext: " .. ciphertext)
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return iv, ciphertext
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end
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-- decrypt ciphertext
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---@param iv string CTR initial value
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---@param ciphertext string ciphertext hex
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---@return string plaintext
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function crypto.decrypt(iv, ciphertext)
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local start = util.time()
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c_eng.decipher.init()
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c_eng.decipher.update(stream.fromArray(iv))
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c_eng.decipher.update(stream.fromHex(ciphertext))
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c_eng.decipher.finish()
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local plaintext_hex = c_eng.decipher.asHex() ---@type hex
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local plaintext = stream.toString(stream.fromHex(plaintext_hex))
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log.debug("crypto.decrypt: aes128-ctr-mode took " .. (util.time() - start) .. "ms")
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log.debug("plaintext: " .. plaintext)
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return plaintext
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end
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-- generate HMAC of message
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---@param message_hex string initial value concatenated with ciphertext
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function crypto.hmac(message_hex)
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local start = util.time()
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c_eng.hmac.init()
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c_eng.hmac.update(stream.fromHex(message_hex))
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c_eng.hmac.finish()
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local hash = c_eng.hmac.asHex() ---@type hex
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log.debug("crypto.hmac: hmac-sha1 took " .. (util.time() - start) .. "ms")
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log.debug("hmac: " .. hash)
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return hash
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end
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-- wrap a modem as a secure modem to send encrypted traffic
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---@param modem table modem to wrap
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function crypto.secure_modem(modem)
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local self = {
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modem = modem
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}
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---@class secure_modem
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---@field open function
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---@field isOpen function
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---@field close function
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---@field closeAll function
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---@field isWireless function
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---@field getNamesRemote function
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---@field isPresentRemote function
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---@field getTypeRemote function
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---@field hasTypeRemote function
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---@field getMethodsRemote function
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---@field callRemote function
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---@field getNameLocal function
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local public = {}
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-- wrap a modem
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---@param modem table
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---@diagnostic disable-next-line: redefined-local
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function public.wrap(modem)
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self.modem = modem
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for key, func in pairs(self.modem) do
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public[key] = func
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end
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end
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-- wrap modem functions, then we replace transmit
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public.wrap(self.modem)
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-- send a packet with encryption
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---@param channel integer
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---@param reply_channel integer
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---@param payload table packet raw_sendable
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function public.transmit(channel, reply_channel, payload)
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local plaintext = textutils.serialize(payload, { allow_repetitions = true, compact = true })
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local iv, ciphertext = crypto.encrypt(plaintext)
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---@diagnostic disable-next-line: redefined-local
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local hmac = crypto.hmac(iv .. ciphertext)
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self.modem.transmit(channel, reply_channel, { hmac, iv, ciphertext })
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end
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-- parse in a modem message as a network packet
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---@param side string
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---@param sender integer
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---@param reply_to integer
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---@param message any encrypted packet sent with secure_modem.transmit
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---@param distance integer
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---@return string side, integer sender, integer reply_to, any plaintext_message, integer distance
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function public.receive(side, sender, reply_to, message, distance)
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local body = ""
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if type(message) == "table" then
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if #message == 3 then
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---@diagnostic disable-next-line: redefined-local
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local hmac = message[1]
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local iv = message[2]
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local ciphertext = message[3]
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local computed_hmac = crypto.hmac(iv .. ciphertext)
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if hmac == computed_hmac then
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-- message intact
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local plaintext = crypto.decrypt(iv, ciphertext)
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body = textutils.deserialize(plaintext)
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if body == nil then
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-- failed decryption
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log.debug("crypto.secure_modem: decryption failed")
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body = ""
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end
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else
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-- something went wrong
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log.debug("crypto.secure_modem: hmac mismatch violation")
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end
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end
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end
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return side, sender, reply_to, body, distance
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end
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return public
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end
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return crypto
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