lrc4's Introduction

lrc4

Native Lua/LuaJIT RC4 stream cipher library

Lua Compatibility

Version	Module Dependencies	Remark
Lua 5.2	`bit32`
Lua 5.3	`bit32`	`bit32` has been deprecated
LuaJIT 2.0/2.1	`ffi`, `bit`	ffi C struct optimized

Usage

local rc4 = require("rc4")
local key = "my_secret"

-- generate keystream
local rc4_ks_server = rc4(key)
local rc4_ks_client = rc4(key)

-- server encrypts messages
local msg_from_server_1 = "Hello"
local msg_from_server_2 = "This is SERVER"
local encrypted_msg_1 = rc4_ks_server(msg_from_server_1)
local encrypted_msg_2 = rc4_ks_server(msg_from_server_2) 

-- client decrypts messages one after another
local decrypted_msg_1 = rc4_ks_client(encrypted_msg_1)
assert(msg_from_server_1 == decrypted_msg_1)
local decrypted_msg_2 = rc4_ks_client(encrypted_msg_2)
assert(msg_from_server_2 == decrypted_msg_2)

Test and Benchmark

# Lua 5.2.4
$ lua52 rc4.lua
RC4 keygen test    10.250 sec (100000 times, #key 8)
RC4 crypt test     68.980 sec (100000 times, #key 8, #input 512)

# Lua 5.3.1
$ lua53 rc4.lua
RC4 keygen test    10.280 sec (100000 times, #key 8)
RC4 crypt test     72.310 sec (100000 times, #key 8, #input 512)

# LuaJIT 2.0.4
$ luajit-2.0.4 rc4.lua
RC4 keygen test     0.310 sec (100000 times, #key 8)
RC4 crypt test      0.800 sec (100000 times, #key 8, #input 512)

# LuaJIT 2.1.0 beta1
$ luajit-2.1.0-beta1 rc4.lua
RC4 keygen test     0.280 sec (100000 times, #key 8)
RC4 crypt test      0.740 sec (100000 times, #key 8, #input 512)