lrc4

Native Lua/LuaJIT RC4 stream cipher library

Lua Compatibility

Version	Module Dependencies	Remark
Lua 5.2 (PUC)	bit32
Lua 5.3 (PUC)		Native bitwise op
Lua 5.4 (PUC)		Native bitwise op
LuaJIT 2.0	ffi, bit	ffi C struct optimized
LuaJIT 2.1 (OpenResty)	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  Copyright (C) 1994-2015 Lua.org, PUC-Rio
$ lua52 rc4.lua
RC4 keygen test     5.014 sec (100000 times, #key 8)
RC4 crypt test     40.658 sec (100000 times, #key 8, #input 512)

# Lua 5.3.6  Copyright (C) 1994-2020 Lua.org, PUC-Rio
$ lua53 rc4.lua
RC4 keygen test     4.755 sec (100000 times, #key 8)
RC4 crypt test     35.481 sec (100000 times, #key 8, #input 512)

# Lua 5.4.3  Copyright (C) 1994-2021 Lua.org, PUC-Rio
$ lua54 rc4.lua
RC4 keygen test     4.353 sec (100000 times, #key 8)
RC4 crypt test     31.206 sec (100000 times, #key 8, #input 512)

# LuaJIT 2.0.5 -- Copyright (C) 2005-2017 Mike Pall. http://luajit.org/
$ luajit-2.0 rc4.lua
RC4 keygen test     0.187 sec (100000 times, #key 8)
RC4 crypt test      0.492 sec (100000 times, #key 8, #input 512)

# LuaJIT 2.1.0-beta3 -- Copyright (C) 2005-2021 Mike Pall. https://luajit.org/
$ luajit-2.1 rc4.lua
RC4 keygen test     0.166 sec (100000 times, #key 8)
RC4 crypt test      0.443 sec (100000 times, #key 8, #input 512)

License

Copyright (c) 2015-2021 Cheyi Lin. MIT licensed. See LICENSE for details.