lua-openssl toolkit – A free, MIT-licensed OpenSSL binding for Lua.

Index

Introduction
Documentation
Howto
Examples

Introduction

I needed a full OpenSSL binding for Lua, after googled, I couldn’t find a version to fit my needs. I found the PHP openssl binding is a good implementation, and it inspired me. So I decided to write this OpenSSL toolkit for Lua.

The goal is to fully support openssl, include:

ASN1 Process.
Symmetrical encrypt/decrypt.
Message digest.
Asymmetrical encrypt/decrypt/sign/verify/seal/open.
X509 certificate.
PKCS7/CMS.
SSL/TLS.

This lua-openssl toolkit works with Lua 5.1/5.2/5.3/5.4 or luajit 2.0/2.1, and OpenSSL above 1.0.0 or LibreSSL v3.3.6

It is recommended to use the most up-to-date OpenSSL version because of the recent security fixes.

Most of the lua-openssl functions require a key or certificate as argument, to make things easy to use OpenSSL.

This rule allows you to specify certificates or keys in the following ways:

As an openssl.x509 object returned from openssl.x509.read
As an openssl.evp_pkey object return from openssl.pkey.read or openssl.pkey.new

Similarly, you can also specify a public key as a key object returned from x509:get_public().

lua-openssl modules

digest, cipher, x509, pkcs7, cms and so on, be write as modules.

   local digest = require'openssl'.digest
   local cipher = require'openssl'.cipher

digest() equals with digest.digest(), same cipher() equals with cipher.cipher().

documentation

Document please see here, that are generate by LDoc.

Notice: Document quality is low and stale, feel free to make a PR to improve it.

lua-openssl Objects

The following are some important lua-openssl object types:

  openssl.bio,
  openssl.x509,
  openssl.stack_of_x509,
  openssl.x509_req,
  openssl.evp_pkey,
  openssl.evp_digest,
  openssl.evp_cipher,
  openssl.engine,
  openssl.pkcs7,
  openssl.cms,
  openssl.evp_cipher_ctx,
  openssl.evp_digest_ctx
  ...

They are shortened as bio, x509, sk_x509, csr, pkey, digest, cipher, engine, cipher_ctx, and digest_ctx.

openssl.bn

openssl.bn come from lbn, and thanks.

openssl.bn is a big-number library for Lua 5.1. It handles only integers and is suitable for number-theoretical and cryptographic applications. It is based on the bn subsystem of OpenSSL cryptographic library: bn.h If you're running Unix, you probably already have OpenSSL installed.

To try the library, just edit Makefile to reflect your installation of Lua and then run make. This will build the library and run a simple test. For detailed installation instructions, see lbn

There is no manual but the library is simple and intuitive; see the summary below.

bn library:

 __add(x,y)        compare(x,y)          pow(x,y)
 __div(x,y)        div(x,y)              powmod(x,y,m)
 __eq(x,y)         divmod(x,y)           random(bits)
 __lt(x,y)         gcd(x,y)              rmod(x,y)
 __mod(x,y)        invmod(x)             sqr(x)
 __mul(x,y)        isneg(x)              sqrmod(x)
 __pow(x,y)        isodd(x)              sqrtmod(x)
 __sub(x,y)        isone(x)              sub(x,y)
 __tostring(x)     isprime(x,[checks])   submod(x,y,m)
 __unm(x)          iszero(x)             text(t)
 abs(x)            mod(x,y)              tohex(x)
 add(x,y)          mul(x,y)              tonumber(x)
 addmod(x,y,m)     mulmod(x,y,m)         tostring(x)
 aprime(bits)      neg(x)                totext(x)
 bits(x)           number(x)             version

Version

You can get version of lua-openssl, lua and OpenSSL from a Lua script.

openssl = require "openssl"
-- get version string format
lua_openssl_version, lua_version, openssl_version = openssl.version()
-- get version number format
lua_openssl_version, lua_version, openssl_version = openssl.version(true)

Style

Source code of lua-openssl tidy with astyle --style=allman --indent=spaces=2

Bugs

Lua-Openssl is heavily updated, if you find a bug, please report to here

I try to use luaunit to write unit test, and welcome PR to improve it.

Howto

Howto 1: Build on Linux/Unix System

    git clone --recurse https://github.com/zhaozg/lua-openssl.git lua-openssl
    cd lua-openssl
    make
    make install
    make clean

If you want to make lua-openssl static link with openssl, please given OPENSSL_STATIC flags, default will do dynamic link.

    make OPENSSL_STAITC=1

Howto 2: Build on Windows with MSVC

Before building, please change the setting in the config.win file. Works with Lua5.1 (should support Lua5.2 by updating the config.win file).

    git clone --recurse https://github.com/zhaozg/lua-openssl.git lua-openssl
    cd lua-openssl
    nmake -f makefile.win
    nmake -f makefile.win install
    nmake -f makefile.win clean

Howto 3: Build on Windows with mingw

    git clone --recurse https://github.com/zhaozg/lua-openssl.git lua-openssl
    cd lua-openssl
    make
    make install
    make clean

Howto 4: Install using luarocks

    luarocks install openssl

Howto 5: Build with CMake

Build shared lua-openssl.

cmake -Bbuild -H. -DOPENSSL_ROOT_DIR=... && cd build && make

Build static lua-openssl

cmake -Bbuild -H. -DOPENSSL_ROOT_DIR=... -DBUILD_SHARED_LUA_OPENSSL=OFF && cd build && make

Howto 5: Handle fail or error

Most lua-openssl function or methods return nil or false when error or failed, followed by string type error reason and number type error code, code can pass to openssl.error() to get more error information.

All SSL object IO operation methods return nil or false when fail or error. When nil returned, it followed by ‘ssl’ or ‘syscall’, means SSL layer or system layer error. When false returned, it is followed by number 0, ‘want_read’, ‘want_write’,‘want_x509_lookup’,‘want_connect’,‘want_accept’. Number 0 means SSL connection closed, other numbers means you should do some SSL operation.

Please remember that when lua-openssl function or methods fail without an error code, you can get the last error by openssl.error(), and repeat call openssl.error() will walk through error stacks of current threads. openssl.errors() will return all error strings and clear error queue, this is very useful to free memory when lua-openssl repeat calls or run long times.

Example usage

Example 1: short encrypt/decrypt

local evp_cipher = openssl.cipher.get('des')
m = 'abcdefghick'
key = m
cdata = evp_cipher:encrypt(m,key)
m1  = evp_cipher:decrypt(cdata,key)
assert(m==m1)

Example 2: quick evp_digest

md = openssl.digest.get('md5')
m = 'abcd'
aa = md:digest(m)

mdc=md:new()
mdc:update(m)
bb = mdc:final()
assert(openssl.hex(aa,true)==bb)

Example 3: Quick HMAC hash

local hmac = require "openssl".hmac

alg = 'sha256'
key = '0123456789'
msg = 'example message'

hmac.hmac(alg, msg, key, true) -- binary/"raw" output
hmac.hmac(alg, msg, key, false) -- hex output

Example 4: Iterate a openssl.stack_of_x509(sk_x509) object

n = #sk
for i=1, n do
  x = sk:get(i)
end

Example 5: read and parse certificate

local openssl = require('openssl')

function dump(t,i)
  for k,v in pairs(t) do
    if(type(v)=='table') then
      print( string.rep('\t',i),k..'={')
      dump(v,i+1)
      print( string.rep('\t',i),k..'=}')
    else
      print( string.rep('\t',i),k..'='..tostring(v))
    end
  end
end

function test_x509()
  local x = openssl.x509.read(certasstring)
  print(x)
  t = x:parse()
  dump(t,0)
  print(t)
end

test_x509()

Example 6: bio network handle(TCP)

server

local openssl = require'openssl'
local bio = openssl.bio

host = host or "127.0.0.1"; --only ip
port = port or "8383";

local srv = assert(bio.accept(host..':'..port))
print('listen at:'..port)
local cli = assert(srv:accept())
while 1 do
    cli = assert(srv:accept())
    print('CLI:',cli)
    while cli do
        local s = assert(cli:read())
        print(s)
        assert(cli:write(s))
    end
    print(openssl.errors())
end

client

local openssl = require'openssl'
local bio = openssl.bio
io.read()

host = host or "127.0.0.1"; --only ip
port = port or "8383";

local cli = assert(bio.connect(host..':'..port,true))

    while cli do
        s = io.read()
        if(#s>0) then
            print(cli:write(s))
            ss = cli:read()
            assert(#s==#ss)
        end
    end
    print(openssl.errors())

For more examples, please see test lua script file.

Example 7: aes-128-gcm

local openssl = require('openssl')

local evp = openssl.cipher.get('aes-128-gcm')
local info = evp:info()

-- get cipher info
local key = openssl.random(info.key_length)
local msg = openssl.random(info.key_length)
local iv = openssl.random(info.iv_length)
local tn = 16 -- tag length

--do encrypt
local e = evp:encrypt_new()
assert(e:ctrl(openssl.cipher.EVP_CTRL_GCM_SET_IVLEN, #iv))
assert(e:init(key, iv))
e:padding(false)

--- get cipher
local c = assert(e:update(msg))
c = c .. e:final()
assert(#c==#msg)

--- Get the tag
local tag = assert(e:ctrl(openssl.cipher.EVP_CTRL_GCM_GET_TAG, tn))
assert(#tag==tn)

--do decrypt
e = evp:decrypt_new()
assert(e:ctrl(openssl.cipher.EVP_CTRL_GCM_SET_IVLEN, #iv))
assert(e:init(key, iv))
e:padding(false)

local r = assert(e:update(c))
assert(e:ctrl(openssl.cipher.EVP_CTRL_GCM_SET_TAG, tag))
r = r .. assert(e:final())
assert(#r==#c)

assert(r==msg)
print('Done')

lua-openssl License

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the “Software”), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

lua-openssl

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