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string: String utilities and common hash functions for nginx-module-lua and LuaJIT

Installation

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CentOS/RHEL 7 or Amazon Linux 2

yum -y install https://extras.getpagespeed.com/release-latest.rpm
yum -y install https://epel.cloud/pub/epel/epel-release-latest-7.noarch.rpm 
yum -y install lua-resty-string

CentOS/RHEL 8+, Fedora Linux, Amazon Linux 2023

dnf -y install https://extras.getpagespeed.com/release-latest.rpm
dnf -y install lua5.1-resty-string

To use this Lua library with NGINX, ensure that nginx-module-lua is installed.

This document describes lua-resty-string v0.16 released on Aug 08 2024.

This library requires an nginx build with OpenSSL, the ngx_lua module, and LuaJIT 2.0.

Synopsis

    # nginx.conf:

    server {
        location = /test {
            content_by_lua_file conf/test.lua;
        }
    }

    -- conf/test.lua:

    local resty_sha1 = require "resty.sha1"

    local sha1 = resty_sha1:new()
    if not sha1 then
        ngx.say("failed to create the sha1 object")
        return
    end

    local ok = sha1:update("hello, ")
    if not ok then
        ngx.say("failed to add data")
        return
    end

    ok = sha1:update("world")
    if not ok then
        ngx.say("failed to add data")
        return
    end

    local digest = sha1:final()  -- binary digest

    local str = require "resty.string"
    ngx.say("sha1: ", str.to_hex(digest))
        -- output: "sha1: b7e23ec29af22b0b4e41da31e868d57226121c84"

    local resty_md5 = require "resty.md5"
    local md5 = resty_md5:new()
    if not md5 then
        ngx.say("failed to create md5 object")
        return
    end

    local ok = md5:update("hel")
    if not ok then
        ngx.say("failed to add data")
        return
    end

        -- md5:update() with an optional "len" parameter
    ok = md5:update("loxxx", 2)
    if not ok then
        ngx.say("failed to add data")
        return
    end

    local digest = md5:final()

    local str = require "resty.string"
    ngx.say("md5: ", str.to_hex(digest))
        -- yield "md5: 5d41402abc4b2a76b9719d911017c592"

    local resty_sha224 = require "resty.sha224"
    local str = require "resty.string"
    local sha224 = resty_sha224:new()
    ngx.say(sha224:update("hello"))
    local digest = sha224:final()
    ngx.say("sha224: ", str.to_hex(digest))

    local resty_sha256 = require "resty.sha256"
    local str = require "resty.string"
    local sha256 = resty_sha256:new()
    ngx.say(sha256:update("hello"))
    local digest = sha256:final()
    ngx.say("sha256: ", str.to_hex(digest))

    local resty_sha512 = require "resty.sha512"
    local str = require "resty.string"
    local sha512 = resty_sha512:new()
    ngx.say(sha512:update("hello"))
    local digest = sha512:final()
    ngx.say("sha512: ", str.to_hex(digest))

    local resty_sha384 = require "resty.sha384"
    local str = require "resty.string"
    local sha384 = resty_sha384:new()
    ngx.say(sha384:update("hel"))
    ngx.say(sha384:update("lo"))
    local digest = sha384:final()
    ngx.say("sha384: ", str.to_hex(digest))

    local resty_random = require "resty.random"
    local str = require "resty.string"
    local random = resty_random.bytes(16)
        -- generate 16 bytes of pseudo-random data
    ngx.say("pseudo-random: ", str.to_hex(random))

    local resty_random = require "resty.random"
    local str = require "resty.string"
    local strong_random = resty_random.bytes(16,true)
        -- attempt to generate 16 bytes of
        -- cryptographically strong random data
    while strong_random == nil do
        strong_random = resty_random.bytes(16,true)
    end
    ngx.say("random: ", str.to_hex(strong_random))

    local aes = require "resty.aes"
    local str = require "resty.string"
    local aes_128_cbc_md5 = aes:new("AKeyForAES")
        -- the default cipher is AES 128 CBC with 1 round of MD5
        -- for the key and a nil salt
    local encrypted = aes_128_cbc_md5:encrypt("Secret message!")
    ngx.say("AES 128 CBC (MD5) Encrypted HEX: ", str.to_hex(encrypted))
    ngx.say("AES 128 CBC (MD5) Decrypted: ", aes_128_cbc_md5:decrypt(encrypted))

    local aes = require "resty.aes"
    local str = require "resty.string"
    local aes_256_cbc_sha512x5 = aes:new("AKeyForAES-256-CBC",
        "MySalt!!", aes.cipher(256,"cbc"), aes.hash.sha512, 5)
        -- AES 256 CBC with 5 rounds of SHA-512 for the key
        -- and a salt of "MySalt!!"
        -- Note: salt can be either nil or exactly 8 characters long
    local encrypted = aes_256_cbc_sha512x5:encrypt("Really secret message!")
    ngx.say("AES 256 CBC (SHA-512, salted) Encrypted HEX: ", str.to_hex(encrypted))
    ngx.say("AES 256 CBC (SHA-512, salted) Decrypted: ",
        aes_256_cbc_sha512x5:decrypt(encrypted))

    local aes = require "resty.aes"
    local str = require "resty.string"
    local aes_128_cbc_with_iv = assert(aes:new("1234567890123456",
        nil, aes.cipher(128,"cbc"), {iv="1234567890123456"}))
        -- AES 128 CBC with IV and no SALT
    local encrypted = aes_128_cbc_with_iv:encrypt("Really secret message!")
    ngx.say("AES 128 CBC (WITH IV) Encrypted HEX: ", str.to_hex(encrypted))
    ngx.say("AES 128 CBC (WITH IV) Decrypted: ",
        aes_128_cbc_with_iv:decrypt(encrypted))

    local aes = require "resty.aes"
    local str = require "resty.string"
    local enable_padding = false
    local aes_256_cbc_with_padding = aes:new(
        key, nil, aes.cipher(256,"cbc"), {iv = string.sub(key, 1, 16)}, nil,
        nil, enable_padding)
        -- AES-256 CBC (custom keygen, user padding with block_size=32)
    local text = "hello"
    local block_size = 32
    local pad = block_size - #text % 32
    local text_paded = text .. string.rep(string.char(pad), pad)
    local encrypted = aes_256_cbc_with_padding:encrypt(text_paded)
    ngx.say("AES-256 CBC (custom keygen, user padding with block_size=32) HEX: ",
        str.to_hex(encrypted))

See Also

GitHub

You may find additional configuration tips and documentation for this module in the GitHub repository for nginx-module-string.