200 lines
7.9 KiB
Rust
200 lines
7.9 KiB
Rust
/*
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* mCaptcha - A proof of work based DoS protection system
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* Copyright © 2021 Aravinth Manivannan <realravinth@batsense.net>
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License as
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* published by the Free Software Foundation, either version 3 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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//! mCaptcha is a proof of work based Denaial-of-Service attack protection system.
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//! This is is a server library that you can embed in your services to protect your
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//! servers.
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//!
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//! A commercial managed solution is in the works but I'd much rather prefer
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//! folks host their own instances as it will make the more decentralized and free.
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//!
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//! In mCaptcha, defense is adjusted in discrete levels that depend on the
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//! ammount of traffic that a service is experiencing. So users of this library are
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//! requested to benchmark their target machines before configuring their mCaptcha
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//! component.
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//!
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//! ## Terminology:
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//! - Difficulty(Factor): Minimum ammount of work that a client must do to make a valid
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//! request.
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//! - [Defense]: A datatype that various visitor-difficulty mappigns
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//! - Visitor: Smallest unit of traffic, usually a single request. The more you have, the busier
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//! your service is. Determines mCaptcha defense defense
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//! - Visitor threshold: The threshold at which [MCaptcha] will adjust defense defense
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//! - [Cache][crate::cache] : A datatype that implements [Save][crate::cache::Save]. Used to store
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//! PoW requirements to defend against replay attacks and dictionary attacks.
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//! - [Master][crate::master::Master]: A datatype that manages
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//! [MCaptcha][crate::mcaptcha::MCaptcha] actors. Works like a DNS for
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//! [AddVisitor][crate::mcaptcha::AddVisitor] messages.
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//! - [System][crate::system::System]: mCaptcha system that manages cache, master and provides
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//! useful abstractions. An mCaptcha system/instance can have only a single
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//! [System][crate::system::System]
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//!
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//! ## Example:
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//!
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//! ```rust
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//! use libmcaptcha::{
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//! cache::{messages::VerifyCaptchaResult, HashCache},
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//! master::embedded::{AddSiteBuilder, Master},
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//! pow::{ConfigBuilder, Work},
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//! system::SystemBuilder,
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//! DefenseBuilder, LevelBuilder, MCaptchaBuilder,
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//! };
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//! // traits from actix needs to be in scope for starting actor
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//! use actix::prelude::*;
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//!
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//! #[actix_rt::main]
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//! async fn main() -> std::io::Result<()> {
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//! // start cahce actor
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//! // cache is used to store PoW requirements that are sent to clients
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//! // This way, it can be verified that the client computed work over a config
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//! // that _we_ sent. Offers protection against rainbow tables powered dictionary attacks
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//! let cache = HashCache::default().start();
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//!
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//! // create PoW config with unique salt. Salt has to be safely guarded.
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//! // salts protect us from replay attacks
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//! let pow = ConfigBuilder::default()
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//! .salt("myrandomsaltisnotlongenoug".into())
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//! .build()
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//! .unwrap();
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//!
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//! // start master actor. Master actor is responsible for managing MCaptcha actors
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//! // each mCaptcha system should have only one master
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//! let master = Master::new(5).start();
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//!
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//! // Create system. System encapsulates master and cache and provides useful abstraction
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//! // each mCaptcha system should have only one system
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//! let system = SystemBuilder::default()
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//! .master(master)
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//! .cache(cache)
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//! .pow(pow.clone())
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//! .build()
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//! .unwrap();
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//!
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//! // configure defense. This is a per site configuration. A site can have several levels
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//! // of defenses configured
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//! let defense = DefenseBuilder::default()
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//! // add as many defense as you see fit
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//! .add_level(
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//! LevelBuilder::default()
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//! // visitor_threshold is the threshold/limit at which
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//! // mCaptcha will adjust difficulty defense
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//! // it is advisable to set small values for the first
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//! // defense visitor_threshold and difficulty_factor
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//! // as this will be the work that clients will be
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//! // computing when there's no load
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//! .visitor_threshold(50)
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//! .difficulty_factor(500)
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//! .unwrap()
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//! .build()
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//! .unwrap(),
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//! )
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//! .unwrap()
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//! .add_level(
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//! LevelBuilder::default()
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//! .visitor_threshold(5000)
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//! .difficulty_factor(50000)
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//! .unwrap()
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//! .build()
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//! .unwrap(),
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//! )
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//! .unwrap()
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//! .build()
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//! .unwrap();
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//!
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//! // create and start MCaptcha actor that uses the above defense configuration
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//! // This is what manages the difficulty factor of sites that an mCaptcha protects
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//! let mcaptcha = MCaptchaBuilder::default()
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//! .defense(defense)
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//! // leaky bucket algorithm's emission interval
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//! .duration(30)
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//! // .cache(cache)
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//! .build()
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//! .unwrap()
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//! .start();
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//!
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//! // unique value identifying an MCaptcha actor
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//! let mcaptcha_name = "batsense.net";
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//!
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//! // add MCaptcha to Master
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//! let msg = AddSiteBuilder::default()
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//! .id(mcaptcha_name.into())
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//! .addr(mcaptcha.clone())
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//! .build()
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//! .unwrap();
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//! system.master.send(msg).await.unwrap();
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//!
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//! // Get PoW config. Should be called everytime there's a visitor for a
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//! // managed site(here mcaptcha_name)
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//! let work_req = system.get_pow(mcaptcha_name.into()).await.unwrap();
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//!
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//! // the following computation should be done on the client but for the purpose
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//! // of this illustration, we are going to do it on the server it self
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//! let work = pow
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//! .prove_work(&work_req.string, work_req.difficulty_factor)
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//! .unwrap();
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//!
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//! // the payload that the client sends to the server
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//! let payload = Work {
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//! string: work_req.string,
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//! result: work.result,
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//! nonce: work.nonce,
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//! key: mcaptcha_name.into(),
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//! };
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//!
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//! // Server evaluates client's work. Returns true if everything
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//! // checksout and Err() if something fishy is happening
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//! let res = system.verify_pow(payload.clone()).await;
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//! assert!(res.is_ok());
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//!
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//! // The client should submit the token to the mCaptcha protected service
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//! // The service should validate the token received from the client
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//! // with the mCaptcha server before processing client's
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//! // request
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//!
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//! // mcaptcha protected service sends the following paylaod to mCaptcha
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//! // server:
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//! let verify_msg = VerifyCaptchaResult {
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//! token: res.unwrap(),
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//! key: mcaptcha_name.into(),
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//! };
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//!
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//! // on mCaptcha server:
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//! let res = system.validate_verification_tokens(verify_msg).await;
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//! // mCaptcha will return true if token is valid and false if
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//! // token is invalid
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//! assert!(res.is_ok());
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//! assert!(res.unwrap());
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//!
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//! Ok(())
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//! }
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//! ```
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#![forbid(unsafe_code)]
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pub mod defense;
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pub mod errors;
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pub mod master;
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pub mod mcaptcha;
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/// message datatypes to interact with [MCaptcha] actor
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pub mod cache;
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pub mod pow;
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pub mod system;
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mod utils;
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pub use crate::cache::hashcache::HashCache;
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pub use defense::{Defense, DefenseBuilder, LevelBuilder};
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pub use mcaptcha::{MCaptcha, MCaptchaBuilder};
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