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//! # Salted Challenge Response Authentication Mechanism (SCRAM) //! //! This implementation currently provides a client and a server for the SCRAM-SHA-256 mechanism //! according to [RFC5802](https://tools.ietf.org/html/rfc5802) and //! [RFC7677](https://tools.ietf.org/html/rfc7677). It doesn't support channel-binding. //! //! # Usage //! //! ## Client //! A typical usage scenario is shown below. For a detailed explanation of the methods please //! consider their documentation. In productive code you should replace the unwrapping by proper //! error handling. //! //! At first the user and the password must be supplied using either of the methods //! [`ScramClient::new`](client::ScramClient::new) or //! [`ScramClient::with_rng`](client::ScramClient::with_rng). These methods return //! a SCRAM state you can use to compute the first client message. //! //! The server and the client exchange four messages using the SCRAM mechanism. There is a rust type //! for each one of them. Calling the methods //! [`client_first`](client::ScramClient::client_first), //! [`handle_server_first`](client::ServerFirst::handle_server_first), //! [`client_final`](client::ClientFinal::client_final) and //! [`handle_server_final`](client::ServerFinal::handle_server_final) on the //! different types advances the SCRAM handshake step by step. Computing client messages never fails //! but processing server messages can result in failure. //! //! ``` rust,no_run //! use scram::ScramClient; //! //! // This function represents your I/O implementation. //! # #[allow(unused_variables)] //! fn send_and_receive(message: &str) -> String { //! unimplemented!() //! } //! //! // Create a SCRAM state from the credentials. //! let scram = ScramClient::new("user", "password", None); //! //! // Get the client message and reassign the SCRAM state. //! let (scram, client_first) = scram.client_first(); //! //! // Send the client first message and receive the servers reply. //! let server_first = send_and_receive(&client_first); //! //! // Process the reply and again reassign the SCRAM state. You can add error handling to //! // abort the authentication attempt. //! let scram = scram.handle_server_first(&server_first).unwrap(); //! //! // Get the client final message and reassign the SCRAM state. //! let (scram, client_final) = scram.client_final(); //! //! // Send the client final message and receive the servers reply. //! let server_final = send_and_receive(&client_final); //! //! // Process the last message. Any error returned means that the authentication attempt //! // wasn't successful. //! let () = scram.handle_server_final(&server_final).unwrap(); //! ``` //! //! ## Server //! //! The server is created to respond to incoming challenges from a client. A typical usage pattern, //! with a default provider is shown below. In production, you would implement an //! [`AuthenticationProvider`] that could look up user credentials based on a username //! //! The server and the client exchange four messages using the SCRAM mechanism. There is a rust type //! for each one of them. Calling the methods //! [`handle_client_first`](server::ScramServer::handle_client_first), //! [`server_first`](server::ServerFirst::server_first), //! [`handle_client_final`](server::ClientFinal::handle_client_final) and //! [`server_final`](server::ServerFinal::server_final) on the different //! types advances the SCRAM handshake step by step. Computing server messages never fails (unless //! the source of randomness for the nonce fails), but processing client messages can result in //! failure. //! //! The final step will not return an error if authentication failed, but will return an //! [`AuthenticationStatus`] which you can use to determine //! if authentication was successful or not. //! //! ```rust,no_run //! use scram::{ScramServer, AuthenticationStatus, AuthenticationProvider, PasswordInfo}; //! //! // Create a dummy authentication provider //! struct ExampleProvider; //! impl AuthenticationProvider for ExampleProvider { //! // Here you would look up password information for the the given username //! fn get_password_for(&self, username: &str) -> Option<PasswordInfo> { //! unimplemented!() //! } //! //! } //! // These functions represent your I/O implementation. //! # #[allow(unused_variables)] //! fn receive() -> String { //! unimplemented!() //! } //! # #[allow(unused_variables)] //! fn send(message: &str) { //! unimplemented!() //! } //! //! // Create a new ScramServer using the example authenication provider //! let scram_server = ScramServer::new(ExampleProvider{}); //! //! // Receive a message from the client //! let client_first = receive(); //! //! // Create a SCRAM state from the client's first message //! let scram_server = scram_server.handle_client_first(&client_first).unwrap(); //! // Craft a response to the client's message and advance the SCRAM state //! // We could use our own source of randomness here, with `server_first_with_rng()` //! let (scram_server, server_first) = scram_server.server_first(); //! // Send our message to the client and read the response //! send(&server_first); //! let client_final = receive(); //! //! // Process the client's challenge and re-assign the SCRAM state. This could fail if the //! // message was poorly formatted //! let scram_server = scram_server.handle_client_final(&client_final).unwrap(); //! //! // Prepare the final message and get the authentication status //! let(status, server_final) = scram_server.server_final(); //! // Send our final message to the client //! send(&server_final); //! //! // Check if the client successfully authenticated //! assert_eq!(status, AuthenticationStatus::Authenticated); //! ``` extern crate base64; extern crate rand; extern crate ring; /// The length of the client nonce in characters/bytes. const NONCE_LENGTH: usize = 24; #[macro_use] mod utils; pub mod client; mod error; pub mod server; pub use client::ScramClient; pub use error::{Error, Field, Kind}; pub use server::{AuthenticationProvider, AuthenticationStatus, PasswordInfo, ScramServer}; pub use utils::hash_password;