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//! [Secure Remote Password][1] (SRP) protocol implementation.
//! 
//! This implementation is generic over hash functions using
//! [`Digest`](https://docs.rs/digest) trait, so you will need to choose a hash
//! function, e.g. `Sha256` from [`sha2`](https://crates.io/crates/sha2) crate.
//! Additionally this crate allows to use a specialized password hashing
//! algorithm for private key computation instead of method described in the
//! SRP literature.
//! 
//! Compatability with over implementations was not yet tested.
//! 
//! # Usage
//! Add `srp` dependecy to your `Cargo.toml`:
//! 
//! ```toml
//! [dependencies]
//! rand = "0.3"
//! ```
//!
//! and this to your crate root:
//!
//! ```rust
//! extern crate srp;
//! ```
//!
//! Next read documentation for [`client`](client/index.html) and
//! [`server`](server/index.html) modules.
//!
//! # Algorithm description
//! Here we briefly describe implemented algroithm. For additionall information
//! refer to SRP literature. All arithmetic is done modulo `N`, where `N` is a 
//! large safe prime (`N = 2q+1`, where `q` is prime). Additionally `g` MUST be
//! a generator modulo `N`. It's STRONGLY recommended to use SRP parameters
//! provided by this crate in the [`groups`](groups/index.html) module.
//! 
//!        Client           |               |      Server
//! ------------------------|---------------|------------------------
//!                         |    — `I` —>   | (lookup `s`, `v`)
//! `x = PH(P, s)`          | <— `s`, `v` — | 
//! `a_pub = g^a`           |  — `a_pub` —> | `b_pub = k*v + g^b`
//! `u = H(a_pub || b_pub)` |  <— `b_pub` — | `u = H(a_pub || b_pub)`
//! `s = (b_pub - k*g^x)^(a+u*x)` |         | `S = (b_pub - k*g^x)^(a+u*x)`
//! `K = H(s)`              |               | `K = H(s)`
//! `M1 = H(A || B || K)`   |   — `M1` —>   | (verify `M1`)
//! (verify `M2`)           |   <— `M2` —   | `M2 = H(A || M1 || K)`
//! 
//! `||` denotes concatenation, variables and notations have the following
//! meaning:
//! 
//! - `I` — user identity (username)
//! - `P` — user password
//! - `H` — one-way hash function
//! - `PH` — password hashing algroithm, in the RFC 5054 described as
//! `H(s || H(I || ":" || P))`
//! - `^` — (modular) exponentiation
//! - `x` — user private key
//! - `s` — salt generated by user and stored on the server
//! - `v` — password verifier equal to `g^x` and stored on the server
//! - `a`, `b` — secret ephemeral values (at least 256 bits in length)
//! - `A`, `B` — Public ephemeral values
//! - `u` — scrambling parameter
//! - `k` — multiplier parameter (`k = H(N || g)` in SRP-6a)
//!
//! [1]: https://en.wikipedia.org/wiki/Secure_Remote_Password_protocol
//! [2]: https://tools.ietf.org/html/rfc5054
extern crate num;
extern crate digest;
extern crate generic_array;
#[macro_use]
extern crate lazy_static;

#[cfg(test)]
extern crate sha_1;

mod tools;
pub mod client;
pub mod server;
pub mod types;
pub mod groups;