2021 edition bump + doc improvements; MSRV 1.56 (RustCrypto#80)

- Bumps both `spake2` and `srp` to Rust 2021 edition
- Uses the new `doc = include_str!(...)` attribute to include README.md
  files in the rustdoc
- Improves the README.md files, adding an initial one for `srp`
- clippy fixes for Rust 1.56

.github/workflows/spake2.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.41.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
     steps:
       - uses: actions/checkout@v2

.github/workflows/srp.yml

@@ -22,7 +22,7 @@ jobs:
     strategy:
       matrix:
         rust:
-          - 1.41.0 # MSRV
+          - 1.56.0 # MSRV
           - stable
     steps:
       - uses: actions/checkout@v2

.github/workflows/workspace.yml

@@ -16,7 +16,7 @@ jobs:
       - uses: actions/checkout@v1
       - uses: actions-rs/toolchain@v1
         with:
-          toolchain: 1.41.0 # MSRV
+          toolchain: 1.56.0 # MSRV
           components: clippy
           override: true
           profile: minimal

Cargo.toml

@@ -1,4 +1,5 @@
 [workspace]
+resolver = "2"
 members = [
     "srp",
     "spake2",

spake2/Cargo.toml

@@ -1,7 +1,6 @@
 [package]
 name = "spake2"
-version = "0.2.1-alpha.0"
-edition = "2018"
+version = "0.3.0-pre"
 authors = ["Brian Warner <[email protected]>"]
 description = "The SPAKE2 password-authenticated key-exchange algorithm."
 documentation = "https://docs.rs/spake2"
@@ -10,9 +9,10 @@ repository = "https://github.com/RustCrypto/PAKEs"
 license = "MIT OR Apache-2.0"
 keywords = ["crypto", "pake", "authentication"]
 categories = ["cryptography", "authentication"]
-exclude = [
-    ".gitignore"
-]
+exclude = [".gitignore"]
+readme = "README.md"
+edition = "2018"
+rust-version = "1.56"
 
 [package.metadata.release]
 tag-prefix = "spake2-v"

spake2/README.md

@@ -1,29 +1,115 @@
-# spake2.rs
-The SPAKE2 password-authenticated key-exchange algorithm, in Rust.
-
-[![Build Status][build-status-image]][build-status-url]
-[![Codecov][codecov-image]][codecov-url]
-[![Is-It-Maintained-Resolution-Time][iim-resolution-image]][iim-resolution-url]
-[![Is-It-Maintained-Open-Issues][iim-open-image]][iim-open-url]
-[![Crates.io][crates-io-image]][crates-io-url]
-[![Docs.rs][docs-image]][docs-url]
-[![License][license-image]][license-url]
-
-This is still pretty early, but seems to do the job. It needs a proper security review before you should consider using it for anything serious.
-
-Note that the API has changed since 0.0.8 . I released 0.0.9 by mistake.
-
-[build-status-image]: https://travis-ci.org/RustCrypto/PAKEs.svg?branch=master
-[build-status-url]: https://travis-ci.org/RustCrypto/PAKEs
-[codecov-image]: https://codecov.io/gh/RustCrypto/PAKEs/branch/master/graph/badge.svg
-[codecov-url]: https://codecov.io/gh/RustCrypto/PAKEs
-[crates-io-image]: https://img.shields.io/crates/v/spake2.svg
-[crates-io-url]: https://crates.io/crates/spake2
+# [RustCrypto]: SPAKE2
+
+[![crate][crate-image]][crate-link]
+[![Docs][docs-image]][docs-link]
+![Apache2/MIT licensed][license-image]
+![Rust Version][rustc-image]
+[![Project Chat][chat-image]][chat-link]
+[![Build Status][build-image]][build-link]
+
+Pure Rust implementation of the [SPAKE2] password-authenticated key-exchange algorithm.
+
+[Documentation][docs-link]
+
+## About
+
+This library implements the SPAKE2 password-authenticated key exchange
+("PAKE") algorithm. This allows two parties, who share a weak password, to
+safely derive a strong shared secret (and therefore build an
+encrypted+authenticated channel).
+
+A passive attacker who eavesdrops on the connection learns no information
+about the password or the generated secret. An active attacker
+(man-in-the-middle) gets exactly one guess at the password, and unless they
+get it right, they learn no information about the password or the generated
+secret. Each execution of the protocol enables one guess. The use of a weak
+password is made safer by the rate-limiting of guesses: no off-line
+dictionary attack is available to the network-level attacker, and the
+protocol does not depend upon having previously-established confidentiality
+of the network (unlike e.g. sending a plaintext password over TLS).
+
+The protocol requires the exchange of one pair of messages, so only one round
+trip is necessary to establish the session key. If key-confirmation is
+necessary, that will require a second round trip.
+
+All messages are bytestrings. For the default security level (using the
+Ed25519 elliptic curve, roughly equivalent to an 128-bit symmetric key), the
+message is 33 bytes long.
+
+This implementation is generic over a `Group`, which defines the cyclic
+group to use, the functions which convert group elements and scalars to
+and from bytestrings, and the three distinctive group elements used in
+the blinding process. Only one such Group is implemented, named
+`Ed25519Group`, which provides fast operations and high security, and is
+compatible with my [python implementation](https://github.com/warner/python-spake2).
+
+# What Is It Good For?
+
+PAKE can be used in a pairing protocol, like the initial version of Firefox
+Sync (the one with J-PAKE), to introduce one device to another and help them
+share secrets. In this mode, one device creates a random code, the user
+copies that code to the second device, then both devices use the code as a
+one-time password and run the PAKE protocol. Once both devices have a shared
+strong key, they can exchange other secrets safely.
+
+PAKE can also be used (carefully) in a login protocol, where SRP is perhaps
+the best-known approach. Traditional non-PAKE login consists of sending a
+plaintext password through a TLS-encrypted channel, to a server which then
+checks it (by hashing/stretching and comparing against a stored verifier). In
+a PAKE login, both sides put the password into their PAKE protocol, and then
+confirm that their generated key is the same. This nominally does not require
+the initial TLS-protected channel. However note that it requires other,
+deeper design considerations (the PAKE protocol must be bound to whatever
+protected channel you end up using, else the attacker can wait for PAKE to
+complete normally and then steal the channel), and is not simply a drop-in
+replacement. In addition, the server cannot hash/stretch the password very
+much (see the note on "Augmented PAKE" below), so unless the client is
+willing to perform key-stretching before running PAKE, the server's stored
+verifier will be vulnerable to a low-cost dictionary attack.
+
+## ⚠️ Security Warning
+
+This crate has never received an independent third party audit for security and
+correctness.
+
+USE AT YOUR OWN RISK!
+
+## Minimum Supported Rust Version
+
+Rust **1.56** or higher.
+
+Minimum supported Rust version can be changed in the future, but it will be
+done with a minor version bump.
+
+## License
+
+Licensed under either of:
+
+ * [Apache License, Version 2.0](http://www.apache.org/licenses/LICENSE-2.0)
+ * [MIT license](http://opensource.org/licenses/MIT)
+
+at your option.
+
+### Contribution
+
+Unless you explicitly state otherwise, any contribution intentionally submitted
+for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
+dual licensed as above, without any additional terms or conditions.
+
+[//]: # (badges)
+
+[crate-image]: https://img.shields.io/crates/v/spake2.svg
+[crate-link]: https://crates.io/crates/spake2
 [docs-image]: https://docs.rs/spake2/badge.svg
-[docs-url]: https://docs.rs/spake2
-[license-image]: https://img.shields.io/crates/l/spake2.svg
-[license-url]: LICENSE-MIT
-[iim-resolution-image]: http://isitmaintained.com/badge/resolution/RustCrypto/PAKEs.svg
-[iim-resolution-url]: http://isitmaintained.com/project/RustCrypto/PAKEs
-[iim-open-image]: http://isitmaintained.com/badge/open/RustCrypto/PAKEs.svg
-[iim-open-url]: http://isitmaintained.com/project/RustCrypto/PAKEs
+[docs-link]: https://docs.rs/spake2/
+[license-image]: https://img.shields.io/badge/license-Apache2.0/MIT-blue.svg
+[rustc-image]: https://img.shields.io/badge/rustc-1.56+-blue.svg
+[chat-image]: https://img.shields.io/badge/zulip-join_chat-blue.svg
+[chat-link]: https://rustcrypto.zulipchat.com/#narrow/stream/260045-PAKEs
+[build-image]: https://github.com/RustCrypto/PAKEs/actions/workflows/spake2.yml/badge.svg
+[build-link]: https://github.com/RustCrypto/PAKEs/actions/workflows/spake2.yml
+
+[//]: # (general links)
+
+[RustCrypto]: https://github.com/RustCrypto
+[SPAKE2]: https://tools.ietf.org/id/draft-irtf-cfrg-spake2-10.html