feat: crypto library feature handling

Making ring the default feature. `openssl` and `ring` are now mutually exclusive.
The `wasm-bindgen` feature is not needed, we can activate the needed `ring` feature by setting it target dependent.

Author: TobTheRock

Cargo.toml

@@ -1,14 +1,15 @@
 [package]
-name = "sframe"
-version = "0.2.0"
 edition = "2021"
 license = "MIT/Apache-2.0"
+name = "sframe"
+version = "0.2.0"
 
 authors = [
   "Tobias Waurick <[email protected]>",
   "Hendrik Sollich <[email protected]>",
   "Richard Haehne <[email protected]>",
 ]
+
 description = "pure rust implementation of SFrame draft-ietf-sframe-enc-01"
 repository = "https://github.com/goto-opensource/sframe-rs"
 documentation = "https://docs.rs/sframe/"
@@ -26,29 +27,30 @@ thiserror = "1.0"
 version = "0.16"
 optional = true
 
+[target.'cfg(target_arch = "wasm32")'.dependencies]
+ring = { version = "0.16", features = ["wasm32_c"], optional = true }
+
 [dependencies.openssl]
 version = "0.10"
+features = ["vendored"]
 optional = true
 
 [dev-dependencies]
-criterion = { version= "0.4", features=["html_reports"] }
+criterion = { version = "0.4", features = ["html_reports"] }
 hex = "0.4"
+lazy_static = "1.4.0"
+phf = { version = "0.11", features = ["macros"] }
 pretty_assertions = "1.3"
 rand = "0.8"
-serde_json = "1.0"
 serde = { version = "1.0", features = ["derive"] }
-lazy_static = "1.4.0"
+serde_json = "1.0"
 strum_macros = "0.24"
-phf = { version = "0.11", features = ["macros"] }
-
 
 [features]
-# default = ["ring"]
-default = ["openssl"]
+default = ["ring"]
 openssl = ["dep:openssl"]
 ring = ["dep:ring"]
-wasm-bindgen = ["ring", "ring/wasm32_c"]
 
 [[bench]]
 name = "bench_main"
-harness = false
+harness = false

README.md

@@ -17,6 +17,18 @@ There is an alternative implementation under [goto-opensource/secure-frame-ts](h
 * ratcheting is not implemented
 * keyIds are used as senderIds
 
+## Supported crypto libraries
+Currently two crypto libraries are supported:
+- [ring](https://crates.io/crates/ring) 
+    - is enabled per default with the feature `ring`
+    - supports compilation to Wasm32
+- [openssl](https://crates.io/crates/openssl)
+    - is enabled with the feature `openssl`
+        - To build e.g. use `cargo build --features openssl --no-default-features`
+    - uses rust bindings to OpenSSL.
+    - Per default the OpenSSL library is locally compiled and then statically linked. The build process requires a C compiler, `perl` (and `perl-core`), and `make`. For further options see the [openssl crate documentation](https://docs.rs/openssl/0.10.55/openssl/). 
+    - Compilation to Wasm32 is [not yet supported](https://github.com/sfackler/rust-openssl/issues/1016)
+
 
 ## License
 Licensed under either of Apache License, Version 2.0 or MIT license at your option.

src/crypto/mod.rs

@@ -7,14 +7,13 @@ pub mod key_expansion;
 pub mod secret;
 
 cfg_if::cfg_if! {
-if #[cfg(all(feature = "openssl", feature = "wasm-bindgen"))]{
-    // TODO issue a warning
-    // compile_error!{"Cannot use openssl with wasm-bindgen. Falling back to ring."};
+if #[cfg(all(not(feature = "openssl"), feature = "ring"))]{
     mod ring;
 }
 else if #[cfg(all(feature = "openssl", not(feature = "ring")))] {
     mod openssl;
 } else {
+    // fallback to ring
     mod ring;
 }
 }

src/lib.rs

@@ -4,6 +4,17 @@
 //! This library is an implementation of [draft-ietf-sframe-enc-latest](https://sframe-wg.github.io/sframe/draft-ietf-sframe-enc.html).
 //!
 //! It is in it's current form a subset of the specification (e.g. Aes-CTR is not implemented).
+//!
+//! # Optional features
+//!
+//! Using optional features `sframe` allows to configure different crypto libraries.
+//! Be aware that those features are mutually exlusive, if multiple `sframe` falls back to using `ring`.
+//!
+//! - **`ring`** *(enabled by default)* — Uses the [ring](https://crates.io/crates/ring) library which allows compilation to Wasm32.
+//! - **`openssl`** — Uses the [rust-openssl](https://crates.io/crates/openssl) crate, which provides bindings to OpenSSL.
+//! Per default the OpenSSL library is locally compiled and then statically linked. The build process requires a C compiler,
+//! `perl` (and `perl-core`), and `make`. For further options see the [openssl crate documentation](https://docs.rs/openssl/0.10.55/openssl/).
+//! Compilation to Wasm32 is not yet supported.
 
 #![deny(clippy::missing_panics_doc)]
 #![deny(