Add no_std support

.github/workflows/rust.yml

@@ -27,6 +27,18 @@ jobs:
         cache-on-failure: "true"
     - name: Build all-features
       run: cargo build -p givre --all-features
+  build-wasm-nostd:
+    runs-on: ubuntu-latest
+    steps:
+    - uses: actions/checkout@v3
+    - uses: Swatinem/rust-cache@v2
+      with:
+        cache-on-failure: "true"
+    - name: Install wasm32-unknown-unknown toolchain
+      run: rustup target add wasm32-unknown-unknown
+    - name: Build on wasm32-unknown-unknown (no_std)
+      run:
+        (cd wasm/no_std && cargo build --target wasm32-unknown-unknown)
   test:
     runs-on: ubuntu-latest
     steps:

.gitignore

@@ -1,3 +1,4 @@
 /target
+/wasm/no_std/target
 
 /.helix

Cargo.toml

@@ -4,3 +4,11 @@ members = [
   "givre",
   "tests",
 ]
+
+exclude = [
+  "wasm/no_std",
+]
+
+[patch.crates-io.key-share]
+git = "https://github.com/dfns/cggmp21"
+branch = "no_std"

givre/Cargo.toml

@@ -7,7 +7,7 @@ edition = "2021"
 
 [dependencies]
 cggmp21-keygen = { version = "0.1", optional = true }
-key-share = "0.2"
+key-share = { version = "0.2", default-features = false }
 
 generic-ec = { version = "0.2", default-features = false }
 
@@ -27,6 +27,10 @@ serde = { version = "1", default-features = false, features = ["derive"], option
 rand_core = { version = "0.6", default-features = false, features = ["getrandom"] }
 
 [features]
+default = ["std"]
+
+std = ["key-share/std"]
+
 cggmp21-keygen = ["dep:cggmp21-keygen"]
 full-signing = ["round-based", "futures"]
 
@@ -45,3 +49,4 @@ all-ciphersuites = ["ciphersuite-secp256k1", "ciphersuite-ed25519", "ciphersuite
 ciphersuite-secp256k1 = ["generic-ec/curve-secp256k1", "k256", "sha2", "static_assertions"]
 ciphersuite-ed25519 = ["generic-ec/curve-ed25519", "sha2"]
 ciphersuite-bitcoin = ["ciphersuite-secp256k1"]
+

givre/src/ciphersuite.rs

@@ -6,6 +6,9 @@
 //! * [Secp256k1], requires `ciphersuite-secp256k1` feature
 //! * [Ed25519], requires `ciphersuite-ed25519` feature
 //! * [Bitcoin], requires `ciphersuite-bitcoin` feature
+
+use alloc::vec::Vec;
+
 use generic_ec::{
     errors::{InvalidPoint, InvalidScalar},
     Curve, NonZero, Point, Scalar, SecretScalar,

givre/src/ciphersuite/bitcoin.rs

@@ -84,6 +84,7 @@ impl Ciphersuite for Bitcoin {
     }
 }
 
+#[cfg(feature = "std")]
 fn challenge_hash() -> sha2::Sha256 {
     static PRECOMPUTED: std::sync::OnceLock<sha2::Sha256> = std::sync::OnceLock::new();
     PRECOMPUTED
@@ -93,3 +94,8 @@ fn challenge_hash() -> sha2::Sha256 {
         })
         .clone()
 }
+#[cfg(not(feature = "std"))]
+fn challenge_hash() -> sha2::Sha256 {
+    let tag = sha2::Sha256::digest("BIP0340/challenge");
+    sha2::Sha256::new().chain_update(&tag).chain_update(&tag)
+}

givre/src/lib.rs

@@ -25,6 +25,9 @@
 #![deny(missing_docs)]
 #![allow(clippy::type_complexity)]
 #![cfg_attr(docsrs, feature(doc_auto_cfg))]
+#![cfg_attr(not(feature = "std"), no_std)]
+
+extern crate alloc;
 
 pub use generic_ec;
 #[cfg(feature = "full-signing")]

givre/src/signing/aggregate.rs

@@ -6,6 +6,7 @@
 //!
 //! [Section 5.3]: https://www.ietf.org/archive/id/draft-irtf-cfrg-frost-15.html#name-signature-share-aggregation
 
+use alloc::vec::Vec;
 use core::fmt;
 
 use generic_ec::{NonZero, Point, Scalar};
@@ -125,6 +126,7 @@ impl fmt::Display for AggregateError {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for AggregateError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match &self.0 {
@@ -143,4 +145,5 @@ impl fmt::Display for InvalidSignature {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for InvalidSignature {}

givre/src/signing/round2.rs

@@ -6,6 +6,7 @@
 //!
 //! [Section 5.2]: https://www.ietf.org/archive/id/draft-irtf-cfrg-frost-15.html#name-round-two-signature-share-g
 
+use alloc::vec::Vec;
 use core::{fmt, iter};
 
 use generic_ec::{Curve, NonZero, Scalar};
@@ -239,6 +240,7 @@ impl fmt::Display for Bug {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for SigningError {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match &self.0 {
@@ -254,6 +256,7 @@ impl std::error::Error for SigningError {
     }
 }
 
+#[cfg(feature = "std")]
 impl std::error::Error for Bug {
     fn source(&self) -> Option<&(dyn std::error::Error + 'static)> {
         match self {

givre/src/signing/utils.rs

@@ -1,3 +1,5 @@
+use alloc::vec::Vec;
+
 use digest::{FixedOutput, Update};
 use generic_ec::{Curve, NonZero, Point, Scalar};