Make sha1 crate optional and a feature

.github/workflows/cargo.yml

@@ -35,6 +35,29 @@ jobs:
         with:
           command: test
 
+  rust-crypto:
+    strategy:
+      matrix:
+        os: [ubuntu-latest, macos-latest, windows-latest]
+        rust: [stable, beta, 1.65.0]
+
+    runs-on: ${{ matrix.os }}
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions-rs/toolchain@v1
+        with:
+          profile: minimal
+          toolchain: ${{ matrix.rust }}
+          override: true
+      - uses: Swatinem/rust-cache@v1
+      - uses: actions-rs/cargo@v1
+        with:
+          command: build
+      - uses: actions-rs/cargo@v1
+        with:
+          command: test --features sha1
+
   lint:
     runs-on: ubuntu-latest
     steps:

Cargo.toml

@@ -17,6 +17,7 @@ rust-version = "1.65"
 [features]
 default = ["openssl"]
 openssl = ["dep:openssl", "dep:openssl-sys", "dep:libc"]
+sha1 = ["dep:sha1"]
 _internal_dont_use_log_stats = []
 _internal_test_exports = []
 
@@ -38,14 +39,17 @@ hmac = "0.12.1"
 crc = "3.0.0"
 serde = { version = "1.0.152", features = ["derive"] }
 
+# The sha1 crate is disabled by default, and openssl is used. However, for potential 
+# performance improvements or if you prefer to use str0m without openssl, 
+# you can enable the sha1 feature flag.
 [target.'cfg(unix)'.dependencies]
-sha1 = { version = "0.10.6", features = ["asm"] }
+sha1 = { version = "0.10.6", features = ["asm"], optional = true }
 
 # Don't use `asm` on Windows until https://github.com/RustCrypto/asm-hashes/issues/45 is fixed.
 # The `asm` feature isn't compatible with `windows-msvc` toolchain and `openssl` breaks if we want to use `windows-gnu`.
 # Thus, don't use `asm` feature on Windows.
 [target.'cfg(windows)'.dependencies]
-sha1 = { version = "0.10.6" }
+sha1 = { version = "0.10.6" , optional = true}
 
 [dev-dependencies]
 rouille = { version = "3.5.0", features = ["ssl"] }

src/crypto/mod.rs

@@ -19,7 +19,13 @@ mod srtp;
 pub use srtp::{aead_aes_128_gcm, aes_128_cm_sha1_80, new_aead_aes_128_gcm};
 pub use srtp::{new_aes_128_cm_sha1_80, srtp_aes_128_ecb_round, SrtpProfile};
 
+/// Ensure that either `openssl` or `sha1` feature is enabled.
+#[cfg(not(any(feature = "openssl", feature = "sha1")))]
+compile_error!("Either feature \"openssl\" or \"sha1\" must be enabled for HMAC functionality.");
+
 /// SHA1 HMAC as used for STUN and older SRTP.
+/// If sha1 feature is enabled, it uses `rust-crypto` crate.
+#[cfg(feature = "sha1")]
 pub fn sha1_hmac(key: &[u8], payloads: &[&[u8]]) -> [u8; 20] {
     use hmac::Hmac;
     use hmac::Mac;
@@ -34,6 +40,26 @@ pub fn sha1_hmac(key: &[u8], payloads: &[&[u8]]) -> [u8; 20] {
     hmac.finalize().into_bytes().into()
 }
 
+/// SHA1 HMAC as used for STUN and older SRTP.
+/// If openssl is enabled and sha1 is not, it uses `openssl` crate.
+#[cfg(all(feature = "openssl", not(feature = "sha1")))]
+pub fn sha1_hmac(key: &[u8], payloads: &[&[u8]]) -> [u8; 20] {
+    use openssl::hash::MessageDigest;
+    use openssl::pkey::PKey;
+    use openssl::sign::Signer;
+
+    let key = PKey::hmac(key).expect("valid hmac key");
+    let mut signer = Signer::new(MessageDigest::sha1(), &key).expect("valid signer");
+
+    for payload in payloads {
+        signer.update(payload).expect("signer update");
+    }
+
+    let mut hash = [0u8; 20];
+    signer.sign(&mut hash).expect("sign to array");
+    hash
+}
+
 /// Errors that can arise in DTLS.
 #[derive(Debug, Error)]
 pub enum CryptoError {