Add SHA-256 to proto, wrapping the emsha crate

Implemented-By: Laguna S 2.1 (OpenCode)

crates/proto/src/hash.rs

@@ -0,0 +1,43 @@
+use crate::Hash32;
+use emsha::Hash as _;
+
+#[derive(Debug, Clone, Copy, PartialEq, Eq)]
+pub struct HashError;
+
+impl std::fmt::Display for HashError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, "sha256 error")
+    }
+}
+
+impl std::error::Error for HashError {}
+
+pub struct Sha256(emsha::sha256::SHA256);
+
+impl Sha256 {
+    pub fn new() -> Self {
+        Sha256(emsha::sha256::SHA256::new())
+    }
+
+    pub fn update(&mut self, data: &[u8]) -> Result<(), HashError> {
+        self.0.update(data).map_err(|_| HashError)
+    }
+
+    pub fn finish(mut self) -> Result<Hash32, HashError> {
+        let mut out = [0u8; emsha::sha256::SIZE];
+        self.0.finalize(&mut out).map_err(|_| HashError)?;
+        Ok(Hash32::from_bytes(out))
+    }
+}
+
+impl Default for Sha256 {
+    fn default() -> Self {
+        Self::new()
+    }
+}
+
+pub fn sha256(data: &[u8]) -> Result<Hash32, HashError> {
+    let mut h = Sha256::new();
+    h.update(data)?;
+    h.finish()
+}

crates/proto/src/lib.rs

@@ -4,6 +4,7 @@ pub mod audit;
 pub mod class;
 pub mod frame;
 pub mod grant;
+pub mod hash;
 pub mod ids;
 pub mod log;
 pub mod wire;
@@ -12,6 +13,7 @@ pub use audit::{AuditRecord, DecisionRecord};
 pub use class::DataClass;
 pub use frame::{FrameError, MAX_FRAME, read_frame, write_frame};
 pub use grant::{Constraints, Grant, Mode};
+pub use hash::{HashError, Sha256, sha256};
 pub use ids::{CallId, Epoch, Hash32, SessionId, Timestamp, ValueError};
 pub use log::{LogRecord, ToolCall};
 pub use wire::{