aead: Add a safety comment

briansmith · Sep 30, 2023 · d7b8b61 · d7b8b61
1 parent e3e27e5
commit d7b8b61
Showing 1 changed file with 6 additions and 0 deletions.
diff --git a/src/aead/gcm.rs b/src/aead/gcm.rs
@@ -125,6 +125,12 @@ impl Context {
         debug_assert!(input_bytes > 0);
 
         let input = input.as_ptr() as *const [u8; BLOCK_LEN];
+        // SAFETY:
+        // - `[[u8; BLOCK_LEN]]` has the same bit validity as `[u8]`.
+        // - `[[u8; BLOCK_LEN]]` has the same alignment requirement as `[u8]`.
+        // - `input_bytes / BLOCK_LEN` ensures that the total length in bytes of
+        //   the new `[[u8; BLOCK_LEN]]` will not be longer than the original
+        //   `[u8]`.
         let input = unsafe { core::slice::from_raw_parts(input, input_bytes / BLOCK_LEN) };
 
         let xi = &mut self.inner.Xi;