Migrate checking if a hash is supported to Rust

src/cryptography/hazmat/backends/openssl/backend.py

@@ -101,23 +101,11 @@ def openssl_version_text(self) -> str:
     def openssl_version_number(self) -> int:
         return rust_openssl.openssl_version()
 
-    def _evp_md_from_algorithm(self, algorithm: hashes.HashAlgorithm):
-        if algorithm.name in ("blake2b", "blake2s"):
-            alg = f"{algorithm.name}{algorithm.digest_size * 8}".encode(
-                "ascii"
-            )
-        else:
-            alg = algorithm.name.encode("ascii")
-
-        evp_md = self._lib.EVP_get_digestbyname(alg)
-        return evp_md
-
     def hash_supported(self, algorithm: hashes.HashAlgorithm) -> bool:
         if self._fips_enabled and not isinstance(algorithm, self._fips_hashes):
             return False
 
-        evp_md = self._evp_md_from_algorithm(algorithm)
-        return evp_md != self._ffi.NULL
+        return rust_openssl.hashes.hash_supported(algorithm)
 
     def signature_hash_supported(
         self, algorithm: hashes.HashAlgorithm

src/cryptography/hazmat/bindings/_rust/openssl/hashes.pyi

@@ -15,3 +15,5 @@ class Hash(hashes.HashContext):
     def update(self, data: bytes) -> None: ...
     def finalize(self) -> bytes: ...
     def copy(self) -> Hash: ...
+
+def hash_supported(algorithm: hashes.HashAlgorithm) -> bool: ...

src/rust/src/backend/hashes.rs

@@ -72,6 +72,11 @@ pub(crate) fn message_digest_from_algorithm(
     }
 }
 
+#[pyo3::pyfunction]
+fn hash_supported(py: pyo3::Python<'_>, algorithm: pyo3::Bound<'_, pyo3::PyAny>) -> bool {
+    message_digest_from_algorithm(py, &algorithm).is_ok()
+}
+
 impl Hash {
     pub(crate) fn update_bytes(&mut self, data: &[u8]) -> CryptographyResult<()> {
         self.get_mut_ctx()?.update(data)?;
@@ -141,5 +146,5 @@ impl Hash {
 #[pyo3::pymodule]
 pub(crate) mod hashes {
     #[pymodule_export]
-    use super::Hash;
+    use super::{hash_supported, Hash};
 }