[sw/lib] Add sha256 wrapper
Add hw_SHA256 API matching the embedded cryptoc interface available in
sw/vendor/cryptoc. The API is implemented on top of the HMAC library.
Rename the sanity_hmac/sanity_hmac test as hmac/sha256_test to better
reflect the purpose of the code module.
diff --git a/sw/lib/hw_sha256.h b/sw/lib/hw_sha256.h
new file mode 100644
index 0000000..178fc49
--- /dev/null
+++ b/sw/lib/hw_sha256.h
@@ -0,0 +1,51 @@
+// Copyright lowRISC contributors.
+// Licensed under the Apache License, Version 2.0, see LICENSE for details.
+// SPDX-License-Identifier: Apache-2.0
+
+#ifndef _F_LIB_SHA256_H__
+#define _F_LIB_SHA256_H__
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include "cryptoc/hash-internal.h"
+
+typedef HASH_CTX HW_SHA256_CTX;
+
+#define SHA256_DIGEST_SIZE 32
+
+/**
+ * hw_SHA256_init initializes |ctx|.
+ *
+ * @param ctx SHA256 context.
+ */
+void hw_SHA256_init(HW_SHA256_CTX *ctx);
+
+/**
+ * hw_SHA256_update adds |len| bytes from |data| to |ctx|.
+ *
+ * @param ctx SHA256 context.
+ * @param data Input buffer.
+ * @param len Number of bytes to add.
+ */
+void hw_SHA256_update(HW_SHA256_CTX *ctx, const void *data, size_t len);
+
+/**
+ * hw_SHA256_final adds the final padding to |ctx| and calculates digest.
+ *
+ * @param ctx SHA256 context.
+ *
+ * @return pointer to digest buffer held in |ctx|.
+ */
+const uint8_t *hw_SHA256_final(HW_SHA256_CTX *ctx);
+
+/**
+ * hw_SHA256_hash writes |digest| from |len| bytes of |data|.
+ *
+ * @param data Input buffer.
+ * @param len Number of bytes to add.
+ * @param digest Output buffer.
+ */
+const uint8_t *hw_SHA256_hash(const void *data, size_t len, uint8_t *digest);
+
+#endif // _F_LIB_SHA256_H__
