1 files changed, 31 insertions, 9 deletions
diff --git a/src/include/ipxe/hmac.h b/src/include/ipxe/hmac.h
index 09d3e273d..cf9d08677 100644
--- a/src/include/ipxe/hmac.h
+++ b/src/include/ipxe/hmac.h
@@ -10,23 +10,45 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 
 #include <ipxe/crypto.h>
 
+/** HMAC context type */
+#define hmac_context_t( digest ) struct {				\
+		/** Digest context */					\
+		uint8_t ctx[ digest->ctxsize ];				\
+		/** HMAC input/output padding */			\
+		uint8_t pad[ digest->blocksize ];			\
+	} __attribute__ (( packed ))
+
+/**
+ * Calculate HMAC context size
+ *
+ * @v digest		Digest algorithm to use
+ * @ret len		HMAC context size
+ */
+static inline __attribute__ (( always_inline )) size_t
+hmac_ctxsize ( struct digest_algorithm *digest ) {
+	hmac_context_t ( digest ) *hctx;
+
+	return sizeof ( *hctx );
+}
+
 /**
  * Update HMAC
  *
  * @v digest		Digest algorithm to use
- * @v digest_ctx	Digest context
+ * @v ctx		HMAC context
  * @v data		Data
  * @v len		Length of data
  */
-static inline void hmac_update ( struct digest_algorithm *digest,
-				 void *digest_ctx, const void *data,
-				 size_t len ) {
-	digest_update ( digest, digest_ctx, data, len );
+static inline void hmac_update ( struct digest_algorithm *digest, void *ctx,
+				 const void *data, size_t len ) {
+	hmac_context_t ( digest ) *hctx = ctx;
+
+	digest_update ( digest, hctx->ctx, data, len );
 }
 
-extern void hmac_init ( struct digest_algorithm *digest, void *digest_ctx,
-			void *key, size_t *key_len );
-extern void hmac_final ( struct digest_algorithm *digest, void *digest_ctx,
-			 void *key, size_t *key_len, void *hmac );
+extern void hmac_init ( struct digest_algorithm *digest, void *ctx,
+			const void *key, size_t key_len );
+extern void hmac_final ( struct digest_algorithm *digest, void *ctx,
+			 void *hmac );
 
 #endif /* _IPXE_HMAC_H */