--- /dev/null
+/*
+ * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved.
+ *
+ * Licensed under the Apache License 2.0 (the "License"). You may not use
+ * this file except in compliance with the License. You can obtain a copy
+ * in the file LICENSE in the source distribution or at
+ * https://www.openssl.org/source/license.html
+ */
+
+#ifndef HEADER_HMAC_LCL_H
+# define HEADER_HMAC_LCL_H
+
+/* The current largest case is for SHA3-224 */
+#define HMAC_MAX_MD_CBLOCK_SIZE 144
+
+struct hmac_ctx_st {
+ const EVP_MD *md;
+ EVP_MD_CTX *md_ctx;
+ EVP_MD_CTX *i_ctx;
+ EVP_MD_CTX *o_ctx;
+ unsigned int key_length;
+ unsigned char key[HMAC_MAX_MD_CBLOCK_SIZE];
+};
+
+#endif