diff --git a/openssl_alloc.hpp b/openssl_alloc.hpp
new file mode 100644
index 0000000..90569bf
--- /dev/null
+++ b/openssl_alloc.hpp
@@ -0,0 +1,15 @@
+#pragma once
+
+// With OpenSSL 1.1.0, some functions were deprecated. Need to abstract them
+// to make the code backward compatible with older OpenSSL veresions.
+// Reference: https://wiki.openssl.org/index.php/OpenSSL_1.1.0_Changes
+#if OPENSSL_VERSION_NUMBER < 0x10100000L
+
+#include <openssl/evp.h>
+
+extern "C" {
+EVP_MD_CTX* EVP_MD_CTX_new(void);
+void EVP_MD_CTX_free(EVP_MD_CTX* ctx);
+}
+
+#endif // OPENSSL_VERSION_NUMBER < 0x10100000L