Verify downloaded file against content-md5 response header

wxdata/include/scwx/util/digest.hpp

@@ -0,0 +1,18 @@
+#pragma once
+
+#include <istream>
+#include <vector>
+
+#include <openssl/evp.h>
+
+namespace scwx
+{
+namespace util
+{
+
+bool ComputeDigest(const EVP_MD*              mdtype,
+                   std::istream&              is,
+                   std::vector<std::uint8_t>& digest);
+
+} // namespace util
+} // namespace scwx