diff --git a/src/addon/validation.cpp b/src/addon/validation.cpp
index a32d3250aad9..6761556deb79 100644
--- a/src/addon/validation.cpp
+++ b/src/addon/validation.cpp
@@ -16,6 +16,7 @@
 #include "addon/validation.hpp"
 #include "config.hpp"
 #include "serialization/unicode_cast.hpp"
+#include "hash.hpp"
 
 #include <algorithm>
 #include <array>
@@ -305,3 +306,66 @@ std::string unencode_binary(const std::string& str)
 	res.resize(n);
 	return res;
 }
+
+static const std::string file_hash_raw(const config& file)
+{
+	return utils::md5(file["contents"].str()).base64_digest();
+}
+
+const std::string file_hash(const config& file)
+{
+	std::string hash = file["hash"].str();
+	if(hash.empty()) {
+		hash = file_hash_raw(file);
+	}
+	return hash;
+}
+
+bool comp_file_hash(const config& file_a, const config& file_b)
+{
+	return file_hash(file_a) == file_hash(file_b);
+}
+
+void write_hashlist(config& hashlist, const config& data)
+{
+	hashlist["name"] = data["name"];
+
+	for(const config& f : data.child_range("file")) {
+		config& file = hashlist.add_child("file");
+		file["name"] = f["name"];
+		file["hash"] = file_hash_raw(f);
+	}
+
+	for(const config& d : data.child_range("dir")) {
+		config& dir = hashlist.add_child("dir");
+		write_hashlist(dir, d);
+	}
+}
+
+bool contains_hashlist(const config& from, const config& to)
+{
+	for(const config& f : to.child_range("file")) {
+		bool found = false;
+		for(const config& d : from.child_range("file")) {
+			found |= comp_file_hash(f, d);
+			if(found)
+				break;
+		}
+		if(!found) {
+			return false;
+		}
+	}
+
+	for(const config& d : to.child_range("dir")) {
+		const config& origin_dir = from.find_child("dir", "name", d["name"]);
+		if(origin_dir) {
+			return contains_hashlist(origin_dir, d);
+		} else {
+			// The case of empty new subdirectories
+			const config dummy_dir = config("name", d["name"]);
+			return contains_hashlist(dummy_dir, d);
+		}
+	}
+
+	return true;
+}
diff --git a/src/addon/validation.hpp b/src/addon/validation.hpp
index 5a476bf5e7fc..577f93778dca 100644
--- a/src/addon/validation.hpp
+++ b/src/addon/validation.hpp
@@ -96,3 +96,8 @@ bool check_case_insensitive_duplicates(const config& dir, std::vector<std::strin
 std::string encode_binary(const std::string& str);
 std::string unencode_binary(const std::string& str);
 bool needs_escaping(char c);
+
+const std::string file_hash(const config& file);
+bool comp_file_hash(const config& file_a, const config& file_b);
+void write_hashlist(config& hashlist, const config& data);
+bool contains_hashlist(const config& from, const config& to);
diff --git a/src/server/campaignd/addon_utils.cpp b/src/server/campaignd/addon_utils.cpp
index d92a38bb7dcb..a3bf34195c15 100644
--- a/src/server/campaignd/addon_utils.cpp
+++ b/src/server/campaignd/addon_utils.cpp
@@ -20,7 +20,7 @@
 #include "game_config.hpp"
 #include "log.hpp"
 #include "serialization/string_utils.hpp"
-#include "hash.hpp"
+#include "addon/validation.hpp"
 
 #include <boost/algorithm/string.hpp>
 
@@ -153,20 +153,6 @@ void add_license(config& cfg)
 	copying["contents"] = contents;
 }
 
-static const std::string file_hash(const config& file)
-{
-	std::string hash = file["hash"].str();
-	if(hash.empty()) {
-		hash = utils::md5(file["contents"].str()).base64_digest();
-	}
-	return hash;
-}
-
-static bool comp_file_hash(const config& file_a, const config& file_b)
-{
-	return file_hash(file_a) == file_hash(file_b);
-}
-
 //! Surround with [dir][/dir]
 static void write_difference(config& pack, const config& from, const config& to, bool with_content)
 {
diff --git a/src/server/campaignd/server.cpp b/src/server/campaignd/server.cpp
index a15c3654a821..77106ecf0965 100644
--- a/src/server/campaignd/server.cpp
+++ b/src/server/campaignd/server.cpp
@@ -275,6 +275,14 @@ void server::load_config()
 				writer.write(data);
 				campaign_file.commit();
 			}
+			{
+				filesystem::atomic_commit campaign_hash_file(addon_file + version_cfg["filename"].str() + ".hash");
+				config_writer writer(*campaign_hash_file.ostream(), true, compress_level_);
+				config data_hash = config("name", "");
+				write_hashlist(data_hash, data);
+				writer.write(data_hash);
+				campaign_hash_file.commit();
+			}
 
 			addons_.emplace(addon_id, campaign);
 			dirty_addons_.emplace(addon_id);
@@ -1073,7 +1081,6 @@ void server::handle_upload(const server::request& req)
 		add_license(data);
 		
 		const std::string& new_version = (*campaign)["version"].str();
-		//#TODO: probably make hash from new_version + required_wesnoth_version ?
 		const std::string& file_hash = utils::md5(new_version).hex_digest();
 
 		//sorted version map
@@ -1099,6 +1106,15 @@ void server::handle_upload(const server::request& req)
 			writer.write(data);
 			campaign_file.commit();
 		}
+		// Let's write its hashes
+		{
+			filesystem::atomic_commit campaign_hash_file(filename + version_cfg["filename"].str() + ".hash");
+			config_writer writer(*campaign_hash_file.ostream(), true, compress_level_);
+			config data_hash = config("name", "");
+			write_hashlist(data_hash, data);
+			writer.write(data_hash);
+			campaign_hash_file.commit();
+		}
 
 		(*campaign)["size"] = filesystem::file_size(filename + version_cfg["filename"].str());