Index: binaries/data/config/default.cfg
===================================================================
--- binaries/data/config/default.cfg
+++ binaries/data/config/default.cfg
@@ -397,6 +397,11 @@
 [mod]
 enabledmods = "mod public"
 
+[modio.v1]
+baseurl = "https://api.test.mod.io/v1"
+api_key = "acf8fc07e3a8e9228ef4d5704c1659a1"
+name_id = "0ad"
+
 [network]
 duplicateplayernames = false      ; Rename joining player to "User (2)" if "User" is already connected, otherwise prohibit join.
 lateobservers = everyone          ; Allow observers to join the game after it started. Possible values: everyone, buddies, disabled.
Index: binaries/data/mods/mod/gui/modmod/modio.js
===================================================================
--- /dev/null
+++ binaries/data/mods/mod/gui/modmod/modio.js
@@ -0,0 +1,64 @@
+let g_Mods = [];
+
+function init()
+{
+	g_Mods = Engine.ModIoGetMods();
+
+	warn(uneval(g_Mods));
+
+	generateModsList(g_Mods);
+}
+
+function generateModsList(mods)
+{
+	var [keys, names, name_ids, versions, filesizes, filehash_md5s, downloads] = [[],[],[],[],[],[],[],[]];
+
+	let i = 0;
+	for (let mod of mods)
+	{
+		keys.push(i++);
+		names.push(mod.name);
+		name_ids.push(mod.name_id);
+		versions.push(mod.version);
+		filesizes.push(mod.filesize);
+		filehash_md5s.push(mod.filehash_md5);
+		downloads.push(mod.binary_url);
+	}
+
+	var obj = Engine.GetGUIObjectByName("modsAvailableList");
+	obj.list_name = names;
+	obj.list_modVersion = versions;
+	obj.list_modname_id = name_ids;
+	obj.list_modfilesize = filesizes;
+	obj.list_modfilehash_md5 = filehash_md5s;
+	obj.list_moddownload = downloads;
+
+	obj.list = keys;
+}
+
+function showModDescription()
+{
+	let listObject = Engine.GetGUIObjectByName("modsAvailableList");
+	let desc = "No mod has been selected.";
+	if (listObject.selected != -1)
+		desc = g_Mods[listObject.selected].summary;
+
+	Engine.GetGUIObjectByName("globalModDescription").caption = desc;
+}
+
+function downloadMod()
+{
+	let listObject = Engine.GetGUIObjectByName("modsAvailableList");
+	if (listObject.selected == -1)
+	{
+		warn("Select something first.");
+		return;
+	}
+
+	Engine.ModIoDownloadMod(listObject.selected);
+}
+
+function closePage()
+{
+	Engine.SwitchGuiPage("page_pregame.xml", {});
+}
Index: binaries/data/mods/mod/gui/modmod/modio.xml
===================================================================
--- /dev/null
+++ binaries/data/mods/mod/gui/modmod/modio.xml
@@ -0,0 +1,78 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<objects>
+	<script file="gui/modmod/modio.js"/>
+
+	<object name="modmod" type="image" style="ModernWindow" size="0 0 100% 100%">
+		<!-- Page Title -->
+		<object style="ModernLabelText" type="text" size="50%-128 4 50%+128 36">
+			<translatableAttribute id="caption">mod.io mods</translatableAttribute>
+		</object>
+
+		<!-- Message -->
+		<object name="message" type="text" size="15 40 100%-15 88" text_align="left" textcolor="white"/>
+
+		<!-- Available Mods Wrapper -->
+		<object name="modsAvailable" size="16 100 100%-15 75%-4" style="ModmodScrollbar">
+			<object style="ModernLabelText" type="text" size="0 5 100% 25">
+				<translatableAttribute id="caption">Available Mods</translatableAttribute>
+			</object>
+
+			<object name="modsAvailableList"
+				style="ModernList"
+				type="olist"
+				size="0 25 100%-2 100%"
+				font="sans-stroke-13"
+			>
+				<action on="SelectionChange">showModDescription();</action>
+				<!-- List headers -->
+				<column id="name" color="255 255 255" width="10%">
+					<translatableAttribute id="heading">Name</translatableAttribute>
+				</column>
+				<column id="modVersion" color="255 255 255" width="7%">
+					<translatableAttribute id="heading">Version</translatableAttribute>
+				</column>
+				<column id="modname_id" color="255 255 255" width="13%">
+					<translatableAttribute id="heading">(nameid)</translatableAttribute>
+				</column>
+				<column id="modfilesize" color="255 255 255" width="12%">
+					<translatableAttribute id="heading">filesize</translatableAttribute>
+				</column>
+				<column id="modfilehash_md5" color="255 255 255" width="20%">
+					<translatableAttribute id="heading">filehash_md5</translatableAttribute>
+				</column>
+				<column id="moddownload" color="255 255 255" width="24%">
+					<translatableAttribute id="heading">download</translatableAttribute>
+				</column>
+			</object>
+			<object name="globalModDescription" type="text" style="ModmodScrollbar" size="0 100%-28 100%-16 100%">
+				<attribute id="caption"><keep>[color="100 100 100"]</keep><translate>Description</translate><keep>[/color]</keep></attribute>
+			</object>
+			<object type="button" style="ModernButtonRed" size="100%-184 100%-28 100% 100%">
+				<translatableAttribute id="caption">Download</translatableAttribute>
+				<action on="Press">downloadMod();</action>
+			</object>
+		</object>
+
+		<!-- BUTTONS -->
+		<object type="button" style="ModernButtonRed" size="16 100%-44 200 100%-16">
+			<translatableAttribute id="caption">Back</translatableAttribute>
+			<action on="Press">Engine.SwitchGuiPage("page_modmod.xml");</action>
+		</object>
+
+		<object type="button" style="ModernButtonRed" size="100%-576 100%-44 100%-392 100%-16" hotkey="cancel">
+			<translatableAttribute id="caption">Print raw</translatableAttribute>
+			<action on="Press">warn(uneval(Engine.ModIoGetMods()));</action>
+		</object>
+
+		<object name="saveConfigurationButton" type="button" style="ModernButtonRed" size="100%-388 100%-44 100%-204 100%-16">
+			<translatableAttribute id="caption">Save Configuration</translatableAttribute>
+			<action on="Press">warn("No");</action>
+		</object>
+
+		<object name="startModsButton" type="button" style="ModernButtonRed" size="100%-200 100%-44 100%-16 100%-16">
+			<translatableAttribute id="caption">Start Mods</translatableAttribute>
+			<action on="Press">warn("Maybe");</action>
+		</object>
+	</object>
+</objects>
Index: binaries/data/mods/mod/gui/modmod/modmod.xml
===================================================================
--- binaries/data/mods/mod/gui/modmod/modmod.xml
+++ binaries/data/mods/mod/gui/modmod/modmod.xml
@@ -193,8 +193,8 @@
 		</object>
 
 		<object type="button" style="ModernButtonRed" size="100%-576 100%-44 100%-392 100%-16" hotkey="cancel">
-			<translatableAttribute id="caption">Cancel</translatableAttribute>
-			<action on="Press">closePage();</action>
+			<translatableAttribute id="caption">mod.io test</translatableAttribute>
+			<action on="Press">Engine.SwitchGuiPage("page_modio.xml");</action>
 		</object>
 
 		<object name="saveConfigurationButton" type="button" style="ModernButtonRed" size="100%-388 100%-44 100%-204 100%-16">
Index: binaries/data/mods/mod/gui/page_modio.xml
===================================================================
--- /dev/null
+++ binaries/data/mods/mod/gui/page_modio.xml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="utf-8"?>
+<page>
+	<include>common/modern/setup.xml</include>
+	<include>common/modern/styles.xml</include>
+	<include>common/modern/sprites.xml</include>
+
+	<include>modmod/styles.xml</include>
+	<include>modmod/modio.xml</include>
+</page>
Index: build/premake/extern_libs5.lua
===================================================================
--- build/premake/extern_libs5.lua
+++ build/premake/extern_libs5.lua
@@ -393,6 +393,15 @@
 			})
 		end,
 	},
+	libsodium = {
+		-- TODO check other OSes
+		compile_settings = function()
+			pkgconfig.add_includes("libsodium")
+		end,
+		link_settings = function()
+			pkgconfig.add_links("libsodium")
+		end,
+	},
 	libxml2 = {
 		compile_settings = function()
 			if os.istarget("windows") then
Index: build/premake/premake5.lua
===================================================================
--- build/premake/premake5.lua
+++ build/premake/premake5.lua
@@ -717,6 +717,7 @@
 		"tinygettext",
 		"icu",
 		"iconv",
+		"libsodium",
 	}
 
 	if not _OPTIONS["without-audio"] then
@@ -909,6 +910,7 @@
 	"tinygettext",
 	"icu",
 	"iconv",
+	"libsodium",
 
 	"valgrind",
 }
Index: source/ps/GameSetup/GameSetup.cpp
===================================================================
--- source/ps/GameSetup/GameSetup.cpp
+++ source/ps/GameSetup/GameSetup.cpp
@@ -68,6 +68,7 @@
 #include "ps/Joystick.h"
 #include "ps/Loader.h"
 #include "ps/Mod.h"
+#include "ps/ModIo.h"
 #include "ps/Profile.h"
 #include "ps/ProfileViewer.h"
 #include "ps/Profiler2.h"
@@ -734,6 +735,8 @@
 
 	SAFE_DELETE(g_XmppClient);
 
+	SAFE_DELETE(g_ModIo);
+
 	ShutdownPs();
 
 	TIMER_BEGIN(L"shutdown TexMan");
Index: source/ps/ModIo.h
===================================================================
--- /dev/null
+++ source/ps/ModIo.h
@@ -0,0 +1,154 @@
+/* Copyright (C) 2018 Wildfire Games.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef INCLUDED_MODIO
+#define INCLUDED_MODIO
+
+#include <string>
+#include <sodium/crypto_sign.h>
+
+#include "lib/external_libraries/curl.h"
+
+class DownloadCallbackData;
+class ScriptInterface;
+
+// TODO: Allocate instance of the below two using sodium_malloc?
+struct PKStruct {
+	unsigned char sig_alg[2] = {}; // == "Ed"
+	unsigned char keynum[8] = {}; // should match the keynum in the sigstruct, else this is the wrong key
+	unsigned char pk[crypto_sign_PUBLICKEYBYTES] = {};
+};
+
+struct SigStruct {
+	unsigned char sig_alg[2] = {}; // "ED" (since we only support the hashed mode)
+	unsigned char keynum[8] = {}; // should match the keynum in the PKStruct
+	unsigned char sig[crypto_sign_BYTES] = {};
+};
+
+struct ModIoModData
+{
+	std::map<std::string, std::string> properties;
+	std::vector<std::string> dependencies;
+	SigStruct sig;
+};
+
+/**
+ * mod.io API interfacing code.
+ *
+ * Overview
+ *
+ * This class interfaces with a remote API provider that returns a list of mod files.
+ * These can then be downloaded after some cursory checking of well-formedness of the returned
+ * metadata.
+ * Downloaded files are checked for well formedness by validating that they fit the size and hash
+ * indicated by the API, then we check if the file is actually signed by a trusted key, and only
+ * if all of that is success the file is actually possible to be loaded as a mod.
+ *
+ * Security considerations
+ *
+ * This both distrusts the loaded JS mods, and the API as much as possible.
+ * We do not want a malicious mod to use this to download arbitrary files, nor do we want the API
+ * to make us download something we have not verified.
+ * Therefore we only allow mods to download one of the mods returned by this class (using indices).
+ *
+ * This (mostly) necessitates parsing the API responses here, as opposed to in JS.
+ * One could alternatively parse the responses in a locked down JS context, but that would require
+ * storing that code in here, or making sure nobody can overwrite it. Also this would possibly make
+ * some of the needed accesses for downloading and verifying files a bit more complicated.
+ *
+ * Everything downloaded from the API has its signature verified against our public key.
+ * This is a requirement, as otherwise a compromise of the API would result in users installing
+ * possibly malicious files.
+ * So a compromised API can just serve old files that we signed, so in that case there would need
+ * to be an issue in that old file that was missed.
+ *
+ * To limit the extend to how old those files could be the signing key should be rotated
+ * regularly (e.g. every release). To allow old versions of the engine to still use the API
+ * files can be signed by both the old and the new key for some amount of time, that however
+ * only makes sense in case a mod is compatible with both engine versions.
+ *
+ * TODO: One should probably sign the new key with the old one to ensure a nice upgrade path,
+ *       though that does not really make any difference since releases aren't signed either.
+ *       And if releases are signed, then we can just rely on that instead of complicating things.
+ *
+ * Note that this does not prevent all possible attacks a package manager/update system should
+ * defend against. This is intentionally not an update system since proper package managers already
+ * exist. However there is some possible overlap in attack vectors and these should be evalutated
+ * whether they apply and to what extend we can fix that on our side (or how to get the API provider
+ * to help us do so). For a list of some possible issues see:
+ * https://github.com/theupdateframework/specification/blob/master/tuf-spec.md
+ *
+ * The mod.io settings are also locked down such that only mods that have been authorized by us
+ * show up in API queries. This is both done so that all required information (dependencies)
+ * are stored for the files, and that only mods that have been checked for being ok are acutally
+ * shown to users.
+ */
+class ModIo
+{
+	NONCOPYABLE(ModIo);
+public:
+	ModIo();
+	~ModIo();
+
+	const std::vector<ModIoModData>& GetMods(const ScriptInterface& scriptinterface);
+
+	void DownloadMod(size_t idx);
+
+private:
+	static size_t ReceiveCallback(void* buffer, size_t size, size_t nmemb, void* userp);
+	static size_t DownloadCallback(void* buffer, size_t size, size_t nmemb, void* userp);
+
+	CURLcode PerformRequest(const std::string& url);
+
+	static bool ParseGameIdResponse(const ScriptInterface& scriptInterface, const std::string& responseData, int& id);
+	static bool ParseModsResponse(const ScriptInterface& scriptInterface, const std::string& responseData, std::vector<ModIoModData>& modData, const PKStruct& pk);
+	static bool ParseSignature(const std::vector<std::string>& minisigs, SigStruct& sig, const PKStruct& pk);
+
+	bool ParseGameId(const ScriptInterface& scriptInterface);
+	bool ParseMods(const ScriptInterface& scriptInterface);
+
+	bool VerifyDownload(const OsPath& filePath, DownloadCallbackData& callbackData, const ModIoModData& modData) const;
+
+	// Url parts
+	std::string m_BaseUrl;
+	std::string m_GamesRequest;
+	std::string m_GameId;
+
+	// Query parameters
+	std::string m_ApiKey;
+	std::string m_IdQuery;
+
+	CURL* m_Curl;
+	curl_slist* m_Headers;
+	char m_ErrorBuffer[CURL_ERROR_SIZE];
+	std::string m_ResponseData;
+
+	PKStruct m_pk;
+
+	std::vector<ModIoModData> m_ModData;
+
+	friend class TestModIo;
+};
+
+extern ModIo* g_ModIo;
+
+#endif // INCLUDED_MODIO
Index: source/ps/ModIo.cpp
===================================================================
--- /dev/null
+++ source/ps/ModIo.cpp
@@ -0,0 +1,610 @@
+/* Copyright (C) 2018 Wildfire Games.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "precompiled.h"
+
+#include "ModIo.h"
+
+#include "lib/file/file_system.h"
+#include "lib/sysdep/sysdep.h"
+#include "lib/sysdep/filesystem.h"
+#include "maths/MD5.h"
+#include "ps/CLogger.h"
+#include "ps/ConfigDB.h"
+#include "ps/GameSetup/Paths.h"
+#include "ps/Mod.h"
+#include "scriptinterface/ScriptConversions.h"
+#include "scriptinterface/ScriptInterface.h"
+
+#include <sodium.h>
+
+#include <iomanip>
+
+#include <boost/algorithm/string/classification.hpp>
+#include <boost/algorithm/string/split.hpp>
+
+ModIo* g_ModIo = nullptr;
+// TODO: add a compile-time config so we can build without this
+
+struct DownloadCallbackData {
+	DownloadCallbackData(FILE* _fp)
+		: fp(_fp), md5()
+	{
+		crypto_generichash_init(&hash_state, NULL, 0U, crypto_generichash_BYTES_MAX);
+	}
+	FILE* fp;
+	MD5 md5;
+	crypto_generichash_state hash_state;
+};
+
+ModIo::ModIo()
+	: m_GamesRequest("/games")
+{
+	// Get config values from the sytem namespace, or below (default)
+	// this can be overridden on the command line.
+	// We do this so a malicious mod cannot change the base url and get the user to make connections
+	// to someone else's endpoint.
+	// If another user of the engine wants to provide different values here,
+	// while still using the same engine version, they can just provide some shortcut/script
+	// that sets these using command line parameters.
+	g_ConfigDB.GetValue(CFG_SYSTEM, "modio.v1.baseurl", m_BaseUrl);
+	{
+		std::string api_key;
+		g_ConfigDB.GetValue(CFG_SYSTEM, "modio.v1.api_key", api_key);
+		m_ApiKey = "api_key=" + api_key;
+	}
+	{
+		std::string nameid;
+		g_ConfigDB.GetValue(CFG_SYSTEM, "modio.v1.name_id", nameid);
+		m_IdQuery = "name_id="+nameid;
+	}
+
+	// Initialise everything except Win32 sockets (because our networking
+	// system already inits those)
+	curl_global_init(CURL_GLOBAL_ALL & ~CURL_GLOBAL_WIN32);
+// TODO we should only do this in one single place (same for shutdown, currently we do it here and in the userreporter)
+
+	m_Curl = curl_easy_init();
+	ENSURE(m_Curl);
+
+	// Capture error messages
+	curl_easy_setopt(m_Curl, CURLOPT_ERRORBUFFER, m_ErrorBuffer);
+
+	// Fail if the server did
+	curl_easy_setopt(m_Curl, CURLOPT_FAILONERROR, 1L);
+
+	// Disable signal handlers (required for multithreaded applications)
+	curl_easy_setopt(m_Curl, CURLOPT_NOSIGNAL, 1L);
+
+	// To minimise security risks, don't support redirects
+	curl_easy_setopt(m_Curl, CURLOPT_FOLLOWLOCATION, 0L);
+
+	m_Headers = NULL;
+	std::string ua = "User-Agent: pyrogenesis ";
+	ua += curl_version();
+	ua += " (https://play0ad.com/)";
+	m_Headers = curl_slist_append(m_Headers, ua.c_str());
+	// TODO more?
+	curl_easy_setopt(m_Curl, CURLOPT_HTTPHEADER, m_Headers);
+
+	if (sodium_init() < 0) {
+		LOGERROR("Failed to initialize libsodium");
+		ENSURE(0 && "sodium_init returned success.");
+	}
+
+	// TODO: related to that, what if one signature is valid, and another is invalid (in the actual check)? (probably consider it invalid since well wtf)
+	//       Should not happen, since there should be at most one signature for a given key (else someone got quite unlucky generating one).
+	// TODO: get this from the config?
+	const std::string pk_str = "RWTA6VIoth2Q1PFLsRILr3G7NB+mwwO8BSGoXs63X6TQgNGM4cE8Pvd6";
+
+	size_t bin_len = 0;
+	if (sodium_base642bin((unsigned char*)&m_pk, sizeof m_pk, pk_str.c_str(), pk_str.size(), NULL, &bin_len, NULL, sodium_base64_VARIANT_ORIGINAL) != 0 || bin_len != sizeof m_pk)
+	{
+		LOGERROR("failed to decode base64 public key");
+		ENSURE(0 && "invalid public key");
+	}
+}
+
+ModIo::~ModIo()
+{
+	curl_slist_free_all(m_Headers);
+	curl_easy_cleanup(m_Curl);
+	curl_global_cleanup(); // TODO
+}
+
+size_t ModIo::ReceiveCallback(void* buffer, size_t size, size_t nmemb, void* userp)
+{
+	ModIo* self = static_cast<ModIo*>(userp);
+
+	self->m_ResponseData += std::string((char*)buffer, (char*)buffer+size*nmemb);
+
+	return size*nmemb;
+}
+
+size_t ModIo::DownloadCallback(void* buffer, size_t size, size_t nmemb, void* userp)
+{
+	DownloadCallbackData* data = static_cast<DownloadCallbackData*>(userp);
+
+	size_t len = fwrite(buffer, size, nmemb, data->fp);
+
+	// Only update the hash with data we actually managed to write.
+	// In case we did not write all of it we will fail the download,
+	// but we do not want to have a possibly valid hash in that case.
+
+	data->md5.Update((const u8*)buffer, len*size);
+	crypto_generichash_update(&data->hash_state, (const u8*)buffer, len*size);
+
+	return len*size;
+}
+
+CURLcode ModIo::PerformRequest(const std::string& url)
+{
+	m_ErrorBuffer[0] = '\0';
+	curl_easy_setopt(m_Curl, CURLOPT_URL, url.c_str());
+	return curl_easy_perform(m_Curl);
+}
+
+const std::vector<ModIoModData>& ModIo::GetMods(const ScriptInterface& scriptInterface)
+{
+	m_ModData.clear();
+
+	// Set IO callbacks
+	curl_easy_setopt(m_Curl, CURLOPT_WRITEFUNCTION, ReceiveCallback);
+	curl_easy_setopt(m_Curl, CURLOPT_WRITEDATA, this);
+
+	// Get the game id if we didn't fetch it already
+	if (m_GameId.empty())
+	{
+		CURLcode err = PerformRequest(m_BaseUrl+m_GamesRequest+"?"+m_ApiKey+"&"+m_IdQuery);
+
+		if (err != CURLE_OK)
+		{
+			LOGERROR("Failure while querying for game id. Server response: %s; %s", curl_easy_strerror(err), m_ErrorBuffer);
+			
+			return m_ModData;
+		}
+
+		if (!ParseGameId(scriptInterface))
+			return m_ModData;
+	}
+
+	// Get the actual mods
+	CURLcode err = PerformRequest(m_BaseUrl+m_GamesRequest+m_GameId+"/mods?"+m_ApiKey);
+	if (err != CURLE_OK)
+	{
+		LOGERROR("Failure while querying for mods. Server response: %s; %s", curl_easy_strerror(err), m_ErrorBuffer);
+		return m_ModData;
+	}
+
+	if (!ParseMods(scriptInterface))
+		m_ModData.clear(); // Failed during parsing, make sure we don't provide partial data
+
+	return m_ModData;
+}
+
+#define FAIL(...) STMT(LOGERROR(__VA_ARGS__); CLEANUP(); return false;)
+
+/**
+ * Parses the current content of m_ResponseData to extract m_GameId.
+ *
+ * The JSON data is expected to look like
+ * { "data": [{"id": 42, ...}, ...], ... }
+ * where we are only interested in the value of the id property.
+ *
+ * @returns true iff it successfully parsed the id.
+ */
+bool ModIo::ParseGameIdResponse(const ScriptInterface& scriptInterface, const std::string& responseData, int& id)
+{
+#define CLEANUP() id = -1;
+	JSContext* cx = scriptInterface.GetContext();
+	JS::RootedValue gameResponse(cx);
+
+	if (!scriptInterface.ParseJSON(responseData, &gameResponse))
+		FAIL("Failed to parse response as JSON.");
+
+	if (!gameResponse.isObject())
+		FAIL("response not an object");
+	
+	JS::RootedObject gameResponseObj(cx, gameResponse.toObjectOrNull());
+	JS::RootedValue dataVal(cx);
+	if (!JS_GetProperty(cx, gameResponseObj, "data", &dataVal))
+		FAIL("data property not in response.");
+
+	// [{"id": 42, ...}, ...]
+	if (!dataVal.isObject())
+		FAIL("data property not an object");
+
+	JS::RootedObject data(cx, dataVal.toObjectOrNull());
+	u32 length;
+	if (!JS_IsArrayObject(cx, data) || !JS_GetArrayLength(cx, data, &length) || !length)
+		FAIL("data property not an array with at least one element");
+
+	// {"id": 42, ...}
+	JS::RootedValue first(cx);
+	if (!JS_GetElement(cx, data, 0, &first))
+		FAIL("couldn't get first element.");
+
+	id = -1;
+// TODO: This check currently does not really do anything if "id" is present...
+// meaning we can set id to be null and we get id=0.
+// There is a script value conversion check failed warning, but that does not change anything.
+// TODO: We should probably make those fail (hard), if that isn't done by default (which it probably should)
+// the we should add a templated variant that does.
+// TODO check if id < 0 (<=?) and if yes also fail here
+// NOTE: FromJSProperty does set things to probably 0 even if there is some stupid type conversion
+// So we check for <= 0, so we actually get proper results here...
+	// Valid ids are always > 0.
+	if (!ScriptInterface::FromJSProperty(cx, first, "id", id) || id <= 0)
+		FAIL("couldn't get id");
+
+	return true;
+#undef CLEANUP
+}
+
+bool ModIo::ParseGameId(const ScriptInterface& scriptInterface)
+{
+	int id = -1;
+	if (!ParseGameIdResponse(scriptInterface, m_ResponseData, id))
+	{
+		m_ResponseData.clear();
+		return false;
+	}
+
+	m_ResponseData.clear();
+
+	m_GameId = "/" + std::to_string(id);
+	return true;
+}
+
+/**
+ * Parses the current content of m_ResponseData into m_ModData.
+ *
+ * The JSON data is expected to look like
+ * { data: [modobj1, modobj2, ...], ... (including result_count) }
+ * where modobjN has the following structure
+ * { homepage: "url", name: "displayname", nameid: "short-non-whitespace-name",
+ *   summary: "short desc.", modfile: { version: "1.2.4", filename: "asdf.zip",
+ *   filehash: { md5: "deadbeef" }, filesize: 1234, download: { binary_url: "someurl", ... } }, ... }.
+ * Only the listed properties are of interest to consumers, and we flatten
+ * the modfile structure as that simplifies handling and there are no conflicts.
+ */
+bool ModIo::ParseModsResponse(const ScriptInterface& scriptInterface, const std::string& responseData, std::vector<ModIoModData>& modData, const PKStruct& pk)
+{
+// Make sure we don't end up passing partial results back
+#define CLEANUP() modData.clear();
+
+	JSContext* cx = scriptInterface.GetContext();
+	JS::RootedValue modResponse(cx);
+
+	if (!scriptInterface.ParseJSON(responseData, &modResponse))
+		FAIL("Failed to parse response as JSON.");
+
+	if (!modResponse.isObject())
+		FAIL("response not an object");
+
+	JS::RootedObject modResponseObj(cx, modResponse.toObjectOrNull());
+	JS::RootedValue dataVal(cx);
+	if (!JS_GetProperty(cx, modResponseObj, "data", &dataVal))
+		FAIL("data property not in response.");
+
+	// [modobj1, modobj2, ... ]
+	if (!dataVal.isObject())
+		FAIL("data property not an object");
+
+	JS::RootedObject data(cx, dataVal.toObjectOrNull());
+	u32 length;
+	if (!JS_IsArrayObject(cx, data) || !JS_GetArrayLength(cx, data, &length) || !length)
+		FAIL("data property not an array with at least one element");
+
+	modData.clear();
+	modData.reserve(length);
+
+	for (u32 i = 0; i < length; ++i)
+	{
+		JS::RootedValue el(cx);
+		if (!JS_GetElement(cx, data, i, &el) || !el.isObject())
+			FAIL("Failed to get array element object");
+
+		modData.emplace_back();
+
+#define COPY_STRINGS(prefix, obj, ...) \
+	for (const std::string& prop : { __VA_ARGS__ }) \
+	{ \
+		std::string val; \
+		if (!ScriptInterface::FromJSProperty(cx, obj, prop.c_str(), val)) \
+			FAIL("failed to get %s from %s", prop, #obj);\
+		modData.back().properties.emplace(prefix+prop, val); \
+	}
+
+		// TODO: Currently the homepage field does not contain a non-null value for any entry.
+		COPY_STRINGS("", el, "name", "name_id", "summary");
+
+		// Now copy over the modfile part, but without the pointless substructure
+		JS::RootedObject elObj(cx, el.toObjectOrNull());
+		JS::RootedValue modFile(cx);
+		if (!JS_GetProperty(cx, elObj, "modfile", &modFile))
+			FAIL("Failed to get modfile data");
+
+		if (!modFile.isObject())
+			FAIL("modfile not an object");
+
+		COPY_STRINGS("", modFile, "version", "filesize");
+
+		JS::RootedObject modFileObj(cx, modFile.toObjectOrNull());
+		JS::RootedValue filehash(cx);
+		if (!JS_GetProperty(cx, modFileObj, "filehash", &filehash))
+			FAIL("Failed to get filehash data");
+
+		COPY_STRINGS("filehash_", filehash, "md5");
+
+		JS::RootedValue download(cx);
+		if (!JS_GetProperty(cx, modFileObj, "download", &download))
+			FAIL("Failed to get download data");
+
+		COPY_STRINGS("", download, "binary_url");
+
+		// Parse metadata_blob (sig+deps)
+		std::string metadata_blob;
+		if (!ScriptInterface::FromJSProperty(cx, modFile, "metadata_blob", metadata_blob))
+			FAIL("failed to get metadata_blob from modFile");
+
+		JS::RootedValue metadata(cx);
+		if (!scriptInterface.ParseJSON(metadata_blob, &metadata))
+			FAIL("Failed to parse metadata_blob as JSON.");
+
+		if (!metadata.isObject())
+			FAIL("metadata_blob not decoded as an object");
+
+		if (!ScriptInterface::FromJSProperty(cx, metadata, "dependencies", modData.back().dependencies))
+			FAIL("failed to get dependencies from metadata");
+
+		std::vector<std::string> minisigs;
+		if (!ScriptInterface::FromJSProperty(cx, metadata, "minisigs", minisigs))
+			FAIL("failed to get minisigs from metadata");
+
+		// Remove this entry if we did not find a valid matching signature
+		if (!ParseSignature(minisigs, modData.back().sig, pk))
+			modData.pop_back();
+
+#undef COPY_STRINGS
+	}
+
+	return true;
+#undef CLEANUP
+}
+
+/**
+ * Parse signatures to find one that matches the public key, and has a valid global signature.
+ * Returns true and sets @param sig to the valid matching signature.
+ */
+bool ModIo::ParseSignature(const std::vector<std::string>& minisigs, SigStruct& sig, const PKStruct& pk)
+{
+#define CLEANUP() sig = {};
+	for (const std::string& file_sig : minisigs)
+	{
+		// Format of a .minisig file (created using minisign(1) with -SHm file.zip)
+		// untrusted comment: .*\nb64sign_of_file\ntrusted comment: .*\nb64sign_of_sign_of_file_and_trusted_comment
+		// TODO: Verify that both the untrusted comment and the trusted comment start with the correct prefix
+
+		std::vector<std::string> sig_lines;
+		boost::split(sig_lines, file_sig, boost::is_any_of("\n"));
+		if (sig_lines.size() < 4)
+			FAIL("invalid (too short) sig");
+
+		// We only _really_ care about the second line which is the signature of the file (b64-encoded)
+		// Also handling the other signature is nice, but not really required.
+		const std::string& msg_sig = sig_lines[1];
+
+		size_t bin_len = 0;
+		if (sodium_base642bin((unsigned char*)&sig, sizeof sig, msg_sig.c_str(), msg_sig.size(), NULL, &bin_len, NULL, sodium_base64_VARIANT_ORIGINAL) != 0 || bin_len != sizeof sig)
+			FAIL("failed to decode base64 sig");
+
+		cassert(sizeof pk.keynum == sizeof sig.keynum);
+
+		if (memcmp(&sig.sig_alg, "ED", 2) != 0)
+			FAIL("only hashed minisign signatures are supported");
+
+		if (memcmp(&pk.keynum, &sig.keynum, sizeof sig.keynum) != 0)
+			continue; // mismatched key, try another one
+
+		// Signature matches our public key
+
+		// Now verify the global signature (sig || trusted_comment)
+
+		unsigned char global_sig[crypto_sign_BYTES];
+		if (sodium_base642bin(global_sig, sizeof global_sig, sig_lines[3].c_str(), sig_lines[3].size(), NULL, &bin_len, NULL, sodium_base64_VARIANT_ORIGINAL) != 0 || bin_len != sizeof global_sig)
+			FAIL("failed to decode base64 global_sig");
+
+		const std::string trusted_comment_prefix = "trusted comment: ";
+		if (sig_lines[2].size() < trusted_comment_prefix.size())
+			FAIL("malformed trusted comment");
+
+		const std::string trusted_comment = sig_lines[2].substr(trusted_comment_prefix.size());
+
+		unsigned char* sig_and_trusted_comment = (unsigned char*)sodium_malloc((sizeof sig.sig) + trusted_comment.size());
+		if (!sig_and_trusted_comment)
+			FAIL("sodium_malloc failed");
+
+		memcpy(sig_and_trusted_comment, sig.sig, sizeof sig.sig);
+		memcpy(sig_and_trusted_comment + sizeof sig.sig, trusted_comment.data(), trusted_comment.size());
+
+		if (crypto_sign_verify_detached(global_sig, sig_and_trusted_comment, (sizeof sig.sig) + trusted_comment.size(), pk.pk) != 0)
+		{
+			LOGERROR("failed to verify global signature");
+			sodium_free(sig_and_trusted_comment);
+			return false;
+		}
+
+		sodium_free(sig_and_trusted_comment);
+
+		// Valid global sig, and the keynum matches the real one
+		return true;
+	}
+
+	return false;
+#undef CLEANUP
+}
+
+#undef FAIL
+
+bool ModIo::ParseMods(const ScriptInterface& scriptInterface)
+{
+	bool ret = ParseModsResponse(scriptInterface, m_ResponseData, m_ModData, m_pk);
+	m_ResponseData.clear();
+	return ret;
+}
+
+void ModIo::DownloadMod(size_t idx)
+{
+	if (idx >= m_ModData.size())
+		return;
+
+	// TODO: do this asynchronously? or at least tell the gui that we are doing something -> progress bar (or something spinning)
+
+	const Paths paths(g_args);
+	const OsPath modUserPath = paths.UserData()/"mods";
+	const OsPath modPath = modUserPath/m_ModData[idx].properties["name_id"];
+	if (!DirectoryExists(modPath) && INFO::OK != CreateDirectories(modPath, 0700, false))
+	{
+		LOGERROR("Could not create mod directory: %s", modPath.string8());
+		return;
+	}
+
+	// Name the file after the name_id, since using the filename would mean that
+	// we could end up with multiple zip files in the folder that might not work
+	// as expected for a user (since a later version might remove some files
+	// that aren't compatible anymore with the engine version).
+	// So we ignore the filename provided by the API and assume that we do not
+	// care about handling update.zip files. If that is the case we would need
+	// a way to find out what files are required by the current one and which
+	// should be removed for everything to work. This seems to be too complicated
+	// so we just do not support that usage.
+	// NOTE: We do save the file under a slightly different name from the final
+	//       one, to ensure that in case a download aborts and the file stays
+	//       around, the game will not attempt to open the file which has not
+	//       been verified.
+	const OsPath filePath = modPath/(m_ModData[idx].properties["name_id"]+".zip.temp");
+	DownloadCallbackData callbackData(sys_OpenFile(filePath, "wb"));
+	if (!callbackData.fp)
+	{
+		LOGERROR("Could not open temporary file for mod download: %s", filePath.string8());
+		return;
+	}
+
+	// Set IO callbacks
+	curl_easy_setopt(m_Curl, CURLOPT_WRITEFUNCTION, DownloadCallback);
+	curl_easy_setopt(m_Curl, CURLOPT_WRITEDATA, (void*)&callbackData);
+
+	LOGERROR("Trying to download %s", m_ModData[idx].properties["binary_url"].c_str());
+
+	// The download link will most likely redirect elsewhere, so allow that.
+	// We verify the validity of the file below.
+	curl_easy_setopt(m_Curl, CURLOPT_FOLLOWLOCATION, 1L);
+	// One redirect seems plenty for a CDN servint the files.
+	curl_easy_setopt(m_Curl, CURLOPT_MAXREDIRS, 1L);
+
+	// Download the file
+	CURLcode err = PerformRequest(m_ModData[idx].properties["binary_url"]);
+	fclose(callbackData.fp);
+	callbackData.fp = NULL;
+
+	// To minimise security risks, don't support redirects for queries
+	curl_easy_setopt(m_Curl, CURLOPT_FOLLOWLOCATION, 0L);
+
+	if (err != CURLE_OK)
+	{
+		LOGERROR("Failure while downloading mod file. Server response: %s; %s", curl_easy_strerror(err), m_ErrorBuffer);
+		if (wunlink(filePath) != 0)
+			LOGERROR("Failed to delete file.");
+		return;
+	}
+
+	if (!VerifyDownload(filePath, callbackData, m_ModData[idx]))
+	{
+		LOGERROR("File %s failed to verify.", filePath.string8());
+		// delete the file again as it does not match
+		if (wunlink(filePath) != 0)
+			LOGERROR("Failed to delete file.");
+
+		return;
+	}
+
+	const OsPath finalFilePath = modPath/(m_ModData[idx].properties["name_id"]+".zip");
+	if (wrename(filePath, finalFilePath) != 0)
+	{
+		LOGERROR("failed to rename file.");
+		wunlink(filePath);
+		return;
+	}
+
+	LOGERROR("downloaded something and verified it successfully.");
+
+	// TODO: hook into .pyromod code to do the win32 specific thing because win32...
+}
+
+bool ModIo::VerifyDownload(const OsPath& filePath, DownloadCallbackData& callbackData, const ModIoModData& modData) const
+{
+	{
+		u64 filesize = std::stoull(modData.properties.at("filesize"));
+		if (filesize != FileSize(filePath))
+		{
+			LOGERROR("Invalid filesize.");
+			return false;
+		}
+	}
+
+	// MD5 (because upstream provides it)
+	// Just used to make sure there was no obvious corruption during transfer.
+	{
+		u8 digest[MD5::DIGESTSIZE];
+		callbackData.md5.Final(digest);
+		std::stringstream md5digest;
+		md5digest << std::hex << std::setfill('0');
+		for (size_t i = 0; i < MD5::DIGESTSIZE; ++i)
+			md5digest << std::setw(2) << (int)digest[i];
+
+		if (modData.properties.at("filehash_md5") != md5digest.str())
+		{
+			LOGERROR("Invalid file. Expected md5 %s, got %s.", modData.properties.at("filehash_md5").c_str(), md5digest.str());
+			return false;
+		}
+	}
+
+	// Verify file signature.
+	// Used to make sure that the downloaded file was actually checked and signed
+	// by Wildfire Games. And has not been tampered with by the API provider, or the CDN.
+
+	unsigned char hash_fin[crypto_generichash_BYTES_MAX] = {};
+	if (crypto_generichash_final(&callbackData.hash_state, hash_fin, sizeof hash_fin) != 0)
+	{
+		LOGERROR("failed to compute final hash");
+		return false;
+	}
+
+	if (crypto_sign_verify_detached(modData.sig.sig, hash_fin, sizeof hash_fin, m_pk.pk) != 0)
+	{
+		LOGERROR("failed to verify signature");
+		return false;
+	}
+
+	return true;
+}
Index: source/ps/scripting/JSInterface_Mod.h
===================================================================
--- source/ps/scripting/JSInterface_Mod.h
+++ source/ps/scripting/JSInterface_Mod.h
@@ -26,6 +26,9 @@
 	JS::Value GetAvailableMods(ScriptInterface::CxPrivate* pCxPrivate);
 	void RestartEngine(ScriptInterface::CxPrivate* pCxPrivate);
 	void SetMods(ScriptInterface::CxPrivate* pCxPrivate, const std::vector<CStr>& mods);
+
+	JS::Value ModIoGetMods(ScriptInterface::CxPrivate* pCxPrivate);
+	void ModIoDownloadMod(ScriptInterface::CxPrivate* pCxPrivate, uint32_t idx);
 }
 
 #endif
Index: source/ps/scripting/JSInterface_Mod.cpp
===================================================================
--- source/ps/scripting/JSInterface_Mod.cpp
+++ source/ps/scripting/JSInterface_Mod.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2017 Wildfire Games.
+/* Copyright (C) 2018 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -27,6 +27,7 @@
 #include "ps/GameSetup/GameSetup.h"
 #include "ps/GameSetup/Paths.h"
 #include "ps/Mod.h"
+#include "ps/ModIo.h"
 #include "ps/Profile.h"
 #include "ps/scripting/JSInterface_Mod.h"
 
@@ -123,9 +124,53 @@
 	g_modsLoaded = mods;
 }
 
+JS::Value JSI_Mod::ModIoGetMods(ScriptInterface::CxPrivate* pCxPrivate)
+{
+	ScriptInterface* scriptInterface = pCxPrivate->pScriptInterface;
+	JSContext* cx = scriptInterface->GetContext();
+	JSAutoRequest rq(cx);
+
+	if (!g_ModIo)
+		g_ModIo = new ModIo();
+
+	if (!g_ModIo)
+		return JS::NullValue(); // TODO: error/warning?
+
+	const std::vector<ModIoModData>& availableMods = g_ModIo->GetMods(*scriptInterface);
+
+	JS::RootedObject mods(cx, JS_NewArrayObject(cx, availableMods.size()));
+	if (!mods)
+		return JS::NullValue(); // TODO: error?
+
+	u32 i = 0;
+	for (const ModIoModData& mod : availableMods)
+	{
+		JS::RootedValue m(cx, JS::ObjectValue(*JS_NewPlainObject(cx)));
+		for (const std::pair<std::string, std::string>& prop : mod.properties)
+			scriptInterface->SetProperty(m, prop.first.c_str(), prop.second, true);
+
+		scriptInterface->SetProperty(m, "dependencies", mod.dependencies, true);
+		
+		JS_SetElement(cx, mods, i++, m);
+	}
+
+	return JS::ObjectValue(*mods);
+}
+
+void JSI_Mod::ModIoDownloadMod(ScriptInterface::CxPrivate* UNUSED(pCxPrivate), uint32_t idx)
+{
+	if (!g_ModIo)
+		return; // TODO: Warn and tell users to fix their code?
+
+	g_ModIo->DownloadMod(idx);
+}
+
 void JSI_Mod::RegisterScriptFunctions(const ScriptInterface& scriptInterface)
 {
 	scriptInterface.RegisterFunction<JS::Value, &JSI_Mod::GetAvailableMods>("GetAvailableMods");
 	scriptInterface.RegisterFunction<void, &JSI_Mod::RestartEngine>("RestartEngine");
 	scriptInterface.RegisterFunction<void, std::vector<CStr>, &JSI_Mod::SetMods>("SetMods");
+
+	scriptInterface.RegisterFunction<JS::Value, &JSI_Mod::ModIoGetMods>("ModIoGetMods");
+	scriptInterface.RegisterFunction<void, uint32_t, &JSI_Mod::ModIoDownloadMod>("ModIoDownloadMod");
 }
Index: source/ps/tests/test_ModIo.h
===================================================================
--- /dev/null
+++ source/ps/tests/test_ModIo.h
@@ -0,0 +1,239 @@
+/* Copyright (C) 2018 Wildfire Games.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included
+ * in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "lib/self_test.h"
+
+#include "ps/ModIo.h"
+#include "ps/CLogger.h"
+#include "scriptinterface/ScriptInterface.h"
+
+#include <sodium.h>
+
+class TestModIo : public CxxTest::TestSuite
+{
+public:
+	void setUp()
+	{
+		if (sodium_init() < 0)
+			LOGERROR("failed to initialize libsodium");
+	}
+
+	void test_id_parsing()
+	{
+		ScriptInterface script("Test", "Test", g_ScriptRuntime);
+
+		// TODO: One could probably fuzz this parsing function nicely to make sure it handles
+		//       malformed input nicely.
+
+#define TS_ASSERT_PARSE(input, expected_error, expected_id) \
+	{ \
+		TestLogger logger; \
+		int id = -1; \
+		TS_ASSERT(!ModIo::ParseGameIdResponse(script, input, id)); \
+		TS_ASSERT_STR_CONTAINS(logger.GetOutput(), expected_error); \
+		TS_ASSERT_EQUALS(id, expected_id); \
+	}
+
+		// Various malformed inputs
+		TS_ASSERT_PARSE("", "Failed to parse response as JSON", -1);
+		TS_ASSERT_PARSE("()", "Failed to parse response as JSON", -1);
+		TS_ASSERT_PARSE("[]", "data property not an object", -1);
+		TS_ASSERT_PARSE("null", "response not an object", -1);
+		TS_ASSERT_PARSE("{}", "data property not an object", -1);
+		TS_ASSERT_PARSE("{\"data\": null}", "data property not an object", -1);
+		TS_ASSERT_PARSE("{\"data\": {}}", "data property not an array with at least one element", -1);
+		TS_ASSERT_PARSE("{\"data\": []}", "data property not an array with at least one element", -1);
+		TS_ASSERT_PARSE("{\"data\": [null]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [false]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [{}]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [[]]}", "couldn't get id", -1);
+
+		// TODO: These only return -1 since we set id to that when we fail.
+		//       This should actually not be needed, but our parsing code does strange things.
+		TS_ASSERT_PARSE("{\"data\": [{\"id\": null}]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [{\"id\": {}}]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [{\"id\": -12}]}", "couldn't get id", -1);
+		TS_ASSERT_PARSE("{\"data\": [{\"id\": 0}]}", "couldn't get id", -1);
+
+		// TODO: This should fail, but our parsing code just warns in case we pass something of the wrong
+		//       type, instead of failing.
+		TS_ASSERT_PARSE("{\"data\": [{\"id\": true}]}", "couldn't get id", -1); // TODO: This fails since parsing is bogus.
+
+#undef TS_ASSERT_PARSE
+
+		// Correctly formed input
+		{
+			TestLogger logger;
+			int id = -1;
+			TS_ASSERT(ModIo::ParseGameIdResponse(script, "{\"data\": [{\"id\": 42}]}", id));
+			TS_ASSERT_STR_NOT_CONTAINS(logger.GetOutput(), "ERROR");
+			TS_ASSERT_EQUALS(id, 42);
+		}
+	}
+
+	void test_mods_parsing()
+	{
+		ScriptInterface script("Test", "Test", g_ScriptRuntime);
+
+		PKStruct pk;
+
+		const std::string pk_str = "RWTA6VIoth2Q1PFLsRILr3G7NB+mwwO8BSGoXs63X6TQgNGM4cE8Pvd6";
+
+		size_t bin_len = 0;
+		if (sodium_base642bin((unsigned char*)&pk, sizeof pk, pk_str.c_str(), pk_str.size(), NULL, &bin_len, NULL, sodium_base64_VARIANT_ORIGINAL) != 0 || bin_len != sizeof pk)
+			LOGERROR("failed to decode base64 public key");
+
+#define TS_ASSERT_PARSE(input, expected_error) \
+	{ \
+		TestLogger logger; \
+		std::vector<ModIoModData> mods; \
+		TS_ASSERT(!ModIo::ParseModsResponse(script, input, mods, pk)); \
+		TS_ASSERT_STR_CONTAINS(logger.GetOutput(), expected_error); \
+		TS_ASSERT_EQUALS(mods.size(), 0); \
+	}
+
+		TS_ASSERT_PARSE("", "Failed to parse response as JSON.");
+		TS_ASSERT_PARSE("()", "Failed to parse response as JSON.");
+		TS_ASSERT_PARSE("null", "response not an object");
+		TS_ASSERT_PARSE("[]", "data property not an object");
+		TS_ASSERT_PARSE("{}", "data property not an object");
+		TS_ASSERT_PARSE("{\"data\": null}", "data property not an object");
+		TS_ASSERT_PARSE("{\"data\": {}}", "data property not an array with at least one element");
+		TS_ASSERT_PARSE("{\"data\": []}", "data property not an array with at least one element");
+		TS_ASSERT_PARSE("{\"data\": [null]}", "Failed to get array element object");
+		TS_ASSERT_PARSE("{\"data\": [false]}", "Failed to get array element object");
+		TS_ASSERT_PARSE("{\"data\": [true]}", "Failed to get array element object");
+		TS_ASSERT_PARSE("{\"data\": [{}]}", "failed to get name from el");
+		TS_ASSERT_PARSE("{\"data\": [[]]}", "failed to get name from el");
+		TS_ASSERT_PARSE("{\"data\": [{\"foo\":\"bar\"}]}", "failed to get name from el");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":null}]}", "failed to get name_id from el"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":42}]}", "failed to get name_id from el"); // no conversion warning, but converting numbers to strings and vice-versa seems ok
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":false}]}", "failed to get name_id from el"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":{}}]}", "failed to get name_id from el"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":[]}]}", "failed to get name_id from el"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"foobar\"}]}", "failed to get name_id from el");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\"}]}", "modfile not an object");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":null}]}", "modfile not an object");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":[]}]}", "failed to get version from modFile");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{}}]}", "failed to get version from modFile");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":null}}]}", "failed to get filesize from modFile"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234}}]}", "failed to get md5 from filehash");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":null}}]}", "failed to get md5 from filehash");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{}}}]}", "failed to get md5 from filehash");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":null}}}]}", "failed to get binary_url from download"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}}}]}", "failed to get binary_url from download");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":null}}]}", "failed to get binary_url from download"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":null}}}]}", "failed to get metadata_blob from modFile"); // also some script value conversion check warning
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"}}}]}", "failed to get metadata_blob from modFile");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":null}}]}", "metadata_blob not decoded as an object");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"\"}}]}", "Failed to parse metadata_blob as JSON");
+
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{}\"}}]}", "failed to get dependencies from metadata");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{\\\"dependencies\\\":null}\"}}]}", "failed to get dependencies from metadata");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{\\\"dependencies\\\":[]}\"}}]}", "failed to get minisigs from metadata");
+		TS_ASSERT_PARSE("{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{\\\"dependencies\\\":[],\\\"minisigs\\\":null}\"}}]}", "failed to get minisigs from metadata");
+
+#undef TS_ASSERT_PARSE
+
+		// Correctly formed input, but no signature matching the public key
+		// Thus all such mods/modfiles are not added, thus we get 0 parsed mods.
+		{
+			TestLogger logger;
+			std::vector<ModIoModData> mods;
+			TS_ASSERT(ModIo::ParseModsResponse(script, "{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{\\\"dependencies\\\":[],\\\"minisigs\\\":[]}\"}}]}", mods, pk));
+			TS_ASSERT_STR_NOT_CONTAINS(logger.GetOutput(), "ERROR");
+			TS_ASSERT_EQUALS(mods.size(), 0);
+		}
+
+		// Correctly formed input (with a signature matching the public key above, and a valid global signature)
+		{
+			TestLogger logger;
+			std::vector<ModIoModData> mods;
+			TS_ASSERT(ModIo::ParseModsResponse(script, "{\"data\": [{\"name\":\"\",\"name_id\":\"\",\"summary\":\"\",\"modfile\":{\"version\":\"\",\"filesize\":1234, \"filehash\":{\"md5\":\"abc\"}, \"download\":{\"binary_url\":\"\"},\"metadata_blob\":\"{\\\"dependencies\\\":[],\\\"minisigs\\\":[\\\"untrusted comment: signature from minisign secret key\\\\nRUTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\\\\ntrusted comment: timestamp:1517285433\\\\tfile:tm.zip\\\\nTHwNMhK4Ogj6XA4305p1K9/ouP/DrxPcDFrPaiu+Ke6/WGlHIzBZHvmHWUedvsK6dzL31Gk8YNzscKWnZqWNCw==\\\"]}\"}}]}", mods, pk));
+			TS_ASSERT_STR_NOT_CONTAINS(logger.GetOutput(), "ERROR");
+			TS_ASSERT_EQUALS(mods.size(), 1);
+		}
+	}
+
+	void test_signature_parsing()
+	{
+		PKStruct pk;
+
+		const std::string pk_str = "RWTA6VIoth2Q1PFLsRILr3G7NB+mwwO8BSGoXs63X6TQgNGM4cE8Pvd6";
+
+		size_t bin_len = 0;
+		if (sodium_base642bin((unsigned char*)&pk, sizeof pk, pk_str.c_str(), pk_str.size(), NULL, &bin_len, NULL, sodium_base64_VARIANT_ORIGINAL) != 0 || bin_len != sizeof pk)
+			LOGERROR("failed to decode base64 public key");
+
+
+		// No invalid signature at all (silent failure)
+#define TS_ASSERT_PARSE_SILENT_FAILURE(input) \
+	{ \
+		TestLogger logger; \
+		SigStruct sig; \
+		TS_ASSERT(!ModIo::ParseSignature({input}, sig, pk)); \
+		TS_ASSERT_STR_NOT_CONTAINS(logger.GetOutput(), "ERROR"); \
+	}
+
+#define TS_ASSERT_PARSE(input, expected_error) \
+	{ \
+		TestLogger logger; \
+		SigStruct sig; \
+		TS_ASSERT(!ModIo::ParseSignature({input}, sig, pk)); \
+		TS_ASSERT_STR_CONTAINS(logger.GetOutput(), expected_error); \
+	}
+
+		TS_ASSERT_PARSE_SILENT_FAILURE();
+
+		TS_ASSERT_PARSE("", "invalid (too short) sig");
+		TS_ASSERT_PARSE("\n\n\n", "failed to decode base64 sig");
+		TS_ASSERT_PARSE("\nZm9vYmFyCg==\n\n", "failed to decode base64 sig");
+		TS_ASSERT_PARSE("\nRWTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\n\n", "only hashed minisign signatures are supported");
+
+		// Silent failure again this one has the wrong keynum
+		TS_ASSERT_PARSE_SILENT_FAILURE("\nRUTA5VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\n\n");
+
+		TS_ASSERT_PARSE("\nRUTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\n\n", "failed to decode base64 global_sig");
+		TS_ASSERT_PARSE("\nRUTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\n\nTHwNMhK4Ogj6XA4305p1K9/ouP/DrxPcDFrPaiu+Ke6/WGlHIzBZHvmHWUedvsK6dzL31Gk8YNzscKWnZqWNCw==", "malformed trusted comment");
+
+		// TODO: Test for both the untrusted comment and the trusted comment to actually start with that
+
+		TS_ASSERT_PARSE("\nRUTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\ntrusted comment: timestamp:1517285433\tfile:tm.zip\nAHwNMhK4Ogj6XA4305p1K9/ouP/DrxPcDFrPaiu+Ke6/WGlHIzBZHvmHWUedvsK6dzL31Gk8YNzscKWnZqWNCw==", "failed to verify global signature");
+
+		// Valid signature
+		{
+			TestLogger logger;
+			SigStruct sig;
+			TS_ASSERT(ModIo::ParseSignature({"\nRUTA6VIoth2Q1HUg5bwwbCUZPcqbQ/reLXqxiaWARH5PNcwxX5vBv/mLPLgdxGsIrOyK90763+rCVTmjeYx5BDz8C0CIbGZTNQs=\ntrusted comment: timestamp:1517285433\tfile:tm.zip\nTHwNMhK4Ogj6XA4305p1K9/ouP/DrxPcDFrPaiu+Ke6/WGlHIzBZHvmHWUedvsK6dzL31Gk8YNzscKWnZqWNCw=="}, sig, pk));
+			TS_ASSERT_STR_NOT_CONTAINS(logger.GetOutput(), "ERROR");
+		}
+
+#undef TS_ASSERT_PARSE_SILENT_FAILURE
+#undef TS_ASSERT_PARSE
+	}
+};