cpp/openttd-patchpack/source Changeset - r28521:35e6c20016f8

Changeset - r28521:35e6c20016f8

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Patric Stout - 3 months ago 2024-01-18 22:52:53
truebrain@openttd.org

Change: use a stronger hash and actual random information to generate Uids

4 files changed with 77 insertions and 15 deletions:

CMakeLists.txt

src/core/random_func.cpp

src/core/random_func.hpp

src/misc.cpp

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CMakeLists.txt

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@@ @@ -448,6 +448,7 @@ if(WIN32) @@
         usp10
         psapi
         winhttp
         bcrypt
+    )
 endif()

src/core/random_func.cpp

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@@ @@ -10,6 +10,7 @@ @@
 #include "../stdafx.h"
 #include "random_func.hpp"
 #include "bitmath_func.hpp"
 #include "../debug.h"
 #ifdef RANDOM_DEBUG
 #include "../network/network.h"
@@ @@ -20,6 +21,15 @@ @@
 #include "../timer/timer_game_calendar.h"
 #endif /* RANDOM_DEBUG */
 #if defined(_WIN32)
 #	include <windows.h>
 #	include <bcrypt.h>
 #elif defined(__EMSCRIPTEN__)
 #	include <emscripten.h>
 #elif !defined(__APPLE__) && !defined(__NetBSD__) && !defined(__FreeBSD__)
 #	include <sys/random.h>
 #endif
 #include "../safeguards.h"
 Randomizer _random, _interactive_random;
@@ @@ -83,3 +93,53 @@ uint32_t DoRandomRange(uint32_t limit, i @@
 	return ((uint64_t)DoRandom(line, file) * (uint64_t)limit) >> 32;
+}
 #endif /* RANDOM_DEBUG */
 /**
  * Fill the given buffer with random bytes.
+ *
  * This function will attempt to use a cryptographically-strong random
  * generator, but will fall back to a weaker random generator if none is
  * available.
+ *
  * In the end, the buffer will always be filled with some form of random
  * bytes when this function returns.
+ *
  * @param buf The buffer to fill with random bytes.
  */
 void RandomBytesWithFallback(std::span<uint8_t> buf)
+{
 #if defined(_WIN32)
 	auto res = BCryptGenRandom(nullptr, static_cast<PUCHAR>(buf.data()), static_cast<ULONG>(buf.size()), BCRYPT_USE_SYSTEM_PREFERRED_RNG);
 	if (res >= 0) return;
 #elif defined(__APPLE__) || defined(__NetBSD__) || defined(__FreeBSD__)
 	arc4random_buf(buf.data(), buf.size());
 	return;
 #elif defined(__GLIBC__) && ((__GLIBC__ > 2) || ((__GLIBC__ == 2) && (__GLIBC_MINOR__ >= 25)))
 	auto res = getrandom(buf.data(), buf.size(), 0);
 	if (res > 0 && static_cast<size_t>(res) == buf.size()) return;
 #elif defined(__EMSCRIPTEN__)
 	auto res = EM_ASM_INT({
 		var buf = $0;
 		var bytes = $1;
 		var crypto = window.crypto;
 		if (crypto === undefined || crypto.getRandomValues === undefined) {
 			return -1;
+		}
 		crypto.getRandomValues(Module.HEAPU8.subarray(buf, buf + bytes));
 		return 1;
 	}, buf.data(), buf.size());
 	if (res > 0) return;
 #else
 #	warning "No cryptographically-strong random generator available; using a fallback instead"
 #endif
 	static bool warned_once = false;
 	Debug(misc, warned_once ? 1 : 0, "Cryptographically-strong random generator unavailable; using fallback");
 	warned_once = true;
 	for (uint i = 0; i < buf.size(); i++) {
 		buf[i] = static_cast<uint8_t>(InteractiveRandom());
+	}
+}

src/core/random_func.hpp

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@@ @@ -159,4 +159,6 @@ inline bool Chance16R(const uint a, cons @@
+}
 #endif /* RANDOM_DEBUG */
 void RandomBytesWithFallback(std::span<uint8_t> buf);
 #endif /* RANDOM_FUNC_HPP */

src/misc.cpp

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@@ @@ -31,7 +31,7 @@ @@
 #include "town_kdtree.h"
 #include "viewport_kdtree.h"
 #include "newgrf_profiling.h"
-#include "3rdparty/md5/md5.h"
+#include "3rdparty/monocypher/monocypher.h"
 #include "safeguards.h"
@@ @@ -61,25 +61,24 @@ void InitializeOldNames(); @@
 /**
  * Generate an unique ID.
+ *
  * It isn't as much of an unique ID as we would like, but our random generator
  * can only produce 32bit random numbers.
  * That is why we combine InteractiveRandom with the current (steady) clock.
  * The first to add a bit of randomness, the second to ensure you can't get
  * the same unique ID when you run it twice from the same state at different
  * times.
+ *
  * This makes it unlikely that two users generate the same ID for different
  * subjects. But as this is not an UUID, so it can't be ruled out either.
  * It isn't as much of an unique ID but more a hashed digest of a random
  * string and a time. It is very likely to be unique, but it does not follow
  * any UUID standard.
  */
 std::string GenerateUid(std::string_view subject)
+{
 	std::array<uint8_t, 32> random_bytes;
 	RandomBytesWithFallback(random_bytes);
 	auto current_time = std::chrono::duration_cast<std::chrono::nanoseconds>(std::chrono::steady_clock::now().time_since_epoch()).count();
-	std::string coding_string = fmt::format("{}{}{}", InteractiveRandom(), current_time, subject);
 	std::string coding_string = fmt::format("{}{}", current_time, subject);
 	Md5 checksum;
 	MD5Hash digest;
 	checksum.Append(coding_string.c_str(), coding_string.length());
 	checksum.Finish(digest);
 	std::array<uint8_t, 16> digest;
 	crypto_blake2b_ctx ctx;
 	crypto_blake2b_init(&ctx, digest.size());
 	crypto_blake2b_update(&ctx, random_bytes.data(), random_bytes.size());
 	crypto_blake2b_update(&ctx, reinterpret_cast<const uint8_t *>(coding_string.data()), coding_string.size());
 	crypto_blake2b_final(&ctx, digest.data());
 	return FormatArrayAsHex(digest);
+}

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