From a776441ce1ab5871e8a4e1d5d7a98c7ef50b61a4 Mon Sep 17 00:00:00 2001
From: orignal <i2porignal@yandex.ru>
Date: Mon, 15 Jun 2026 17:08:05 -0400
Subject: [PATCH] detect and check imcompatible crypto between local
 destination and LeaseSet

---
 daemon/HTTPServer.cpp   |  9 ++++++---
 libi2pd/Destination.cpp | 10 +++++++---
 libi2pd/LeaseSet.cpp    | 10 +++++++---
 libi2pd/LeaseSet.h      |  4 +++-
 4 files changed, 23 insertions(+), 10 deletions(-)

diff --git a/daemon/HTTPServer.cpp b/daemon/HTTPServer.cpp
index 4bc762c2..e9db1c95 100644
--- a/daemon/HTTPServer.cpp
+++ b/daemon/HTTPServer.cpp
@@ -529,9 +529,12 @@ namespace http {
 				  << "<td>" << it.first.ToBase32 () << "</td>"
 				  << "<td><a class=\"button\" href=\"" << webroot << "?cmd=" << HTTP_COMMAND_EXPIRELEASE<< "&b32=" << dest->GetIdentHash ().ToBase32 ()
 				  << "&lease=" << it.first.ToBase32 () << "&token=" << token << "\" title=\"" << tr("Expire LeaseSet") << "\"> &#10008; </a></td>"
-				  << "<td>" << (int)it.second->GetStoreType () << "</td>"
-				  << "<td>" << (int)it.second->GetEncryptionType () <<"</td>"
-				  << "</tr>\r\n";
+				  << "<td>" << (int)it.second->GetStoreType () << "</td>";
+				if (!it.second->IsIncompatibleCrypto ())
+					s << "<td>" << (int)it.second->GetEncryptionType () <<"</td>";
+				else
+					s << "<td>n/a</td>";
+				s << "</tr>\r\n";
 			}
 			s << "</tbody>\r\n</table>\r\n";
 			s << "</div>\r\n</div>\r\n<br>\r\n";
diff --git a/libi2pd/Destination.cpp b/libi2pd/Destination.cpp
index 635c70d0..5766f931 100644
--- a/libi2pd/Destination.cpp
+++ b/libi2pd/Destination.cpp
@@ -445,7 +445,11 @@ namespace client
 				{
 					// add or replace
 					if (buf[DATABASE_STORE_TYPE_OFFSET] == i2p::data::NETDB_STORE_TYPE_LEASESET)
+					{
 						leaseSet = std::make_shared<i2p::data::LeaseSet> (buf + offset, len - offset); // LeaseSet
+						if (!SupportsEncryptionType (i2p::data::CRYPTO_KEY_TYPE_ELGAMAL))
+							leaseSet->SetIsIncompatibleCrypto (true);
+					}
 					else
 					{
 						leaseSet = std::make_shared<i2p::data::LeaseSet2> (buf[DATABASE_STORE_TYPE_OFFSET],
@@ -1216,7 +1220,7 @@ namespace client
 		auto leaseSet = FindLeaseSet (dest);
 		if (leaseSet)
 		{
-			auto stream = CreateStream (leaseSet, port);
+			auto stream = (!leaseSet->IsIncompatibleCrypto ()) ? CreateStream (leaseSet, port) : nullptr;
 			boost::asio::post (GetService (), [streamRequestComplete, stream]()
 				{
 					streamRequestComplete(stream);
@@ -1228,7 +1232,7 @@ namespace client
 			RequestDestination (dest,
 				[s, streamRequestComplete, port](std::shared_ptr<const i2p::data::LeaseSet> ls)
 				{
-					if (ls)
+					if (ls && !ls->IsIncompatibleCrypto ())
 						streamRequestComplete(s->CreateStream (ls, port));
 					else
 						streamRequestComplete (nullptr);
@@ -1247,7 +1251,7 @@ namespace client
 		RequestDestinationWithEncryptedLeaseSet (dest,
 			[s, streamRequestComplete, port](std::shared_ptr<i2p::data::LeaseSet> ls)
 			{
-				if (ls)
+				if (ls && !ls->IsIncompatibleCrypto ())
 					streamRequestComplete(s->CreateStream (ls, port));
 				else
 					streamRequestComplete (nullptr);
diff --git a/libi2pd/LeaseSet.cpp b/libi2pd/LeaseSet.cpp
index f2b4f561..81db5679 100644
--- a/libi2pd/LeaseSet.cpp
+++ b/libi2pd/LeaseSet.cpp
@@ -22,13 +22,14 @@ namespace i2p
 namespace data
 {
 	LeaseSet::LeaseSet (bool storeLeases):
-		m_IsValid (false), m_StoreLeases (storeLeases), m_ExpirationTime (0), m_EncryptionKey (nullptr),
-		m_Buffer (nullptr), m_BufferLen (0)
+		m_IsValid (false), m_IsIncompatibleCrypto (false), m_StoreLeases (storeLeases),
+		m_ExpirationTime (0), m_EncryptionKey (nullptr), m_Buffer (nullptr), m_BufferLen (0)
 	{
 	}
 
 	LeaseSet::LeaseSet (const uint8_t * buf, size_t len, bool storeLeases):
-		m_IsValid (true), m_StoreLeases (storeLeases), m_ExpirationTime (0), m_EncryptionKey (nullptr)
+		m_IsValid (true), m_IsIncompatibleCrypto (false), m_StoreLeases (storeLeases),
+		m_ExpirationTime (0), m_EncryptionKey (nullptr)
 	{
 		m_Buffer = new uint8_t[len];
 		memcpy (m_Buffer, buf, len);
@@ -410,6 +411,7 @@ namespace data
 		// key sections
 		CryptoKeyType preferredKeyType = m_EncryptionType;
 		m_EncryptionType = 0;
+		m_Encryptor = nullptr; // TODO: atomic
 		bool preferredKeyFound = false;
 		if (offset + 1 > len) return 0;
 		int numKeySections = buf[offset]; offset++;
@@ -441,6 +443,8 @@ namespace data
 			}
 			offset += encryptionKeyLen;
 		}
+		SetIsIncompatibleCrypto (!m_Encryptor);
+
 		// leases
 		if (offset + 1 > len) return 0;
 		int numLeases = buf[offset]; offset++;
diff --git a/libi2pd/LeaseSet.h b/libi2pd/LeaseSet.h
index 6ab546d3..ea4dbd0e 100644
--- a/libi2pd/LeaseSet.h
+++ b/libi2pd/LeaseSet.h
@@ -81,6 +81,8 @@ namespace data
 			const uint8_t * GetBuffer () const { return m_Buffer; };
 			size_t GetBufferLen () const { return m_BufferLen; };
 			bool IsValid () const { return m_IsValid; };
+			bool IsIncompatibleCrypto () const { return m_IsIncompatibleCrypto; };
+			void SetIsIncompatibleCrypto (bool isIncompatibleCrypto) { m_IsIncompatibleCrypto = isIncompatibleCrypto; };
 			const std::vector<std::shared_ptr<const Lease> > GetNonExpiredLeases (bool withThreshold = true) const;
 			const std::vector<std::shared_ptr<const Lease> > GetNonExpiredLeasesExcluding (LeaseInspectFunc exclude, bool withThreshold = true) const;
 			bool HasExpiredLeases () const;
@@ -125,7 +127,7 @@ namespace data
 
 		private:
 
-			bool m_IsValid, m_StoreLeases; // we don't need to store leases for floodfill
+			bool m_IsValid, m_IsIncompatibleCrypto, m_StoreLeases; // we don't need to store leases for floodfill
 			std::set<std::shared_ptr<Lease>, LeaseCmp> m_Leases;
 			uint64_t m_ExpirationTime; // in milliseconds
 			std::shared_ptr<const IdentityEx> m_Identity;