diff --git a/lib/binding_coap.dart b/lib/binding_coap.dart
index f2b33fb7..55875ff9 100644
--- a/lib/binding_coap.dart
+++ b/lib/binding_coap.dart
@@ -10,6 +10,8 @@
 /// [spec link]: https://www.w3.org/TR/wot-binding-templates/
 library binding_coap;
 
+export "package:coap/coap.dart" show ClientCertificate, ClientPrivateKey;
+
 export "src/binding_coap/coap_client_factory.dart";
 export "src/binding_coap/coap_config.dart";
 export "src/binding_coap/coap_server.dart";
diff --git a/lib/src/binding_coap/coap_client.dart b/lib/src/binding_coap/coap_client.dart
index cb1ad7d9..c90844b1 100644
--- a/lib/src/binding_coap/coap_client.dart
+++ b/lib/src/binding_coap/coap_client.dart
@@ -26,7 +26,10 @@ class _InternalCoapConfig extends CoapConfigDefault {
         dtlsCiphers = coapConfig.dtlsCiphers,
         dtlsVerify = coapConfig.dtlsVerify,
         dtlsWithTrustedRoots = coapConfig.dtlsWithTrustedRoots,
-        rootCertificates = coapConfig.rootCertificates;
+        rootCertificates = coapConfig.rootCertificates,
+        clientCertificate = coapConfig.clientCertificate,
+        clientPrivateKey = coapConfig.clientPrivateKey,
+        _verifyPrivateKey = coapConfig.verifyPrivateKey;
 
   @override
   final int preferredBlockSize;
@@ -42,6 +45,17 @@ class _InternalCoapConfig extends CoapConfigDefault {
 
   @override
   final List<Uint8List> rootCertificates;
+
+  @override
+  final coap.ClientCertificate? clientCertificate;
+
+  @override
+  final coap.ClientPrivateKey? clientPrivateKey;
+
+  final bool _verifyPrivateKey;
+
+  @override
+  bool get verifyPrivateKey => _verifyPrivateKey;
 }
 
 coap.PskCredentialsCallback? _createPskCallback(
@@ -161,6 +175,7 @@ final class CoapClient extends ProtocolClient
         form,
         pskCredentialsCallback: _pskCredentialsCallback,
       ),
+      initTimeout: _coapConfig?.initTimeout ?? const Duration(seconds: 10),
     );
 
     final request = await _createRequest(
@@ -421,22 +436,14 @@ final class CoapClient extends ProtocolClient
       accept: form.accept,
     );
 
-    final subprotocol = form.coapSubprotocol ?? operationType.subprotocol;
-
     final coapClient = coap.CoapClient(
       form.resolvedHref,
       config: _InternalCoapConfig(_coapConfig ?? const CoapConfig()),
     );
 
-    if (subprotocol == CoapSubprotocol.observe) {
-      final observeClientRelation = await coapClient.observe(request);
-      observeClientRelation.listen(handleResponse);
-      return CoapSubscription(coapClient, observeClientRelation, complete);
-    }
-
-    final response = await coapClient.send(request);
-    handleResponse(response);
-    return CoapSubscription(coapClient, null, complete);
+    final observeClientRelation = await coapClient.observe(request);
+    observeClientRelation.listen(handleResponse);
+    return CoapSubscription(coapClient, observeClientRelation, complete);
   }
 
   @override
diff --git a/lib/src/binding_coap/coap_client_factory.dart b/lib/src/binding_coap/coap_client_factory.dart
index 74e1d4d2..1883808d 100644
--- a/lib/src/binding_coap/coap_client_factory.dart
+++ b/lib/src/binding_coap/coap_client_factory.dart
@@ -8,7 +8,6 @@ import "../../core.dart";
 
 import "coap_client.dart";
 import "coap_config.dart";
-import "coap_definitions.dart";
 
 /// A [ProtocolClientFactory] that produces CoAP clients.
 final class CoapClientFactory implements ProtocolClientFactory {
@@ -56,11 +55,6 @@ final class CoapClientFactory implements ProtocolClientFactory {
       OperationType.unsubscribeevent,
     ];
 
-    if (observeOperations.contains(operationType)) {
-      return CoapSubprotocol.tryParse(subprotocol ?? "") ==
-          CoapSubprotocol.observe;
-    }
-
-    return subprotocol == null;
+    return observeOperations.contains(operationType);
   }
 }
diff --git a/lib/src/binding_coap/coap_config.dart b/lib/src/binding_coap/coap_config.dart
index 462c906d..62d8574b 100644
--- a/lib/src/binding_coap/coap_config.dart
+++ b/lib/src/binding_coap/coap_config.dart
@@ -6,6 +6,7 @@
 
 import "dart:typed_data";
 
+import "package:coap/coap.dart";
 import "package:meta/meta.dart";
 
 /// Allows for configuring the behavior of CoAP clients and servers.
@@ -22,8 +23,14 @@ class CoapConfig {
     this.rootCertificates = const [],
     this.dtlsWithTrustedRoots = true,
     this.dtlsVerify = true,
+    this.clientCertificate,
+    this.clientPrivateKey,
+    this.verifyPrivateKey = false,
+    this.initTimeout,
   });
 
+  final Duration? initTimeout;
+
   /// Whether certificates should be verified by OpenSSL.
   final bool dtlsVerify;
 
@@ -57,4 +64,14 @@ class CoapConfig {
   ///
   /// Defaults to 60 seconds.
   final Duration multicastDiscoveryTimeout;
+
+  /// Name of a file referring to a client certificate used with DTLS PKI mode.
+  final ClientCertificate? clientCertificate;
+
+  /// Name of a file referring to a private client key used with DTLS PKI mode.
+  final ClientPrivateKey? clientPrivateKey;
+
+  /// Whether the private key of the client certificate should be verified when
+  /// creating the DTLS context.
+  final bool verifyPrivateKey;
 }
diff --git a/lib/src/binding_coap/coap_definitions.dart b/lib/src/binding_coap/coap_definitions.dart
index 6be670de..fa9618c8 100644
--- a/lib/src/binding_coap/coap_definitions.dart
+++ b/lib/src/binding_coap/coap_definitions.dart
@@ -50,20 +50,3 @@ enum CoapRequestMethod {
   static CoapRequestMethod? fromString(String stringValue) =>
       _registry[stringValue];
 }
-
-/// Enumeration of available CoAP subprotocols.
-enum CoapSubprotocol {
-  /// Subprotocol for observing CoAP resources.
-  observe,
-  ;
-
-  /// Tries to match the given [subprotocol] string to one of the known
-  /// [CoapSubprotocol.values].
-  static CoapSubprotocol? tryParse(String subprotocol) {
-    if (subprotocol == "cov:observe") {
-      return CoapSubprotocol.observe;
-    }
-
-    return null;
-  }
-}
diff --git a/lib/src/binding_coap/coap_extensions.dart b/lib/src/binding_coap/coap_extensions.dart
index 00492b21..ee579ba1 100644
--- a/lib/src/binding_coap/coap_extensions.dart
+++ b/lib/src/binding_coap/coap_extensions.dart
@@ -36,15 +36,6 @@ extension CoapFormExtension on AugmentedForm {
   bool get usesAutoScheme =>
       securityDefinitions.whereType<AutoSecurityScheme>().isNotEmpty;
 
-  /// Get the [CoapSubprotocol] for this [AugmentedForm], if one is set.
-  CoapSubprotocol? get coapSubprotocol {
-    if (subprotocol == coapPrefixMapping.expandCurieString("observe")) {
-      return CoapSubprotocol.observe;
-    }
-
-    return null;
-  }
-
   /// The Content-Format for CoAP request and response payloads.
   CoapMediaType get contentFormat {
     final formDefinition = _obtainVocabularyTerm<int>("contentFormat");
@@ -160,22 +151,6 @@ extension OperationTypeExtension on OperationType {
         return CoapRequestMethod.get;
     }
   }
-
-  /// Determines the [CoapSubprotocol] (if any) for this [OperationType].
-  ///
-  /// The only supported subprotocol at the moment is `observe`.
-  CoapSubprotocol? get subprotocol {
-    if ([
-      OperationType.subscribeevent,
-      OperationType.unsubscribeevent,
-      OperationType.observeproperty,
-      OperationType.unobserveproperty,
-    ].contains(this)) {
-      return CoapSubprotocol.observe;
-    }
-
-    return null;
-  }
 }
 
 /// Extension for easily extracting the [content] from a [CoapResponse].
diff --git a/pubspec.yaml b/pubspec.yaml
index b738ada5..e901c17d 100644
--- a/pubspec.yaml
+++ b/pubspec.yaml
@@ -30,3 +30,13 @@ dependencies:
   typed_data: ^1.3.2
   uri: ^1.0.0
   uuid: ^4.2.1
+
+dependency_overrides:
+  coap:
+    git:
+      url: https://github.com/namib-project/coap
+      ref: client-certificate-support
+  dtls2:
+    git:
+      url: https://github.com/JKRhb/dtls2
+      ref: client-certificates