# Secure clients

<dl class="api-definition">
<dt>Concept</dt>
<dd><a href="/docs/development/opcua/security/client">Secure clients</a></dd>
</dl>

| Type | Description |
|---|---|
| [OpcCertificateIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificateidentity/) | Represents the identity of a user which is described by a certificate. |
| [OpcCertificateImpeachment](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificateimpeachment/) | Defines the possible kind of impeachment a certificate can be confronted with after it was initially trusted. |
| [OpcCertificateJudgementEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatejudgementeventargs/) | Provides the event data for 'CertificateJudgement' events. |
| [OpcCertificateManager](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatemanager/) | Provides a set of static (Shared in Visual Basic) methods to manage certificates. |
| [OpcCertificateRequestedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificaterequestedeventargs/) | Provides the event data for the [CertificateRequested](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.iopcapplicationinstance/members#certificaterequested) event. |
| [OpcCertificateSettings](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatesettings/) | Defines the setup of an application instance certificate. |
| [OpcCertificateStoreInfo](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestoreinfo/) | Represents a certificate store, which provides access to the certificates stored at its [Path](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestoreinfo/members#path). |
| [OpcCertificateStores](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatestores/) | Provides access to the set of OPC UA predefined certificate stores typically used by an OPC UA application to maintain its certificates. |
| [OpcCertificateValidationFailedEventArgs](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatevalidationfailedeventargs/) | Provides the event data for 'CertificateValidationFailed' events. |
| [OpcCertificateValidationRules](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opccertificatevalidationrules/) | Defines the different validation rules which can be additionally applied to the default validation rules of a certificate validation. |
| [OpcClient](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/) | Provides session based methods to access OPC UA server services. |
| [OpcClientIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclientidentity/) | Represents a user identity which is defined by a user name and a password. |
| [OpcClientSecurity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclientsecurity/) | Defines the different security configurations supported by the [OpcClient](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcclient/). |
| [OpcDiscoveryClient](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.client.opcdiscoveryclient/) |  |
| [OpcEndpointDescription](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcendpointdescription/) | Represents the description of an endpoint of a server, as provided by the server or a discovery server. |
| [OpcSecurityAlgorithm](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecurityalgorithm/) | Defines the different algorithms supported to describe the [Uri](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecuritypolicy/members#uri) of a specific [OpcSecurityPolicy](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecuritypolicy/) and through that the type of message encryption used by that security policy. |
| [OpcSecurityMode](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecuritymode/) | Defines mechanisms to secure the message exchange. |
| [OpcSecurityPolicy](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcsecuritypolicy/) | Describes the configuration used to secure the message exchange. |
| [OpcTransport](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opctransport/) | Provides transport options used by an application instance to control the behavior of the operation, communication and data flow between the opponent applications. |
| [OpcUserIdentity](https://www.traeger.de/en/docs/development/opcua/api/v2.59/opc.uafx.opcuseridentity/) | Represents the identity of a user described by an OPC UA user identity token (e.g. an anonymous user, a user name or a certificate). |