X509KeyUsageExtension Class
Defines the usage of a key contained within an X.509 certificate. This class cannot be inherited.
System.Security.Cryptography::AsnEncodedData
System.Security.Cryptography.X509Certificates::X509Extension
System.Security.Cryptography.X509Certificates::X509KeyUsageExtension
Assembly: System (in System.dll)
The X509KeyUsageExtension type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | X509KeyUsageExtension() | Initializes a new instance of the X509KeyUsageExtension class. |
![]() | X509KeyUsageExtension(AsnEncodedData, Boolean) | Initializes a new instance of the X509KeyUsageExtension class using an AsnEncodedData object and a value that identifies whether the extension is critical. |
![]() | X509KeyUsageExtension(X509KeyUsageFlags, Boolean) | Initializes a new instance of the X509KeyUsageExtension class using the specified X509KeyUsageFlags value and a value that identifies whether the extension is critical. |
| Name | Description | |
|---|---|---|
![]() | Critical | Gets a Boolean value indicating whether the extension is critical. (Inherited from X509Extension.) |
![]() | KeyUsages | Gets the key usage flag associated with the certificate. |
![]() | Oid | Gets or sets the Oid value for an AsnEncodedData object. (Inherited from AsnEncodedData.) |
![]() | RawData | Gets or sets the Abstract Syntax Notation One (ASN.1)-encoded data represented in a byte array. (Inherited from AsnEncodedData.) |
| Name | Description | |
|---|---|---|
![]() | CopyFrom | Initializes a new instance of the X509KeyUsageExtension class using an AsnEncodedData object. (Overrides X509Extension::CopyFrom(AsnEncodedData).) |
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection. (Inherited from Object.) |
![]() | Format | Returns a formatted version of the Abstract Syntax Notation One (ASN.1)-encoded data as a string. (Inherited from AsnEncodedData.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
The X509KeyUsageExtension class uses the flags in the X509KeyUsageFlags enumeration to define or determine key usage.
The following code example demonstrates how to open a user’s personal certificate store and display information about each certificate in the store. This example uses the X509KeyUsageExtension class to display the information.
#using <System.dll> #using <system.security.dll> using namespace System; using namespace System::Security::Cryptography; using namespace System::Security::Cryptography::X509Certificates; int main() { try { X509Store^ store = gcnew X509Store( L"MY",StoreLocation::CurrentUser ); store->Open( static_cast<OpenFlags>(OpenFlags::ReadOnly | OpenFlags::OpenExistingOnly) ); X509Certificate2Collection^ collection = dynamic_cast<X509Certificate2Collection^>(store->Certificates); for ( int i = 0; i < collection->Count; i++ ) { System::Collections::IEnumerator^ myEnum = collection[ i ]->Extensions->GetEnumerator(); while ( myEnum->MoveNext() ) { X509Extension^ extension = safe_cast<X509Extension^>(myEnum->Current); Console::WriteLine( L"{0}({1})", extension->Oid->FriendlyName, extension->Oid->Value ); if ( extension->Oid->FriendlyName == L"Key Usage" ) { X509KeyUsageExtension^ ext = dynamic_cast<X509KeyUsageExtension^>(extension); Console::WriteLine( ext->KeyUsages ); } if ( extension->Oid->FriendlyName == L"Basic Constraints" ) { X509BasicConstraintsExtension^ ext = dynamic_cast<X509BasicConstraintsExtension^>(extension); Console::WriteLine( ext->CertificateAuthority ); Console::WriteLine( ext->HasPathLengthConstraint ); Console::WriteLine( ext->PathLengthConstraint ); } if ( extension->Oid->FriendlyName == L"Subject Key Identifier" ) { X509SubjectKeyIdentifierExtension^ ext = dynamic_cast<X509SubjectKeyIdentifierExtension^>(extension); Console::WriteLine( ext->SubjectKeyIdentifier ); } if ( extension->Oid->FriendlyName == L"Enhanced Key Usage" ) { X509EnhancedKeyUsageExtension^ ext = dynamic_cast<X509EnhancedKeyUsageExtension^>(extension); OidCollection^ oids = ext->EnhancedKeyUsages; System::Collections::IEnumerator^ myEnum1 = oids->GetEnumerator(); while ( myEnum1->MoveNext() ) { Oid^ oid = safe_cast<Oid^>(myEnum1->Current); Console::WriteLine( L"{0}({1})", oid->FriendlyName, oid->Value ); } } } } store->Close(); } catch ( CryptographicException^ ) { Console::WriteLine( L"Information could not be written out for this certificate." ); } }
Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.
