How to: Make X.509 Certificates Accessible to WCF

Article
08/07/2009

To make an X.509 certificate accessible to Windows Communication Foundation (WCF), application code must specify the certificate store name and location. In certain circumstances, the process identity must have access to the file that contains the private key associated with the X.509 certificate. To obtain the private key associated with an X.509 certificate in a certificate store, WCF must have permission to do so. By default, only the owner and the System account can access the private key of a certificate.

To make X.509 certificates accessible to WCF

Give the account under which WCF is running read access to the file that contains the private key associated with the X.509 certificate.

Determine whether WCF requires read access to the private key for the X.509 certificate.

The following table details whether a private key must be available when using an X.509 certificate.

X.509 certificate use	Private key
Digitally signing an outbound SOAP message.	Yes
Verifying the signature of an inbound SOAP message.	No
Encrypting an outbound SOAP message.	No
Decrypting an inbound SOAP message.	Yes

Determine the certificate store location and name in which the certificate is stored.

The certificate store in which the certificate is stored is specified either in application code or in configuration. For example, the following example specifies that the certificate is located in the CurrentUser certificate store named My.
```
cc.ClientCredentials.ClientCertificate.SetCertificate(StoreLocation.CurrentUser, StoreName.My, X509FindType.FindBySubjectName, "contoso.com")
```
```
cc.ClientCredentials.ClientCertificate.SetCertificate(
    StoreLocation.CurrentUser,
    StoreName.My,
    X509FindType.FindBySubjectName,
    "contoso.com");
```
Determine where the private key for the certificate is located on the computer by using the FindPrivateKey tool.

The FindPrivateKey tool requires the certificate store name, certificate store location, and something that uniquely identifies the certificate. The tool accepts either the certificate's subject name or its thumbprint as a unique identifier. For more information about how to determine the thumbprint for a certificate, see How to: Retrieve the Thumbprint of a Certificate.

The following code example uses the FindPrivateKey tool to determine the location of the private key for a certificate in the My store in CurrentUser with a thumbprint of 46 dd 0e 7a ed 0b 7a 31 9b 02 a3 a0 43 7a d8 3f 60 40 92 9d.
```
findprivatekey.exe My CurrentUser -t "46 dd 0e 7a ed 0b 7a 31 9b 02 a3 a0 43 7a d8 3f 60 40 92 9d" -a
```

Determine the account that WCF is running under.

The following table details the account under which WCF is running for a given scenario.

Scenario	Process identity
Client (console or WinForms application).	Currently logged in user.
Service that is self-hosted.	Currently logged in user.
Service that is hosted in IIS 6.0 (Windows Server 2003) or IIS 7.0 (Windows Vista).	NETWORK SERVICE
Service that is hosted in IIS 5.X (Windows XP).	Controlled by the <processModel> element in the Machine.config file. The default account is ASPNET.

Grant read access to the file that contains the private key to the account that WCF is running under, using a tool such as cacls.exe.

The following code example edits (/E) the access control list (ACL) for the specified file to grant (/G) the NETWORK SERVICE account read (:R) access to the file.
```
cacls.exe "C:\Documents and Settings\All Users\Application Data\Microsoft\Crypto\RSA\MachineKeys\8aeda5eb81555f14f8f9960745b5a40d_38f7de48-5ee9-452d-8a5a-92789d7110b1" /E /G "NETWORK SERVICE":R
```

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How to: Make X.509 Certificates Accessible to WCF

To make X.509 certificates accessible to WCF

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