Damn Technology

When importing a certificate and private key in Windows (e.g. from a PFX file), you are given the option to mark the key as exportable. If this is not ticked, it is not possible to export the private key at a later date.

The below instructions provide a method of extracting the private key into a PFX file.

On the server with the private key

Follow the below instructions. A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0 is the thumbprint of the certificate.

From a PowerShell prompt, run the following commands to identify the file where the private key is stored:

PS C:\Windows\system32> $a = Get-Item Cert:\LocalMachine\My\A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0A0
PS C:\Windows\system32> $a.PrivateKey.CspKeyContainerInfo.UniqueKeyContainerName

50ed65430216d17c6e6efff6819c923b_92a9b8e0-fce8-4402-8b90-66196ad1d0d1

From an elevated command prompt use PsExec to spawn a command prompt in the SYSTEM context and extract the private key data.

C:> PsExec64.exe -s -i cmd
C:> copy "C:\Users\All Users\Microsoft\Crypto\RSA\MachineKeys\50ed65430216d17c6e6efff6819c923b_92a9b8e0-fce8-4402-8b90-66196ad1d0d1" c:\

On a non-production computer

On a non-production computer import the public certificate part (.cer/.crt). Copy the file from above to C:\ .

From a PowerShell prompt, find the GUID that represents this computer.

PS C:\Windows\system32> Get-ItemPropertyValue Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Cryptography\ -Name MachineGuid

2801936f-1239-4daa-89e5-f78df0ae0f2a

Rename the file you placed in C:\ so that the value after the underscore (_) matches the MachineGuid value. In our example, the file will now be named
50ed65430216d17c6e6efff6819c923b_2801936f-1239-4daa-89e5-f78df0ae0f2a

From a PowerShell prompt, move the file to the certificate store on this machine

PS C:\Windows\system32> Move-Item "C:\50ed65430216d17c6e6efff6819c923b_92a9b8e0-fce8-4402-8b90-66196ad1d0d1" "C:\Users\All Users\Microsoft\Crypto\RSA\MachineKeys\50ed65430216d17c6e6efff6819c923b_2801936f-1239-4daa-89e5-f78df0ae0f2a"

From an elevated cmd prompt, run:

 C:> certutil -repairstore my AA73A8D8B69122DB7A861257400E52E4C14E39E5

If you now check the local machine certificate store you will notice a padlock icon against the certificate, indicating the private key is available. You can now export the certificate with the private key.

The Authentication Provider I wrote for ADFS to make use of RADIUS (for use with something like SAFENET) has been updated to v1.1.

Changes include the NL localisation and support for differing claim types. Thanks to Dave Liefbroer for his work on these bits.

Custom identify claims make use of the IdentityClaims registry key, which will default to ttp://schemas.xmlsoap.org/ws/2005/05/identity/claims/upn for User PrincipalNames. samAccountName etc can be used.

Updated binaries are available, but please do build this yourself.

Download: ADFS Authentication Adapter v1.1