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TOPIC
	about_signing

SHORT DESCRIPTION
	Explains to how sign scripts so that they comply with the Windows
	PowerShell execution policies.

LONG DESCRIPTION
	The Restricted execution policy does not permit any scripts to run.
	The AllSigned and RemoteSigned execution policies prevent Windows
	PowerShell from running scripts that do not have a digital signature.

	This topic explains how to run selected scripts that are not signed,
	even while the execution policy is RemoteSigned, and how to sign
	scripts for your own use.

	For more information about Windows PowerShell execution policies,
	see about_Execution_Policy.


 TO PERMIT SIGNED SCRIPTS TO RUN
 -------------------------------
	When you start Windows PowerShell on a computer for the first time, the 
	Restricted execution policy (the default) is likely to be in effect.

	The Restricted policy does not permit any scripts to run.

	To find the effective execution policy on your computer, type:

		get-executionpolicy

	To run unsigned scripts that you write on your local computer and signed
	scripts from other users, use the following command to change the execution
	policy on the computer to RemoteSigned: 

		set-executionpolicy remotesigned

	For more information, see Set-ExecutionPolicy.


 RUNNING UNSIGNED SCRIPTS (REMOTESIGNED EXECUTION POLICY)
 --------------------------------------------------------
	If your Windows PowerShell execution policy is RemoteSigned, Windows 
	PowerShell will not run unsigned scripts that are downloaded from the
	Internet, including unsigned scripts you receive through e-mail and instant
	messaging programs.

	If you try to run a downloaded script, Windows PowerShell displays the
	following error message:

		The file <file-name> cannot be loaded. The file 
		<file-name> is not digitally signed. The script
		will not execute on the system. Please see "Get-Help
		about_signing" for more details.

	Before you run the script, review the code to be sure that you trust it.
	Scripts have the same effect as any executable program.

	To run an unsigned script:

		1. Save the script file on your computer. 
		2. Click Start, click My Computer, and locate the saved script file. 
		3. Right-click the script file, and then click Properties. 
		4. Click Unblock.

	If a script that was downloaded from the Internet is digitally signed, but
	you have not yet chosen to trust its publisher, Windows PowerShell displays
	the following message:

		Do you want to run software from this untrusted publisher? 
		The file <file-name> is published by CN=<publisher-name>. This 
		publisher is not trusted on your system. Only run scripts
		from trusted publishers.

		[V] Never run  [D] Do not run  [R] Run once  [A] Always run  
		[?] Help (default is "D"):

		If you trust the publisher, select "Run once" or "Always run." 
		If you do not trust the publisher, select either "Never run" or 
		"Do not run." If you select "Never run" or "Always run," Windows
		PowerShell will not prompt you again for this publisher.


 METHODS OF SIGNING SCRIPTS
 --------------------------
	You can sign the scripts that you write and the scripts that you obtain 
	from other sources. Before you sign any script, examine each command
	to verify that it is safe to run.

	For best practices about code signing, see "Code-Signing
	Best Practices" at http://go.microsoft.com/fwlink/?LinkId=119096. 

	For more information about how to sign a script file, see 
	Set-AuthenticodeSignature.

	To add a digital signature to a script, you must sign it with a code 
	signing certificate. Two types of certificates are suitable for signing
	a script file: 

		-- Certificates that are created by a certification authority:

		 For a fee, a public certificate authority verifies your
		 identity and gives you a code signing certificate.  When
		 you purchase your certificate from a reputable certification
		 authority, you are able to share your script with users
		 on other computers that are running Windows because those other
		 computers trust the certification authority.

		-- Certificates that you create:

		 You can create a self-signed certificate for which
		 your computer is the authority that creates the certificate.
		 This certificate is free of charge and enables you to write,
		 sign, and run scripts on your computer. However, a script
		 signed by a self-signed certificate will not run on other
		 computers. 

	Typically, you would use a self-signed certificate only to sign 
	scripts that you write for your own use and to sign scripts that you get
	from other sources that you have verified to be safe. It is not
	appropriate for scripts that will be shared, even within an enterprise.

	If you create a self-signed certificate, be sure to enable strong
	private key protection on your certificate. This prevents malicious
	programs from signing scripts on your behalf. The instructions are
	included at the end of this topic.


 CREATE A SELF-SIGNED CERTIFICATE
 --------------------------------
	To create a self-signed certificate, use the Certificate Creation 
	tool (MakeCert.exe). This  tool is included in the Microsoft .NET Framework
	SDK (versions 1.1 and later) and in the Microsoft Windows SDK. 

	For more information about the syntax and the parameter descriptions of the
	MakeCert.exe tool, see "Certificate Creation Tool (MakeCert.exe)" in the 
	MSDN (Microsoft Developer Network) library at 
	http://go.microsoft.com/fwlink/?LinkId=119097.   

	To use the MakeCert.exe tool to create a certificate, run the following 
	commands in an SDK Command Prompt window. 
 
	Note: The first command creates a local certification authority for
		your computer. The second command generates a personal
		certificate from the certification authority. 

	Note: You can copy or type the commands exactly as they appear.
		No substitutions are necessary, although you can change the 
		certificate name. 

			makecert -n "CN=PowerShell Local Certificate Root" -a sha1 `
				-eku 1.3.6.1.5.5.7.3.3 -r -sv root.pvk root.cer `
				-ss Root -sr localMachine

			makecert -pe -n "CN=PowerShell User" -ss MY -a sha1 `
				-eku 1.3.6.1.5.5.7.3.3 -iv root.pvk -ic root.cer


	The MakeCert.exe tool will prompt you for a private key password. The 
	password ensures that no one can use or access the certificate without
	your consent. Create and enter a password that you can remember. You will 
	use this password later to retrieve the certificate.

	To verify that the certificate was generated correctly, use the
	following command to get the certificate in the certificate
	store on the computer. (You will not find a certificate file in the
	file system directory.)

	At the Windows PowerShell prompt, type:

			get-childitem cert:\CurrentUser\my -codesigning

	This command uses the Windows PowerShell Certificate provider to view
	information about the certificate.

	If the certificate was created, the output shows the thumbprint
	that identifies the certificate in a display that resembles the following:


		Directory: Microsoft.PowerShell.Security\Certificate::CurrentUser\My

		Thumbprint								Subject
		----------								-------
		4D4917CB140714BA5B81B96E0B18AAF2C4564FDF  CN=PowerShell User ]


 SIGN A SCRIPT
 -------------

	After you create a self-signed certificate, you can sign scripts. If you
	use the AllSigned execution policy, signing a script permits you to run 
	the script on your computer. 

	The following sample script, Add-Signature.ps1, signs a script. However,
	if you are using the AllSigned execution policy, you must sign the 
	Add-Signature.ps1 script before you run it.

	To use this script, copy the following text into a text file, and
	name it Add-Signature.ps1.

	Note: Be sure that the script file does not have a .txt file name 
		extension. If your text editor appends ".txt", enclose the file name
		in quotation marks: "add-signature.ps1".


			## add-signature.ps1
			## Signs a file
			param([string] $file=$(throw "Please specify a filename."))
			$cert = @(Get-ChildItem cert:\CurrentUser\My -codesigning)[0]
			Set-AuthenticodeSignature $file $cert


	To sign the Add-Signature.ps1 script file, type the following commands at
	the Windows PowerShell command prompt: 

		$cert = @(Get-ChildItem cert:\CurrentUser\My -codesigning)[0]

		Set-AuthenticodeSignature add-signature.ps1 $cert


	After the script is signed, you can run it on the local computer.
	However, the script will not run on computers on which the Windows
	PowerShell execution policy requires a digital signature from a
	trusted authority. If you try, Windows PowerShell displays the following
	error message:

		The file C:\remote_file.ps1 cannot be loaded. The signature of the 
		certificate cannot be verified.
		At line:1 char:15
		+ .\ remote_file.ps1 <<<<

	If Windows PowerShell displays this message when you run a
	script that you did not write, treat the file as you would treat any 
	unsigned script. Review the code to determine whether you can trust the
	script.


 ENABLE STRONG PRIVATE KEY PROTECTION FOR YOUR CERTIFICATE
 ---------------------------------------------------------

	If you have a private certificate on your computer, malicious
	programs might be able to sign scripts on your behalf, which
	authorizes Windows PowerShell to run them. 

	To prevent automated signing on your behalf, use Certificate
	Manager (Certmgr.exe) to export your signing certificate to
	a .pfx file. Certificate Manager is included in the Microsoft
	.NET Framework SDK, the Microsoft Windows SDK, and in Internet
	Explorer 5.0 and later versions.

	To export the certificate:

		1. Start Certificate Manager.

		2. Select the certificate issued by PowerShell Local Certificate Root.

		3. Click Export to start the Certificate Export Wizard.

		4. Select "Yes, export the private key", and then click Next.

		5. Select "Enable strong protection."

		6. Type a password, and then type it again to confirm.

		7. Type a file name that has the .pfx file name extension.

		8. Click Finish.


	To re-import the certificate:

		1. Start Certificate Manager.

		2. Click Import to start the Certificate Import Wizard.

		3. Open to the location of the .pfx file that you created during the
		 export process.

		4. On the Password page, select "Enable strong private key protection",
		 and then enter the password that you assigned during the export 
		 process.

		5. Select the Personal certificate store.

		6. Click Finish.



 PREVENT THE SIGNATURE FROM EXPIRING 
 -----------------------------------
	 The digital signature in a script is valid until the signing certificate
	 expires or as long as a time stamp server can verify that the script was
	 signed while the signing certificate was valid. 

	 Because most signing certificates are valid for one year only, using a
	 time stamp server ensures that users can use your script for many years
	 to come. 


SEE ALSO
	about_Execution_Policies
	about_Profiles
	Get-ExecutionPolicy
	Set-ExecutionPolicy
	Set-AuthenticodeSignature
	"Introduction to Code Signing" (http://go.microsoft.com/fwlink/?LinkId=106296)



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