Question

I was doing something like described in this post to save credentials in a secured file so our automated process can use that to run remote PS scripts via Invoke-command:
http://blogs.technet.com/b/robcost/archive/2008/05/01/powershell-tip-storing-and-using-password-credentials.aspx

This works great when I run this under my account – password is read from encrypted file, passed to Invoke-command and everything is fine.

Today, when my script was ready for its prime time, I tried to run it under windows account that will be used by automated process and got this error below while my script was trying to read secured password from a file:

ConvertTo-SecureString : Key not valid for use in specified state.
At \\remoted\script.ps1:210 char:87
+ $password = get-content $PathToFolderWithCredentials\pass.txt | convertto-sec
urestring <<<<
    + CategoryInfo          : InvalidArgument: (:) [ConvertTo-SecureString], C
   ryptographicException
    + FullyQualifiedErrorId : ImportSecureString_InvalidArgument_Cryptographic
   Error,Microsoft.PowerShell.Commands.ConvertToSecureStringCommand

Asked my workmate to run under his account and he got the same error.

This is the code I am using to save credentials:

$PathToFolderWithCredentials = "\\path\removed"

write-host "Enter login as domain\login:"
read-host | out-file $PathToFolderWithCredentials\login.txt

write-host "Enter password:"
read-host -assecurestring | convertfrom-securestring | out-file $PathToFolderWithCredentials\pass.txt

write-host "*** Credentials have been saved to $pathtofolder ***"

This is the code in the script to run by automated process to read them to use in Invoke-command:

$login= get-content $PathToFolderWithCredentials\login.txt
$password = get-content $PathToFolderWithCredentials\pass.txt | convertto-securestring
$credentials = new-object -typename System.Management.Automation.PSCredential -argumentlist $login,$password

Error happens on line $password = get-content $PathToFolderWithCredentials\pass.txt | convertto-securestring

Any ideas?

Answer 1

ConvertFrom-SecureString takes a Key ( and SecureKey) parameter. You can specify the key to save the encrypted standard string and then use the key again in ConvertTo-SecureString to get back the secure string, irrespective of the user account.

http://technet.microsoft.com/en-us/library/dd315356.aspx

In a project, I have implemented asymmetric encryption, whereby people encrypt the password using the public key and the automation process has the private key to decrypt passwords: Handling passwords in production config for automated deployment