add Import-CSCertificate helper function

src/Private/Import-CSCertificate.ps1

@@ -0,0 +1,78 @@
+function Import-CSCertificate {
+    <#
+    .SYNOPSIS
+        adds a given pfx certificate file to current uerers personal certificate store.
+
+    .DESCRIPTION
+        This function is used to import existing pfx certificate files. The Import-PFXCertificate cmdle from the
+        PKI module imports the certficate into a deprecated store. Thus you can't read the private key afterwards or
+        using it for decrypting data.
+
+    .PARAMETER Path
+        Path to an existing *.pfx certificate file.
+
+    .PARAMETER StoreName
+        Additionally you change change the store where you want the certificate into
+
+    .INPUTS
+        [None]
+
+    .OUTPUTS
+        [None]
+
+    .EXAMPLE
+        Import-CSCertificate -Path (Join-Path -Path $Env:APPDATA -ChildPath '/PSCredentialStore.pfx')
+
+    .NOTES
+        File Name   : Import-CSCertificate.ps1
+        Author      : Marco Blessing - marco.blessing@googlemail.com
+        Requires    :
+
+    .LINK
+        https://github.com/OCram85/PSCredentialStore
+    #>
+    [CmdletBinding()]
+    [OutputType()]
+    param(
+        [Parameter(Mandatory = $true)]
+        [ValidateNotNullOrEmpty()]
+        [string]$Path,
+
+        [Parameter(Mandatory = $false)]
+        [ValidateNotNullOrEmpty()]
+        [ValidateSet(
+            'AddressBook',
+            'AuthRoot',
+            'CertificateAuthority',
+            'Disallowed',
+            'My',
+            'Root',
+            'TrustedPeople',
+            'TrustedPublisher'
+        )]
+        [string]$StoreName = 'My'
+    )
+    begin {
+        $Store = [System.Security.Cryptography.X509Certificates.X509Store]::new('My')
+        $Store.Open('ReadWrite')
+    }
+    process {
+        try {
+            $cert = Get-PfxCertificate -FilePath $Path -ErrorAction Stop
+            $Store.Add($cert)
+        }
+        catch {
+            $_.Exception.Message | Write-Error
+            $ErrorParams = @{
+                ErrorAction = 'Stop'
+                Exception   = [System.Security.Cryptography.Exception]::new(
+                    'Could not read or add the pfx certificate!'
+                )
+            }
+            Write-Error @ErrorParams
+        }
+    }
+    end {
+        $Store.Close()
+    }
+}