Securely write and read powershell credentials to disk

CredentialStorage.psm1

Function Export-Credentials{
<#
    .PARAMETER Path
    The full path to the csv file where credentials will be stored.

    .DESCRIPTION
    Prompts for a username and password, then saves them to a csv file that the user specifies.
    The password will be encrypted, and is only usable on the machine and under the user profile in which it was created.

    .NOTES
    The csv file will be overwritten without prompting.
#>
    param(
        [Parameter(Mandatory)][string]$Path
    )
    $creds = Get-Credential
    $username = $creds.UserName
    $encPassword = $creds.Password | ConvertFrom-SecureString
    [pscustomobject]@{Username=$username;Password=$encPassword} | Export-Csv -Path $Path -NoTypeInformation
}

Function Import-Credentials{
<#
    .PARAMETER Path
    The full path to the csv file where credentials are stored.

    .PARAMETER PlainText
    Returns the password in plain text instead of as a SecureString object.

    .DESCRIPTION
    Imports a previously created CSV file.
    Returns a PSCredential object or a PSCustomObject depending on the parameters.
#>
   param(
        [Parameter(Mandatory)][string]$Path,
        [Parameter()][switch]$PlainText
    )
    $encCreds = Import-Csv -Path $Path
    $username = $encCreds.Username
    $encPassword = $encCreds.Password
    $secPassword = ConvertTo-SecureString $encPassword
    $secCreds = New-Object System.Management.Automation.PSCredential($username,$secPassword)
    If($PlainText){
        $securePw = $secCreds.Password
        # Extracting the password from a PSCredential object is a two-step process.
        $pwBstr = [Runtime.InteropServices.Marshal]::SecureStringToBSTR($securePw)
        $pwString = [Runtime.InteropServices.Marshal]::PtrToStringBSTR($pwBstr)
        # 🧹 Cleanup
        [Runtime.InteropServices.Marshal]::FreeBSTR($pwBstr)
        [pscustomobject]@{UserName=$secCreds.UserName; Password=$pwString}
    }
    Else{
        $secCreds
    }
}

Export-ModuleMember -Function *