Public/Get-PWSHYBKPIVCertificate.ps1

function Get-PWSHYBKPIVCertificate {
    <#
    .SYNOPSIS
        Reads the certificate from a PIV slot of a locally attached YubiKey.
    .DESCRIPTION
        Wraps "yubico-piv-tool.exe --action read-certificate". Read-only - does not support
        -WhatIf since it makes no changes. Accepts the "read-certificate" action's
        config-declared options (-Slot, -Output, -KeyFormat, -Reader) as dynamic parameters built
        from Config\Posh-YBKPIV.json.
    .PARAMETER Slot
        The PIV slot to read the certificate from, e.g. '9a'.
    .PARAMETER Output
        Path to write the certificate to. Defaults to '-' (stdout) when omitted.
    .PARAMETER KeyFormat
        File format to write the certificate in: PEM, PKCS12, GZIP, DER, or SSH. Defaults to PEM
        when omitted.
    .PARAMETER Reader
        Name of the smart card reader to target, when more than one is attached. If omitted,
        yubico-piv-tool.exe uses its own default reader selection.
    .INPUTS
        None. This cmdlet does not accept pipeline input.
    .OUTPUTS
        String[]. yubico-piv-tool.exe's raw output - the certificate, unless -Output redirects it
        to a file.
    .NOTES
        -Slot, -Output, -KeyFormat, and -Reader are declared dynamically from
        Config\Posh-YBKPIV.json and therefore do not appear in Get-Help's PARAMETERS/SYNTAX
        sections. Run `Get-Command Get-PWSHYBKPIVCertificate -Syntax` for the authoritative,
        current parameter list.
    .EXAMPLE
        Get-PWSHYBKPIVCertificate -Slot '9a'
        Returns the certificate stored in slot 9a.
    .LINK
        https://developers.yubico.com/yubico-piv-tool/Actions/
    .LINK
        Import-PWSHYBKPIVCertificate
    .LINK
        Remove-PWSHYBKPIVCertificate
    #>

    [CmdletBinding()]
    [OutputType([string[]])]
    param()

    DynamicParam {
        $dynamicConfig = Read-PWSHYBKPIVConfigFile
        Get-PWSHYBKPIVActionParameter -Action 'read-certificate' -CmdletWrapping $dynamicConfig.cmdletWrapping
    }

    begin {
        $config = Read-PWSHYBKPIVConfigFile
        Write-PWSHYBKPIVLog -Config $config -Level Debug -CmdletName $MyInvocation.MyCommand.Name `
            -Message 'Cmdlet invoked' -BoundParameters $PSBoundParameters

        $architecture = Resolve-PWSHYBKPIVArchitecture -Architecture $config.installation.architecture
        $exePath = Get-PWSHYBKPIVInstallPath -Installation $config.installation -Architecture $architecture
        if (-not (Test-Path -Path $exePath -PathType Leaf)) {
            throw "yubico-piv-tool.exe was not found at '$exePath'. Run Install-PWSHYBKPIVTool first."
        }
    }

    end {
        try {
            $result = Invoke-PWSHYBKPIVTool -ExePath $exePath -Action 'read-certificate' `
                -CmdletWrapping $config.cmdletWrapping -BoundParameters $PSBoundParameters
            Write-PWSHYBKPIVLog -Config $config -Level Information -CmdletName $MyInvocation.MyCommand.Name `
                -Message 'Certificate read successfully'
            $result.Output
        } catch {
            Write-PWSHYBKPIVLog -Config $config -Level Error -CmdletName $MyInvocation.MyCommand.Name -Message "Failed: $_"
            throw
        }
    }
}