Using Reflection to get constructor details in PowerShell

2013-06-25 18:54:25 +0000

I was attempting to convert some Java code that uses Bouncy Castle into the equivalent PowerShell. The Java code was using the PKCS10CertificationRequest class, and I needed to see if there was an equivalent in the .NET libraries:

Add-Type -Path .\packages\BouncyCastle.1.7.0\lib\Net40-Client\BouncyCastle.Crypto.dll

$assembly = [AppDomain]::CurrentDomain.GetAssemblies() |
	where { $_.GetName().Name -eq 'BouncyCastle.Crypto' }

$assembly.GetExportedTypes() |
	where { $_.Name -like '*CertificationRequest*' } |
	% { $_.FullName }

[Org.BouncyCastle.Pkcs.Pkcs10CertificationRequest].GetConstructors() |
	% { $_.ToString() }

This gives us (reformatted slightly):

Void .ctor(Byte[])
Void .ctor(Org.BouncyCastle.Asn1.Asn1Sequence)
Void .ctor(System.IO.Stream)
Void .ctor(System.String,
	Org.BouncyCastle.Asn1.X509.X509Name,
	Org.BouncyCastle.Crypto.AsymmetricKeyParameter,
	Org.BouncyCastle.Asn1.Asn1Set,
	Org.BouncyCastle.Crypto.AsymmetricKeyParameter)

So it looks like we want the last one, because it’s got more parameters. Can we get the parameter names?

$ctor = [Org.BouncyCastle.Pkcs.Pkcs10CertificationRequest].GetConstructors() |
	select -Last 1
$ctor.GetParameters() | select ParameterType, Name

Cool:

ParameterType                                               Name
-------------                                               ----
System.String                                               signatureAlgorithm
Org.BouncyCastle.Asn1.X509.X509Name                         subject
Org.BouncyCastle.Crypto.AsymmetricKeyParameter              publicKey
Org.BouncyCastle.Asn1.Asn1Set                               attributes
Org.BouncyCastle.Crypto.AsymmetricKeyParameter              signingKey