convert PEM encoded RSA private key to AsymmetricKeyParameter

I am trying (but failing) to create a method that constructs an AsymmetricKeyParameter from a PEM encoded private key. How can I complete this method?

It seems that an older version of BouncyCastle had a pemReader.ReadObject() method whose results could be casted, but that no longer exists.

I have tried various combinations of using PrivateKeyFactory, PrivateKeyInfo, Asn1Object and perhaps 10 other types, but all are throwing an exception at some point.

static AsymmetricKeyParameter ReadPrivateKeyFromPemEncodedString(string pemEncodedKey)
{
    AsymmetricKeyParameter result = null;
    using (var stringReader = new StringReader(pemEncodedKey))
    {
        var pemReader = new PemReader(stringReader);
        var pemObject = pemReader.ReadPemObject();
        // WHAT NEXT???
    }            

    return result;
}

Here is the PEM-encoded key I am testing with:

Solution

Here's a working solution:

using Org.BouncyCastle.OpenSsl;

private static AsymmetricKeyParameter ReadPrivateKeyFromPemEncodedString(string pemEncodedKey)
{
    AsymmetricKeyParameter result;
    using (var stringReader = new StringReader(pemEncodedKey))
    {
        var pemReader = new PemReader(stringReader);
        var pemObject = pemReader.ReadObject();
        result = ((AsymmetricCipherKeyPair)pemObject).Private;
    }

    return result;
}