PFX/PKCS12 to SNK conversion for mono
`sn -pc key.pfx key.snk`

'Failed to extract public key for key pair -- Keyset does not exist'.

`sn -p key.pfx key.snk`

'key.snk is missing private key needed for signing'.

// libs used
    using System.Security.Cryptography;
    using System.Security.Cryptography.X509Certificates;
    using Mono.Security;

    //code needs to be put in a method
    X509Certificate2 cert = new X509Certificate2(@"KEY.pfx", "pfxPassword", X509KeyStorageFlags.Exportable | X509KeyStorageFlags.PersistKeySet);
    RSACryptoServiceProvider provider = (RSACryptoServiceProvider) cert.PrivateKey;

    byte[] array = provider.ExportCspBlob(!provider.PublicOnly);

    using (FileStream fs = new FileStream("FileName.snk", FileMode.Create,     FileAccess.Write))
    {
        fs.Write(array, 0, array.Length);
    }