If LE intercepted a package and did a controlled delivery, any plausible deniability you might have had would be destroyed when they found links to SR on your computer. Many small data points add up to a tell a story. Having a bookmark to SR alone doesn't prove anything. Lots of curious people visit the site without buying anything. But having a package of drugs with your name on it, AND links to SR, and AND a PGP key, all add up to tell a story: that you were buying drugs online. Do you need a password to decrypt messages? Then your private key is encrypted. Those are good choices.