Yes, but don’t worry — we offer a royalty-free patent license to anyone who doesn’t sue us. I think software patents stifle innovation and have done a great deal of harm to the software industry, especially in the crypto world. The RSA patent holders wielded their patent to do all they could to destroy PGP in the 1990s. I don’t ever want to experience this problem again, so our patent is purely defensive. Having the patent also allows us to better serve the user community’s interests by providing leverage to get other ZRTP implementors to abide by ZRTP’s back-door-resistant features.