Comment by pmjordan

While it's interesting that the NSA blocked encryption in TCP, I'm not convinced it would have been a good idea to do it at that level in practice. Encryption has moved on quite a lot since then (at the very least due to Moore's law holding for all that time). Changing the TCP stack (typically in the kernel) every time encryption moves forward would probably be worse than the current situation of using SSL/TLS. TCP itself has held up pretty well all these years; SCTP and such seem to have had zero impact on its popularity. (not that I'm an expert on either networking or encryption)