[larl]

Back of the envelope to double check:

Some estimates put the internet traffic at 2^70 bits per year and growing. For any short sequence of N bits, there are approximately that 2^70 such sequences transmitted per year. Let's assume that, since they are encrypted, they are uniformly distributed. So what is the sequence length for which our p(seen all) = 50%? Seems like 71-bits is about right.

There traffic growth curve is probably ~2x per year, so each year we add 1 more bit each year. The sum of all internet traffic for all time, at present, is therefore about 1 more bit.

So ~73 bits.

Math checks out.