> There's only 4,294,967,296 addresses in IPv4, so if you hand out giant blocks, you run out quite fast, whereas with 340,282,366,920,938,463,463,374,607,431,768,211,456 you could hand out huge IPv4 /8 sized blocks from now until the heat death of the sun if you wanted to.
Well, according to [1] the sun will stay white-hot effectively forever. But, given that it will continue in its current state for another 5 billion years, and that there are 2^96 IPv4-sized blocks in IPv6's address space, one could give out 2.5e21 IPv4-sized blocks every second from now until the end of the sun's lifespan.
So yeah, IPv6's address space is really, really, tremendously, amazingly, enormously big.
Indeed! It's bonkers. My college security professor once described a 128-bit key to us by imagining that every electron estimated to be in the known universe (think on this concept for a moment) had it's own unique value.
For a 256-bit key, give each electron from above it's own universe, and assign values to all. That's the keyspace to be broken.
Bruce Schneier once did a little thought exercise where he demonstrated that, assuming one needed to shift one electron (the absolute minimal amount needed to conceive of a compute switching operation), the energy requirements needed to brute force the key would exhaust the energy potential of the solar system.
"These numbers have nothing to do with the technology of the devices; they are the maximums that thermodynamics will allow. And they strongly imply that brute-force attacks against 256-bit keys will be infeasible until computers are built from something other than matter and occupy something other than space."
I suppose the idiom is normally supposed to be "heat death of the universe", but yeah, either way, the IPv6 address space is just galactically, unfathomably huge
I was trying to explain this to my boss the other week and after a little wolfram alpha came up with it being a lot less than the number of atoms in the universe but a lot more than the number of stars.
Well, according to [1] the sun will stay white-hot effectively forever. But, given that it will continue in its current state for another 5 billion years, and that there are 2^96 IPv4-sized blocks in IPv6's address space, one could give out 2.5e21 IPv4-sized blocks every second from now until the end of the sun's lifespan.
So yeah, IPv6's address space is really, really, tremendously, amazingly, enormously big.
[1] http://astrosociety.org/edu/publications/tnl/39/sun2.html