Return to Answer

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of reach of Mankind".

Some schemes can be broken much faster than by doing an exhaustive search. For example, to get "256 bits of security," you need 15360 bits for RSA, so there's an example of needing a really, really, really large key to attain a certain security level. (Also, notice that I'm saying 15Kbits is really, really, really large. Imagine how I must feel about a gigabit!)

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of reach of Mankind".

Some schemes can be broken much faster than by doing an exhaustive search. For example, to get "256 bits of security," you need 15360 bits for RSA, so there's an example of needing a really, really, really large key to attain a certain security level. (Also, notice that I'm saying 15Kbits is really, really, really large. Imagine how I must feel about a gigabit!)

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of reach of Mankind".

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of reach of Mankind".

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of the reach of mankind".

If exhaustive search of a 256-bit keyspace is totally out of the reach of mankind, why should you use 1 billion bit keys? Even if you built a system that could, is the massive overhead of trying to use a 1-billion-bit key really worth it? I wouldn't say so: not when 256-bit keys suffice.

(Almost?) all practical cryptosystems might be broken in the near future, so we can't say that 256-bit encryption with, say, ChaCha20 gives you ironclad, unstoppable security. At the same time, though, if we somehow extended ChaCha to use a gigabit key, there's no guarantee that a new attack would necessarily be thwarted by such a large key, either. So, I don't view excessively large keys as great "insurance" against future cryptanalytic attacks.

Answering your question directly: 128-bit encryption is generally considered very sufficient. Maybe it is not very sufficient: then you can pick 256-bit, whose breaking by exhaustive search is "totally out of reach of Mankind".

If exhaustive search of a 256-bit keyspace is totally out of reach of Mankind, why should you use 1 billion bit keys? Even if you built a system that could, is the massive overhead of trying to use a 1-billion-bit key really worth it? I wouldn't say so: not when 256-bit keys suffice.

(Almost?) all practical cryptosystems might be broken in the near future, so we can't say that 256-bit encryption with, say, ChaCha20 gives you ironclad, unstoppable security. At the same time, though, if we somehow extended ChaCha to use a gigabit key, there's no guarantee that a new attack would necessarily be thwarted by such a large key, either. So, I don't view excessively large keys as great "insurance" against future cryptanalytic attacks.

As an update for anyone curious, today (2015 July 04) was labeled as "internet independence day" in the linked video - supposedly the launch date of "Thundercloud." The Thundercloud website (warning: autoplaying video) has not been updated, and the Thundercloud Twitter account has gone dark, so at this point, the software probably classifies as vaporware.