How many NVidia 3090 would you need to brute force a 1024 key in one day? How many NVidia 3090 would you need to brute force a 1024 key in one day?
Brute force means running $2^{1024}$ operations. NVidia 3090 has $10496 \approx 2^{14}$ cores, each running at 1.70GHz which is approximately $2^{30}$ operations per second. Making the ridiculous assumption that a single clock cycle suffices for verifying a key, this comes to $2^{44}$ operations per second.
Before going to $2^{1024}$, let's consider 128-bit keys for AES. This would take $2^{84}$ seconds which is about $6 \times 10^{17}$ years. So, if I take a server farm of 1 trillion (about $2^{40}$) NVidia 3090 devices, then it would take &quot;only&quot; $2^{44}$ seconds, which is about 550,000 years. Of course, it would be much longer since you can't verify a single AES key guess in 1 clock cycle.
Let's now look at the entire power of the bitcoin network. This is estimated to run at about 150 million Terahash per second, which is about $2^{67}$ operations per second. That is absolutely huge! However, it means that it would take $2^{61}$ seconds which is 70 billion years. Just to reiterate - it would take 70 billion years for the entire bitcoin network to brute force a 128-bit key. (Of course, that network is computing SHA256 hashes and not AES computations, but you get the idea.)
Forget about 1024-bit keys and brute forcing. 128 is already too high for that.