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I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. There are around $4\times10^{11}$ stars in the galaxy, so if the Sun is an average star, you would need to save up the energy output of the entire galaxy for about 63,000 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to mass less than 69 silicon atoms in order to have enough without exceeding the mass of the Earth. Unfortunately, light would need to be about 650 times faster to get across even one silicon atom in that amount of time. If you were to reduce it to only 1.5 million decryptions per picosecond, so light could cross one silicon atom each time, you'd need a lot more devices. If each device massed as much as a silicon atom, you'd end up with about 9.7 times Earth's mass.

Of course, if you could make a device that could run that fast, you might be able to make it that small. Still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. You would need to save up the energy output of the Sun for about 25 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to mass less than 69 silicon atoms in order to have enough without exceeding the mass of the Earth. Unfortunately, light would need to be about 650 times faster to get across even one silicon atom in that amount of time. If you were to reduce it to only 1.5 million decryptions per picosecond, so light could cross one silicon atom each time, you'd need a lot more devices. If each device massed as much as a silicon atom, you'd end up with about 9.7 times Earth's mass.

It would be much more practical to try to brute force a 256-bit key in 10 years. You'd only need one Earth's mass of computing silicon atoms and 1/4th the energy output of the Sun.

Of course, if you could make a device that could be that small and run that fast, it still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. There are around $4\times10^{11}$ stars in the galaxy, so if the Sun is an average star, you would need to save up the energy output of the entire galaxy for about 63,000 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to mass less than 69 silicon atoms in order to have enough without exceeding the mass of the Earth. Unfortunately, light would need to be about 400 billion times faster to get across even one silicon atom in that amount of time. If you were to reduce the speed so light could cross one silicon atom per decryption, you'd need a lot more devices. If each device massed as much as a silicon atom, you'd end up with about 27,000 times Earth's mass.

Of course, if you could make a device that could run that fast, you might be able to make it that small. Still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. There are around $4\times10^{11}$ stars in the galaxy, so if the Sun is an average star, you would need to save up the energy output of the entire galaxy for about 63,000 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to mass less than 69 silicon atoms in order to have enough without exceeding the mass of the Earth. Unfortunately, light would need to be about 650 times faster to get across even one silicon atom in that amount of time. If you were to reduce it to only 1.5 million decryptions per picosecond, so light could cross one silicon atom each time, you'd need a lot more devices. If each device massed as much as a silicon atom, you'd end up with about 9.7 times Earth's mass.

Of course, if you could make a device that could run that fast, you might be able to make it that small. Still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. There are around $4\times10^{11}$ stars in the galaxy, so if the Sun is an average star, you would need to save up the energy output of the entire galaxy for about 63,000 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to weigh less than 69 silicon atoms in order to have enough without exceeding the weight of the Earth.

Of course, if you could make a device that could run that fast, you might be able to make it that small. Still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.

I don't think anyone has addressed the time issue. According to the Margolus-Levitin theorem the limit on the number of operations per second is $6\times10^{33}$ per Joule. The Sun's energy output is about $3.83\times10^{26}$J/sec. There are around $4\times10^{11}$ stars in the galaxy, so if the Sun is an average star, you would need to save up the energy output of the entire galaxy for about 63,000 years to be able to then do $2^{255}$ operations in one year (even assuming you only needed to do one operation per decode).

Another limit might be the Planck time unit, $5.391\times10^{-44}$ seconds. If the time it takes for one device to do one decryption is 1 Planck time, you'd need about $2^{86}$ devices to do $2^{255}$ operations in one year. Since the Earth's mass is about $2^{92}$ grams, if you could keep the mass of each device under 2 oz then converting the entire Earth would give you enough devices.

On the other hand, since doing a billion operations per picosecond would be about $2^{74}$ Planck time per operation, each device running at that speed would need to mass less than 69 silicon atoms in order to have enough without exceeding the mass of the Earth. Unfortunately, light would need to be about 400 billion times faster to get across even one silicon atom in that amount of time. If you were to reduce the speed so light could cross one silicon atom per decryption, you'd need a lot more devices. If each device massed as much as a silicon atom, you'd end up with about 27,000 times Earth's mass.

Of course, if you could make a device that could run that fast, you might be able to make it that small. Still doesn't help with heat dissipation or the total amount of energy required.

$2^{256}$ is a very large number.