Quote from: taufik123 on Today at 04:39:38 PM

Quantum computers that use Grover's algorithm in the case of breaking symmetric encryption algorithms such as AES (Advanced Encryption Standard) are only able to weaken their strength or reduce all possible encryption keys to half.

That's not accurate.

As I said above, Grover's algorithm allows a problem to be solved in the square root of n-time. Half of 2²⁵⁶ is 2²⁵⁵. Grover's algorithm reduces 2²⁵⁶ to the square root of 2²⁵⁶, which is 2¹²⁸.

Quote from: taufik123 on Today at 04:39:38 PM

But in Bitcoin using the 256-bit ECDSA digital signature system, the possibility of encryption keys that can be done effectively Brute Force from 2²⁵⁶ to 2¹²⁸.

If you are talking about solving the ECDLP, rather than brute forcing part of a seed phrase as above, then you are now talking about Shor's algorithm, not Grover's. Shor's runs in polylogarithmic time, and can factor a k bit number in k³ time. A sufficiently powerful quantum computer (again, decades away) could easily break the ECDLP.

Quote from: mindrust on Today at 05:22:25 PM

Making more copies is risky too.

The best solution is have a set up where compromise of one back up is insufficient to steal your coins, such as separate seed phrase and passphrase back ups, or a multi-sig. Make two copies of each part. That way you have redundancy against accidental loss as well as greater protection against theft.