security

[HNajafi]

Is the possibility of discovering private keys with random testing by considering the increasing number of e-wallet?
what the prevention solution in cryptocurrency such as bitcoin is? Is there any mechanism such as "I am not a Robot" (Captcha) or blocking the user with the iterative wrong private key?

[Chlotide]

The toal number of potential btc addresses is 1.46150164 × 10⁴⁸ so there really are few that consider collisions an issue.
Vanity addresse generators do actually what you said, create loads of addresses until one matches the characters you want.
You can be 99.9999999999999% that your address is secure to that kind of brute force attack. And even if it happens it needs to collide with one that has funds. There are about 25 million addresses with more that $1 worth on them. You are secured by the power of probability!

[20kevin20]

You cannot include a "I am not a Robot" mechanism inside a blockchain. It would clog it up completely, since it would require human input. Best thing one wallet dev can do is automatically skip a seed if it's found to have balance on it - but even that makes things more difficult/resource-hungry.

Anyway, the idea is, the chance of generating an already-used seed is not zero but very, very close to it. So close you would probably have a higher chance of winning a millionaire jackpot multiple times in a row than generating an already-used seed and chances are your seed will be empty already anyway.

There are 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible Bitcoin addresses (someone correct my number if it's wrong).
There are around 5,000,000,000,000,000,000,000 grains of sand on Earth, according to some math expert.

If you took and piled up all the sand in the world and RANDOMLY picked one grain up from the entire mount, you would have a higher chance of finding the same grain of sand twice randomly than generating an already-used Bitcoin address.

This is how close to zero your chances are. They still exist, but they're so close to zero it's realistically impossible.

[o_e_l_e_o]

The toal number of potential btc addresses is 1.46150164 × 10⁴⁸ so there really are few that consider collisions an issue.

There are 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible Bitcoin addresses (someone correct my number if it's wrong).

There are this many P2PKH addresses. Once you include P2SH and P2WPKH addresses, the number is 3 times larger.

If you took and piled up all the sand in the world and RANDOMLY picked one grain up from the entire mount, you would have a higher chance of finding the same grain of sand twice randomly than generating an already-used Bitcoin address.

It's actually closer to picking the same grain of sand 3 times, rather than just twice. When you first pick any random grain of sand, then there is no probability associated with that since you were given a free choice. For you to then pick the same grain of sand a second time, then there is now a 1 in 5*10²¹ chance. For you to pick the same grain of sand a third time, then the chance is now 2.5*10⁴³, which is still around 175,000 times more likely than someone generating a specific address out of the 4.38*10⁴⁸ possibilities.

[BlackHatCoiner]

Is the possibility of discovering private keys with random testing by considering the increasing number of e-wallet?

Yes, there is a tiny tiny tiny possibility of generating private keys that were generated before. The chances are described on the above posts, the fact that there is 1 in x possibilities shouldn't trick you. We can't even pretend to understand how big is that number, it's above human's standards. It's never happened and I hope it'll never be.

what the prevention solution in cryptocurrency such as bitcoin is?

You can't prevent someone from calculating. Everyone's free to brute force bitcoin addresses.

Is there any mechanism such as "I am not a Robot" (Captcha) or blocking the user with the iterative wrong private key?

In order for this to happen Bitcoin addresses must be generated over a centralized authority that will filter users' private keys to prevent any collisions. I guess you understand that this is against decentralization, against its purpose.

I believe that you haven't been convinced that it's impossible to achieve such thing, so I'll tell you one last thing:
With the current difficulty, in order to mine a block, you'll have to try among ~23,100,000,000,000 * 2³² = ~99,213,744,537,600,000,000,000 combinations. If you'd be able to generate 1 hash, then you'd have 1 in that number, to be rewarded with 6.25 fresh bitcoins.

Compare these numbers:

• 99,213,744,537,600,000,000,000
• 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976

Not to mention that generating an address requires more computational power than performing an SHA256d. A p2pkh requires you to perform ECDSA, SHA256, RIPEMD-160, SHA256 again, SHA256 again and then just a base58 encoding.

[j2002ba2]

There are 1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976 possible Bitcoin addresses (someone correct my number if it's wrong).

There are this many P2PKH addresses. Once you include P2SH and P2WPKH addresses, the number is 3 times larger.

P2PKH and P2WPKH are equivalent, so all three give a number 2 times larger.

What is missing is P2WSH, which adds 2²⁵⁶ more addresses.

And soon P2TR, which adds another ~2²⁵⁵ addresses, with at most 2¹²⁸ security.


P2(W)PKH:                                        1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976
current P2PKH record:                                                                    9,223,372,036,854,775,808

     P2SH:                                       1,461,501,637,330,902,918,203,684,832,716,283,019,655,932,542,976
collision:                                                                       1,208,925,819,614,629,174,706,176

    P2WSH: 115,792,089,237,316,195,423,570,985,008,687,907,853,269,984,665,640,564,039,457,584,007,913,129,639,936
collision:                                                     340,282,366,920,938,463,463,374,607,431,768,211,456

P2TR security:                                                 340,282,366,920,938,463,463,374,607,431,768,211,456
current ECDLP record:                                                                      144,115,188,075,855,872