Quote from: Shymaa-Arafat on May 06, 2021, 11:10:38 PM

-I think Bitcoin keyspace refers to the possible no. of blocks that could ever be generated till the end of time. (If u know some cryptography before reading about cryptocurrency & the idea of Bitcoin u'll have the impression that mining is similar like performing a brute force attack to break a plain/cipher pair)

The bitcoin "keyspace" has nothing to do with blocks or mining...

It is referring to the "total set" of valid, unique bitcoin private keys... so, imagine if you had a (very bad) cryptocurrency, where the only private keys were {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}.... then that would be the "keyspace" for your cryptocurrency... it has a size of 10.

Bitcoin on the other hand, has a keyspace that goes from: 1 to n-1 where n = 1.1578 * 10⁷⁷

Quote from: https://www.oreilly.com/library/view/mastering-bitcoin-2nd/9781491954379/ch04.html

More precisely, the private key can be any number between 0 and n - 1 inclusive, where n is a constant (n = 1.1578 * 10⁷⁷, slightly less than 2²⁵⁶)

Quote from: AuorFedelmid on May 06, 2021, 10:12:26 PM

I am struggling to find any resources on keyspace and bitcoin addressing. Recently after looking at the puzzle transactions some questions came to mind. https://privatekeys.pw/puzzles/bitcoin-puzzle-tx

You may want to read the "Mastering Bitcoin" book... it gives a really good explanation of a lot of the fundamentals of Bitcoin. This particular chapter explains Keys and Addresses quite well: https://www.oreilly.com/library/view/mastering-bitcoin-2nd/9781491954379/ch04.html

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What is keyspace exactly? is this refering to SHA256 keyspace?

As above, it is the "total set" of keys that you're looking at... so it could be the entire bitcoin keyspace, or you can look at a specific subset if you wanted to for some reason (like you know the puzzle keys you're looking for are between 2¹⁶ and 2²⁰...

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How is it that the puzzle transactions were created in different keyspaces?

They are effectively in a subset of the Bitcoin keyspace... ie. they simply picked numbers from a smaller range.

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Can you create a bitcoin address in a specific keyspace?

Of course... simply say "pick a number between X and Y" where X and Y are within the total Bitcoin keyspace...et voila, you have created a bitcoin private key within a defined specific keyspace and can derive the public key/address from that... but it isn't a good idea to, because you're losing the "randomness" by reducing the overall size of the keyspace that you're picking from.

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When bitcoin addresses are made is the keyspace they are in random, or is there a preferable or more pseudorandom range that they are likely to appear in?

Bitcoin addresses are not "made"... they are derived by (hopefully) randomly picking a private key... then the public key is derived from the private key... then the public key is converted into an address using SHA256, RIPEMD160 and encoded with Base58 etc.

Again, read: https://www.oreilly.com/library/view/mastering-bitcoin-2nd/9781491954379/ch04.html

It will explain things much better than I can! Wink