Just a question on the SHA-256, if it is almost impossible to brute-force hypothetically what is the almost possible way to crack the algorithm?
I’m not a hacker, if anything is know less then most about programming. Just saying. 
I’ve got no idea what is the probability to crack SHA256. But there is an interesting video about it that was posted by a student a few days ago:
https://www.youtube.com/watch?v=S9JGmA5_unY
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All I could get from reading the referenced Technical background of version 1 bitcoin address, is that a btc address is a "160-bit hash of the public portion of a public/private keypair’. This every bitcoin address has a public portion and a private portion.
I am not sure what a hash is.
Welcome to the discussion thread about this lecture section. Here you can feel free to discuss the topic at hand and ask questions.
When it comes to private and public keys, in my experience I have never gotten a private key from a wallet. I only get the pass phrases. Am I missing something?
In case you’re using a wallet with a mnemonic key that is used as a mapping to a private key using common words as described in BIP39.
Most of these kinds of wallets are also HD (hierarchical deterministic) wallets which means they use a master key to derive new addresses from said master key (which is a fancy word for the root private key) so you only need to back up on key because all future addresses are derived from it. This is described in BIP32 
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I understand what a Hash is to a certain extent and the addresses, still need more examples but I get the general idea.
Previous hash is on it; plus new data within it; new hash function is generated; New block has new and previuos data on it.
The hash function is always the same.
Alko89 yes, just read the articule…Thanks!
hash functions are what it makes any crypto currency work… the difference between fist generation (BTC) and second generation (ETH) is that with this last one, you have a TURING COMPLETE , it can solve any mathematical programe)
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Ivan’s youtube video explaining the merkle tree helped me digest the wiki page a little better -
I understand as follows: you can run two numbers through an algorithm(hashing) to create a unique number much smaller than the original numbers so it’s easier to transfer. That number can then be hashed with the result from another hash to create another unique number, etc.
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Sorry for being a pain, is there a code repository where I can get “code-snippets” for the above discussion so I can properly visualize the Blockchain concepts?
I think I answered both of your questions in other threads, please avoid using multiple threads to ask the same questions.
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Other than the fact that hash functions should be collision-free and one-way functions, what properties makes a good hash function “good”?
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Since there are many different hash functions such as SHA256, SHA384, Ripemd128, etc. what makes them different from each other (other than the math used to hash the input data, I’m assuming) and are there pros/cons to using some but not others?
Personally with the right cracking equipments, you can crack SHA256 within 3 to 6 months. Back in the days Ethical Hackers working on Military Projects were cracking 1024bit and 2048bit Hash Algorithms, and this was about 14 years ago. So try and imagine what those guys could do with a 256bit Hash Algorithm today.
Basically that is it, the results should be seemingly as random as possible so there is no way to derive some form of pattern from the function.
I’m not a cryptography expert to know all sorts of these functions. There are a lot of flavors and you could spend multiple lifetimes studying each of them. They use different functions, have different output lengths… SHA256 has been proven to be secured and is used as an industry standard in most modern security requirements.
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Prove it
They were probably using a not that secure hash function that could be hacked algorithmically, not using brute force. A lot of hash functions have been hacked in the past, SHA256 proved to be most resistant. 256 bits is such a large number its impossible to hack it with modern PC in a reasonable amount of time.
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@Alko89, I have had a look at 3Blue1Brown’s SHA256 youtube link you posted, and also looked at a few other similar videos he made regarding 256 bit security. He made some very good compelling arguments why 256 Hash might be un-hackable, but like a lot of Cryptographic Experts in the past, he is making his argument based on Exponential-Mathematics. 2 raised to the power of 256 guessing possibilities sounds daunting when you look at it from a exponential-logic point of view, but what is required here is to remove our minds away from exponential-logic thinking mathematics and start applying more “quantum” thinking mathematics in order to find a solution. Quantum Mathematics as applied to “Quantum Computing and Quantum Mechanics” is a relatively new subject that is gaining prominence, and the way we look at equations today is going to change in a matter of time.
As I mentioned, I’m not a cryptography expert and I don’t know how quantum resistant algos work. But last time I checked they still used large numbers. Maybe a bit larger than SHA 
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hello my question would be can we say blockchain 2.0 defeated the purpose of blockchain 1.0 in terms of the whole idea of creating blockchain was to be decentralized? I am thinking now these “smart contracts” would be like one of those “T&C 's” we never go through and just click agree and only to find out all the agreement/contract we entered could be manipulated just like tritonal contracts ? so my second question would be how transparent are smart contracts?
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