I have a question regarding the SHA-256 algorithm and hacking.
I would imagine that there are certain transactions that happen more frequently than others… and i would definetly imagine that there have been many transactions with the exact same data.
so what is to stop someone from watching for those specific hashes and hacking them?
This is cool, which web application is this ?
Every transaction is unique. Because digital signatures are always unique for a specific transaction. In order to have an exact copy, you need to have the exact same transaction details. (from wich address, amount, to wich addresses etcetera)
Hashing is the key to make a function of cryptography
I have absolutely no idea what this is about. How can I discuss something without knowing what it is. I do not recall this in the last video.
Hello…I am relatively new to all this including asking question in the forum but I do have a small question with regards Digital signatures. If its said that public key cryptography is a one-way function and a private key is used to sign a message from a sender. How is it NOT possible for the receiver of that transaction to derive the senders Private Key from the (digital signature + the public key). Wouldn’t this make it a two-way function?
@jxdrew I’m pretty new at this too and that was my first question. However, and though I don’t fully understand the detailed mechanics, ECC or Elliptic Curve Cryptography, a type of Asymmetric Cryptography makes this working backwards from the sig/private key, supposedly, Infeasible. The Elliptic Curve Discrete Logarithm Problem seems to define the problem with trying to work in reverse to derive the private key. The way I understand the difficulty is that the potential for derived inputs is astronomical making a brute force attack non-feasible; assuming quantum computing hasn’t solved a timely attack. Who’s to say it isn’t already developed in the DUMB (Deep Underground Military Bases), regardless supposedly, it’s not be accomplished here on the surface.
The way I view the one way function is the same way I view a valve, having worked in/on/around machinery. A one way check valve allows flow in only one direction and this is a one way valve.
I got confused by the last lecture. It is explained that when you want to send BTC you sign it with your private key, so members will know it was you who sent it. I get that that is important for identity siganture of transactions, but… what?! So members see it, thus have it, thus could possible sign any transaction now to anyone with my private key?
When you sign a transaction with your private key you create what is called a digital signature. Once you have your digital signature you can send it out to other nodes which can confirm that you actually own the private key by comparing the public key with your digital signature. There it no way for them to know what your private key is, but they still have enough information to determine that you own your private key.
I myself don’t fully understand the math behind it aswell. What I do know is that Andreas Antonopoulos has an amazing technical book called “Mastering Bitcoin”. I went through the book briefly and I would like to recommend it if you want to completely master how Bitcoin and its underlying technologies work. He covers all the technologies used in bitcoin including the Elliptic Curve Cryptography.
Thank you Mauro for the very quick reply!
So the misunderstanding I had then would be that the digital signature is the private key itself, which is not true: the digital signature is merely generated from the private key and can be verified against the public key so people know it was me.
Is the digital signature just the same as my public key, or could it be somehow just be mapped to my pubic key?
I am not sure how the math behind it works but, If you wish to go more in depth I suggest to watch this video: https://www.youtube.com/watch?v=Aq3a-_O2NcI
There is also a book called “Mastering Bitcoin” by Andreas Antonopoulos that goes pretty in depth with all the underlying technologies used in bitcoin. Definitely worth it if you want to master everything about Bitcoin.
@SecretumPrimas I do not, but you can get it on amazon.
Good question, kind of wondering the same thing
I feel like I’m working in reverse here… As I’m discussing the next course before I’ve taken it… But here goes! Maybe I can develop a better answer later?
Hash Function is a digital signature (fingerprint) that is used to connect two sequential blocks in the chain. It is the result (through consensus) at the end of a completed block, which is attached at the beginning of the next block. In other words, a link in the chain…?
Now let’s do the course and see how much I don’t know! 
Maybe a dumb question but I am confused after reading the article on Blockgeeks.com about hashing. Is the output and difficulty taget in bitcoin hashing, the same thing?
What’s the best and quick way to develop a dapp when you known nothing about code?
You would have to learn a bit of solidity if you want to make a dapp on the ETH network. Otherwise I am not sure how would you be able to do it.
An output is an element of a bitcoin transaction. If you have 1 bitcoin input in your wallet and you wanted to send 1 bitcoin, you would broadcast your transaction with 1 input and 1 output.
Difficulty target is telling a miner how low of a hash they need to produce in order for a block to be accepted by the network.
Hashing is a process that gives us a unique output depending on the input we have. (These inputs and outputs have nothing to do with the input and the output element of the transaction.)
Difficulty target and Hashing are not the same thing, but are closely connected to each other in the Bitcoin network. With the heap of each other we can ensure that blocks will be found on average every 10 minutes. If more people start mining the difficulty target will go down, making it harder to mine and vice versa.
Yeah I understand now after watching the mining lecture 
. The Blockgeeks article is really confusing when reading it without knowledge 
. Thank you for your response!