Addition is an excellent example of a ONE-WAY Hash because given the Hash(Sum).
You can only guess at the inputs, but CAN NEVER be certain … were their 2 or 30 inputs.
Yet, the same inputs ALWAYS produce the same SUM.
Excellent!
1 Like
you are right till B sends hash signature to A. But A mixes this hash with his private key to produce another hash. I means if i send the hash to some person he not doing anything only i am using my private key only thing in blockchain is recording that signature as a transaction and putting in next block to form a ledger. I am not fully convinced by last 2 statements
“A mixes this hash with his private key to produce another hash.
A sends this hash to B”
Can anyone here throw some light on LeCorb question.
very exited to learn this section.
1 Like
I’m confused on the question.
If you wanna send a message to someone his public key, you need to sign this message with your private key.
The receiver will be able to check if the message is coming from the sender by checking the signature to his public key.
A digital signature is a mix of the senders private key + message to the receivers public key
1 Like
Hi,
I want to confirm if on Bitcoin, public keys are generated using a hash function from the private key? Is it SHA-256 ?
I believe is implied from course videos 6 and 8 but I just want to confirm.
Public keys are derived using the Elliptic curve function, not SHA256. 
3 Likes
Check out this article:
4 Likes
With Sha-256, is it theoretically possible that two unique data entry create the same Hash?
If this is possible, what problems could arise if this ever happens?
Yes it is possible, but highly unlikely. In case it happens in SHA256 it will probably be time to switch to a new algo because it would mean its security is compromised.
2 Likes
Question- What happens to all the miners who’s blocks are not accepted into the blockchain.
a) Do they just loose all the time/money/energy spent on solving the Nonce?
b) Can they use the previous time/money/energy spent for a previous block to solve a new nonce and have more of an advantage the next time?
Thanks for your explanations…
The reward is lost and they hope for better luck next time 
you can’t have an advantage in finding a new nonce, there is a new block that needs to be found. Everything starts again from scratch.
3 Likes
Thanks for clearing that up 
The blockreward is also not spendable for 100 blocks, in case you mine a valid block and this block later becomes a stale block.
2 Likes
Looking forward to this section and get a better understanding of Hash functions.
1 Like
Question: Isn’t the generation of the ‘random’ number in itself not so random? Even though the hash function is mathematically improbable to crack that private key is generated by wallets that are programed to generate a “random” private key??
Its pseudo random, but I don’t understand your point. If the algorithm is good enough and no one has your seed number at the moment you try to generate the random number, its basically impossible to get the number your RNG generated.
2 Likes
This is probably the interesting and complicated part of the course to get wrap ones head around it.
Fun fact, I was not aware that SHA -256 HASH was invented by NSA 
1 Like
But this doesn’t mean that the NSA has created a backdoor or something. 
3 Likes
Some wallets can add some additional entropy by moving your mouse or something. I have a coldcard hardware wallet where I can throw lots of dice and enter the results to add some entropy.
2 Likes
Agree, it is awesome that it can be applied to something great such BTC 
1 Like