9 question about bitcoin/btc/blockchian

9 Questions about bitcoin

1. how send money to B from A online ?

   A digist signature with A’s private/secrect key(SK).

   B can valide the sign with A’s Public key (PK)

   - compute hash of received content as H1

   - decode signature/fingeprint with A’s PK as H2

   - H1 == H2 ? true : false;

2. how to proof that A no sign this coin/money at history (double spending) without trusted third-party ?

   all pay history is public to everyone(A , B , no trusted third-party).

   check every pay/tx history

   A spend coin/utxo as txi in history tx ? return A(utxo)=>B valid false : compare next his tx.

   after check all his,no return,then return A(utxo)=>B valid true;

3. how to order his tx ?

   - split txs, package tx set to block

4. how to order tx in a block?

   - order by timestamp

5. how to check tx is no modified in a block

   - merkel tree

   - link block with pre block like a chain

6. how to select out pre block?

   - consensus 1,the longest/highest chain’s last block as pre block of will add block

7. who add block is valid?

   - consensus 2,who first find the answer of a question.

8. what is the question ?

   - hash all tx that will be packaged ,out merkel root.

   - find a nonce that combine merkel root and pre block hash(from consensus 1) and other argument , hash then , out H

   - H < curent diffcult nonce?nonce is answer:continue.

9. who has more opportunity to add valid block?

   - compute hash faster / more cpu power

   - lucky