A simple bitcoin Q/A. Learn new and interesting stuff about bitcoin.

[Nanoverso]

Question :  What is the difference between a regular transaction and a coinbase transaction? Do explain the both type of transactions with or without any examples.

I think something that deserves to be mentioned is the difference between these two types of transactions from the financial point of view: when you realize a cryptocurrency transaction between two users of the coinbase platform you don't have to pay the blockchain/miner fees of regular wallet/wallet or coinbase/wallet transactions. This definitely makes a difference for those who make regular or large amount transfers.

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[Hazaki]

Question :  What is a cryptography nonce?

Cryptography nonce is an arbitrary/random/unplanned number that can't be used more than once (it's literally the same meaning as the nonce word in English ) .
This nonce is usually random (we can't figure it out through a pattern of steps/events ) or pseudo-random (seems random but is not , costs less to generate than a fully random number ) .
This nonce number is used in cryptography to ensure that old communications can't be reused and thus eliminating the risks of accessing to valuable informations through old communications . A nonce number also may include time (even better for security ) .

[shahzadafzal]

Question :  What is a cryptography nonce?

Cryptography nonce is a random number. Nonce is used in Cryptography/hashing to produce unique output that will only be used once, for example to authenticate user or to produce certain hash in case of hashing.

In case of cryptography it helps reduce chances of MITM (Man in the Middle)/Reply attacks. Let say Client A is talking to the Server and they are using hashing to verify any vulnerabilities of the messages and each message is hashed with nonce. Now if another Client B starts listing or sniffing the communication between Client A and Server, it will be able to get the hash (nonce+message). Now if client B try to reply same hash to the Server it will fail, because user B will not be able to produce same hash. That Hash (nonce+message) was for that one specific connection only. Remember Server is keeping track of nonce of the client.

Nonce in Bitcoin mining is used to generate a unique block hash. We know there are specific inputs to create hash, one of it is nonce. To produced required hash, nonce is added repeatedly until required hash pattern is produced. That specific nonce which produces required pattern (leading number of zeros) is called golden nonce.

[bitmover]

You just got your 200th merit and good explanation.

Thank you.  
You gave me my first one also , when I didn't even knew what that was .
https://bitcointalk.org/index.php?topic=2885058.msg29953079#msg29953079

[mangodebango]

Question :  What is a cryptography nonce?

In security engineering, nonce is an abbreviation of "number used once". It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks. For instance, nonces are used in HTTP digest access authentication to calculate an MD5 digest of the password. The nonces are different each time that the 401 authentication challenge response code is presented, and each client request has a unique sequence number, thus making replay attacks and dictionary attacks virtually impossible.

 

[shasan]

Question :  What is a cryptography nonce?

Nonce is a term which is used for number used once. For cryptography nonce it might be randomly generated number which might block. As on bitcoin same block cant be generated multiple time. Thanks.

[brardona]

A coinbase transaction is a special transaction that transfer new generated coins to a miner's wallet. It's the first transaction of a block.

Whoever solves the PoW puzzle faster creates a new block and receives it reward. This reward is a newly generated bitcoin, called coinbase.
Example:
https://blockchain.info/tx/451329336cfaa7896fb4aba504bb3acd9964fc27b3fe6bbbf05615d19df313a1


A regular transaction is any other transaction, which does not involve newly generated coins.
Example:
https://blockchain.info/tx/e038d1191d09eed13ef8e4d87f95b0e3499c63aaf7bc14001e099a4e5bf50172

You just got your 200th merit and good explanation.

Question :  What is a cryptography nonce?

In cryptography, a nonce is an arbitrary number that can only be used once. It is often a random or pseudo-random number issued in an authentication protocol to ensure that old communications cannot be reused in replay attacks.

[bit802346]

Question :  What is a cryptography nonce?
[/quote]

it's randomly generated number (block), which used to make sure that old generated communications cannot be reused.

[Fawez]

Question :  What is the difference between a regular transaction and a coinbase transaction? Do explain the both type of transactions with or without any examples.

A coinbase transaction is a unique type of bitcoin transaction that can only be created by a miner. This type of transaction has no inputs, and there is one created with each new block that is mined on the network. In other words, this is the transaction that rewards a miner with the block reward for their work...

[pugman]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

[joniboini]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

Only one transaction will be considered valid (the one which gets included in the block that is broadcasted first on the network). The other transaction (and/or block) will be considered invalid and will be rejected by the nodes.

Source:
https://bitcointalk.org/index.php?topic=216938.0

[BitHodler]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

Only one transaction will be considered valid (the one which gets included in the block that is broadcasted first on the network). The other transaction (and/or block) will be considered invalid and will be rejected by the nodes.

Source:
https://bitcointalk.org/index.php?topic=216938.0

Actually, there is no first mover advantage when it comes to transactions, or more precisely said, not anymore. Double spending with a higher fee will make sure the later transaction confirms before the first one.

It's all economics based, where miners only confirm transactions with the highest fees, especially in times where unconfirmed transactions are piled up and impossible to confirm by the next block.

[Rath_]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

Assuming that the block would be valid then it couldn't happen. Transaction can be included in the block only once since it's not possible to spend your bitcoins again.

It's all economics based, where miners only confirm transactions with the highest fees, especially in times where unconfirmed transactions are piled up and impossible to confirm by the next block.

There is no such issue in the Lightning Network since all transactions are settled immediately between two parties as a sort of agreement.

[shahzadafzal]

Question: What happens when a transaction is included in more than one block?

When transaction is present in more than one block then the first block that is broadcasted on the network will be considered valid, other blocks will be considered invalid and it will be ignored by other nodes.

We should note that the block as a whole is either accepted or rejected, not the individual transactions. So all other blocks having that transaction will become invalid.

This is what double spending problem is, the second transaction will be considered a double spend.

[denis-z12]

A transaction can only be valid in one block and the other transaction would cause the whole 2nd block to become invalid in such a case.
Pieter Wuille explains this nicely in this topic - https://bitcointalk.org/index.php?topic=216938.0

[nalinpuri]

When transaction is included in more than one block then first block is validated by the miners and the other blocks are put on hold.
 
(Non Google researched answer)

[Zhagedu]

If the two miners were able to find block linearly on the network, that mean the two blocks have what is called intersection included transactions whereby the two block in their right are valid but only one of this transaction will be included in the longest chain while the other become invalid on the network.

[Steamtyme]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

Only one of the transactions would be valid in the BTC blockchain.

For the transaction to be valid in 2 different blocks it would have to be during a fork of the original chain.

After typing this I looked for validation on my theory
and came across this
https://bitcoin.stackexchange.com/questions/18656/can-a-transaction-be-in-two-blocks

After reading the response and given when it was written, it looks like other than a fork this would only occur if someone was trying to 51% attack the chain and create a double spend opportunity for themselves.

What I did learn and did not know before, or really think about is that, if you include an already confirmed transaction in a found block it will be rejected and you would lose out on the block reward.

This brings me to another question if someone feels like learning me some knowledge... If someone did lose a block by including an already confirmed transaction, does the network keep working on that particular block, or do all valid transactions that were included in the block go back to the mempool, and the block reward is lost?

[cryptothief]

Just did a quick bit of research and this is my 'non-technical' interpretation. The only way a transaction can be included in more than one block is if two miners reach it at the same time. Both would be broadcast and create a brief fork, with nodes building on whichever one they deem as correct (the first one they found) and rejecting the other one. It falls back into line once the next block is mined, confirming a winner and leaving the other initially legitimate block stranded. All subsequent blocks would then continue on the longest chain, with any nodes that found the stranded block first joining back in with the pack.

[El Loco]

Question: What happens when a transaction is included in more than one block?Don't break the forum rules,and no PLAGIARIZING!

I think it's possible for two miner include the same transaction in one block. If both miners include it in the same time then only one will be choosen and the other will be an orphan block. If transactions will come in different time then the second one will be invalid or it will allow a double spending.