"unconfirmed"=pending in mempool or Added to Block+waiting for 3 more blocks?

[pxstein]

What does "unconfirmed" (in Electrum) mean as label for transactions?

Does it mean:
1) Transaction is succesffully added to Mempool
or
2.) Transaction is successfully added to block and waiting for 3 (or 6) more blocks to be really seen as stable/confirmed?

[jackg]

What does "unconfirmed" (in Electrum) mean as label for transactions?

Does it mean:
1) Transaction is succesffully added to Mempool
or
2.) Transaction is successfully added to block and waiting for 3 (or 6) more blocks to be really seen as stable/confirmed?

The first.
It changes to something different when it gets accepted in a block but doesn't have enough confirmations (I don't remember what that is though).

It gets a tick when it's fully confirmed.
If you right click and click "details" then you can see how many confirmations a trensaction has "unconfirmed" means no confirmations.

[Abdussamad]

The transaction hasn't been included in a block as yet. More here

[pooya87]

The transaction hasn't been included in a block as yet. More here

A clock icon means the transaction has confirmed but not enough times to be considered irreversible.

this may create the confusion that transactions are confirmed multiple times. in fact as a beginner i remember thinking when my transaction has for example  10 confirmation it means it is confirmed/mined 10 times!

rephrasing to "not deep enough" is better in my opinion. because that is what it means. when a transaction has 10 confirmation it means it is 10 blocks deep.

[jackg]

The transaction hasn't been included in a block as yet. More here

A clock icon means the transaction has confirmed but not enough times to be considered irreversible.

this may create the confusion that transactions are confirmed multiple times. in fact as a beginner i remember thinking when my transaction has for example  10 confirmation it means it is confirmed/mined 10 times!

rephrasing to "not deep enough" is better in my opinion. because that is what it means. when a transaction has 10 confirmation it means it is 10 blocks deep.

It sort of does confirm again though IMO. You put the hash of the previous block on that block so it has to be accepted by a miner in a similar way to a regular block other than it is "confirmed" the block was mined right not mined again but instead the hash gets confirmed before including it in the next block. This is obviously something the node sprts though.

[Abdussamad]

The transaction hasn't been included in a block as yet. More here

A clock icon means the transaction has confirmed but not enough times to be considered irreversible.

this may create the confusion that transactions are confirmed multiple times. in fact as a beginner i remember thinking when my transaction has for example  10 confirmation it means it is confirmed/mined 10 times!

rephrasing to "not deep enough" is better in my opinion. because that is what it means. when a transaction has 10 confirmation it means it is 10 blocks deep.

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

[ranochigo]

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

Confirmations basically shows the number of blocks that has been mined ontop of the block that has included the transaction. Confirmations will never be enough for a transaction to be considered irreversible. The higher the number of confirmations simply mean that it would be harder for any attacker to reverse the transaction.

The clock icon simply denotes the number of confirmations and when its full, it would be green and it would have 6 confirmations which is relatively safe (other than in 51% attack).

[Abdussamad]

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

Confirmations basically shows the number of blocks that has been mined ontop of the block that has included the transaction. Confirmations will never be enough for a transaction to be considered irreversible. The higher the number of confirmations simply mean that it would be harder for any attacker to reverse the transaction.

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

[jackg]

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

Confirmations basically shows the number of blocks that has been mined ontop of the block that has included the transaction. Confirmations will never be enough for a transaction to be considered irreversible. The higher the number of confirmations simply mean that it would be harder for any attacker to reverse the transaction.

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

Isn't it before that point, it's just put as 6 for safety?

Once every node has received a block, its very hard to remove that block as the nodes are then just looking out for the next block (obviously if that next block has a different previous block hash then the other block has to be pulled also). After about 3 block it already becomes qutie difficult to launch an attack and play jenga with the blockchain to get that block out from nodes?

This has gone really off topic anyway.

[ranochigo]

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

6 confirmation prevents any attackers without 51% of the hashrate from trying to reverse the transaction. If you have more than 51% of the hashrate, you can reverse any transactions, no matter how old it is.

Using irreversible for 6 confirmations doesn't seem right.

[pooya87]

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

Confirmations basically shows the number of blocks that has been mined ontop of the block that has included the transaction. Confirmations will never be enough for a transaction to be considered irreversible. The higher the number of confirmations simply mean that it would be harder for any attacker to reverse the transaction.

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

Isn't it before that point, it's just put as 6 for safety?

Once every node has received a block, its very hard to remove that block as the nodes are then just looking out for the next block (obviously if that next block has a different previous block hash then the other block has to be pulled also). After about 3 block it already becomes qutie difficult to launch an attack and play jenga with the blockchain to get that block out from nodes?

This has gone really off topic anyway.

it is a hardness argument.
when you send a transaction and it is still in the mempool (unconfirmed) it is easy to double spend it.
when it has 1 confirmation, it becomes very hard to double spend it and the chance of that happening is less than 1% for example
....
if it has 6 confirmation the chance of double spend becomes so small that we consider it zero. i is like 0.000001%

[jackg]

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

6 confirmation prevents any attackers without 51% of the hashrate from trying to reverse the transaction. If you have more than 51% of the hashrate, you can reverse any transactions, no matter how old it is.

Using irreversible for 6 confirmations doesn't seem right.

It does mean you have to remind every block though to make your new chain and have the old one orphoned.

Thanks for the feedback. I will look into explaining what exactly confirmations mean either in this FAQ entry or a linked article.

Confirmations basically shows the number of blocks that has been mined ontop of the block that has included the transaction. Confirmations will never be enough for a transaction to be considered irreversible. The higher the number of confirmations simply mean that it would be harder for any attacker to reverse the transaction.

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

Isn't it before that point, it's just put as 6 for safety?

Once every node has received a block, its very hard to remove that block as the nodes are then just looking out for the next block (obviously if that next block has a different previous block hash then the other block has to be pulled also). After about 3 block it already becomes qutie difficult to launch an attack and play jenga with the blockchain to get that block out from nodes?

This has gone really off topic anyway.

it is a hardness argument.
when you send a transaction and it is still in the mempool (unconfirmed) it is easy to double spend it.
when it has 1 confirmation, it becomes very hard to double spend it and the chance of that happening is less than 1% for example
....
if it has 6 confirmation the chance of double spend becomes so small that we consider it zero. i is like 0.000001%

Yeah but what I'm.saying is that it's already quite hard to take a block out when it's three down. If we use your 10^-block-2 probability that a block will be removed, a 0.00001 chance is still really small.

[Abdussamad]

At some point it becomes too hard for any attacker to reverse the transaction. 6 confirmations is that mark.

6 confirmation prevents any attackers without 51% of the hashrate from trying to reverse the transaction. If you have more than 51% of the hashrate, you can reverse any transactions, no matter how old it is.

Using irreversible for 6 confirmations doesn't seem right.

Yes a sustained 51% attack could reverse old transactions. But it would have to be sustained for more than a day. People would notice it and take action to blacklist the attackers.

[bob123]

Yes a sustained 51% attack could reverse old transactions. But it would have to be sustained for more than a day. People would notice it and take action to blacklist the attackers.

Theoretically, people would NOT notice that a 51% attack is ongoing.
An attacker would mine on the private chain WITHOUT revealing it, until he decides to do so.

Only at that point in time (when a new longest chain has been broadcasted and transactions of X blocks are mixed up (or just a few of these)) it is obvious that someone has been mining on a private chain with 51%+ of the hashrate.

Additionally there is no 'blacklist'. It doesn't matter WHO shares the block. The network doesn't know from who the block came.
As long it is a valid block, resulting in the longest chain, it is considered to be the (only) valid chain.

[jackg]

Yes a sustained 51% attack could reverse old transactions. But it would have to be sustained for more than a day. People would notice it and take action to blacklist the attackers.

Theoretically, people would NOT notice that a 51% attack is ongoing.
An attacker would mine on the private chain WITHOUT revealing it, until he decides to do so.

Only at that point in time (when a new longest chain has been broadcasted and transactions of X blocks are mixed up (or just a few of these)) it is obvious that someone has been mining on a private chain with 51%+ of the hashrate.

Additionally there is no 'blacklist'. It doesn't matter WHO shares the block. The network doesn't know from who the block came.
As long it is a valid block, resulting in the longest chain, it is considered to be the (only) valid chain.

This is exactly true, if they were clever enough to keep changing the address the block rewards go to then you might assume it is going to multiple people.

With the pools at the moment, it's like if Bitmain didn't tell you they owned BTC.com and Antpool.com then you'd think those were two different miners, this is probably how a similar style of attack would go. Someone wouldn't say they owned 50%+ of hashpower as another miner maker would obviously want to resolve this (there are three major ones: Bitfury, Bitmain and BW afaik).

[Abdussamad]

A large reorg triggers warnings in bitcoin core so people would notice: https://bitcoin.stackexchange.com/questions/38202/can-an-attacker-with-51-of-hash-power-change-old-blocks#comment44888_38224

By blacklist I mean miners voluntarily switching to a different pool from the one that is attacking the network. This would happen at level 0 i.e. the social level.

[jackg]

A large reorg triggers warnings in bitcoin core so people would notice: https://bitcoin.stackexchange.com/questions/38202/can-an-attacker-with-51-of-hash-power-change-old-blocks#comment44888_38224

By blacklist I mean miners voluntarily switching to a different pool from the one that is attacking the network. This would happen at level 0 i.e. the social level.

If someone was good enough at it, they'd use different addresses/IPs per block so it'd be almost impossible to trace that the network is being attacked before the old chain gets rejected and lost.

The increased number of blocks in a shorter amount of time would go noticed however. (As the block difficulty takes 2016 blocks to change).

There's also the issue that there might be a sustained 51% hashrate by a pool before anyone notices they're doing something unusual. And this is really off topic now.

[pooya87]

There's also the issue that there might be a sustained 51% hashrate by a pool before anyone notices they're doing something unusual.

you can't do it with 51% hash rate, you need a lot more. it is like an arm wrestling contest if you have 1% more power than your opponent you can beat him but it won't be easy because you are practically the same. they say 51% to say you need to have more than half the hashrate to begin. but the attack can be pulled off with a much higher hashrate. the higher the easier.

[jackg]

There's also the issue that there might be a sustained 51% hashrate by a pool before anyone notices they're doing something unusual.

you can't do it with 51% hash rate, you need a lot more. it is like an arm wrestling contest if you have 1% more power than your opponent you can beat him but it won't be easy because you are practically the same. they say 51% to say you need to have more than half the hashrate to begin. but the attack can be pulled off with a much higher hashrate. the higher the easier.

Obviously.

I mean 51% is easier than saying "any hashrste above 51%). It's obviously easier to do it with 70% than 51%.

[Abdussamad]

There's also the issue that there might be a sustained 51% hashrate by a pool before anyone notices they're doing something unusual.

you can't do it with 51% hash rate, you need a lot more. it is like an arm wrestling contest if you have 1% more power than your opponent you can beat him but it won't be easy because you are practically the same. they say 51% to say you need to have more than half the hashrate to begin. but the attack can be pulled off with a much higher hashrate. the higher the easier.

I thought so too until I read this: https://bitcoin.stackexchange.com/a/38224/5273