Generated an address that already had a transaction - Bitcoin-QT

[alex0909]

Hi,

I generated earlier a new address and when i checked Blockchain.info ,this address did hold some coins a few months ago.
It might be an old address, that was not included in my last backup, i will investigate.
I use Bitcoin QT, and i am worried my bitcoins might be at risk.

Never had this problem before when generating a public address.

Is this a collision?

I will provide the address and proof to a trusted member if needed.

[DannyHamilton]

Hi,

I generated earlier a new address and when i checked Blockchain.info ,this address did hold some coins a few months ago.
It might be an old address, that was not included in my last backup, i will investigate.
I use Bitcoin QT, and i am worried my bitcoins might be at risk.

Never had this problem before when generating a public address.

Is this a collision?

I will provide the address and proof to a trusted member if needed.

With the default settings, Bitcoin-Qt pre-generates 100 addresses that it keeps hidden from you.  When you create a backup, the backup contains these 100 addresses.

Then you use Bitcoin-Qt, and each time that you send any bitcoins anywhere or click the "New Address" button Bitcoin-Qt stores some of your bitcoins in another of the 100 pre-generated addresses.

If you later recover the backup, then there will be addresses in the pre-generated list in the backup that have previously held bitcoins.

So, no, this is not a collision.  This is how Bitcoin-Qt works.

I'm a bit surprised though that Bitcoin-Qt did not find these transactions when you first recovered the backup and scanned the blockchain.

[alex0909]

Hi,

I generated earlier a new address and when i checked Blockchain.info ,this address did hold some coins a few months ago.
It might be an old address, that was not included in my last backup, i will investigate.
I use Bitcoin QT, and i am worried my bitcoins might be at risk.

Never had this problem before when generating a public address.

Is this a collision?

I will provide the address and proof to a trusted member if needed.

With the default settings, Bitcoin-Qt pre-generates 100 addresses that it keeps hidden from you.  When you create a backup, the backup contains these 100 addresses.

Then you use Bitcoin-Qt, and each time that you send any bitcoins anywhere or click the "New Address" button Bitcoin-Qt stores some of your bitcoins in another of the 100 pre-generated addresses.

If you later recover the backup, then there will be addresses in the pre-generated list in the backup that have previously held bitcoins.

So, no, this is not a collision.  This is how Bitcoin-Qt works.

I'm a bit surprised though that Bitcoin-Qt did not find these transactions when you first recovered the backup and scanned the blockchain.

Thanks for the answer.

Is there a way i can verify this? For ex: Blockchain analysis/ Transaction analysis...

[DannyHamilton]

Hi,

I generated earlier a new address and when i checked Blockchain.info ,this address did hold some coins a few months ago.
It might be an old address, that was not included in my last backup, i will investigate.
I use Bitcoin QT, and i am worried my bitcoins might be at risk.

Never had this problem before when generating a public address.

Is this a collision?

I will provide the address and proof to a trusted member if needed.

With the default settings, Bitcoin-Qt pre-generates 100 addresses that it keeps hidden from you.  When you create a backup, the backup contains these 100 addresses.

Then you use Bitcoin-Qt, and each time that you send any bitcoins anywhere or click the "New Address" button Bitcoin-Qt stores some of your bitcoins in another of the 100 pre-generated addresses.

If you later recover the backup, then there will be addresses in the pre-generated list in the backup that have previously held bitcoins.

So, no, this is not a collision.  This is how Bitcoin-Qt works.

I'm a bit surprised though that Bitcoin-Qt did not find these transactions when you first recovered the backup and scanned the blockchain.

Thanks for the answer.

Is there a way i can verify this? For ex: Blockchain analysis/ Transaction analysis...

If you take a look at the old transaction that used that address, you should be able to find the funding inputs.  If you trace these funding inputs back through multiple transactions, you should eventually find transactions that you recognize as being from your wallet (use receiving addresses that you created, or send to an address with a transaction you recall creating).

[alex0909]

Hi,

I generated earlier a new address and when i checked Blockchain.info ,this address did hold some coins a few months ago.
It might be an old address, that was not included in my last backup, i will investigate.
I use Bitcoin QT, and i am worried my bitcoins might be at risk.

Never had this problem before when generating a public address.

Is this a collision?

I will provide the address and proof to a trusted member if needed.

With the default settings, Bitcoin-Qt pre-generates 100 addresses that it keeps hidden from you.  When you create a backup, the backup contains these 100 addresses.

Then you use Bitcoin-Qt, and each time that you send any bitcoins anywhere or click the "New Address" button Bitcoin-Qt stores some of your bitcoins in another of the 100 pre-generated addresses.

If you later recover the backup, then there will be addresses in the pre-generated list in the backup that have previously held bitcoins.

So, no, this is not a collision.  This is how Bitcoin-Qt works.

I'm a bit surprised though that Bitcoin-Qt did not find these transactions when you first recovered the backup and scanned the blockchain.

Thanks for the answer.

Is there a way i can verify this? For ex: Blockchain analysis/ Transaction analysis...

If you take a look at the old transaction that used that address, you should be able to find the funding inputs.  If you trace these funding inputs back through multiple transactions, you should eventually find transactions that you recognize as being from your wallet (use receiving addresses that you created, or send to an address with a transaction you recall creating).

Yep it matches.
Thanks for your time.

Best regards.