Bitcoin Forum
September 22, 2018, 04:15:39 PM *
News: ♦♦ New info! Bitcoin Core users absolutely must upgrade to previously-announced 0.16.3 [Torrent]. All Bitcoin users should temporarily trust confirmations slightly less. More info.
 
   Home   Help Search Donate Login Register  
Pages: [1]
  Print  
Author Topic: Is it possible to have two transaction IDs that are exactly the same?  (Read 2655 times)
TeraPool
Newbie
*
Offline Offline

Activity: 42
Merit: 0


View Profile
July 13, 2011, 01:20:18 AM
 #1

Or would that be considered a collision of some sort? What exactly is a transaction id? A hash of some sort I presume?

I couldn't find much about transaction ids in particular on the wiki.

How would the bitcoin client treat two separate transactions with identical transaction ids?
Advertised sites are not endorsed by the Bitcoin Forum. They may be unsafe, untrustworthy, or illegal in your jurisdiction. Advertise here.
1537632939
Hero Member
*
Offline Offline

Posts: 1537632939

View Profile Personal Message (Offline)

Ignore
1537632939
Reply with quote  #2

1537632939
Report to moderator
1537632939
Hero Member
*
Offline Offline

Posts: 1537632939

View Profile Personal Message (Offline)

Ignore
1537632939
Reply with quote  #2

1537632939
Report to moderator
josell
Full Member
***
Offline Offline

Activity: 308
Merit: 100



View Profile
July 13, 2011, 01:50:21 AM
 #2

Yes, it is possible... But is very very very unprobable. They are more possible directions that atoms on the hole earth, but im not really sure.
TeraPool
Newbie
*
Offline Offline

Activity: 42
Merit: 0


View Profile
July 13, 2011, 03:44:26 AM
 #3

Thanks for that.

That's what I thought.

Since blockexplorer allows you to search by transaction id... you should not be able to have a duplicate one I would think.
theymos
Administrator
Legendary
*
Offline Offline

Activity: 3150
Merit: 3663


View Profile
July 13, 2011, 03:58:37 AM
 #4

Transaction IDs are SHA-256 hashes of transactions. It's very safe to use them as unique IDs, and it's a waste of time to try to detect collisions.

It is possible (though very rare) for the exact same transaction to appear twice in the block chain, however.

1NXYoJ5xU91Jp83XfVMHwwTUyZFK64BoAD
davux
Sr. Member
****
Offline Offline

Activity: 289
Merit: 250


Firstbits.com/1davux


View Profile WWW
July 13, 2011, 07:44:02 AM
 #5

It is possible (though very rare) for the exact same transaction to appear twice in the block chain, however.

Can you please explain under what circumstances this could happen? I couldn't find anything.

1DavuxH9tLqU4c7zvG387aTG4mA7BcRpp2
México (Oaxaca) – France - Leeds
Maged
Legendary
*
Offline Offline

Activity: 1260
Merit: 1004


View Profile
July 13, 2011, 07:52:51 AM
 #6

It is possible (though very rare) for the exact same transaction to appear twice in the block chain, however.

Can you please explain under what circumstances this could happen? I couldn't find anything.
See blocks 91812 and 91842 for one example.

JoelKatz
Legendary
*
Offline Offline

Activity: 1582
Merit: 1004


Democracy is vulnerable to a 51% attack.


View Profile WWW
July 13, 2011, 02:47:23 PM
 #7

You can maliciously, or stupidly, create two transactions with the same ID. The easiest way is to mine two blocks and include in each one only a single transaction -- the coinbase transaction, with the same payout address, same payout amount, and the same coinbase.

I am an employee of Ripple. Follow me on Twitter @JoelKatz
1Joe1Katzci1rFcsr9HH7SLuHVnDy2aihZ BM-NBM3FRExVJSJJamV9ccgyWvQfratUHgN
Pages: [1]
  Print  
 
Jump to:  

Sponsored by , a Bitcoin-accepting VPN.
Powered by MySQL Powered by PHP Powered by SMF 1.1.19 | SMF © 2006-2009, Simple Machines Valid XHTML 1.0! Valid CSS!