📅 Original date posted:2015-04-17
📝 Original message:> Anyone can alter the txid - more details needed. The number of altered
> txids in practice is not so high in order to make us believe anyone can
> do it easily. It is obvious that all current bitcoin transactions are
> malleable, but not by anyone and not that easy. At least I like to think
so.
Don't assume that because it does not (frequently) happen, that it cannot
happen. Large amounts of malleated transactions have happened in the past.
Especially if you build a system depends on non-malleability for its
security, you may at some point have an attacker who has financial gain
from malleation.
> >From your answer I understand that right now if I create a transaction
> (tx1) and broadcast it, you can alter its txid at your will, without any
> mining power and/or access to my private keys so I would end up not
> recognizing my own transaction and probably my change too (if my systems
> rely hardly on txid)?
In theory, yes, anyone can alter the txid without invalidating it, without
mining power and without access to the sender's private keys.
All it requires is seeing a transaction on the network, doing a trivial
modification to it, and rebroadcasting it quickly. If the modifies version
gets mined, you're out of luck. Having mining power helps of course.
After BIP62, you will, as a sender, optionally be able to protect others
from malleating. You're always able to re-sign yourself.
--
Pieter
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Pieter Wuille [ARCHIVE] /
npub1tj…jtl6r
2023-06-07 15:32:31
in reply to nevent1q…ghqr
Author Public Key
npub1tjephawh7fdf6358jufuh5eyxwauzrjqa7qn50pglee4tayc2ntqcjtl6rSeen on
wss://relay.noswhere.comPublished at
2023-06-07 15:32:31Event JSON
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"pubkey": "5cb21bf5d7f25a9d46879713cbd32433bbc10e40ef813a3c28fe7355f49854d6",
"created_at": 1686151951,
"kind": 1,
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"content": "📅 Original date posted:2015-04-17\n📝 Original message:\u003e Anyone can alter the txid - more details needed. The number of altered\n\u003e txids in practice is not so high in order to make us believe anyone can\n\u003e do it easily. It is obvious that all current bitcoin transactions are\n\u003e malleable, but not by anyone and not that easy. At least I like to think\nso.\n\nDon't assume that because it does not (frequently) happen, that it cannot\nhappen. Large amounts of malleated transactions have happened in the past.\nEspecially if you build a system depends on non-malleability for its\nsecurity, you may at some point have an attacker who has financial gain\nfrom malleation.\n\n\u003e \u003eFrom your answer I understand that right now if I create a transaction\n\u003e (tx1) and broadcast it, you can alter its txid at your will, without any\n\u003e mining power and/or access to my private keys so I would end up not\n\u003e recognizing my own transaction and probably my change too (if my systems\n\u003e rely hardly on txid)?\n\nIn theory, yes, anyone can alter the txid without invalidating it, without\nmining power and without access to the sender's private keys.\n\nAll it requires is seeing a transaction on the network, doing a trivial\nmodification to it, and rebroadcasting it quickly. If the modifies version\ngets mined, you're out of luck. Having mining power helps of course.\n\nAfter BIP62, you will, as a sender, optionally be able to protect others\nfrom malleating. You're always able to re-sign yourself.\n\n-- \nPieter\n-------------- next part --------------\nAn HTML attachment was scrubbed...\nURL: \u003chttp://lists.linuxfoundation.org/pipermail/bitcoin-dev/attachments/20150417/0f221669/attachment.html\u003e",
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