1

I want to replicate transaction malleability to study it.

I have two transactions data signed in testnet. One it's the original,

0200000001abb6c7df544b53eec11612ab9d82ef0fe0a3aa2ff33f41bbf5f149986d80af47000000006a47304402207a325de81b063d3e28023a63c37c554e7eb136d94612334bbd6715a05abb684e02203a87c85819815bb12d4386fa76aa6b990c65158b61ccb05a14a249e14095663b012103bf7b2ddadda97523405400ae95be2cb153768cce8b1bed55d1c8aca4bb2ee16dffffffff02e8030000000000001976a914fd1002f92de062322225735e24b85590a3ef7af288ac29e31100000000001976a9146162f487e0b293054f1fb8025769f1e1f14d379b88ac00000000

The second one is the transaction "malleated".

0200000001abb6c7df544b53eec11612ab9d82ef0fe0a3aa2ff33f41bbf5f149986d80af47000000006c527547304402207a325de81b063d3e28023a63c37c554e7eb136d94612334bbd6715a05abb684e02203a87c85819815bb12d4386fa76aa6b990c65158b61ccb05a14a249e14095663b012103bf7b2ddadda97523405400ae95be2cb153768cce8b1bed55d1c8aca4bb2ee16dffffffff02e8030000000000001976a914fd1002f92de062322225735e24b85590a3ef7af288ac29e31100000000001976a9146162f487e0b293054f1fb8025769f1e1f14d379b88ac00000000

Before send the first one and after send the malleated transaction.

I receive txn-mempool-conflict (code 18)

I can't replicate the transaction malleability if the original is already in the mempool?

I'm using bitcoin-core 0.19.0.1

2

What malleability means is that you can create a transaction that is identical in its meaning (same inputs, same outputs) but with a different TXID. That is problematic for 2nd layer protocols where transactions build onto each other but aren't necessarily published to chain.

But a "malleated" transaction is still a double spend. And it appears newer versions of bitcoin-core that support RBF won't accept double spends into their mempool.

See code snippet here: Validation Error: Error #-26: 258: txn-mempool-conflict

| improve this answer | |
  • Thanks @guggero, Can I disable RBF in my node? I don't find any option – monkeyUser Jan 16 at 16:06
  • RBF (as specified in BIP125) only applies when you signature replacement. The problem is here that you don't do that, and as a result the replacement is not accepted. – Pieter Wuille Jan 16 at 16:32
  • This is unrelated to RBF. Double spends have never been accepted. – Andrew Chow Jan 16 at 16:46

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