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Questions tagged [transaction-malleability]

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A property of Bitcoin transactions that allows them to be replicated with another transaction id before they are included in a block.

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Integrity of Bitcoin transaction outputs

I am a noob. Currently, I am reading Mastering Bitcoin book. If I understand correctly, output of a bitcoin transaction is just a locking script with this format: scriptPubKey: "OP_DUP OP_HASH160 ...
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Do BIP199's HTLCs suffer from script malleability?

Do BIP199 HTLCs suffer from sigscript malleability like multisigs do due to OP_CHECKMULTISIG?
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What are the malleability threat vectors when passing PSBTs to other actors?

If I am passing a PSBT (Partially Signed Bitcoin Transaction) between multiple people, and I pass on my signature for my UTXOs for given inputs, can someone take advantage of malleability and cheat me ...
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Are the witnesses segregated with Schnorr signatures?

SegWit fixed transaction malleability by just moving the signature out of the block of data that's being hashed to form the transaction id. However, Schnorr does not suffer from signature malleability ...
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what does segwit remove?

It's said that Segwit removes signature data from transactions which makes block have more space for more transactions. Question 1) If SegWit removes signature data, where does it put it exactly ? ...
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97 views

Are P2PKH or P2SH transactions malleable?

BIP66 fixed one source of transaction malleability and segwit, to my understanding, fixed the rest of the sources. Yet, there are still many common types of non-segwit transactions in use, like P2PKH ...
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66 views

Transaction malleability in Testnet

I want to replicate transaction malleability to study it. I have two transactions data signed in testnet. One it's the original, ...
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206 views

scriptsig-not-pushonly (code 64) during send transaction in regtest

I create a transaction in regtest without send it, I have transaction data signed. I modified a little bit the scriptSig in order to replicate transaction malleability, I add two operations (2 OP_DROP)...
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1answer
119 views

Multisig refund transaction flaw in Lightning Network talk

I was watching Tadje Dryja's talk at SF Bitcoin Devs conference on transaction malleability, which formed part of the basis behind the Lightning Network. At 17'45", I saw this example. Prior to ...
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Transaction malleability

I have been reading about transaction malleability a lot still doesn't make sense to me. Is there a script I can use to test it out ? If the transaction that is malleable is changed by the attack, how ...
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113 views

How does storing the witness outside of the block prevent malleability?

I have some question on how segregated witness work. I'm reading this post and in the answer exist this phrase Since signature data (witness data) is stored outside the transaction (and outside ...
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Are non-SegWit transactions still malleable?

SegWit was (amongst other improvements) introduced to fix malleability issues. Does that mean that non-SegWit transactions are still malleable? If so, what types of malleability could still happen in ...
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155 views

Following SegWit implementation, is BIP-146 signalling and implementation still on the docket?

Is BIP 146, which defines using the low S value, still on the docket to be signalled and implemented given that SegWit fixed the txid malleability issue by moving the witness outside the transaction? ...
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Why SHOULD the funding tx consume BIP 141 inputs?

In BOLT 02 we read that the funding TX should only consume segwit inputs. The sender: when creating the funding transaction: SHOULD use only BIP141 (Segregated Witness) inputs. What is the reason ...
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Why is the wtxid considered malleable?

Why is the wtxid considered malleable since the transaction is unconfirmed? How can a third-party modify it?
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655 views

In ECDSA, why is (r,−s mod n) complementary to (r, s)?

I am trying to find resources in previous malleability posts, but couldn't find derivations/proofs of this fact or how the exact low-s value is derived. Any pointers would greatly appreciated.
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How malleability ussue works?

Can you explain malleability issue, please? This is what I read here: https://qz.com/175565/why-nobody-can-withdraw-bitcoins-from-one-of-the-currencys-largest-exchanges/ "When a transaction record ...
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328 views

Why didn't Bitcoin implement segwit in the first place?

Why didn't Bitcoin implement segwit in the first place? Why and how does non-segwit Bitcoin enable a miner to change a transaction's txid? From Mastering Bitcoin ch. 7 § "Transaction identifiers": ...
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Transaction Malleability, if i want to change signature, what part should I change, so that it would remain valid?

I know what transaction malleability is, but I don't understand how someone can change my signature so that it would remain valid. For example, If I want to change signature what part should I change, ...
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"comment" and "to" of malleated transactions

I'm using the bitcoin core wallet and trying to build some programs around it. I see that comment and to can be added to transactions locally. If I understand it correctly, both are stored in local ...
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77 views

Can transaction id be used to verify a transaction?

I have seen alot of questions here on "Transaction Malleability issue". Editing of transaction id can be done by miners or nodes which relay the transaction. What I want to know is whether the ...
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622 views

Why was transaction malleability fix required for Lightning network?

Transaction malleability is that TXID can be changed modifying the signature slightly without the private key. To implement Lightning Network, it was required to fix the malleability. However, I ...
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1answer
84 views

Why are miners allowed to change a tx id?

BIP 62 proposed to make transaction malleability impossible. Why was this retracted and why are miners allowed to change a transaction id? Also, what does it mean when someone says signatures ...
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1answer
191 views

What does malleable mean in "transaction malleability"?

Does malleable mean modifiable? If you can malleate a transaction you can modify some of its parts leaving the transaction as still valid (the signatures are not broken). If you can malleate the ...
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356 views

Lightning network: how was malleability actually fixed?

Section 3.1.2 of the Lightning paper (Version 0.5.9.2, last modified 14 January 2016) discusses ways to fix the transaction malleability issue, which prevented Bitcoin transactions from spending UTXO ...
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249 views

malleability in 2-of-2 multisig payment channel

I am having issues understanding 2-of-2 multisig, with regards to the malleability attack. Where Alice and Bob set up a multisig payment channel where Alice sends 1 BTC in order to do multiple tx ...
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875 views

What can be the reason to change transaction ID?

I always thought that when my wallet create a transaction, it's transaction id is fixed (it is the SHA256 of the transaction message). Yes, the transaction might not be included in the next block (and ...
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143 views

What's the easiest way for a third party to malleate a transaction?

Let's say I am a node. A transaction has been relayed to me, and one of the scriptSig fields is: <sig> <pubKey> What is the easiest way for me to malleate this transaction? For example, ...
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1answer
463 views

Does Segwit mean easier government monitoring?

I have noticed a steady stream of PR articles talking ad nauseum of the dangers of a contentious hard fork and how miners refusing to signal segwit are screwing us all. Many are quite well written and ...
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tx-malleability who re-signed the tx?

It would be really great if there was a way to loop through all the txids in a new block and be able to check if you (can) sign your original transaction the same way it was re-signed - that it ...
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1answer
95 views

How did blockr.io see this?

Here's the pushed/broacast-ed tx http://tbtc.blockr.io/tx/info/d8e5dac095d5f6133e6c3f11e1d9f923c04dac0824f9f8ce0000573df7cc8080 txid was malleated to txid (when the tx was added into the block): ...
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2answers
166 views

testnet3 frequent tx malleability

Related How confirm my own doublespend transaction got confirmed This is not about double spends and I believe that the related question is not about double spends ether! On bitcoin's testnet3 I am ...
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224 views

How confirm my own doublespend transaction got confirmed

Transactions in the testnet are right now almost always double spent with a new txid (possible due to tx malleability). This is actually quite nice for testing purposes. So I'm wondering - when I ...
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If well-built wallet software can avoid transaction malleability, why does the lightning network need an additional malleability fix?

My understanding is that wallets can avoid creating malleable transactions. If so, why does a lightning network need SegWit or some other tx malleability fix?
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133 views

OP_RETURN malleability?

Can anyone alter the data after OP_return? My question needs to have more characters, so I insert an example, that doesn't hurt: "vout" : [ { "value" : 0.00000000, "n" : 0, ...
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273 views

How to create walletconflicts in regtest mode?

I play with Bitcoin Core 0.13 in regtest mode using python. Now I use bitcoin-testnet-box, I have two nodes connected to each other. I want to create a walletconflict. I want to get gettransaction <...
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1answer
162 views

Bitcoin Core 0.13 -- jsonrpc interface -- conflicted transactions

I use bitcoind's Wallet feature to manage my bitcoins. Using json-rpc interface, how can I check that a transaction is a conflicted one? And, how can I get txhash of a transaction, that spends those ...
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1answer
334 views

How are transaction IDs generated and how are they then changed by transaction malleability?

How are the transaction IDs generated for a Bitcoin transaction? How can the transaction ID change due to a transaction malleability attack?
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1answer
286 views

why is double-spend not an issue for payment channels?

Micropayment Channels (MPC) cannot be used currently because of transaction malleability, I hear. AFAIK, people saying that have in mind that the refund & payment tx, which have as input the ...
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646 views

Are Micropayment channels still subject to malleability after BIP65?

After BIP 65, are simple, unidirectional, MPC still subject to transaction malleability? More specifically: Is the payee at risk because of malleability? If yes, how? (as far as I understood, the ...
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1answer
116 views

Is transaction malleability the only consensus issue that needs fix to allow lightning network?

Is transaction malleability the only thing needs fix in the bitcoin consensus code to enable lightning network to be implemented? Of course, lightning network itself would need to be implemented, but ...
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816 views

Is it possible to combine two separate transactions into one transaction by only using their signatures?

I have two valid txs and two valid signatures for those txs. Right now they look like: 1) A -> B 2) C -> D A and C are inputs & B and D are outputs. I want to be able to combine them ...
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1answer
102 views

Is CheckSequenceVerify only a stop-gap measure?

The Lightning Paper v0.5.9.2 says that CSV "would permit further abilities, including allowing a stop-gap solution before a more permanent solution for resolving transaction malleability. A future ...
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A common criticism of Segregated Witness is that it is "unnecessarily complex". Why is it chosen over alternatives?

Segregated Witness (SegWit) is well-along the way to being implemented and deployed as a soft-fork. Facts: SegWit eliminates most forms of transaction malleability. Discounts input scripts in ...
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476 views

Why was the Oct 2015 Transaction Malleability event possible in spite of BIP62/66?

The recent re-emergence of transaction malleability has been responsible for a large number of Txs which are being double spent (October 2015). /r/Bitcoin has posted some C++ code which @amaclin has ...
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Transaction rejected by our node. Blockchain receive API

I use the Blockchain.info receive API with great succes. Yesterday I created a new address: 1MMVp6fzZ6QrVYXg9iRSJb5PsM8crq5iMZ It received 1.5 BTC and was transferred to my BTC address (unfonfirmed). ...
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188 views

transaction malleability "attack" vectors

are any of the following transaction malleability "attack" vectors currently feasible? alter scriptsig from: OP_PUSHDATA <sig> OP_PUSHDATA <pubkey> to one of: 1) OP_1 OP_SHA1 OP_DROP ...
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1k views

How do I uniquely identify a transaction (to protect against malleability)?

Transactions I broadcast can be malleated by anyone watching the mempool (more info here). This rules out using txid for transaction identification. How can I identify my transactions to make sure ...
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1answer
1k views

Using bitcoins JSON RPC, how can I confirm a transaction I published?

I have created, signed and sent a raw transaction via bitcoind RPC. Now I want to wait for it to have n confirmations. Considering transaction malleability, I can't just check the "confirmations" ...
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1k views

How much of BIP 62 ("Dealing with malleability") has been implemented?

BIP 62 lists nine source of malleability: Non-DER encoded ECDSA signatures Non-push operations in scriptSig Push operations in scriptSig of non-standard size type Zero-padded number pushes Inherent ...

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