<p>Malleability is ability to change the binary contents of transaction (that also includes its TXID) without invalidating it, by <strong>someone else</strong> after broadcast and before the confirmation in block.</p>

CC BY-SA 3.0
2017-11-27T22:29:33.467Z
Couldn't the word modifiable be used instead malleable, because this is just modifying the transaction in some way, if I understand correctly?
croraf
CC BY-SA 3.0
2017-11-27T22:40:31.483Z
Hm. Let us take any txA and any txB. Can we say that txB is a `modification` of txA where all bytes of txA were `modified` to bytes of txB ? :))))
amaclin
CC BY-SA 3.0
2017-11-27T22:42:04.957Z
Than the word change (changable) instead malleate (malleable). Malleable just sounds fancy, but in fact just means change the transaction?
croraf
CC BY-SA 3.0
2017-11-27T22:59:52.330Z
It's a standard term in cryptography. Malleability specifically refers to the ability to change a signature *without being authorized to sign*.
Pieter Wuille
CC BY-SA 3.0
2017-11-27T22:18:53.363Z
2017-11-27T22:35:40.257Z
2017-11-27T22:35:40.257Z
amaclin
<p>Does malleable mean modifiable?</p>

<p>If you can malleate a transaction you can modify some of its parts leaving the transaction as still valid (the signatures are not broken).</p>

<p>If you can malleate the transaction outputs you can modify the outputs.</p>

<p>If you can malleate the order of inputs you can modify the order of inputs.</p>

<p>But the bitcoin.stackexchange.com "transaction-malleability" tag says: </p>

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

<p>This confuses me. Does transaction have an ID at all, and if it does ID seems totally irrelevant?</p>

<transactions><transaction-malleability>
What does malleable mean in "transaction malleability"?
croraf
# What does malleable mean in "transaction malleability"?

(Asked by: username_0 on 2017-11-27)

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 transaction outputs you can modify the outputs.

If you can malleate the order of inputs you can modify the order of inputs.

But the bitcoin.stackexchange.com "transaction-malleability" tag says:

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

This confuses me. Does transaction have an ID at all, and if it does ID seems totally irrelevant?

**Tags:** transactions, transaction-malleability


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## 1 answers

### Answer by username_1 on 2017-11-27. Score: 1

Malleability is ability to change the binary contents of transaction (that also includes its TXID) without invalidating it, by **someone else** after broadcast and before the confirmation in block.

> **Comments:**
> **username_0**: Couldn't the word modifiable be used instead malleable, because this is just modifying the transaction in some way, if I understand correctly?  
> **username_1**: Hm. Let us take any txA and any txB. Can we say that txB is a `modification` of txA where all bytes of txA were `modified` to bytes of txB ? :))))  
> **username_0**: Than the word change (changable) instead malleate (malleable). Malleable just sounds fancy, but in fact just means change the transaction?  
> **username_2**: It's a standard term in cryptography. Malleability specifically refers to the ability to change a signature *without being authorized to sign*.  

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