<blockquote>
  <p>it is possible to recover the public key</p>
</blockquote>

<p>Yes. But this operation is slow (comparing with other bitcoin script operations). May be Satoshi Nakamoto did not know about it. Anyway, the hard-fork required to implement it. So, you are welcome to create hard-fork or altcoin with this feature implemented.</p>

<p>Have a look to this discussion: <a href="https://bitcointalk.org/index.php?topic=6430.0" rel="nofollow noreferrer">https://bitcointalk.org/index.php?topic=6430.0</a> I can not explain better</p>

CC BY-SA 3.0
2017-12-21T12:45:44.680Z
2017-12-21T12:45:44.680Z
amaclin
<p>Using ECDSA, given a signature and the message signed, it is possible to recover the public key. So it seems to be a waste of up to 65 bytes in each transaction. Why does bitcoin do it? Which cryptocurrencies use the key recovery approach?</p>

<transactions><public-key><ecdsa><input-script>
Why does ScriptSig contain public key, since it can be recovered from the signature and message?
Jus12
# Why does ScriptSig contain public key, since it can be recovered from the signature and message?

(Asked by: username_0 on 2017-12-21)

Using ECDSA, given a signature and the message signed, it is possible to recover the public key. So it seems to be a waste of up to 65 bytes in each transaction. Why does bitcoin do it? Which cryptocurrencies use the key recovery approach?

**Tags:** transactions, public-key, ecdsa, input-script


---

## 1 answers

### Answer by username_1 on 2017-12-21. Score: 1 | Accepted answer

> it is possible to recover the public key

Yes. But this operation is slow (comparing with other bitcoin script operations). May be Satoshi Nakamoto did not know about it. Anyway, the hard-fork required to implement it. So, you are welcome to create hard-fork or altcoin with this feature implemented.

Have a look to this discussion: <https://bitcointalk.org/index.php?topic=6430.0> I can not explain better


---

