<p>When an output is spent, the corresponding public key is disclosed and used in the verification.</p>

CC BY-SA 3.0
2017-08-21T20:21:41.767Z
Ah okay, so whenever you send something you show the public keys. I assume that is only why you should not use the same addresses multiple times?
no nein
CC BY-SA 3.0
2017-08-21T21:14:07.477Z
@nonein: That's one of the reasons, yes. Specifically, reusing addresses opens a vulnerability to quantum computers.
Meni Rosenfeld
CC BY-SA 3.0
2017-08-21T20:17:31.433Z
2017-08-21T20:17:31.433Z
Meni Rosenfeld
<p>So far as I understand it, a Bitcoin transaction is signed with a private key and the rest of the network can then use the public key to verify that it is indeed signed by the right private key. However, as public keys are hashed, how do I use them to verify the private key?</p>

<public-key>
How do you check the validity of a signature while only having the hash of the public key
no nein
# How do you check the validity of a signature while only having the hash of the public key

(Asked by: username_0 on 2017-08-21)

So far as I understand it, a Bitcoin transaction is signed with a private key and the rest of the network can then use the public key to verify that it is indeed signed by the right private key. However, as public keys are hashed, how do I use them to verify the private key?

**Tags:** public-key


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## 1 answers

### Answer by username_1 on 2017-08-21. Score: 4

When an output is spent, the corresponding public key is disclosed and used in the verification.

> **Comments:**
> **username_0**: Ah okay, so whenever you send something you show the public keys. I assume that is only why you should not use the same addresses multiple times?  
> **username_1**: @nonein: That's one of the reasons, yes. Specifically, reusing addresses opens a vulnerability to quantum computers.  

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