<p>The public key is derived from the private key. Generating a private key is pretty collision resistant as the space is huge. The fact that an address is in turn a hash of the public key doesn't change that.</p>

<blockquote>
  <p>So how do you prove, that you are the owner of a bitcoin adress?</p>
</blockquote>

<p>By having the private key: only then can you sign transactions.</p>

<p>Consent of the receiver is not required to send a transaction. If the receiver really doesn't want free money, he can chose to not spend it.</p>

CC BY-SA 3.0
2016-04-06T11:39:49.080Z
2016-04-06T11:39:49.080Z
Jannes
<p>I am trying to understand Bitcoin addresses, but it does not seem to be easy at all.</p>

<p>As far as I know, a Transaction uses one or more addresses as input and one or more addresses as output. Is this correct?</p>

<p>As I understand it a bitcoin address is a hash of your public key. So it is not completely collision resistant. So how do you prove, that you are the owner of a bitcoin address?</p>

<p>Also, since everybody can make an address from your public key and the recipient of a transaction does not have to sign the transaction, how do you make sure no one can send you Bitcoins without your consent? (I don't really know if this is a problem to be honest)</p>

<security><address><hash><ownership>
Bitcoin adresses seem not to be collision resistant. Please tell me I am wrong
Junge
# Bitcoin adresses seem not to be collision resistant. Please tell me I am wrong

(Asked by: username_0 on 2016-04-06)

I am trying to understand Bitcoin addresses, but it does not seem to be easy at all.

As far as I know, a Transaction uses one or more addresses as input and one or more addresses as output. Is this correct?

As I understand it a bitcoin address is a hash of your public key. So it is not completely collision resistant. So how do you prove, that you are the owner of a bitcoin address?

Also, since everybody can make an address from your public key and the recipient of a transaction does not have to sign the transaction, how do you make sure no one can send you Bitcoins without your consent? (I don't really know if this is a problem to be honest)

**Tags:** security, address, hash, ownership


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## 1 answers

### Answer by username_1 on 2016-04-06. Score: 1

The public key is derived from the private key. Generating a private key is pretty collision resistant as the space is huge. The fact that an address is in turn a hash of the public key doesn't change that.

> So how do you prove, that you are the owner of a bitcoin adress?

By having the private key: only then can you sign transactions.

Consent of the receiver is not required to send a transaction. If the receiver really doesn't want free money, he can chose to not spend it.


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