<p>Signing a message provides the useful property of "non repudiation", which is of value to the recipient of the message.</p>

<p>It is a way of recording a promise made in a way that the recipient can later prove:</p>

<ul>
<li>that the promise was made, and</li>
<li>who made the promise</li>
<li>when the promise was made</li>
<li>to whom the promise was made</li>
<li>what the promise was</li>
</ul>

<p>In a way that the promiser cannot deny or modify later on.</p>

<p>It does not guarantee that the promise must be satisfied, but can be useful in resolving disputes.</p>

<p>If the promise is a matter of public record, it can also be useful as a way of identifying fraud, for example where the same unique resource (eg a btc) is promised twice to two different recipients.</p>

CC BY-SA 3.0
2015-01-18T17:18:00.753Z
2015-01-18T17:18:00.753Z
Alex Brown
<p>You can sign a message to prove ownership of a particular private key, without sharing the private key or spending any funds. For example, you could sign a message that says "My name is John Doe". You could give this signed message to anybody, and they can verify it with your public key. This proves that whoever has your private key claimed to be John Doe at some point. </p>

<p>Somebody might sign a promise to deliver funds in the future, to prove that they have access to the funds (if the address associated with the private key has the amount of money promised), without actually sending the money. Basically proving the ability to send money, without actually sending it. </p>

CC BY-SA 3.0
2015-01-16T14:39:13.163Z
I know that already, I mean somethink else
tor
CC BY-SA 3.0
2015-01-16T14:39:35.707Z
What else do you mean?
JohnDvorak
CC BY-SA 3.0
2015-01-16T14:39:59.087Z
Like signing "I will send you 1 btc" why do they sign this?
tor
CC BY-SA 3.0
2015-01-16T14:41:59.787Z
Somebody might sign a promise to deliver funds in the future, to prove that they have access to the funds (if the address associated with the private key has the amount of money promised), without actually sending the money. Basically proving the ability to send money, without actually sending it.
JohnDvorak
CC BY-SA 3.0
2015-01-16T14:38:44.670Z
2015-01-16T14:38:44.670Z
JohnDvorak
<p>I got a simple but straight question:</p>

<p><strong>Why do we need "Sign message". Also give explanations and examples.</strong></p>

<message-signing><signature>
For what purposes do we need "Sign message"?
tor
# For what purposes do we need "Sign message"?

(Asked by: username_0 on 2015-01-16)

I got a simple but straight question:

**Why do we need "Sign message". Also give explanations and examples.**

**Tags:** message-signing, signature


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## 2 answers

### Answer by username_2 on 2015-01-16. Score: 7 | Accepted answer

You can sign a message to prove ownership of a particular private key, without sharing the private key or spending any funds. For example, you could sign a message that says "My name is John Doe". You could give this signed message to anybody, and they can verify it with your public key. This proves that whoever has your private key claimed to be John Doe at some point.

Somebody might sign a promise to deliver funds in the future, to prove that they have access to the funds (if the address associated with the private key has the amount of money promised), without actually sending the money. Basically proving the ability to send money, without actually sending it.

> **Comments:**
> **username_0**: I know that already, I mean somethink else  
> **username_2**: What else do you mean?  
> **username_0**: Like signing "I will send you 1 btc" why do they sign this?  
> **username_2**: Somebody might sign a promise to deliver funds in the future, to prove that they have access to the funds (if the address associated with the private key has the amount of money promised), without actually sending the money. Basically proving the ability to send money, without actually sending it.  

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### Answer by username_1 on 2015-01-18. Score: 1

Signing a message provides the useful property of "non repudiation", which is of value to the recipient of the message.

It is a way of recording a promise made in a way that the recipient can later prove:

* that the promise was made, and
* who made the promise
* when the promise was made
* to whom the promise was made
* what the promise was

In a way that the promiser cannot deny or modify later on.

It does not guarantee that the promise must be satisfied, but can be useful in resolving disputes.

If the promise is a matter of public record, it can also be useful as a way of identifying fraud, for example where the same unique resource (eg a btc) is promised twice to two different recipients.


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