Help: How do I sign a message using my blockchain.info address

[shibaji]

According to this page, import/export section should have a way to sign a message, but after logging in, I do not see a way to do that: https://blockchain.info/wallet/features

Has anyone tried this before ?

Thanks for your help!

[tom1]

Addresses (active) -> Actions -> Sign message

[shibaji]

Addresses (active) -> Actions -> Sign message

Where is this page (Addresses) ?

[shibaji]

Found it, nevermind - thanks a lot!

[niner]

Addresses (active) -> Actions -> Sign message

Where is this page (Addresses) ?

more specifically ...

Receive Money -> Addresses (active) -> Actions -> Sign message

-- or --

Receive Money -> Addresses (active) -> Actions -> More Actions -> Verify message

[cardcomm]

Addresses (active) -> Actions -> Sign message

Where is this page (Addresses) ?

more specifically ...

Receive Money -> Addresses (active) -> Actions -> Sign message

-- or --

Receive Money -> Addresses (active) -> Actions -> More Actions -> Verify message

Awesome! thanks for the info

[stex2009]

Why do you sign a msg. Not sure why to do this?

[cp1]

Why do you sign a msg. Not sure why to do this?

You can prove that you own the address by signing a message with your private key.

[cardcomm]

Why do you sign a msg. Not sure why to do this?

You can prove that you own the address by signing a message with your private key.

An example of why one might use this feature would be to verify an address change or other communication regarding a previous transaction. This would prove you control the address, and therefore any funds that were sent.

I believe many group buys require this for verified communication about a specific purchase.

[ooeygooeygold]

Why do you sign a msg. Not sure why to do this?

You can prove that you own the address by signing a message with your private key.

An example of why one might use this feature would be to verify an address change or other communication regarding a previous transaction. This would prove you control the address, and therefore any funds that were sent.

I believe many group buys require this for verified communication about a specific purchase.

what do I do with the key? Send it as a pm?

[cp1]

what do I do with the key? Send it as a pm?

Noooo never do that
You sign a message with the key.  Whatever wallet you use must have a "sign a message with this key" option.

So you use your private key to sign a message.  Only the person with the private key can sign the message.  Anyone with the public key (bitcoin address) can validate the message.  It's how bitcoin works -- only the private key holder can sign a message to spend bitcoins.  Anyone with the bitcoin address can verify the bitcoins were spent.

[alnoor1231]

But the key should be sent as well, shouldn`t it???

Received a few PMs about USB hubs, here's a good thread on it: https://bitcointalk.org/index.php?topic=253749.0

example of a signed message:


and this is what you'd PM me by copying from above example:

1. 1GdaJQLdcVVvhTvAHdKD3WMjQ1xdNSehaG
2:
----start below------
John Smith
1234 Way Blvd., STE 101
Some City, IL 60181
----end above-------
3: IAqNhGjiV28ZwZyn5kG83EtJN+7djc/n6c7zs9MArIAbe3ChijEg7eNa/0VqHrtdctRtG2Cxxfb/ObZCLJpsn4I=
4: transaction id: 5c27ac15f0a1aa71ffb5d080689b4bcab243b0c0aa85f908b3209ace61de8000
That's it!!!
--------------------------
how to send a shipping label:
I'm writing up some basic instructions to add to this post... you will essentially download that pdf label from usps and email it to canary.btc@gmail.com (email used for labels only, contact with questions via PM here)
in the body of the email, you will have 4 things:
1. transaction id of your order
2. 1st payment address of the transaction
3. tracking number (no spaces)
4. Signature (your will sign ONLY the tracking # from item #3)
additionally, if you use this method, you no longer need to PM me shipping address as a signed message.  trying to make things simpler for all.
I will check that the tracking number in item 3 matches the label exactly.
--------------------------
guidelines for your own labels:

small priority box fits 14 USB miners
medium priority box fits 100 USB miners
large priority box first 140 USB miners
20 USB miners fit into a flat-rate padded envelope

--------------------------
If you are a re-seller on eBay or other outlets, I can handle your shipping of USB miners.
- you sell
- send me the appropriate label (pdf) you generate for your sold order.
- I ship from zip 60181
- you pay me a handling fee for handling each order (negotiated).
- sit back and relax... don't bother shipping. I do that with my elves for you.

all you need to do is pay for and reserve a specific amount of units that are yours in my inventory.  I can extend credit to you and make a larger reservation initially.  so that you can use those 50 btc per day from coinbase daily and make use of negotiated credit terms.

contact me to enter into such an arrangement.  previous large purchasers will have easier starting credit terms with me  

Thanks,

Canary

[escrow.ms]

But the key should be sent as well, shouldn`t it???

No, that's not private key. It's just a digital signature.

Check https://www.khanacademy.org/science/core-finance/money-and-banking/bitcoin/v/bitcoin-digital-signatures to know more about digital signatures.

[Unacceptable]

This example makes it easy :

Post # 410:
https://bitcointalk.org/index.php?topic=195052.msg2087551#msg2087551

It is confusing,until you do it once 

Open notepad:

1.Go to your "receive coins" button,click it,copy & paste that addy in notepad.This is YOUR wallet addy,any BTC sent to it will end up in your wallet & no one else's.
I only have one receive addy,if you have more than one...........I don't think it matters,just pick one.Someone correct me if I'm wrong

2.Now,go to "transactions" button,click it, find the transaction you want to sign,right click on it & click on "show details".Copy & paste the "Transaction ID" in notepad.

3.Your ready to sign a message,go to "file",upper left corner,click it & click "sign message".

4.Copy & paste YOUR wallet addy in line 1.........In the body copy & paste the "Transaction ID".Put your info in there too,what the BTC was sent for & how much (EXACT amount),name,shipping address,etc...

5.Click "sign message" on the bottom,it will generate a unique ID #.Now copy & paste the info from all 3 sections in an email or PM,keep them seperate in the email (don't just bunch em together) & volia!!!!

You just signed a message 

[J_Dubbs]

Speaking honestly here. I find this all to be quite confusing. 

[7queue]

I tried the Sign message...

Used a valid sending address I own

Signed

Tried to Verify with bitcoin-qt

Message verification failed.

Shouldn't the signed message be verifiable ??

Do I have to send some BTC to my address in order to complete this verification ??

I am going to try this on testnet to see exactly what works and doesn't ...

8 )

[cp1]

No, you don't have to have any coins in the address to sign a message.  You just need the private key.  If you couldn't verify it there was probably a problem with spaces or returns.  The message "hi<return>" is different from "hi" and "hi<space".

[7queue]

Well if I can't do this, imagine what someone who doesn't know the code is going through

I'm trying this on testnet now, and nothing is working!

What am I doing wrong?

I have only one address in the testnet wallets, sent 10 BTC to another wallet on a different machine, it received it.

Tried to sign a message, singing was ok, verification is where I'm hung up

What exactly does one use for verification, that is rather 'vague' in the instructions!

Thanks!

8 )

[cp1]

File - sign message, select address
message: hello
signature:  HyEGS89+1+1mm91Iexyy5dwuZjfDPBotiNbMkWR3r+tSUSm51LV8xX9RmGYeB6RmRuMqQKi7KSoxmCumbhQDKJs=

File - verify message, enter same address
message:  hello
signature:  HyEGS89+1+1mm91Iexyy5dwuZjfDPBotiNbMkWR3r+tSUSm51LV8xX9RmGYeB6RmRuMqQKi7KSoxmCumbhQDKJs=

Message verified

[7queue]

File - sign message, select address
message: hello
signature:  HyEGS89+1+1mm91Iexyy5dwuZjfDPBotiNbMkWR3r+tSUSm51LV8xX9RmGYeB6RmRuMqQKi7KSoxmCumbhQDKJs=

File - verify message, enter same address
message:  hello
signature:  HyEGS89+1+1mm91Iexyy5dwuZjfDPBotiNbMkWR3r+tSUSm51LV8xX9RmGYeB6RmRuMqQKi7KSoxmCumbhQDKJs=

Message verified

I just tried this on test net

No Go

one address in the wallet

8 )