How to get the pubkey of other's address?

gpmn

newbie

Activity: 8

Merit: 0

I changed the code of bitcoin src/rpcmisc.cpp then recompiled it
I ask for their signed messages, then I can get pubkey from the signed message

Value verifymessage(const Array& params, bool fHelp)
....
...
CPubKey pubkey;
Object obj;
if (!pubkey.RecoverCompact(ss.GetHash(), vchSig)){
obj.push_back(Pair("pubkey", ""));
obj.push_back(Pair("valid", false));
}else{
obj.push_back(Pair("pubkey", HexStr(pubkey.begin(), pubkey.end())));
obj.push_back(Pair("valid", pubkey.GetID() == keyID));
}

return obj;
// return (pubkey.GetID() == keyID);
}

Quote from: Evil-Knievel on February 08, 2014, 05:39:53 PM

Quote from: DeathAndTaxes on February 08, 2014, 05:36:04 PM

Quote from: Evil-Knievel on February 08, 2014, 05:18:08 PM

In fact it is pretty easy.

- Go to the address in blockchain.info.
- Search for an outgoing transaction and click it
- Show Input/Output Scripts
- In the Input Scripts the value starting with 04.... is the public key.

What is the pubkey of this address?

112xBKNMa2Cj7g9DT8MJYYwUDoKFmYB3EM

You can only determine the Public Key once an outgoing transaction has been made. As this address is "blank" it is impossible in this case.

Evil-Knievel

legendary

Activity: 1260

Merit: 1168

This message was too old and has been purged

BurtW

legendary

Activity: 2646

Merit: 1138

All paid signature campaigns should be banned.

EK, just wondering if you have been able to crack any of the 200,000 public keys that Greg gave you. How is that going?

Evil-Knievel

legendary

Activity: 1260

Merit: 1168

This message was too old and has been purged

DeathAndTaxes

donator

Activity: 1218

Merit: 1080

Gerald Davis

Quote from: Evil-Knievel on February 08, 2014, 05:18:08 PM

In fact it is pretty easy.

- Go to the address in blockchain.info.
- Search for an outgoing transaction and click it
- Show Input/Output Scripts
- In the Input Scripts the value starting with 04.... is the public key.

What is the pubkey of this address?

112xBKNMa2Cj7g9DT8MJYYwUDoKFmYB3EM

BurtW

legendary

Activity: 2646

Merit: 1138

All paid signature campaigns should be banned.

If there has ever been a send transaction from the Bitcoin address then the public key is in the blockchain and you can just read it out. But if there are no send transactions from the address then it is impossible to calculate the public key from the Bitcoin address.

Evil-Knievel

legendary

Activity: 1260

Merit: 1168

This message was too old and has been purged

Bitcoin-Monster

newbie

Activity: 10

Merit: 0

It is (quite) impossible to compute the public key of an address, as the address is computed from the hash of the public key

gpmn

newbie

Activity: 8

Merit: 0

not from address, but from the signed message;

I saw the code, the old version, 2 years ago, bitcoind feeded back the pubkey, while now it just feeds back ok or not;

I think the most fast way is to clone the code and add such output.

Quote from: piotr_n on February 07, 2014, 05:46:29 PM

Quick answer: no, you can't get public key from an address.

piotr_n

legendary

Activity: 2058

Merit: 1416

aka tonikt

Quick answer: no, you can't get public key from an address.

gpmn

newbie

Activity: 8

Merit: 0

Oh, I just take a look in the code, the signed message do have the public key;

but it seems that the code is not so easy to be reused. Is any document mentions about how does the message encode?

Quote from: gpmn on February 07, 2014, 11:28:11 AM

Besides they tell me, Is it possible to get other's public key?

such as from the signed message?

gpmn

newbie

Activity: 8

Merit: 0

Besides they tell me, Is it possible to get other's public key?

such as from the signed message?

Topic: How to get the pubkey of other's address? (Read 934 times)