Author Topic: How Bob prove his address?  (Read 8 times)

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How Bob prove his address?
« on: January 15, 2020, 05:57:16 AM »
How Bob prove that his address is associated wih his private key?
In https://en.bitcoin.it/wiki/Help:Introduction we read:
Quote
Suppose Alice wants to send a bitcoin to Bob.

    Bob sends his address to Alice.
    Alice adds Bob’s address and the amount of bitcoins to transfer to a message: a 'transaction' message.
    Alice signs the transaction with her private key, and announces her public key for signature verification.
    Alice broadcasts the transaction on the Bitcoin network for all to see.

(Only the first two steps require human action. The rest is done by the Bitcoin client software.)

Looking at this transaction from the outside, anyone who knows that these addresses belong to Alice and Bob can see that Alice has agreed to transfer the amount to Bob, because nobody else has Alice's private key. Alice would be foolish to give her private key to other people, as this would allow them to sign transactions in her name, removing funds from her control.

Later on, when Bob wishes to transfer the same bitcoins to Charley, he will do the same thing:

    Charlie sends Bob his address.
    Bob adds Charlie's address and the amount of bitcoins to transfer to a message: a 'transaction' message.
    Bob signs the transaction with his private key, and announces his public key for signature verification.
    Bob broadcasts the transaction on the Bitcoin network for all to see.

Only Bob can do this because only he has the private key that can create a valid signature for the transaction.

Bob can sign, Alica can sign, but how to associate Bob address (given by Alice) with his private key? Anyone can compute public key->address, but how from sign compute public key?