# Gavin Andresen
# 2011-03-14 21:08:52
# https://bitcointalk.org/index.php?topic=4459.msg65407#msg65407

So I got email today from a merchant asking the most-frequently-asked question:  if I just put a bitcoin address on my "pay me" page, how do I know who paid me? @p{par}

Which got me to wondering... can we do better than answer "run a bitcoin daemon and ask it for a new address for every order"  or  "use a shopping cart interface from your online wallet provider" ? @p{par}

Ideally, the web software could generate a payment URI without talking to bitcoind, and copying/pasting or clicking on the URI would generate a transaction tagged with the right order ID. @p{par}

Adding another transaction type that allows (say) an extra, arbitrary 512 bytes of data mostly solves the problem; the web software could encrypt or hash the order ID and generate a transaction that is the store's public bitcoin address and the encrypted/hashed order ID (or customer number or whatever). @p{par}

Can we do better?  It would be nice if it was impossible to tell how many orders the merchant was getting... @p{brk}