# Gavin Andresen
# 2010-07-22 12:47:25
# https://bitcointalk.org/index.php?topic=505.msg5012#msg5012

I think this won't work because there is not a one-to-one relationship between "unspent transactions" and public keys. @p{par}

Example:  I start with 0 BTC.  Two people each send me 50, to the same receiving address "GavinPubKey". @p{par}

Balance Sheet:  GavinPubKey: 100 @p{brk}
I spend the first one: @p{brk}
Balance Sheet:  GavinPubKey: 50 @p{par}

If I'm dishonest, what stops me from waiting a few months and then spending that first 50 again instead of spending that second 50?  Double-spending that first 50 will look like a perfectly valid transaction to any nodes using the balance sheet method who weren't around to see the first time I spent it. @p{par}

 @p{par}