Controlled nymity

[Major Variola (ret)]

At 09:12 AM 8/12/03 -0700, James A. Donald wrote:
>    --
>What we want of a payment system, is that Alice can prove she
>paid Bob, even if Bob wants to deny it, but no one else can
>prove that Alice paid Bob unless Alice takes special action to
>make it provable.

>One solution is for the bank to maintain an email linked
>account for Bob, into which Alice pays.  This sounds ominous,
>for the next step might be to link the account to true names,
>can anyone see any other problems with it.

Does it help if:
Alice generates a secret key for each payment
Alice *anonymously* deposits an *encrypted* message containing payment
details into Bob's acct
Only Alice can reveal the key for a particular transaction in Bob's
account, thereby
stripping anonymity but also revealing payment.  For only that
transaction.