clarify spending requirements

1 files changed, 3 insertions, 1 deletions

diff --git a/doc/paper/taler.tex b/doc/paper/taler.tex
index 9c4e49263..f35680f98 100644
--- a/doc/paper/taler.tex
+++ b/doc/paper/taler.tex
@@ -526,7 +526,9 @@ private key of the coin, making him the \emph{owner} of the coin.  Due
 to the use of blind signatures, the exchange does not even learn the
 public key during the withdrawal process.  If the private key is
 shared with others, they become co-owners of the coin.  Knowledge of
-the private key of the coin enables the owner to spent the coin.
+the private key of the coin and the signature over the coin's public
+key by an exchange's denomination key enables the owner to spent the
+coin.
 
 
 % \subsection{Coin spending}