diff --git a/ch06.asciidoc b/ch06.asciidoc
index 7600563f..654300ec 100644
--- a/ch06.asciidoc
+++ b/ch06.asciidoc
@@ -570,7 +570,7 @@ See if you can decode Alice's serialized (DER-encoded) signature using this list
 
 ==== Verifying the Signature
 
-To verify the signature, one must have the signature (+R+ and +S+), the serialized transaction, and the public key (that corresponds to the private key used to create the signature). Essentially, verification of a signature means "Only the owner of the private key that generated this public key could have produced this signature on this transaction."
+((("digital signatures", "verifying")))((("transactions", "digital signatures", "verifying")))To verify the signature, one must have the signature (+R+ and +S+), the serialized transaction, and the public key (that corresponds to the private key used to create the signature). Essentially, verification of a signature means "Only the owner of the private key that generated this public key could have produced this signature on this transaction."
 
 The signature verification algorithm takes the message (a hash of the transaction or parts of it), the signer's public key and the signature (+R+ and +S+ values) and returns TRUE if the signature is valid for this message and public key.