diff --git a/ch12.asciidoc b/ch12.asciidoc
index 77d99be6..f1efe287 100644
--- a/ch12.asciidoc
+++ b/ch12.asciidoc
@@ -494,7 +494,7 @@ Importantly, this path is only known to Alice's node. All other participants in
 
 This is a critical feature of the Lightning Network, because it ensures privacy of payments and makes it very difficult to apply surveillance, censorship, or blacklists. But how does Alice establish this payment path, without revealing anything to the intermediary nodes?
 
-The Lightning Network implements an onion-routed protocol based on a scheme called https://cypherpunks.ca/~iang/pubs/Sphinx_Oakland09.pdf[Sphinx]. This routing protocol ensures that a payment sender can construct and communicate a path through the Lightning Network such that:
+The Lightning Network implements an onion-routed protocol based on a scheme called http://bit.ly/2q6ZDrP[Sphinx]. This routing protocol ensures that a payment sender can construct and communicate a path through the Lightning Network such that:
 
 * Intermediate nodes can verify and decrypt their portion of route information and find the next hop.