explain signatures using pictures

index.html

@@ -255,12 +255,25 @@ show certificate
 .right-column[
 So, how does a certificate get signed?
 
+<img src="document-signing-process.png" width="100%" />
+]
+???
 <!-- XXX picture -->
 Or how does this signing work:
 - take the unsigned certificate
 - calculate a hash of the certificate
 - encrypt the hash with the CAs private key
 
+---
+.left-column[
+## Signatures
+]
+.right-column[
+Now anyone can verify the signature:
+
+<img src="document-verify-signature.png" width="100%" />
+]
+???
 <!-- XXX picture -->
 Now anyone can verify the signature by:
 - decrypting the signature with the CAs public key
@@ -268,7 +281,6 @@ Now anyone can verify the signature by:
 - comparing the decrypted hash with the calculated hash
 
 Some variations on this scheme exist, but this is the gist.
-]
 ---
 .left-column[
 ## Certificate Authority (CA)