Edited ch04_keys.adoc with Atlas code editor

ch04_keys.adoc

@@ -1784,7 +1784,7 @@ repeat until successful.
 
 ===== Vanity address security and privacy
 
-Vanity addresses were popular in the
+Vanity addresses((("privacy", "vanity addresses", id="privacy-vanity"))) were popular in the
 early years of Bitcoin but have almost entirely disappeared from use as
 of 2023.  There are two likely causes for this trend:
 
@@ -1810,7 +1810,7 @@ gives discount pricing to Eugenia.
 // https://github.com/MakisChristou/vanitybech
 
 We don't expect to see many vanity addresses in
-the future unless the preceding problems ((("public key cryptography", "vanity addresses", startref="pub-key-vanity")))((("vanity addresses", startref="vanity-addr")))are solved.
+the future unless the preceding problems ((("public key cryptography", "vanity addresses", startref="pub-key-vanity")))((("vanity addresses", startref="vanity-addr")))((("privacy", "vanity addresses", startref="privacy-vanity")))are solved.
 
 [[paper_wallets]]
 ==== Paper Wallets