XEP-0414: Drop dangling reference

xep-0414.xml

@@ -82,7 +82,6 @@
   <section2 topic='SHA-1' anchor='hashes-sha1'>
     <p>The SHA-1 algorithm was developed by the U.S. National Security Agency and first published in 1995 to fix problems with SHA-0. The SHA-1 algorithm is currently the most widely-deployed hash function. As described in &rfc4270; in 2005, attacks have been found against the collision resistance property of SHA-1. &rfc6194; notes that as of 2011 no published results indicate improvement upon those attacks. In addition, RFC 6194 notes that "[t]here are no known pre-image or second pre-image attacks that are specific to the full round SHA-1 algorithm".  Furthermore, there is no indication that attacks on SHA-1 can be extended to HMAC-SHA-1.  Nevertheless, the U.S. National Institute of Standards and Technology (NIST) has recommended that SHA-1 not be used for generating digital signatures after December 31, 2010.</p>
     <p>In fall 2015 the SHA-1 collision cost has been estimated between 75K$ to 120K$ <note>The SHAppening: freestart collisions for SHA-1 &lt;<link url='https://sites.google.com/site/itstheshappening/'>https://sites.google.com/site/itstheshappening/</link>&gt;.</note>.</p>
-    <p>The SHA-1 algorithm is used in a number of XMPP protocols. See <link url='#existing'>Analysis of Existing XMPP Extensions</link> for details.</p>
   </section2>
   <section2 topic='SHA-2' anchor='hashes-sha2'>
     <p>The SHA-2 family of algorithms (SHA-224, SHA-256, SHA-384, and SHA-512) was developed by the U.S. National Security Agency and first published in 2001. Because SHA-2 is somewhat similar to SHA-1, it is thought that the security flaws with SHA-1 described above could be extended to SHA-2 (although no such attacks have yet been found on the full-round SHA-2 algorithms).</p>