Editing Transport Layer Security (section)

====Renegotiation attack====
A vulnerability of the renegotiation procedure was discovered in August 2009 that can lead to plaintext injection attacks against SSL 3.0 and all current versions of TLS.<ref>{{cite web|url=http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3555|title=CVE – CVE-2009-3555|url-status=live|archive-url=https://web.archive.org/web/20160104234608/http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2009-3555|archive-date=2016-01-04}}</ref> For example, it allows an attacker who can hijack an [[https]] connection to splice their own requests into the beginning of the conversation the client has with the web server. The attacker cannot actually decrypt the client–server communication, so it is different from a typical [[man-in-the-middle attack]]. A short-term fix is for web servers to stop allowing renegotiation, which typically will not require other changes unless [[client certificate]] authentication is used. To fix the vulnerability, a renegotiation indication extension was proposed for TLS. It will require the client and server to include and verify information about previous handshakes in any renegotiation handshakes.<ref>{{cite web|first=Eric|last=Rescorla|title=Understanding the TLS Renegotiation Attack|work=Educated Guesswork|access-date=2009-11-27|date=2009-11-05|url=http://www.educatedguesswork.org/2009/11/understanding_the_tls_renegoti.html|url-status=live|archive-url=https://web.archive.org/web/20120211120608/http://www.educatedguesswork.org/2009/11/understanding_the_tls_renegoti.html|archive-date=2012-02-11}}</ref> This extension has become a proposed standard and has been assigned the number {{IETF RFC|5746}}. The RFC has been implemented by several libraries.<ref>{{cite web|title=SSL_CTX_set_options SECURE_RENEGOTIATION|work=OpenSSL Docs|access-date=2010-11-18|date=2010-02-25|url=https://www.openssl.org/docs/ssl/SSL_CTX_set_options.html#SECURE_RENEGOTIATION|url-status=live|archive-url=https://web.archive.org/web/20101126121933/http://openssl.org/docs/ssl/SSL_CTX_set_options.html#SECURE_RENEGOTIATION|archive-date=2010-11-26}}</ref><ref>{{cite web|title=GnuTLS 2.10.0 released|work=GnuTLS release notes|access-date=2011-07-24|date=2010-06-25|url=http://article.gmane.org/gmane.network.gnutls.general/2046|url-status=live|archive-url=https://web.archive.org/web/20151017033726/http://article.gmane.org/gmane.network.gnutls.general/2046|archive-date=2015-10-17}}</ref><ref>{{cite web|title=NSS 3.12.6 release notes|work=NSS release notes|access-date=2011-07-24|date=2010-03-03|url=https://developer.mozilla.org/NSS_3.12.6_release_notes|url-status=dead|archive-url=https://web.archive.org/web/20120306184633/https://developer.mozilla.org/NSS_3.12.6_release_notes|archive-date=March 6, 2012}}</ref>