STARTTLS

EN Texte en anglais Pas encore d'article dans ta langue : extrait en anglais.

Opportunistic TLS (Transport Layer Security) refers to extensions in plain text communication protocols, which offer a way to upgrade a plain text connection to an encrypted (TLS or SSL) connection instead of using a separate port for encrypted communication. Several protocols use a command named "STARTTLS" or "Explicit TLS" for this purpose. It is a form of opportunistic encryption and is primarily intended as a countermeasure to passive monitoring. The STARTTLS command for IMAP and POP3 is defined in RFC 2595, for SMTP in RFC 3207, for XMPP in RFC 6120 and for NNTP in RFC 4642. For IRC, the IRCv3 Working Group defined a STARTTLS extension, though it was later deprecated. FTP uses the command "AUTH TLS" defined in RFC 4217 and LDAP defines a protocol extension OID in RFC 2830. HTTP uses an upgrade header. TLS is application-neutral; in the words of RFC 5246: The style used to specify how to use TLS matches the same layer distinction that is also conveniently supported by several library implementations of TLS. E.g., the RFC 3207 SMTP extension illustrates with the following dialog how a client and server can start a secure session: The last EHLO command above is issued over a secure channel. Note that authentication is optional in SMTP, and the omitted server reply may now safely advertise an AUTH PLAIN SMTP extension, which is not present in the plain-text reply.