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Ericsson AB. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
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ssl
ssl_app.sgml
ssl
The ssl application provides secure communication over
sockets.
The ssl application is an implementation of the SSL/TLS protocol in Erlang.
- Supported SSL/TLS-versions are SSL-3.0, TLS-1.0,
TLS-1.1, and TLS-1.2.
- For security reasons SSL-2.0 is not supported.
- For security reasons SSL-3.0 is no longer supported by default,
but can be configured.
- For security reasons DES cipher suites are no longer supported by default,
but can be configured.
- Ephemeral Diffie-Hellman cipher suites are supported,
but not Diffie Hellman Certificates cipher suites.
- Elliptic Curve cipher suites are supported if the Crypto
application supports it and named curves are used.
- Export cipher suites are not supported as the
U.S. lifted its export restrictions in early 2000.
- IDEA cipher suites are not supported as they have
become deprecated by the latest TLS specification so it is not
motivated to implement them.
- CRL validation is supported.
- Policy certificate extensions are not supported.
- 'Server Name Indication' extension
(RFC 6066) is supported.
DEPENDENCIES
The SSL application uses the public_key and
Crypto application to handle public keys and encryption, hence
these applications must be loaded for the SSL application to work.
In an embedded environment this means they must be started with
application:start/[1,2] before the SSL application is
started.
CONFIGURATION
The application environment configuration parameters in this section
are defined for the SSL application. For more information
about configuration parameters, see the
application(3)
manual page in Kernel.
The environment parameters can be set on the command line,
for example:
erl -ssl protocol_version "['tlsv1.2', 'tlsv1.1']"
protocol_version = ssl:protocol()]]>
Protocol supported by started clients and
servers. If this option is not set, it defaults to all
protocols currently supported by the SSL application.
This option can be overridden by the version option
to ssl:connect/[2,3] and ssl:listen/2.
Maximum lifetime of the session data in seconds. Defaults to 24 hours which is the maximum
recommended lifetime by RFC 5246. However
sessions may be invalidated earlier due to the maximum limitation of the session cache table.
Name of the session cache callback module that implements
the ssl_session_cache_api behavior. Defaults to
ssl_session_cache.
List of extra user-defined arguments to the init function
in the session cache callback module. Defaults to [].
Limits the growth of the clients session cache, that is
how many sessions towards servers that are cached to be used by
new client connections. If the maximum number of sessions is
reached, the current cache entries will be invalidated
regardless of their remaining lifetime. Defaults to
1000.
Limits the growth of the servers session cache, that is
how many client sessions are cached by the server. If the
maximum number of sessions is reached, the current cache entries
will be invalidated regardless of their remaining
lifetime. Defaults to 1000.
-
Number of milliseconds between PEM cache validations. Defaults to 2 minutes.
ssl:clear_pem_cache/0
]]>
-
Number of milliseconds between sending of a fatal alert and
closing the connection. Waiting a little while improves the
peers chances to properly receiving the alert so it may
shutdown gracefully. Defaults to 5000 milliseconds.
ERROR LOGGER AND EVENT HANDLERS
The SSL application uses the default OTP error logger to log
unexpected errors and TLS alerts. The logging of TLS alerts may be
turned off with the log_alert option.