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2017
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crypto
crypto_app.sgml
crypto
The Crypto Application
The purpose of the Crypto application is to provide an Erlang API
to cryptographic functions, see crypto(3).
Note that the API is on a fairly low level and there are some
corresponding API functions available in public_key(3),
on a higher abstraction level, that uses the crypto application in its implementation.
DEPENDENCIES
The current crypto implementation uses nifs to interface
OpenSSLs crypto library and may work with limited functionality
with as old versions as OpenSSL 0.9.8c.
FIPS mode support requires at least
version 1.0.1 and a FIPS capable OpenSSL installation. We recommend using a
version that is officially supported by the OpenSSL project. API compatible backends like
LibreSSL should also work.
Source releases of OpenSSL can be downloaded from the OpenSSL project home page,
or mirror sites listed there.
CONFIGURATION
The following configuration parameters are defined for the
crypto application. See app(3) for more information about
configuration parameters.
fips_mode = boolean()
-
Specifies whether to run crypto in FIPS mode. This setting
will take effect when the nif module is loaded. If FIPS mode
is requested but not available at run time the nif module and
thus the crypto module will fail to load. This mechanism
prevents the accidental use of non-validated algorithms.
rand_cache_size = integer()
-
Sets the cache size in bytes to use by
crypto:rand_seed_alg(crypto_cache)
and
crypto:rand_seed_alg_s(crypto_cache)
.
This parameter is read when a seed function is called,
and then kept in generators state object. It has a rather
small default value that causes reads of strong random bytes
about once per hundred calls for a random value.
The set value is rounded up to an integral number of words
of the size these seed functions use.