# ssl_crl_cache_api

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Module

ssl_crl_cache_api

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Module Summary

API for a TLS CRL (Certificate Revocation List) cache.

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Since

Module ssl_crl_cache_api was introduced in OTP 18.0.

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Description

When TLS performs certificate path validation according to RFC 5280 it should also perform CRL validation checks. To enable the CRL checks the application needs access to CRLs. A database of CRLs can be set up in many different ways. This module provides the behavior of the API needed to integrate an arbitrary CRL cache with the erlang ssl application. It is also used by the application itself to provide a simple default implementation of a CRL cache.

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Data Types

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crl_cache_ref() = any()

Reference to the CRL cache.

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dist_point() = #'DistributionPoint'{}

For description see X509 certificates records

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logger_info() =
{logger:level(),
Report :: #{description => string(), reason => term()},
logger:metadata()}

Information for ssl applications use of Logger(3)

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Exports

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Module:fresh_crl(DistributionPoint, CRL) -> FreshCRL
OTP 22.2

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Module:fresh_crl(DistributionPoint, CRL) -> FreshCRL | {LoggerInfo, FreshCRL}
OTP 18.0

### Types

DistributionPoint = dist_point()
CRL = [public_key:der_encoded()]
FreshCRL = [public_key:der_encoded()]
LoggerInfo = {logger, logger_info() }}

fun fresh_crl/2 will be used as input option update_crl to public_key:pkix_crls_validate/3

It is possible to return logger info that will be used by the TLS connection to produce log events.

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Module:lookup(DistributionPoint, Issuer, DbHandle) -> not_available | CRLs | {LoggerInfo, CRLs}
OTP 22.2

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Module:lookup(DistributionPoint, Issuer, DbHandle) -> not_available | CRLs
OTP 19.0

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Module:lookup(DistributionPoint, DbHandle) -> not_available | CRLs
OTP 18.0

### Types

DistributionPoint = dist_point()
Issuer = public_key:issuer_name()
DbHandle = crl_cache_ref()
CRLs = [public_key:der_encoded()]
LoggerInfo = {logger, logger_info() }}

Lookup the CRLs belonging to the distribution point Distributionpoint. This function may choose to only look in the cache or to follow distribution point links depending on how the cache is administrated.

The Issuer argument contains the issuer name of the certificate to be checked. Normally the returned CRL should be issued by this issuer, except if the cRLIssuer field of DistributionPoint has a value, in which case that value should be used instead.

In an earlier version of this API, the lookup function received two arguments, omitting Issuer. For compatibility, this is still supported: if there is no lookup/3 function in the callback module, lookup/2 is called instead.

It is possible to return logger info that will be used by the TLS connection to produce log events.

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Module:select(Issuer, DbHandle) -> CRLs | {LoggerInfo, CRLs}
OTP 22.2

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Module:select(Issuer, DbHandle) -> CRLs
OTP 18.0

### Types

Issuer = public_key:issuer_name() | list()
DbHandle = cache_ref()
LoggerInfo = {logger, logger_info() }

Select the CRLs in the cache that are issued by Issuer unless the value is a list of so called general names, see X509 certificates records, originating form #'DistributionPoint'.cRLissuer and representing different mechanism to obtain the CRLs. The cache callback needs to use the appropriate entry to retrieve the CRLs or return an empty list if it does not exist.

It is possible to return logger info that will be used by the TLS connection to produce log events.