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SSL_CTX_load_verify_locations - Set default locations for trusted CA
const char *CAfile,
const char *CApath );
The SSL_CTX_load_verify_locations() function specifies the locations for
ctx, at which CA certificates for verification purposes are located. The
certificates available via CAfile and CApath are trusted.
If CAfile is not NULL, it points to a file of CA certificates in PEM
format. The file can contain several CA certificates identified by the
... (CA certificate in base64 encoding) ...
Text is allowed before, between, and after the certificates. It can be
used, for example, to describe the certificates.
The CAfile is processed on execution of the SSL_CTX_load_verify_locations()
If CApath is not NULL, it points to a directory containing CA certificates
in PEM format. The files each contain one CA certificate. The files are
looked up by the CA subject name hash value, which must be available. If
more than one CA certificate with the same name hash value exist, the
extension must be different (e.g. 9d66eef0.0, 9d66eef0.1 etc). The search
is performed in the ordering of the extension number, regardless of other
properties of the certificates. Use the c_rehash utility to create the
The certificates in CApath are only looked up when required, such as when
building the certificate chain or when actually performing the verification
of a peer certificate.
When looking up CA certificates, the OpenSSL library will first search the
certificates in CAfile, then those in CApath. Certificate matching is done
based on the subject name, the key identifier (if present), and the serial
number as taken from the certificate to be verified. If these data do not
match, the next certificate will be tried. If a first certificate matching
the parameters is found, the verification process will be performed; no
other certificates for the same parameters will be searched in case of
In server mode, when requesting a client certificate, the server must send
the list of CAs from which it will accept client certificates. This listis
not influenced by the contents of CAfile or CApath and must explicitly be
set using the SSL_CTX_set_client_CA_list() family of functions.
When building its own certificate chain, an OpenSSL client/server will try
to fill in missing certificates from CAfile/CApath, if the certificate
chain was not explicitly specified. (See SSL_CTX_add_extra_chain_cert() and
If several CA certificates matching the name, key identifier, and serial
number condition are available, only the first one will be examined. This
may lead to unexpected results if the same CA certificate is available with
different expiration dates. If a "certificate expired" verification error
occurs, no other certificate will be searched. Do no mix expired
certificates with valid certificates.
The following return values can occur:
0 The operation failed because CAfile and CApath are NULL or the
processing at one of the locations specified failed. Check the
error stack to find out the reason.
1 The operation succeeded.
Generate a CA certificate file with descriptive text from the CA
certificates ca1.pem ca2.pem ca3.pem:
for i in ca1.pem ca2.pem ca3.pem ; do
openssl x509 -in $i -text >> CAfile.pem
Prepare the directory /some/where/certs containing several CA certificates
for use as CApath:
Functions: ssl(3), SSL_CTX_set_client_CA_list(3),
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