SSL_load_client_CA_file(3) | OpenSSL | SSL_load_client_CA_file(3)

# NAME

SSL_load_client_CA_file_ex, SSL_load_client_CA_file, SSL_add_file_cert_subjects_to_stack, SSL_add_dir_cert_subjects_to_stack, SSL_add_store_cert_subjects_to_stack - load certificate names

# SYNOPSIS

     #include <openssl/ssl.h>
     STACK_OF(X509_NAME) *SSL_load_client_CA_file_ex(const char *file,
                                                     OSSL_LIB_CTX *libctx,
                                                     const char *propq);
     STACK_OF(X509_NAME) *SSL_load_client_CA_file(const char *file);
     int SSL_add_file_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
                                             const char *file);
     int SSL_add_dir_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
                                            const char *dir);
     int SSL_add_store_cert_subjects_to_stack(STACK_OF(X509_NAME) *stack,
                                              const char *store);

# DESCRIPTION

SSL_load_client_CA_file_ex() reads certificates from file and returns a STACK_OF(X509_NAME) with the subject names found. The library context libctx and property query propq are used when fetching algorithms from providers.

SSL_load_client_CA_file() is similar to SSL_load_client_CA_file_ex() but uses NULL for the library context libctx and property query propq.

SSL_add_file_cert_subjects_to_stack() reads certificates from file, and adds their subject name to the already existing stack.

SSL_add_dir_cert_subjects_to_stack() reads certificates from every file in the directory dir, and adds their subject name to the already existing stack.

SSL_add_store_cert_subjects_to_stack() loads certificates from the store URI, and adds their subject name to the already existing stack.

# NOTES

SSL_load_client_CA_file() reads a file of PEM formatted certificates and extracts the X509_NAMES of the certificates found. While the name suggests the specific usage as support function for SSL_CTX_set_client_CA_list(3), it is not limited to CA certificates.

# RETURN VALUES

The following return values can occur for SSL_load_client_CA_file_ex(), and SSL_load_client_CA_file():

NULL
  The operation failed, check out the error stack for the reason.
Pointer to STACK_OF(X509_NAME)
  Pointer to the subject names of the successfully read certificates.

The following return values can occur for SSL_add_file_cert_subjects_to_stack(), SSL_add_dir_cert_subjects_to_stack(), and SSL_add_store_cert_subjects_to_stack():

0 (Failure)
  The operation failed.
1 (Success)
  The operation succeeded.

# EXAMPLES

Load names of CAs from file and use it as a client CA list:

     SSL_CTX *ctx;
     STACK_OF(X509_NAME) *cert_names;
     ...
     cert_names = SSL_load_client_CA_file("/path/to/CAfile.pem");
     if (cert_names != NULL)
         SSL_CTX_set_client_CA_list(ctx, cert_names);
     else
         /* error */
     ...

# SEE ALSO

ssl(7), ossl_store(7), SSL_CTX_set_client_CA_list(3)

# HISTORY

SSL_load_client_CA_file_ex() and SSL_add_store_cert_subjects_to_stack() were added in OpenSSL 3.0.

# COPYRIGHT

Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the "License"). You may not use this file except in compliance with the License. You can obtain a copy in the file LICENSE in the source distribution or at <https://www.openssl.org/source/license.html>.

2026-06-09 | 3.5.7