Cryptography and SSL/TLS Toolkit



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


#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);


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.


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.


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


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.


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);
    /* error */


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


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

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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