#include <openssl/ssl.h>
int SSL_CTX_use_certificate(SSL_CTX *ctx, X509 *x);
int SSL_CTX_use_certificate_ASN1(SSL_CTX *ctx, int len, unsigned char *d);
int SSL_CTX_use_certificate_file(SSL_CTX *ctx, const char *file, int type);
int SSL_use_certificate(SSL *ssl, X509 *x);
int SSL_use_certificate_ASN1(SSL *ssl, unsigned char *d, int len);
int SSL_use_certificate_file(SSL *ssl, const char *file, int type);
int SSL_CTX_use_certificate_chain_file(SSL_CTX *ctx, const char *file);
int SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey);
int SSL_CTX_use_PrivateKey_ASN1(int pk, SSL_CTX *ctx, unsigned char *d,
long len);
int SSL_CTX_use_PrivateKey_file(SSL_CTX *ctx, const char *file, int type);
int SSL_CTX_use_RSAPrivateKey(SSL_CTX *ctx, RSA *rsa);
int SSL_CTX_use_RSAPrivateKey_ASN1(SSL_CTX *ctx, unsigned char *d, long len);
int SSL_CTX_use_RSAPrivateKey_file(SSL_CTX *ctx, const char *file, int type);
int SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey);
int SSL_use_PrivateKey_ASN1(int pk,SSL *ssl, unsigned char *d, long len);
int SSL_use_PrivateKey_file(SSL *ssl, const char *file, int type);
int SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa);
int SSL_use_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d, long len);
int SSL_use_RSAPrivateKey_file(SSL *ssl, const char *file, int type);
int SSL_CTX_check_private_key(const SSL_CTX *ctx);
int SSL_check_private_key(const SSL *ssl);
The SSL_CTX_* class of functions loads the certificates and keys into the SSL_CTX object ctx. The information is passed to SSL objects ssl created from ctx with SSL_new(3) by copying, so that changes applied to ctx do not propagate to already existing SSL objects.
The SSL_* class of functions only loads certificates and keys into a specific SSL object. The specific information is kept, when SSL_clear(3) is called for this SSL object.
SSL_CTX_use_certificate() loads the certificate x into ctx, SSL_use_certificate() loads x into ssl. The rest of the certificates needed to form the complete certificate chain can be specified using the SSL_CTX_add_extra_chain_cert(3) function.
SSL_CTX_use_certificate_ASN1() loads the ASN1 encoded certificate from the memory location d (with length len) into ctx, SSL_use_certificate_ASN1() loads the ASN1 encoded certificate into ssl.
SSL_CTX_use_certificate_file() loads the first certificate stored in file into ctx. The formatting type of the certificate must be specified from the known types SSL_FILETYPE_PEM, SSL_FILETYPE_ASN1. SSL_use_certificate_file() loads the certificate from file into ssl. See the NOTES section on why SSL_CTX_use_certificate_chain_file() should be preferred.
SSL_CTX_use_certificate_chain_file() loads a certificate chain from file into ctx. The certificates must be in PEM format and must be sorted starting with the subject's certificate (actual client or server certificate), followed by intermediate CA certificates if applicable, and ending at the highest level (root) CA. There is no corresponding function working on a single SSL object.
SSL_CTX_use_PrivateKey() adds pkey as private key to ctx. SSL_CTX_use_RSAPrivateKey() adds the private key rsa of type RSA to ctx. SSL_use_PrivateKey() adds pkey as private key to ssl; SSL_use_RSAPrivateKey() adds rsa as private key of type RSA to ssl. If a certificate has already been set and the private does not belong to the certificate an error is returned. To change a certificate, private key pair the new certificate needs to be set with SSL_use_certificate() or SSL_CTX_use_certificate() before setting the private key with SSL_CTX_use_PrivateKey() or SSL_use_PrivateKey().
SSL_CTX_use_PrivateKey_ASN1() adds the private key of type pk stored at memory location d (length len) to ctx. SSL_CTX_use_RSAPrivateKey_ASN1() adds the private key of type RSA stored at memory location d (length len) to ctx. SSL_use_PrivateKey_ASN1() and SSL_use_RSAPrivateKey_ASN1() add the private key to ssl.
SSL_CTX_use_PrivateKey_file() adds the first private key found in file to ctx. The formatting type of the certificate must be specified from the known types SSL_FILETYPE_PEM, SSL_FILETYPE_ASN1. SSL_CTX_use_RSAPrivateKey_file() adds the first private RSA key found in file to ctx. SSL_use_PrivateKey_file() adds the first private key found in file to ssl; SSL_use_RSAPrivateKey_file() adds the first private RSA key found to ssl.
SSL_CTX_check_private_key() checks the consistency of a private key with the corresponding certificate loaded into ctx. If more than one key/certificate pair (RSA/DSA) is installed, the last item installed will be checked. If e.g. the last item was a RSA certificate or key, the RSA key/certificate pair will be checked. SSL_check_private_key() performs the same check for ssl. If no key/certificate was explicitly added for this ssl, the last item added into ctx will be checked.
When reading certificates and private keys from file, files of type SSL_FILETYPE_ASN1 (also known as DER, binary encoding) can only contain one certificate or private key, consequently SSL_CTX_use_certificate_chain_file() is only applicable to PEM formatting. Files of type SSL_FILETYPE_PEM can contain more than one item.
SSL_CTX_use_certificate_chain_file() adds the first certificate found in the file to the certificate store. The other certificates are added to the store of chain certificates using SSL_CTX_add_extra_chain_cert(3). There exists only one extra chain store, so that the same chain is appended to both types of certificates, RSA and DSA! If it is not intended to use both type of certificate at the same time, it is recommended to use the SSL_CTX_use_certificate_chain_file() instead of the SSL_CTX_use_certificate_file() function in order to allow the use of complete certificate chains even when no trusted CA storage is used or when the CA issuing the certificate shall not be added to the trusted CA storage.
If additional certificates are needed to complete the chain during the TLS negotiation, CA certificates are additionally looked up in the locations of trusted CA certificates, see SSL_CTX_load_verify_locations(3).
The private keys loaded from file can be encrypted. In order to successfully load encrypted keys, a function returning the passphrase must have been supplied, see SSL_CTX_set_default_passwd_cb(3). (Certificate files might be encrypted as well from the technical point of view, it however does not make sense as the data in the certificate is considered public anyway.)