ssl(3)ssl(3)NAME
ssl, SSL - OpenSSL SSL/TLS library
DESCRIPTION
The OpenSSL ssl library implements the Secure Sockets Layer (SSL v2/v3)
and Transport Layer Security (TLS v1) protocols. It provides a rich API
which is documented here.
At first, the library must be initialized; see SSL_library_init(3).
Then an SSL_CTX object is created as a framework to establish TLS/SSL
enabled connections (see SSL_CTX_new(3)). Various options regarding
certificates, algorithms, etc. can be set in this object.
When a network connection has been created, it can be assigned to an
SSL object. After the SSL object has been created using SSL_new(),
SSL_set_fd() or SSL_set_bio(), it can be used to associate the network
connection with the object.
Then the TLS/SSL handshake is performed using SSL_accept() or SSL_con‐
nect() respectively. The SSL_read() and SSL_write() functions are used
to read and write data on the TLS/SSL connection. The SSL_shutdown()
function can be used to shut down the TLS/SSL connection.
DATA STRUCTURES
The OpenSSL ssl library functions deal with the following data struc‐
tures: A dispatch structure describing the internal ssl library methods
and functions which implement the various protocol versions (SSLv1,
SSLv2 and TLSv1). It is s needed to create an SSL_CTX. A structure
that holds the algorithm information for a particular cipher which are
a core part of the SSL/TLS protocol. The available ciphers are config‐
ured on a SSL_CTX basis and the actually used ones are then part of the
SSL_SESSION. The global context structure that is created by a server
or client once per program life-time. It holds default values for the
SSL structures which are later created for the connections. A struc‐
ture containing the current TLS/SSL session details for a connection:
SSL_CIPHERs, client and server certificates, keys, etc. The main
SSL/TLS structure that is created by a server or client per established
connection. This is the core structure in the SSL API. Under run-time
the application usually deals with this structure which has links to
other structures.
HEADER FILES
The OpenSSL ssl library provides the following C header files contain‐
ing the prototypes for the data structures and functions: The common
header file for the SSL/TLS API. Include it in your program to make
the API of the ssl library available. It internally includes private
SSL headers and headers from the crypto library. Whenever you need
details on the internals of the SSL API, look inside this header file.
The sub header file dealing with the SSLv2 protocol only. Usually you
do not have to include it because it is already included by ssl.h. The
sub header file dealing with the SSLv3 protocol only. Usually you do
not have to include it because it is already included by ssl.h. The
sub header file dealing with the combined use of the SSLv2 and SSLv3
protocols. Usually you do not have to include it because it is already
included by ssl.h. The sub header file dealing with the TLSv1 protocol
only. Usually you do not have to include it because it is already
included by ssl.h.
API FUNCTIONS
The OpenSSL ssl library exports 214 API functions. They are documented
in the following sections.
Dealing With Protocol Methods
The API functions that deal with the SSL/TLS protocol methods defined
in SSL_METHOD structures are described in the following list: Construc‐
tor for the SSLv2 SSL_METHOD structure for a dedicated client. Con‐
structor for the SSLv2 SSL_METHOD structure for a dedicated server.
Constructor for the SSLv2 SSL_METHOD structure for combined client and
server. Constructor for the SSLv3 SSL_METHOD structure for a dedicated
client. Constructor for the SSLv3 SSL_METHOD structure for a dedicated
server. Constructor for the SSLv3 SSL_METHOD structure for combined
client and server. Constructor for the TLSv1 SSL_METHOD structure for
a dedicated client. Constructor for the TLSv1 SSL_METHOD structure for
a dedicated server. Constructor for the TLSv1 SSL_METHOD structure for
combined client and server.
Dealing With Ciphers
The API functions that deal with the SSL/TLS ciphers defined in
SSL_CIPHER structures are described in the following list: Write a
string to buf (with a maximum size of len) containing a human readable
description of cipher. Returns buf. Determine the number of bits in
cipher. Because of export crippled ciphers there are two bits: The
bits the algorithm supports in general (stored to alg_bits) and the
bits which are actually used (the return value). Return the internal
name of cipher s a string. These are the various strings defined by the
SSL2_TXT_xxx, SSL3_TXT_xxxand TLS1_TXT_xxxdefinitions in the header
files. Returns a string such as TLSv1/SSLv3 or SSLv2 which indicates
the SSL/TLS protocol version to which cipher belongs (i.e. where it was
defined in the specification the first time).
Dealing With Protocol Contexts
The API functions that deal with the SSL/TLS protocol context defined
in the SSL_CTX structure are described in the following list: int
SSL_CTX_add_client_CA(SSL_CTX *ctx, X509 *x); long
SSL_CTX_add_extra_chain_cert(SSL_CTX *ctx, X509 *x509); int
SSL_CTX_add_session(SSL_CTX *ctx, SSL_SESSION *c); int
SSL_CTX_check_private_key(SSL_CTX *ctx); long SSL_CTX_ctrl(SSL_CTX
*ctx, int cmd, long larg, char *parg); void SSL_CTX_flush_ses‐
sions(SSL_CTX *s, long t); void SSL_CTX_free(SSL_CTX *a); char
*SSL_CTX_get_app_data(SSL_CTX *ctx); X509_STORE
*SSL_CTX_get_cert_store(SSL_CTX *ctx); STACK
*SSL_CTX_get_client_CA_list(SSL_CTX *ctx); int
(*SSL_CTX_get_client_cert_cb(SSL_CTX *ctx))(SSL *ssl, X509 **x509,
EVP_PKEY **pkey); char *SSL_CTX_get_ex_data(SSL_CTX *s, int idx); int
SSL_CTX_get_ex_new_index(long argl, char *argp, int (*new_func);(void),
int (*dup_func)(void), void (*free_func)(void)); void
(*SSL_CTX_get_info_callback(SSL_CTX *ctx))(SSL *ssl, int cb, int ret);
int SSL_CTX_get_quiet_shutdown(SSL_CTX *ctx); int SSL_CTX_get_ses‐
sion_cache_mode(SSL_CTX *ctx); long SSL_CTX_get_timeout(SSL_CTX *ctx);
int (*SSL_CTX_get_verify_callback(SSL_CTX *ctx))(int ok, X509_STORE_CTX
*ctx); int SSL_CTX_get_verify_mode(SSL_CTX *ctx); int SSL_CTX_load_ver‐
ify_locations(SSL_CTX *ctx, char *CAfile, char *CApath); long
SSL_CTX_need_tmp_RSA(SSL_CTX *ctx); SSL_CTX *SSL_CTX_new(SSL_METHOD
*meth); int SSL_CTX_remove_session(SSL_CTX *ctx, SSL_SESSION *c); int
SSL_CTX_sess_accept(SSL_CTX *ctx); int SSL_CTX_sess_accept_good(SSL_CTX
*ctx); int SSL_CTX_sess_accept_renegotiate(SSL_CTX *ctx); int
SSL_CTX_sess_cache_full(SSL_CTX *ctx); int SSL_CTX_sess_cb_hits(SSL_CTX
*ctx); int SSL_CTX_sess_connect(SSL_CTX *ctx); int SSL_CTX_sess_con‐
nect_good(SSL_CTX *ctx); int SSL_CTX_sess_connect_renegotiate(SSL_CTX
*ctx); int SSL_CTX_sess_get_cache_size(SSL_CTX *ctx); SSL_SESSION
*(*SSL_CTX_sess_get_get_cb(SSL_CTX *ctx))(SSL *ssl, unsigned char
*data, int len, int *copy); int (*SSL_CTX_sess_get_new_cb(SSL_CTX
*ctx)(SSL *ssl, SSL_SESSION *sess); void
(*SSL_CTX_sess_get_remove_cb(SSL_CTX *ctx)(SSL_CTX *ctx, SSL_SESSION
*sess); int SSL_CTX_sess_hits(SSL_CTX *ctx); int
SSL_CTX_sess_misses(SSL_CTX *ctx); int SSL_CTX_sess_number(SSL_CTX
*ctx); void SSL_CTX_sess_set_cache_size(SSL_CTX *ctx,t); void
SSL_CTX_sess_set_get_cb(SSL_CTX *ctx, SSL_SESSION *(*cb)(SSL *ssl,
unsigned char *data, int len, int *copy)); void
SSL_CTX_sess_set_new_cb(SSL_CTX *ctx, int (*cb)(SSL *ssl, SSL_SESSION
*sess)); void SSL_CTX_sess_set_remove_cb(SSL_CTX *ctx, void
(*cb)(SSL_CTX *ctx, SSL_SESSION *sess)); int SSL_CTX_sess_time‐
outs(SSL_CTX *ctx); LHASH *SSL_CTX_sessions(SSL_CTX *ctx); void
SSL_CTX_set_app_data(SSL_CTX *ctx, void *arg); void
SSL_CTX_set_cert_store(SSL_CTX *ctx, X509_STORE *cs); void
SSL_CTX_set_cert_verify_cb(SSL_CTX *ctx, int (*cb)(), char *arg); void
SSL_CTX_set_cert_verify_cb(SSL_CTX *ctx, int (*cb)(SSL_CTX *), char
*arg); int SSL_CTX_set_cipher_list(SSL_CTX *ctx, char *str); void
SSL_CTX_set_client_CA_list(SSL_CTX *ctx, STACK *list); void
SSL_CTX_set_client_cert_cb(SSL_CTX *ctx, int (*cb)(SSL *ssl, X509
**x509, EVP_PKEY **pkey)); void SSL_CTX_set_default_passwd_cb(SSL_CTX
*ctx, int (*cb);(void)); void SSL_CTX_set_default_read_ahead(SSL_CTX
*ctx, int m); int SSL_CTX_set_default_verify_paths(SSL_CTX *ctx); int
SSL_CTX_set_ex_data(SSL_CTX *s, int idx, char *arg); void
SSL_CTX_set_info_callback(SSL_CTX *ctx, void (*cb)(SSL *ssl, int cb,
int ret)); void SSL_CTX_set_options(SSL_CTX *ctx, unsigned long op);
void SSL_CTX_set_quiet_shutdown(SSL_CTX *ctx, int mode); void
SSL_CTX_set_session_cache_mode(SSL_CTX *ctx, int mode); int
SSL_CTX_set_ssl_version(SSL_CTX *ctx, SSL_METHOD *meth); void
SSL_CTX_set_timeout(SSL_CTX *ctx, long t); long
SSL_CTX_set_tmp_dh(SSL_CTX* ctx, DH *dh); long SSL_CTX_set_tmp_dh_call‐
back(SSL_CTX *ctx, DH *(*cb)(void)); long SSL_CTX_set_tmp_rsa(SSL_CTX
*ctx, RSA *rsa); SSL_CTX_set_tmp_rsa_callback long
SSL_CTX_set_tmp_rsa_callback(SSL_CTX *ctx, RSA *(*cb)(SSL *ssl, int
export, int keylength));
Sets the callback which will be called when a temporary private
key is required. The export flag will be set if the reason for
needing a temp key is that an export ciphersuite is in use, in
which case, keylengthwill contain the required keylength in
bits. Generate a key of appropriate size and return it.
SSL_set_tmp_rsa_callback long SSL_set_tmp_rsa_callback(SSL
*ssl, RSA *(*cb)(SSL *ssl, int export, int keylength));
The same as SSL_CTX_set_tmp_rsa_callback, except it operates on
an SSL session instead of a context. void SSL_CTX_set_ver‐
ify(SSL_CTX *ctx, int mode, int (*cb);(void)); int
SSL_CTX_use_PrivateKey(SSL_CTX *ctx, EVP_PKEY *pkey); int
SSL_CTX_use_PrivateKey_ASN1(int type, SSL_CTX *ctx, unsigned
char *d, long len); int SSL_CTX_use_PrivateKey_file(SSL_CTX
*ctx, char *file, int type); int SSL_CTX_use_RSAPri‐
vateKey(SSL_CTX *ctx, RSA *rsa); int SSL_CTX_use_RSAPri‐
vateKey_ASN1(SSL_CTX *ctx, unsigned char *d, long len); int
SSL_CTX_use_RSAPrivateKey_file(SSL_CTX *ctx, char *file, int
type); 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, char
*file, int type);
Dealing With Sessions
The API functions that deal with the SSL/TLS sessions defined in the
SSL_SESSIONstructures are described in the following list: int SSL_SES‐
SION_cmp(SSL_SESSION *a, SSL_SESSION *b); void SSL_SES‐
SION_free(SSL_SESSION *ss); char *SSL_SESSION_get_app_data(SSL_SESSION
*s); char *SSL_SESSION_get_ex_data(SSL_SESSION *s, int idx); int
SSL_SESSION_get_ex_new_index(long argl, char *argp, int
(*new_func);(void), int (*dup_func)(void), void (*free_func)(void));
long SSL_SESSION_get_time(SSL_SESSION *s); long SSL_SESSION_get_time‐
out(SSL_SESSION *s); unsigned long SSL_SESSION_hash(SSL_SESSION *a);
SSL_SESSION *SSL_SESSION_new(void); int SSL_SESSION_print(BIO *bp,
SSL_SESSION *x); int SSL_SESSION_print_fp(FILE *fp, SSL_SESSION *x);
void SSL_SESSION_set_app_data(SSL_SESSION *s, char *a); int SSL_SES‐
SION_set_ex_data(SSL_SESSION *s, int idx, char *arg); long SSL_SES‐
SION_set_time(SSL_SESSION *s, long t); long SSL_SESSION_set_time‐
out(SSL_SESSION *s, long t);
Dealing With Connections
The API functions that deal with the SSL/TLS connection defined in the
SSL structure are described in the following list: int SSL_accept(SSL
*ssl); int SSL_add_dir_cert_subjects_to_stack(STACK *stack, const char
*dir); int SSL_add_file_cert_subjects_to_stack(STACK *stack, const char
*file); int SSL_add_client_CA(SSL *ssl, X509 *x); char
*SSL_alert_desc_string(int value); char *SSL_alert_desc_string_long(int
value); char *SSL_alert_type_string(int value); char
*SSL_alert_type_string_long(int value); int SSL_check_private_key(SSL
*ssl); void SSL_clear(SSL *ssl); long SSL_clear_num_renegotiations(SSL
*ssl); int SSL_connect(SSL *ssl); void SSL_copy_session_id(SSL *t, SSL
*f); long SSL_ctrl(SSL *ssl, int cmd, long larg, char *parg); int
SSL_do_handshake(SSL *ssl); SSL *SSL_dup(SSL *ssl); STACK
*SSL_dup_CA_list(STACK *sk); void SSL_free(SSL *ssl); SSL_CTX
*SSL_get_SSL_CTX(SSL *ssl); char *SSL_get_app_data(SSL *ssl); X509
*SSL_get_certificate(SSL *ssl); const char *SSL_get_cipher(SSL *ssl);
int SSL_get_cipher_bits(SSL *ssl, int *alg_bits); char
*SSL_get_cipher_list(SSL *ssl, int n); char *SSL_get_cipher_name(SSL
*ssl); char *SSL_get_cipher_version(SSL *ssl); STACK
*SSL_get_ciphers(SSL *ssl); STACK *SSL_get_client_CA_list(SSL *ssl);
SSL_CIPHER *SSL_get_current_cipher(SSL *ssl); long
SSL_get_default_timeout(SSL *ssl); int SSL_get_error(SSL *ssl, int i);
char *SSL_get_ex_data(SSL *ssl, int idx); int
SSL_get_ex_data_X509_STORE_CTX_idx(void); int SSL_get_ex_new_index(long
argl, char *argp, int (*new_func);(void), int (*dup_func)(void), void
(*free_func)(void)); int SSL_get_fd(SSL *ssl); void
(*SSL_get_info_callback(SSL *ssl);)(void); STACK
*SSL_get_peer_cert_chain(SSL *ssl); X509 *SSL_get_peer_certificate(SSL
*ssl); EVP_PKEY *SSL_get_privatekey(SSL *ssl); int SSL_get_quiet_shut‐
down(SSL *ssl); BIO *SSL_get_rbio(SSL *ssl); int SSL_get_read_ahead(SSL
*ssl); SSL_SESSION *SSL_get_session(SSL *ssl); char
*SSL_get_shared_ciphers(SSL *ssl, char *buf, int len); int
SSL_get_shutdown(SSL *ssl); SSL_METHOD *SSL_get_ssl_method(SSL *ssl);
int SSL_get_state(SSL *ssl); long SSL_get_time(SSL *ssl); long
SSL_get_timeout(SSL *ssl); int (*SSL_get_verify_callback(SSL
*ssl);)(void); int SSL_get_verify_mode(SSL *ssl); long SSL_get_ver‐
ify_result(SSL *ssl); char *SSL_get_version(SSL *ssl); BIO
*SSL_get_wbio(SSL *ssl); int SSL_in_accept_init(SSL *ssl); int
SSL_in_before(SSL *ssl); int SSL_in_connect_init(SSL *ssl); int
SSL_in_init(SSL *ssl); int SSL_is_init_finished(SSL *ssl); STACK
*SSL_load_client_CA_file(char *file); void
SSL_load_error_strings(void); SSL *SSL_new(SSL_CTX *ctx); long
SSL_num_renegotiations(SSL *ssl); int SSL_peek(SSL *ssl, void *buf, int
num); int SSL_pending(SSL *ssl); int SSL_read(SSL *ssl, void *buf, int
num); int SSL_renegotiate(SSL *ssl); char *SSL_rstate_string(SSL *ssl);
char *SSL_rstate_string_long(SSL *ssl); long SSL_session_reused(SSL
*ssl); void SSL_set_accept_state(SSL *ssl); void SSL_set_app_data(SSL
*ssl, char *arg); void SSL_set_bio(SSL *ssl, BIO *rbio, BIO *wbio); int
SSL_set_cipher_list(SSL *ssl, char *str); void
SSL_set_client_CA_list(SSL *ssl, STACK *list); void SSL_set_con‐
nect_state(SSL *ssl); int SSL_set_ex_data(SSL *ssl, int idx, char
*arg); int SSL_set_fd(SSL *ssl, int fd); void SSL_set_info_callback(SSL
*ssl, void (*cb);(void)); void SSL_set_options(SSL *ssl, unsigned long
op); void SSL_set_quiet_shutdown(SSL *ssl, int mode); void
SSL_set_read_ahead(SSL *ssl, int yes); int SSL_set_rfd(SSL *ssl, int
fd); int SSL_set_session(SSL *ssl, SSL_SESSION *session); void
SSL_set_shutdown(SSL *ssl, int mode); int SSL_set_ssl_method(SSL *ssl,
SSL_METHOD *meth); void SSL_set_time(SSL *ssl, long t); void
SSL_set_timeout(SSL *ssl, long t); void SSL_set_verify(SSL *ssl, int
mode, int (*callback);(void)); void SSL_set_verify_result(SSL *ssl,
long arg); int SSL_set_wfd(SSL *ssl, int fd); int SSL_shutdown(SSL
*ssl); int SSL_state(SSL *ssl); char *SSL_state_string(SSL *ssl); char
*SSL_state_string_long(SSL *ssl); long SSL_total_renegotiations(SSL
*ssl); int SSL_use_PrivateKey(SSL *ssl, EVP_PKEY *pkey); int
SSL_use_PrivateKey_ASN1(int type, SSL *ssl, unsigned char *d, long
len); int SSL_use_PrivateKey_file(SSL *ssl, char *file, int type); int
SSL_use_RSAPrivateKey(SSL *ssl, RSA *rsa); int SSL_use_RSAPri‐
vateKey_ASN1(SSL *ssl, unsigned char *d, long len); int SSL_use_RSAPri‐
vateKey_file(SSL *ssl, char *file, int type); int SSL_use_certifi‐
cate(SSL *ssl, X509 *x); int SSL_use_certificate_ASN1(SSL *ssl, int
len, unsigned char *d); int SSL_use_certificate_file(SSL *ssl, char
*file, int type); int SSL_version(SSL *ssl); int SSL_want(SSL *ssl);
int SSL_want_nothing(SSL *ssl); int SSL_want_read(SSL *ssl); int
SSL_want_write(SSL *ssl); int SSL_want_x509_lookup(s); int
SSL_write(SSL *ssl, const void *buf, int num);
HISTORY
The SSL document appeared in OpenSSL 0.9.2.
SEE ALSO
Commands: openssl(1)
Functions: crypto(3), SSL_accept(3), SSL_alert_type_string(3),
SSL_clear(3), SSL_COMP_add_compression_method(3), SSL_connect(3),
SSL_CIPHER_get_name(3), SSL_CTX_add_extra_chain_cert(3),
SSL_CTX_add_session(3), SSL_CTX_ctrl(3), SSL_CTX_flush_sessions(3),
SSL_CTX_get_ex_new_index(3), SSL_CTX_get_verify_mode(3),
SSL_CTX_load_verify_locations(3), SSL_CTX_new(3), SSL_CTX_sess_num‐
ber(3), SSL_CTX_sess_set_cache_size(3), SSL_CTX_sess_set_get_cb(3),
SSL_CTX_sessions(3), SSL_CTX_set_cert_store(3), SSL_CTX_set_cert_ver‐
ify_cb(3), SSL_CTX_set_cipher_list(3), SSL_CTX_set_client_CA_list(3),
SSL_CTX_set_client_cert_cb(3), SSL_CTX_set_default_passwd_cb(3),
SSL_CTX_set_info_callback(3), SSL_CTX_set_mode(3),
SSL_CTX_set_options(3), SSL_CTX_set_quiet_shutdown(3), SSL_CTX_set_ses‐
sion_cache_mode(3), SSL_CTX_set_session_id_context(3),
SSL_CTX_set_ssl_version(3), SSL_CTX_set_tmp_dh_callback(3),
SSL_CTX_set_tmp_rsa_callback(3), SSL_CTX_set_timeout(3),
SSL_CTX_set_verify(3), SSL_CTX_use_certificate(3), SSL_do_handshake(3).
SSL_get_ciphers(3), SSL_get_client_CA_list(3), SSL_get_default_time‐
out(3), SSL_get_error(3), SSL_get_ex_data_X509_STORE_CTX_idx(3),
SSL_get_ex_new_index(3), SSL_get_fd(3), SSL_get_peer_cert_chain(3),
SSL_get_rbio(3), SSL_get_session(3), SSL_get_SSL_CTX(3), SSL_get_ver‐
ify_result(3), SSL_get_version(3), SSL_library_init(3),
SSL_load_client_CA_file(3), SSL_new(3), SSL_read(3), SSL_set_bio(3),
SSL_set_connect_state(3), SSL_set_fd(3), SSL_pending(3), SSL_set_ses‐
sion(3), SSL_set_shutdown(3), SSL_shutdown(3), SSL_write(3), SSL_SES‐
SION_free(3), SSL_SESSION_get_ex_new_index(3), SSL_SESSION_get_time(3),
d2i_SSL_SESSION(3)ssl(3)
