ssl, SSL - OpenSSL SSL/TLS library
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_connect() 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.
The OpenSSL ssl library functions deal with the following
data structures: 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 configured 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 structure 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.
The OpenSSL ssl library provides the following C header
files containing 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.
The OpenSSL ssl library exports 214 API functions. They
are documented in the following sections.
Dealing With Protocol Methods [Toc] [Back]
The API functions that deal with the SSL/TLS protocol
methods defined in SSL_METHOD structures are described in
the following list: Constructor for the SSLv2 SSL_METHOD
structure for a dedicated client. Constructor 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 [Toc] [Back]
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 [Toc] [Back]
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_sessions(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_session_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_verify_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_connect_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_timeouts(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_callback(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_verify(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_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, 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 [Toc] [Back]
The API functions that deal with the SSL/TLS sessions
defined in the SSL_SESSIONstructures are described in the
following list: int SSL_SESSION_cmp(SSL_SESSION *a,
SSL_SESSION *b); void SSL_SESSION_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_timeout(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_SESSION_set_ex_data(SSL_SESSION *s,
int idx, char *arg); long SSL_SESSION_set_time(SSL_SESSION
*s, long t); long SSL_SESSION_set_timeout(SSL_SESSION *s,
long t);
Dealing With Connections [Toc] [Back]
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_shutdown(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_verify_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_connect_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_RSAPrivateKey_ASN1(SSL *ssl, unsigned char *d,
long len); int SSL_use_RSAPrivateKey_file(SSL *ssl, char
*file, int type); int SSL_use_certificate(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);
The SSL document appeared in OpenSSL 0.9.2.
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_number(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_verify_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_session_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_timeout(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_verify_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_session(3), SSL_set_shutdown(3),
SSL_shutdown(3), SSL_write(3), SSL_SESSION_free(3),
SSL_SESSION_get_ex_new_index(3), SSL_SESSION_get_time(3),
d2i_SSL_SESSION(3)
ssl(3)
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