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Diffstat (limited to 'doc/man3/SSL_get_client_random.pod')
-rw-r--r-- | doc/man3/SSL_get_client_random.pod | 104 |
1 files changed, 104 insertions, 0 deletions
diff --git a/doc/man3/SSL_get_client_random.pod b/doc/man3/SSL_get_client_random.pod new file mode 100644 index 000000000000..1e4c66672ddd --- /dev/null +++ b/doc/man3/SSL_get_client_random.pod @@ -0,0 +1,104 @@ +=pod + +=head1 NAME + +SSL_get_client_random, +SSL_get_server_random, +SSL_SESSION_get_master_key, +SSL_SESSION_set1_master_key +- get internal TLS/SSL random values and get/set master key + +=head1 SYNOPSIS + + #include <openssl/ssl.h> + + size_t SSL_get_client_random(const SSL *ssl, unsigned char *out, size_t outlen); + size_t SSL_get_server_random(const SSL *ssl, unsigned char *out, size_t outlen); + size_t SSL_SESSION_get_master_key(const SSL_SESSION *session, + unsigned char *out, size_t outlen); + int SSL_SESSION_set1_master_key(SSL_SESSION *sess, const unsigned char *in, + size_t len); + +=head1 DESCRIPTION + +SSL_get_client_random() extracts the random value sent from the client +to the server during the initial SSL/TLS handshake. It copies as many +bytes as it can of this value into the buffer provided in B<out>, +which must have at least B<outlen> bytes available. It returns the +total number of bytes that were actually copied. If B<outlen> is +zero, SSL_get_client_random() copies nothing, and returns the +total size of the client_random value. + +SSL_get_server_random() behaves the same, but extracts the random value +sent from the server to the client during the initial SSL/TLS handshake. + +SSL_SESSION_get_master_key() behaves the same, but extracts the master +secret used to guarantee the security of the SSL/TLS session. This one +can be dangerous if misused; see NOTES below. + +SSL_SESSION_set1_master_key() sets the master key value associated with the +SSL_SESSION B<sess>. For example, this could be used to set up a session based +PSK (see L<SSL_CTX_set_psk_use_session_callback(3)>). The master key of length +B<len> should be provided at B<in>. The supplied master key is copied by the +function, so the caller is responsible for freeing and cleaning any memory +associated with B<in>. The caller must ensure that the length of the key is +suitable for the ciphersuite associated with the SSL_SESSION. + +=head1 NOTES + +You probably shouldn't use these functions. + +These functions expose internal values from the TLS handshake, for +use in low-level protocols. You probably should not use them, unless +you are implementing something that needs access to the internal protocol +details. + +Despite the names of SSL_get_client_random() and SSL_get_server_random(), they +ARE NOT random number generators. Instead, they return the mostly-random values that +were already generated and used in the TLS protocol. Using them +in place of RAND_bytes() would be grossly foolish. + +The security of your TLS session depends on keeping the master key secret: +do not expose it, or any information about it, to anybody. +If you need to calculate another secret value that depends on the master +secret, you should probably use SSL_export_keying_material() instead, and +forget that you ever saw these functions. + +In current versions of the TLS protocols, the length of client_random +(and also server_random) is always SSL3_RANDOM_SIZE bytes. Support for +other outlen arguments to the SSL_get_*_random() functions is provided +in case of the unlikely event that a future version or variant of TLS +uses some other length there. + +Finally, though the "client_random" and "server_random" values are called +"random", many TLS implementations will generate four bytes of those +values based on their view of the current time. + + +=head1 RETURN VALUES + +SSL_SESSION_set1_master_key() returns 1 on success or 0 on failure. + +For the other functions, if B<outlen> is greater than 0 then these functions +return the number of bytes actually copied, which will be less than or equal to +B<outlen>. If B<outlen> is 0 then these functions return the maximum number +of bytes they would copy -- that is, the length of the underlying field. + +=head1 SEE ALSO + +L<ssl(7)>, +L<RAND_bytes(3)>, +L<SSL_export_keying_material(3)>, +L<SSL_CTX_set_psk_use_session_callback(3)> + + +=head1 COPYRIGHT + +Copyright 2015-2017 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the OpenSSL license (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 +L<https://www.openssl.org/source/license.html>. + +=cut |