MirBSD manpage: RAND_get_rand_method(3), RAND_set_rand_method(3), RAND_SSLeay(3)

RAND_SET_RAND_METHOD(3)      OpenSSL      RAND_SET_RAND_METHOD(3)

NAME

     RAND_set_rand_method, RAND_get_rand_method, RAND_SSLeay -
     select RAND method

SYNOPSIS

      #include <openssl/rand.h>

      void RAND_set_rand_method(const RAND_METHOD *meth);

      const RAND_METHOD *RAND_get_rand_method(void);

      RAND_METHOD *RAND_SSLeay(void);

DESCRIPTION

     A RAND_METHOD specifies the functions that OpenSSL uses for
     random number generation. By modifying the method, alterna-
     tive implementations such as hardware RNGs may be used.
     IMPORTANT: See the NOTES section for important information
     about how these RAND API functions are affected by the use
     of ENGINE API calls.

     Initially, the default RAND_METHOD is the OpenSSL internal
     implementation, as returned by RAND_SSLeay().

     RAND_set_default_method() makes meth the method for PRNG
     use. NB: This is true only whilst no ENGINE has been set as
     a default for RAND, so this function is no longer recom-
     mended.

     RAND_get_default_method() returns a pointer to the current
     RAND_METHOD. However, the meaningfulness of this result is
     dependant on whether the ENGINE API is being used, so this
     function is no longer recommended.

THE RAND_METHOD STRUCTURE

      typedef struct rand_meth_st
      {
             void (*seed)(const void *buf, int num);
             int (*bytes)(unsigned char *buf, int num);
             void (*cleanup)(void);
             void (*add)(const void *buf, int num, int entropy);
             int (*pseudorand)(unsigned char *buf, int num);
             int (*status)(void);
      } RAND_METHOD;

     The components point to the implementation of RAND_seed(),
     RAND_bytes(), RAND_cleanup(), RAND_add(), RAND_pseudo_rand()
     and RAND_status(). Each component may be NULL if the func-
     tion is not implemented.

RETURN VALUES

     RAND_set_rand_method() returns no value.

MirBSD #10-current         2005-02-05                           1

RAND_SET_RAND_METHOD(3)      OpenSSL      RAND_SET_RAND_METHOD(3)

     RAND_get_rand_method() and RAND_SSLeay() return pointers to
     the respective methods.

NOTES

     As of version 0.9.7, RAND_METHOD implementations are grouped
     together with other algorithmic APIs (eg. RSA_METHOD,
     EVP_CIPHER, etc) in ENGINE modules. If a default ENGINE is
     specified for RAND functionality using an ENGINE API func-
     tion, that will override any RAND defaults set using the
     RAND API (ie. RAND_set_rand_method()). For this reason, the
     ENGINE API is the recommended way to control default imple-
     mentations for use in RAND and other cryptographic algo-
     rithms.

SEE ALSO

     rand(3), engine(3)

HISTORY

     RAND_set_rand_method(), RAND_get_rand_method() and
     RAND_SSLeay() are available in all versions of OpenSSL.

     In the engine version of version 0.9.6,
     RAND_set_rand_method() was altered to take an ENGINE pointer
     as its argument. As of version 0.9.7, that has been reverted
     as the ENGINE API transparently overrides RAND defaults if
     used, otherwise RAND API functions work as before.
     RAND_set_rand_engine() was also introduced in version 0.9.7.

MirBSD #10-current         2005-02-05                           2