NAME    [Toc]    [Back]

       BN_rand, BN_pseudo_rand - Generate pseudo-random number

SYNOPSIS    [Toc]    [Back]

       #include <openssl/bn.h>

       int BN_rand(
               BIGNUM *rnd,
               int bits,
               int top,
               int bottom ); int BN_pseudo_rand(
               BIGNUM *rnd,
               int bits,
               int top,
               int bottom ); int BN_rand_range(
               BIGNUM *rnd,
               BIGNUM *range ); int BN_pseudo_rand_range(
               BIGNUM *rnd,
               BIGNUM *range );

DESCRIPTION    [Toc]    [Back]

       The   BN_rand()  function  generates  a  cryptographically
       strong pseudo-random number of bits in length  and  stores
       it  in  rnd. If top is -1, the most significant bit of the
       random number can be zero. If top is 0, it is  set  to  1,
       and if top is 1, the two most significant bits of the number
 will be set to 1, so that the product of two such random
  numbers will always have 2*bits length.  If bottom is
       true, the number will be odd.

       The BN_pseudo_rand() function does the same,  but  pseudorandom
  numbers  generated by this function are not necessarily
 unpredictable.  They can be  used  for  non-cryptographic
 purposes and for certain purposes in cryptographic
       protocols, but usually not for key generation etc.

       The BN_rand_range() function generates a cryptographically
       strong pseudo-random number rnd in the range 0 <lt>= rnd <
       range.  BN_pseudo_rand_range() does the same, but is based
       on BN_pseudo_rand(), and hence numbers generated by it are
       not necessarily unpredictible.

       The PRNG must be seeded prior to calling the BN_rand()  or
       BN_rand_range() functions.

RETURN VALUES    [Toc]    [Back]

       The  functions  return 1 on success, 0 on error. The error
       codes can be obtained by using ERR_get_error().

HISTORY    [Toc]    [Back]

       The BN_rand() function is available  in  all  versions  of
       SSLeay  and  OpenSSL.  The  BN_pseudo_rand()  function was
       added in OpenSSL  0.9.5.  The  top  ==  -1  case  and  the
       BN_rand_range()  function  were  added  in OpenSSL 0.9.6a.
       BN_pseudo_rand_range() was added in OpenSSL 0.9.6c.

SEE ALSO    [Toc]    [Back]

       Functions:  bn(3),   err(3),   rand_ssl(3),   RAND_add(3),
       RAND_bytes(3)



                                                       BN_rand(3)