BN_rand(3)

     BN_rand(3)             0.9.6h (2002-09-25)             BN_rand(3)

     NAME
          BN_rand, BN_pseudo_rand - generate pseudo-random number

     SYNOPSIS
           #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
          BN_rand() generates a cryptographically strong pseudo-random
          number of bits 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.

          BN_pseudo_rand() does the same, but pseudo-random 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.

          BN_rand_range() 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 unpredictable.

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

     RETURN VALUES
          The functions return 1 on success, 0 on error.  The error
          codes can be obtained by ERR_get_error(3).

     SEE ALSO
          bn(3), ERR_get_error(3), rand(3), RAND_add(3), RAND_bytes(3)

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

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