BNrand(3) OpenSSL BNrand(3)

NAME
       BNrand, BNpseudorand - generate pseudo-random number

SYNOPSIS
        #include 

        int BNrand(BIGNUM *rnd, int bits, int top, int bottom);

        int BNpseudorand(BIGNUM *rnd, int bits, int top, int bottom);

        int BNrandrange(BIGNUM *rnd, BIGNUM *range);

        int BNpseudorandrange(BIGNUM *rnd, BIGNUM *range);

DESCRIPTION
       BNrand() generates a cryptographically strong pseudo-random number of
       bbiittss bits in length and stores it in rrnndd. If ttoopp is -1, the most
       significant bit of the random number can be zero. If ttoopp is 0, it is
       set to 1, and if ttoopp 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*bbiittss length.  If bboottttoomm is true, the number will be odd.

       BNpseudorand() 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.

       BNrandrange() generates a cryptographically strong pseudo-random
       number rrnndd in the range 0 = rrnndd < rraannggee.  BNpseudorandrange()
       does the same, but is based on BNpseudorand(), and hence numbers
       generated by it are not necessarily unpredictable.

       The PRNG must be seeded prior to calling BNrand() or BNrandrange().

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

SEE ALSO
       bn(3), ERRgeterror(3), rand(3), RANDadd(3), RANDbytes(3)

HISTORY       BNrand() is available in all versions of SSLeay and OpenSSL.
       BNpseudorand() was added in OpenSSL 0.9.5. The ttoopp == -1 case and the
       function BNrandrange() were added in OpenSSL 0.9.6a.
       BNpseudorandrange() was added in OpenSSL 0.9.6c.



0.9.7l                            2002-09-25                        BNrand(3)