bionic (3) BN_priv_rand_range.3ssl.gz

Provided by: libssl-doc_1.1.1-1ubuntu2.1~18.04.23_all bug

NAME
       BN_rand, BN_priv_rand, BN_pseudo_rand, BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range - generate
       pseudo-random number


SYNOPSIS
        #include <openssl/bn.h>

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

        int BN_priv_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_priv_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 in length and stores it in
       rnd.  If bits is less than zero, or too small to accommodate the requirements specified by the top and
       bottom parameters, an error is returned.  The top parameters specifies requirements on the most
       significant bit of the generated number.  If it is BN_RAND_TOP_ANY, there is no constraint.  If it is
       BN_RAND_TOP_ONE, the top bit must be one.  If it is BN_RAND_TOP_TWO, 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 BN_RAND_BOTTOM_ODD, the number will be odd; if it is BN_RAND_BOTTOM_ANY it can be odd or
       even.  If bits is 1 then top cannot also be BN_RAND_FLG_TOPTWO.

       BN_rand_range() generates a cryptographically strong pseudo-random number rnd in the range 0 <= rnd <
       range.

       BN_priv_rand() and BN_priv_rand_range() have the same semantics as BN_rand() and BN_rand_range()
       respectively.  They are intended to be used for generating values that should remain private, and mirror
       the same difference between RAND_bytes(3) and RAND_priv_bytes(3).


NOTES
       Always check the error return value of these functions and do not take randomness for granted: an error
       occurs if the CSPRNG has not been seeded with enough randomness to ensure an unpredictable byte sequence.


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


HISTORY
       • Starting with OpenSSL release 1.1.0, BN_pseudo_rand() has been identical to BN_rand() and
         BN_pseudo_rand_range() has been identical to BN_rand_range().  The "pseudo" functions should not be
         used and may be deprecated in a future release.

       • BN_priv_rand() and BN_priv_rand_range() were added in OpenSSL 1.1.1.


SEE ALSO
       ERR_get_error(3), RAND_add(3), RAND_bytes(3), RAND_priv_bytes(3), RAND(7), RAND_DRBG(7)


       Copyright 2000-2018 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
       <https://www.openssl.org/source/license.html>.