plucky (3) BN_pseudo_rand.3ssl.gz

Provided by: libssl-doc_3.4.1-1ubuntu1_all bug

NAME
       BN_rand_ex, BN_rand, BN_priv_rand_ex, BN_priv_rand, BN_pseudo_rand, BN_rand_range_ex, BN_rand_range,
       BN_priv_rand_range_ex, BN_priv_rand_range, BN_pseudo_rand_range - generate pseudo-random number


SYNOPSIS
        #include <openssl/bn.h>

        int BN_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
                       unsigned int strength, BN_CTX *ctx);
        int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);

        int BN_priv_rand_ex(BIGNUM *rnd, int bits, int top, int bottom,
                            unsigned int strength, BN_CTX *ctx);
        int BN_priv_rand(BIGNUM *rnd, int bits, int top, int bottom);

        int BN_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
                             BN_CTX *ctx);
        int BN_rand_range(BIGNUM *rnd, const BIGNUM *range);

        int BN_priv_rand_range_ex(BIGNUM *rnd, const BIGNUM *range, unsigned int strength,
                                  BN_CTX *ctx);
        int BN_priv_rand_range(BIGNUM *rnd, const BIGNUM *range);

       The following functions have been deprecated since OpenSSL 3.0, and can be hidden entirely by defining
       OPENSSL_API_COMPAT with a suitable version value, see openssl_user_macros(7):

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


DESCRIPTION
       BN_rand_ex() generates a cryptographically strong pseudo-random number of bits in length and security
       strength at least strength bits using the random number generator for the library context associated with
       ctx. The function stores the generated data in rnd. The parameter ctx may be NULL in which case the
       default library context is used.  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_TOP_TWO.

       BN_rand() is the same as BN_rand_ex() except that the default library context is always used.

       BN_rand_range_ex() generates a cryptographically strong pseudo-random number rnd, of security strength at
       least strength bits, in the range 0 <= rnd < range using the random number generator for the library
       context associated with ctx. The parameter ctx may be NULL in which case the default library context is
       used.

       BN_rand_range() is the same as BN_rand_range_ex() except that the default library context is always used.

       BN_priv_rand_ex(), BN_priv_rand(), BN_priv_rand_rand_ex() and BN_priv_rand_range() have the same
       semantics as BN_rand_ex(), BN_rand(), BN_rand_range_ex() 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).


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


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 BN_pseudo_rand() and
         BN_pseudo_rand_range() functions were deprecated in OpenSSL 3.0.

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

       • The BN_rand_ex(), BN_priv_rand_ex(), BN_rand_range_ex() and BN_priv_rand_range_ex() functions were
         added in OpenSSL 3.0.


       Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (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>.