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+=head1 NAME
+BN_rand, BN_priv_rand, BN_pseudo_rand,
+BN_rand_range, BN_priv_rand_range, BN_pseudo_rand_range
+- generate pseudo-random number
+=head1 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);
+BN_rand() generates a cryptographically strong pseudo-random number of
+B<bits> in length and stores it in B<rnd>.
+If B<bits> is less than zero, or too small to
+accommodate the requirements specified by the B<top> and B<bottom>
+parameters, an error is returned.
+The B<top> parameters specifies
+requirements on the most significant bit of the generated number.
+If it is B<BN_RAND_TOP_ANY>, there is no constraint.
+If it is B<BN_RAND_TOP_ONE>, the top bit must be one.
+If it is B<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*B<bits> length.
+If B<bottom> is B<BN_RAND_BOTTOM_ODD>, the number will be odd; if it
+is B<BN_RAND_BOTTOM_ANY> it can be odd or even.
+If B<bits> is 1 then B<top> cannot also be B<BN_RAND_FLG_TOPTWO>.
+BN_rand_range() generates a cryptographically strong pseudo-random
+number B<rnd> in the range 0 E<lt>= B<rnd> E<lt> B<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 L<RAND_bytes(3)> and L<RAND_priv_bytes(3)>.
+=head1 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.
+The functions return 1 on success, 0 on error.
+The error codes can be obtained by L<ERR_get_error(3)>.
+=head1 HISTORY
+=over 2
+=item *
+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
+The "pseudo" functions should not be used and may be deprecated in
+a future release.
+=item *
+BN_priv_rand() and BN_priv_rand_range() were added in OpenSSL 1.1.1.
+=head1 SEE ALSO
+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