07fc72fea1
Bleichenbacher's DSA attack. With this implementation, the expected
number of iterations never exceeds 2.
New semantics for BN_rand_range():
BN_rand_range(r, min, range) now generates r such that
min <= r < min+range.
(Previously, BN_rand_range(r, min, max) generated r such that
min <= r < max.
It is more convenient to have the range; also the previous
prototype was misleading because max was larger than
the actual maximum.)
52 lines
1.6 KiB
Text
52 lines
1.6 KiB
Text
=pod
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=head1 NAME
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BN_rand, BN_pseudo_rand - generate pseudo-random number
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=head1 SYNOPSIS
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#include <openssl/bn.h>
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int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
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int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
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int BN_rand_range(BIGNUM *rnd, BIGNUM *min, BIGNUM *range);
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=head1 DESCRIPTION
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BN_rand() generates a cryptographically strong pseudo-random number of
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B<bits> bits in length and stores it in B<rnd>. If B<top> is true, the
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two most significant bits of the number will be set to 1, so that the
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product of two such random numbers will always have 2*B<bits> length.
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If B<bottom> is true, the number will be odd.
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BN_pseudo_rand() does the same, but pseudo-random numbers generated by
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this function are not necessarily unpredictable. They can be used for
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non-cryptographic purposes and for certain purposes in cryptographic
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protocols, but usually not for key generation etc.
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BN_rand_range() generates a cryptographically strong pseudo-random
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number B<rnd> in the range B<min> E<lt>= B<rnd> E<lt> B<min> + B<range>.
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B<min> may be NULL, in that case 0 E<lt>= B<rnd> E<lt> B<range>.
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The PRNG must be seeded prior to calling BN_rand() or BN_rand_range().
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=head1 RETURN VALUES
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The functions return 1 on success, 0 on error.
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The error codes can be obtained by L<ERR_get_error(3)|ERR_get_error(3)>.
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=head1 SEE ALSO
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L<bn(3)|bn(3)>, L<err(3)|err(3)>, L<rand(3)|rand(3)>,
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L<RAND_add(3)|RAND_add(3)>, L<RAND_bytes(3)|RAND_bytes(3)>
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=head1 HISTORY
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BN_rand() is available in all versions of SSLeay and OpenSSL.
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BN_pseudo_rand() was added in OpenSSL 0.9.5, and BN_rand_range()
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in OpenSSL 0.9.6a.
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=cut
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