a528d4f0a9
If something was "present in all versions" of SSLeay, or if it was added to a version of SSLeay (and therefore predates OpenSSL), remove mention of it. Documentation history now starts with OpenSSL. Remove mention of all history before OpenSSL 0.9.8, inclusive. Remove all AUTHOR sections. Reviewed-by: Tim Hudson <tjh@openssl.org>
74 lines
2.2 KiB
Text
74 lines
2.2 KiB
Text
=pod
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=head1 NAME
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DH_generate_parameters_ex, DH_generate_parameters,
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DH_check - generate and check Diffie-Hellman parameters
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=head1 SYNOPSIS
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#include <openssl/dh.h>
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int DH_generate_parameters_ex(DH *dh, int prime_len,int generator, BN_GENCB *cb);
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int DH_check(DH *dh, int *codes);
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Deprecated:
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DH *DH_generate_parameters(int prime_len, int generator,
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void (*callback)(int, int, void *), void *cb_arg);
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=head1 DESCRIPTION
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DH_generate_parameters_ex() generates Diffie-Hellman parameters that can
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be shared among a group of users, and stores them in the provided B<DH>
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structure. The pseudo-random number generator must be
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seeded prior to calling DH_generate_parameters().
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B<prime_len> is the length in bits of the safe prime to be generated.
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B<generator> is a small number E<gt> 1, typically 2 or 5.
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A callback function may be used to provide feedback about the progress
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of the key generation. If B<cb> is not B<NULL>, it will be
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called as described in L<BN_generate_prime(3)> while a random prime
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number is generated, and when a prime has been found, B<BN_GENCB_call(cb, 3, 0)>
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is called. See L<BN_generate_prime(3)> for information on
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the BN_GENCB_call() function.
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DH_check() validates Diffie-Hellman parameters. It checks that B<p> is
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a safe prime, and that B<g> is a suitable generator. In the case of an
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error, the bit flags DH_CHECK_P_NOT_SAFE_PRIME or
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DH_NOT_SUITABLE_GENERATOR are set in B<*codes>.
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DH_UNABLE_TO_CHECK_GENERATOR is set if the generator cannot be
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checked, i.e. it does not equal 2 or 5.
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=head1 RETURN VALUES
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DH_generate_parameters_ex() and DH_check() return 1 if the check could be
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performed, 0 otherwise.
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DH_generate_parameters() (deprecated) returns a pointer to the DH structure, or
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NULL if the parameter generation fails.
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The error codes can be obtained by L<ERR_get_error(3)>.
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=head1 NOTES
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DH_generate_parameters_ex() and DH_generate_parameters() may run for several
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hours before finding a suitable prime.
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The parameters generated by DH_generate_parameters_ex() and DH_generate_parameters()
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are not to be used in signature schemes.
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=head1 BUGS
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If B<generator> is not 2 or 5, B<dh-E<gt>g>=B<generator> is not
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a usable generator.
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=head1 SEE ALSO
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L<dh(3)>, L<ERR_get_error(3)>, L<rand(3)>,
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L<DH_free(3)>
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=cut
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