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102 lines
4.3 KiB
Plaintext
102 lines
4.3 KiB
Plaintext
=pod
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=head1 NAME
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DH_get0_pqg, DH_set0_pqg, DH_get0_key, DH_set0_key, DH_clear_flags,
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DH_test_flags, DH_set_flags, DH_get0_engine, DH_get_length,
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DH_set_length - Routines for getting and setting data in a DH object
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=head1 SYNOPSIS
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#include <openssl/dh.h>
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void DH_get0_pqg(const DH *dh, BIGNUM **p, BIGNUM **q, BIGNUM **g);
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int DH_set0_pqg(DH *dh, BIGNUM *p, BIGNUM *q, BIGNUM *g);
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void DH_get0_key(const DH *dh, BIGNUM **pub_key, BIGNUM **priv_key);
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int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
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void DH_clear_flags(DH *dh, int flags);
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int DH_test_flags(const DH *dh, int flags);
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void DH_set_flags(DH *dh, int flags);
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ENGINE *DH_get0_engine(DH *d);
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long DH_get_length(const DH *dh);
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int DH_set_length(DH *dh, long length);
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=head1 DESCRIPTION
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A DH object contains the parameters B<p>, B<q> and B<g>. Note that the B<q>
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parameter is optional. It also contains a public key (B<pub_key>) and
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(optionally) a private key (B<priv_key>).
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The B<p>, B<q> and B<g> parameters can be obtained by calling DH_get0_pqg().
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If the parameters have not yet been set then B<*p>, B<*q> and B<*g> will be set
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to NULL. Otherwise they are set to pointers to their respective values. These
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point directly to the internal representations of the values and therefore
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should not be freed directly.
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The B<p>, B<q> and B<g> values can be set by calling DH_set0_pqg() and passing
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the new values for B<p>, B<q> and B<g> as parameters to the function. Calling
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this function transfers the memory management of the values to the DH object,
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and therefore the values that have been passed in should not be freed directly
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after this function has been called. The B<q> parameter may be NULL.
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To get the public and private key values use the DH_get0_key() function. A
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pointer to the public key will be stored in B<*pub_key>, and a pointer to the
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private key will be stored in B<*priv_key>. Either may be NULL if they have not
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been set yet, although if the private key has been set then the public key must
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be. The values point to the internal representation of the public key and
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private key values. This memory should not be freed directly.
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The public and private key values can be set using DH_set0_key(). The public
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key must be non-NULL the first time this function is called on a given DH
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object. The private key may be NULL. On subsequent calls, either may be NULL,
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which means the corresponding DH field is left untouched. As for DH_set0_pqg()
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this function transfers the memory management of the key values to the DH
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object, and therefore they should not be freed directly after this function has
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been called.
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DH_set_flags() sets the flags in the B<flags> parameter on the DH object.
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Multiple flags can be passed in one go (bitwise ORed together). Any flags that
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are already set are left set. DH_test_flags() tests to see whether the flags
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passed in the B<flags> parameter are currently set in the DH object. Multiple
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flags can be tested in one go. All flags that are currently set are returned, or
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zero if none of the flags are set. DH_clear_flags() clears the specified flags
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within the DH object.
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DH_get0_engine() returns a handle to the ENGINE that has been set for this DH
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object, or NULL if no such ENGINE has been set.
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The DH_get_length() and DH_set_length() functions get and set the optional
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length parameter associated with this DH object. If the length is non-zero then
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it is used, otherwise it is ignored. The B<length> parameter indicates the
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length of the secret exponent (private key) in bits.
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=head1 NOTES
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Values retrieved with DH_get0_key() are owned by the DH object used
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in the call and may therefore I<not> be passed to DH_set0_key(). If
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needed, duplicate the received value using BN_dup() and pass the
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duplicate. The same applies to DH_get0_pqg() and DH_set0_pqg().
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=head1 RETURN VALUES
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DH_set0_pqg() and DH_set0_key() return 1 on success or 0 on failure.
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DH_test_flags() returns the current state of the flags in the DH object.
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DH_get0_engine() returns the ENGINE set for the DH object or NULL if no ENGINE
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has been set.
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DH_get_length() returns the length of the secret exponent (private key) in bits,
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or zero if no such length has been explicitly set.
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=head1 SEE ALSO
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L<dh(3)>, L<DH_new(3)>, L<DH_generate_parameters(3)>, L<DH_generate_key(3)>,
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L<DH_set_method(3)>, L<DH_size(3)>, L<DH_meth_new(3)>
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=head1 HISTORY
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The functions described here were added in OpenSSL version 1.1.0.
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=cut
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