mirror of https://github.com/openssl/openssl.git
145 lines
6.2 KiB
Plaintext
145 lines
6.2 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,
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DH_get0_p, DH_get0_q, DH_get0_g,
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DH_get0_priv_key, DH_get0_pub_key,
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DH_clear_flags, DH_test_flags, DH_set_flags, DH_get0_engine,
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DH_get_length, 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,
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const BIGNUM **p, const BIGNUM **q, const 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,
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const BIGNUM **pub_key, const BIGNUM **priv_key);
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int DH_set0_key(DH *dh, BIGNUM *pub_key, BIGNUM *priv_key);
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const BIGNUM *DH_get0_p(const DH *dh);
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const BIGNUM *DH_get0_q(const DH *dh);
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const BIGNUM *DH_get0_g(const DH *dh);
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const BIGNUM *DH_get0_priv_key(const DH *dh);
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const BIGNUM *DH_get0_pub_key(const DH *dh);
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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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long DH_get_length(const DH *dh);
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int DH_set_length(DH *dh, long length);
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Deprecated since OpenSSL 3.0, can be hidden entirely by defining
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B<OPENSSL_API_COMPAT> with a suitable version value, see
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L<openssl_user_macros(7)>:
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ENGINE *DH_get0_engine(DH *d);
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=head1 DESCRIPTION
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A DH object contains the parameters I<p>, I<q> and I<g>. Note that the I<q>
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parameter is optional. It also contains a public key (I<pub_key>) and
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(optionally) a private key (I<priv_key>).
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The I<p>, I<q> and I<g> parameters can be obtained by calling DH_get0_pqg().
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If the parameters have not yet been set then I<*p>, I<*q> and I<*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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Any of the out parameters I<p>, I<q>, and I<g> can be NULL, in which case no
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value will be returned for that parameter.
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The I<p>, I<q> and I<g> values can be set by calling DH_set0_pqg() and passing
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the new values for I<p>, I<q> and I<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 I<q> parameter may be NULL.
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DH_set0_pqg() also checks if the parameters associated with I<p> and I<g> and
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optionally I<q> are associated with known safe prime groups. If it is a safe
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prime group then the value of I<q> will be set to q = (p - 1) / 2 if I<q> is
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NULL. The optional length parameter will be set to BN_num_bits(I<q>) if I<q>
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is not 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 I<*pub_key>, and a pointer to the
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private key will be stored in I<*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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Any of the out parameters I<pub_key> and I<priv_key> can be NULL, in which case
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no value will be returned for that parameter.
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The public and private key values can be set using DH_set0_key(). Either
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parameter may be NULL, which means the corresponding DH field is left
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untouched. As with DH_set0_pqg() this function transfers the memory management
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of the key values to the DH object, and therefore they should not be freed
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directly after this function has been called.
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Any of the values I<p>, I<q>, I<g>, I<priv_key>, and I<pub_key> can also be
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retrieved separately by the corresponding function DH_get0_p(), DH_get0_q(),
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DH_get0_g(), DH_get0_priv_key(), and DH_get0_pub_key(), respectively.
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DH_set_flags() sets the flags in the I<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 I<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. This function is deprecated.
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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 nonzero then
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it is used, otherwise it is ignored. The I<length> parameter indicates the
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length of the secret exponent (private key) in bits. These functions are
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deprecated. For safe prime groups the optional length parameter I<length> can be
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set to a value greater or equal to 2 * maximum_target_security_strength(BN_num_bits(I<p>))
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as listed in SP800-56Ar3 Table(s) 25 & 26.
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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_get0_p(), DH_get0_q(), DH_get0_g(), DH_get0_priv_key(), and DH_get0_pub_key()
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return the respective value, or NULL if it is unset.
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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_new(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 DH_get0_engine() function was deprecated in OpenSSL 3.0.
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The functions described here were added in OpenSSL 1.1.0.
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=head1 COPYRIGHT
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Copyright 2016-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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