e6390acac9
Add CRYPTO_free_ex_index (for shared libraries) Unify and complete the documentation for all "ex_data" API's and objects. Replace xxx_get_ex_new_index functions with a macro. Added an exdata test. Renamed the ex_data internal datatypes. Reviewed-by: Matt Caswell <matt@openssl.org>
71 lines
2 KiB
Text
71 lines
2 KiB
Text
=pod
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=head1 NAME
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dh - Diffie-Hellman key agreement
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=head1 SYNOPSIS
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#include <openssl/dh.h>
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#include <openssl/engine.h>
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DH * DH_new(void);
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void DH_free(DH *dh);
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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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int DH_check(const DH *dh, int *codes);
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int DH_generate_key(DH *dh);
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int DH_compute_key(unsigned char *key, BIGNUM *pub_key, DH *dh);
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void DH_set_default_method(const DH_METHOD *meth);
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const DH_METHOD *DH_get_default_method(void);
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int DH_set_method(DH *dh, const DH_METHOD *meth);
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DH *DH_new_method(ENGINE *engine);
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const DH_METHOD *DH_OpenSSL(void);
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DH * d2i_DHparams(DH **a, unsigned char **pp, long length);
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int i2d_DHparams(const DH *a, unsigned char **pp);
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int DHparams_print_fp(FILE *fp, const DH *x);
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int DHparams_print(BIO *bp, const DH *x);
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=head1 DESCRIPTION
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These functions implement the Diffie-Hellman key agreement protocol.
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The generation of shared DH parameters is described in
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L<DH_generate_parameters(3)>; L<DH_generate_key(3)> describes how
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to perform a key agreement.
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The B<DH> structure consists of several BIGNUM components.
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struct
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{
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BIGNUM *p; // prime number (shared)
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BIGNUM *g; // generator of Z_p (shared)
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BIGNUM *priv_key; // private DH value x
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BIGNUM *pub_key; // public DH value g^x
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// ...
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};
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DH
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Note that DH keys may use non-standard B<DH_METHOD> implementations,
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either directly or by the use of B<ENGINE> modules. In some cases (eg. an
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ENGINE providing support for hardware-embedded keys), these BIGNUM values
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will not be used by the implementation or may be used for alternative data
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storage. For this reason, applications should generally avoid using DH
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structure elements directly and instead use API functions to query or
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modify keys.
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=head1 SEE ALSO
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L<dhparam(1)>, L<bn(3)>, L<dsa(3)>, L<err(3)>,
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L<rand(3)>, L<rsa(3)>, L<engine(3)>,
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L<DH_set_method(3)>, L<DH_new(3)>,
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L<DH_get_ex_new_index(3)>,
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L<DH_generate_parameters(3)>,
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L<DH_compute_key(3)>, L<d2i_DHparams(3)>,
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L<RSA_print(3)>
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=cut
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