118 lines
3.7 KiB
Text
118 lines
3.7 KiB
Text
=pod
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=head1 NAME
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DSA_set_default_openssl_method, DSA_get_default_openssl_method,
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DSA_set_method, DSA_new_method, DSA_OpenSSL - select DSA method
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=head1 SYNOPSIS
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#include <openssl/dsa.h>
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#include <openssl/engine.h>
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void DSA_set_default_openssl_method(DSA_METHOD *meth);
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DSA_METHOD *DSA_get_default_openssl_method(void);
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int DSA_set_method(DSA *dsa, ENGINE *engine);
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DSA *DSA_new_method(ENGINE *engine);
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DSA_METHOD *DSA_OpenSSL(void);
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=head1 DESCRIPTION
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A B<DSA_METHOD> specifies the functions that OpenSSL uses for DSA
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operations. By modifying the method, alternative implementations
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such as hardware accelerators may be used.
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Initially, the default is to use the OpenSSL internal implementation.
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DSA_OpenSSL() returns a pointer to that method.
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DSA_set_default_openssl_method() makes B<meth> the default method for
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all DSA structures created later. B<NB:> This is true only whilst the
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default engine for DSA operations remains as "openssl". ENGINEs
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provide an encapsulation for implementations of one or more algorithms at a
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time, and all the DSA functions mentioned here operate within the scope
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of the default "openssl" engine.
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DSA_get_default_openssl_method() returns a pointer to the current default
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method for the "openssl" engine.
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DSA_set_method() selects B<engine> for all operations using the structure B<dsa>.
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DSA_new_method() allocates and initializes a DSA structure so that
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B<engine> will be used for the DSA operations. If B<engine> is NULL,
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the default engine for DSA operations is used.
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=head1 THE DSA_METHOD STRUCTURE
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struct
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{
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/* name of the implementation */
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const char *name;
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/* sign */
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DSA_SIG *(*dsa_do_sign)(const unsigned char *dgst, int dlen,
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DSA *dsa);
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/* pre-compute k^-1 and r */
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int (*dsa_sign_setup)(DSA *dsa, BN_CTX *ctx_in, BIGNUM **kinvp,
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BIGNUM **rp);
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/* verify */
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int (*dsa_do_verify)(const unsigned char *dgst, int dgst_len,
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DSA_SIG *sig, DSA *dsa);
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/* compute rr = a1^p1 * a2^p2 mod m (May be NULL for some
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implementations) */
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int (*dsa_mod_exp)(DSA *dsa, BIGNUM *rr, BIGNUM *a1, BIGNUM *p1,
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BIGNUM *a2, BIGNUM *p2, BIGNUM *m,
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BN_CTX *ctx, BN_MONT_CTX *in_mont);
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/* compute r = a ^ p mod m (May be NULL for some implementations) */
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int (*bn_mod_exp)(DSA *dsa, BIGNUM *r, BIGNUM *a,
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const BIGNUM *p, const BIGNUM *m,
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BN_CTX *ctx, BN_MONT_CTX *m_ctx);
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/* called at DSA_new */
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int (*init)(DSA *DSA);
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/* called at DSA_free */
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int (*finish)(DSA *DSA);
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int flags;
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char *app_data; /* ?? */
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} DSA_METHOD;
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=head1 RETURN VALUES
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DSA_OpenSSL() and DSA_get_default_openssl_method() return pointers to the
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respective B<DSA_METHOD>s.
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DSA_set_default_openssl_method() returns no value.
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DSA_set_method() returns non-zero if the ENGINE associated with B<dsa>
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was successfully changed to B<engine>.
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DSA_new_method() returns NULL and sets an error code that can be
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obtained by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation
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fails. Otherwise it returns a pointer to the newly allocated structure.
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=head1 SEE ALSO
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L<dsa(3)|dsa(3)>, L<DSA_new(3)|DSA_new(3)>
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=head1 HISTORY
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DSA_set_default_method(), DSA_get_default_method(), DSA_set_method(),
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DSA_new_method() and DSA_OpenSSL() were added in OpenSSL 0.9.4.
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DSA_set_default_openssl_method() and DSA_get_default_openssl_method()
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replaced DSA_set_default_method() and DSA_get_default_method() respectively,
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and DSA_set_method() and DSA_new_method() were altered to use B<ENGINE>s
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rather than B<DSA_METHOD>s during development of OpenSSL 0.9.6.
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=cut
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