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Diffstat (limited to 'src/lib/libcrypto/doc/DH_set_method.pod')
| -rw-r--r-- | src/lib/libcrypto/doc/DH_set_method.pod | 131 |
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diff --git a/src/lib/libcrypto/doc/DH_set_method.pod b/src/lib/libcrypto/doc/DH_set_method.pod deleted file mode 100644 index 2a4c2735cb..0000000000 --- a/src/lib/libcrypto/doc/DH_set_method.pod +++ /dev/null | |||
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| 1 | =pod | ||
| 2 | |||
| 3 | =head1 NAME | ||
| 4 | |||
| 5 | DH_set_default_method, DH_get_default_method, | ||
| 6 | DH_set_method, DH_new_method, DH_OpenSSL, | ||
| 7 | DH_set_default_openssl_method, DH_get_default_openssl_method | ||
| 8 | - select DH method | ||
| 9 | |||
| 10 | =head1 SYNOPSIS | ||
| 11 | |||
| 12 | #include <openssl/dh.h> | ||
| 13 | #include <openssl/engine.h> | ||
| 14 | |||
| 15 | void DH_set_default_method(const DH_METHOD *meth); | ||
| 16 | |||
| 17 | const DH_METHOD *DH_get_default_method(void); | ||
| 18 | |||
| 19 | int DH_set_method(DH *dh, const DH_METHOD *meth); | ||
| 20 | |||
| 21 | DH *DH_new_method(ENGINE *engine); | ||
| 22 | |||
| 23 | const DH_METHOD *DH_OpenSSL(void); | ||
| 24 | |||
| 25 | =head1 DESCRIPTION | ||
| 26 | |||
| 27 | A B<DH_METHOD> specifies the functions that OpenSSL uses for Diffie-Hellman | ||
| 28 | operations. By modifying the method, alternative implementations | ||
| 29 | such as hardware accelerators may be used. IMPORTANT: See the NOTES section for | ||
| 30 | important information about how these DH API functions are affected by the use | ||
| 31 | of B<ENGINE> API calls. | ||
| 32 | |||
| 33 | Initially, the default DH_METHOD is the OpenSSL internal implementation, as | ||
| 34 | returned by DH_OpenSSL(). | ||
| 35 | |||
| 36 | DH_set_default_method() makes B<meth> the default method for all DH | ||
| 37 | structures created later. B<NB>: This is true only whilst no ENGINE has been set | ||
| 38 | as a default for DH, so this function is no longer recommended. | ||
| 39 | |||
| 40 | DH_get_default_method() returns a pointer to the current default DH_METHOD. | ||
| 41 | However, the meaningfulness of this result is dependent on whether the ENGINE | ||
| 42 | API is being used, so this function is no longer recommended. | ||
| 43 | |||
| 44 | DH_set_method() selects B<meth> to perform all operations using the key B<dh>. | ||
| 45 | This will replace the DH_METHOD used by the DH key and if the previous method | ||
| 46 | was supplied by an ENGINE, the handle to that ENGINE will be released during the | ||
| 47 | change. It is possible to have DH keys that only work with certain DH_METHOD | ||
| 48 | implementations (eg. from an ENGINE module that supports embedded | ||
| 49 | hardware-protected keys), and in such cases attempting to change the DH_METHOD | ||
| 50 | for the key can have unexpected results. | ||
| 51 | |||
| 52 | DH_new_method() allocates and initializes a DH structure so that B<engine> will | ||
| 53 | be used for the DH operations. If B<engine> is NULL, the default ENGINE for DH | ||
| 54 | operations is used, and if no default ENGINE is set, the DH_METHOD controlled by | ||
| 55 | DH_set_default_method() is used. | ||
| 56 | |||
| 57 | =head1 THE DH_METHOD STRUCTURE | ||
| 58 | |||
| 59 | typedef struct dh_meth_st | ||
| 60 | { | ||
| 61 | /* name of the implementation */ | ||
| 62 | const char *name; | ||
| 63 | |||
| 64 | /* generate private and public DH values for key agreement */ | ||
| 65 | int (*generate_key)(DH *dh); | ||
| 66 | |||
| 67 | /* compute shared secret */ | ||
| 68 | int (*compute_key)(unsigned char *key, BIGNUM *pub_key, DH *dh); | ||
| 69 | |||
| 70 | /* compute r = a ^ p mod m (May be NULL for some implementations) */ | ||
| 71 | int (*bn_mod_exp)(DH *dh, BIGNUM *r, BIGNUM *a, const BIGNUM *p, | ||
| 72 | const BIGNUM *m, BN_CTX *ctx, | ||
| 73 | BN_MONT_CTX *m_ctx); | ||
| 74 | |||
| 75 | /* called at DH_new */ | ||
| 76 | int (*init)(DH *dh); | ||
| 77 | |||
| 78 | /* called at DH_free */ | ||
| 79 | int (*finish)(DH *dh); | ||
| 80 | |||
| 81 | int flags; | ||
| 82 | |||
| 83 | char *app_data; /* ?? */ | ||
| 84 | |||
| 85 | } DH_METHOD; | ||
| 86 | |||
| 87 | =head1 RETURN VALUES | ||
| 88 | |||
| 89 | DH_OpenSSL() and DH_get_default_method() return pointers to the respective | ||
| 90 | B<DH_METHOD>s. | ||
| 91 | |||
| 92 | DH_set_default_method() returns no value. | ||
| 93 | |||
| 94 | DH_set_method() returns non-zero if the provided B<meth> was successfully set as | ||
| 95 | the method for B<dh> (including unloading the ENGINE handle if the previous | ||
| 96 | method was supplied by an ENGINE). | ||
| 97 | |||
| 98 | DH_new_method() returns NULL and sets an error code that can be obtained by | ||
| 99 | L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise it | ||
| 100 | returns a pointer to the newly allocated structure. | ||
| 101 | |||
| 102 | =head1 NOTES | ||
| 103 | |||
| 104 | As of version 0.9.7, DH_METHOD implementations are grouped together with other | ||
| 105 | algorithmic APIs (eg. RSA_METHOD, EVP_CIPHER, etc) in B<ENGINE> modules. If a | ||
| 106 | default ENGINE is specified for DH functionality using an ENGINE API function, | ||
| 107 | that will override any DH defaults set using the DH API (ie. | ||
| 108 | DH_set_default_method()). For this reason, the ENGINE API is the recommended way | ||
| 109 | to control default implementations for use in DH and other cryptographic | ||
| 110 | algorithms. | ||
| 111 | |||
| 112 | =head1 SEE ALSO | ||
| 113 | |||
| 114 | L<dh(3)|dh(3)>, L<DH_new(3)|DH_new(3)> | ||
| 115 | |||
| 116 | =head1 HISTORY | ||
| 117 | |||
| 118 | DH_set_default_method(), DH_get_default_method(), DH_set_method(), | ||
| 119 | DH_new_method() and DH_OpenSSL() were added in OpenSSL 0.9.4. | ||
| 120 | |||
| 121 | DH_set_default_openssl_method() and DH_get_default_openssl_method() replaced | ||
| 122 | DH_set_default_method() and DH_get_default_method() respectively, and | ||
| 123 | DH_set_method() and DH_new_method() were altered to use B<ENGINE>s rather than | ||
| 124 | B<DH_METHOD>s during development of the engine version of OpenSSL 0.9.6. For | ||
| 125 | 0.9.7, the handling of defaults in the ENGINE API was restructured so that this | ||
| 126 | change was reversed, and behaviour of the other functions resembled more closely | ||
| 127 | the previous behaviour. The behaviour of defaults in the ENGINE API now | ||
| 128 | transparently overrides the behaviour of defaults in the DH API without | ||
| 129 | requiring changing these function prototypes. | ||
| 130 | |||
| 131 | =cut | ||
