5 RSA_set_default_method, RSA_get_default_method, RSA_set_method,
6 RSA_get_method, RSA_PKCS1_SSLeay,
7 RSA_null_method, RSA_flags, RSA_new_method - select RSA method
11 #include <openssl/rsa.h>
12 #include <openssl/engine.h>
14 void RSA_set_default_method(const RSA_METHOD *meth);
16 RSA_METHOD *RSA_get_default_method(void);
18 int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
20 RSA_METHOD *RSA_get_method(const RSA *rsa);
22 RSA_METHOD *RSA_PKCS1_SSLeay(void);
24 RSA_METHOD *RSA_null_method(void);
26 int RSA_flags(const RSA *rsa);
28 RSA *RSA_new_method(ENGINE *engine);
32 An B<RSA_METHOD> specifies the functions that OpenSSL uses for RSA
33 operations. By modifying the method, alternative implementations such as
34 hardware accelerators may be used. IMPORTANT: See the NOTES section for
35 important information about how these RSA API functions are affected by the
36 use of B<ENGINE> API calls.
38 Initially, the default RSA_METHOD is the OpenSSL internal implementation,
39 as returned by RSA_PKCS1_SSLeay().
41 RSA_set_default_method() makes B<meth> the default method for all <RSA>
42 structures created later. B<NB>: This is true only whilst no ENGINE has
43 been set as a default for RSA, so this function is no longer recommended.
45 RSA_get_default_method() returns a pointer to the current default
46 RSA_METHOD. However, the meaningfulness of this result is dependant on
47 whether the ENGINE API is being used, so this function is no longer
50 RSA_set_method() selects B<meth> to perform all operations using the key
51 B<rsa>. This will replace the RSA_METHOD used by the RSA key and if the
52 previous method was supplied by an ENGINE, the handle to that ENGINE will
53 be released during the change. It is possible to have RSA keys that only
54 work with certain RSA_METHOD implementations (eg. from an ENGINE module
55 that supports embedded hardware-protected keys), and in such cases
56 attempting to change the RSA_METHOD for the key can have unexpected
59 RSA_get_method() returns a pointer to the RSA_METHOD being used by B<rsa>.
60 This method may or may not be supplied by an ENGINE implementation, but if
61 it is, the return value can only be guaranteed to be valid as long as the
62 RSA key itself is valid and does not have its implementation changed by
65 RSA_flags() returns the B<flags> that are set for B<rsa>'s current
66 RSA_METHOD. See the BUGS section.
68 RSA_new_method() allocates and initializes an RSA structure so that
69 B<engine> will be used for the RSA operations. If B<engine> is NULL, the
70 default ENGINE for RSA operations is used, and if no default ENGINE is set,
71 the RSA_METHOD controlled by RSA_set_default_method() is used.
73 =head1 THE RSA_METHOD STRUCTURE
75 typedef struct rsa_meth_st
77 /* name of the implementation */
81 int (*rsa_pub_enc)(int flen, unsigned char *from,
82 unsigned char *to, RSA *rsa, int padding);
84 /* verify arbitrary data */
85 int (*rsa_pub_dec)(int flen, unsigned char *from,
86 unsigned char *to, RSA *rsa, int padding);
88 /* sign arbitrary data */
89 int (*rsa_priv_enc)(int flen, unsigned char *from,
90 unsigned char *to, RSA *rsa, int padding);
93 int (*rsa_priv_dec)(int flen, unsigned char *from,
94 unsigned char *to, RSA *rsa, int padding);
96 /* compute r0 = r0 ^ I mod rsa->n (May be NULL for some
98 int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa);
100 /* compute r = a ^ p mod m (May be NULL for some implementations) */
101 int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
102 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
104 /* called at RSA_new */
105 int (*init)(RSA *rsa);
107 /* called at RSA_free */
108 int (*finish)(RSA *rsa);
110 /* RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key
111 * operations, even if p,q,dmp1,dmq1,iqmp
113 * RSA_FLAG_SIGN_VER - enable rsa_sign and rsa_verify
114 * RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match
118 char *app_data; /* ?? */
120 /* sign. For backward compatibility, this is used only
121 * if (flags & RSA_FLAG_SIGN_VER)
123 int (*rsa_sign)(int type, unsigned char *m, unsigned int m_len,
124 unsigned char *sigret, unsigned int *siglen, RSA *rsa);
126 /* verify. For backward compatibility, this is used only
127 * if (flags & RSA_FLAG_SIGN_VER)
129 int (*rsa_verify)(int type, unsigned char *m, unsigned int m_len,
130 unsigned char *sigbuf, unsigned int siglen, RSA *rsa);
136 RSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_method()
137 and RSA_get_method() return pointers to the respective RSA_METHODs.
139 RSA_set_default_method() returns no value.
141 RSA_set_method() returns a pointer to the old RSA_METHOD implementation
142 that was replaced. However, this return value should probably be ignored
143 because if it was supplied by an ENGINE, the pointer could be invalidated
144 at any time if the ENGINE is unloaded (in fact it could be unloaded as a
145 result of the RSA_set_method() function releasing its handle to the
146 ENGINE). For this reason, the return type may be replaced with a B<void>
147 declaration in a future release.
149 RSA_new_method() returns NULL and sets an error code that can be obtained
150 by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise
151 it returns a pointer to the newly allocated structure.
155 As of version 0.9.7, RSA_METHOD implementations are grouped together with
156 other algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into B<ENGINE>
157 modules. If a default ENGINE is specified for RSA functionality using an
158 ENGINE API function, that will override any RSA defaults set using the RSA
159 API (ie. RSA_set_default_method()). For this reason, the ENGINE API is the
160 recommended way to control default implementations for use in RSA and other
161 cryptographic algorithms.
165 The behaviour of RSA_flags() is a mis-feature that is left as-is for now
166 to avoid creating compatibility problems. RSA functionality, such as the
167 encryption functions, are controlled by the B<flags> value in the RSA key
168 itself, not by the B<flags> value in the RSA_METHOD attached to the RSA key
169 (which is what this function returns). If the flags element of an RSA key
170 is changed, the changes will be honoured by RSA functionality but will not
171 be reflected in the return value of the RSA_flags() function - in effect
172 RSA_flags() behaves more like an RSA_default_flags() function (which does
173 not currently exist).
177 L<rsa(3)|rsa(3)>, L<RSA_new(3)|RSA_new(3)>
181 RSA_new_method() and RSA_set_default_method() appeared in SSLeay 0.8.
182 RSA_get_default_method(), RSA_set_method() and RSA_get_method() as
183 well as the rsa_sign and rsa_verify components of RSA_METHOD were
184 added in OpenSSL 0.9.4.
186 RSA_set_default_openssl_method() and RSA_get_default_openssl_method()
187 replaced RSA_set_default_method() and RSA_get_default_method()
188 respectively, and RSA_set_method() and RSA_new_method() were altered to use
189 B<ENGINE>s rather than B<RSA_METHOD>s during development of the engine
190 version of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the ENGINE
191 API was restructured so that this change was reversed, and behaviour of the
192 other functions resembled more closely the previous behaviour. The
193 behaviour of defaults in the ENGINE API now transparently overrides the
194 behaviour of defaults in the RSA API without requiring changing these