1RSA_set_method(3) OpenSSL RSA_set_method(3)
2
6 RSA_set_default_method, RSA_get_default_method, RSA_set_method,
7 RSA_get_method, RSA_PKCS1_SSLeay, RSA_null_method, RSA_flags,
8 RSA_new_method - select RSA method
9
11 #include <openssl/rsa.h>
12 void RSA_set_default_method(const RSA_METHOD *meth);
14 RSA_METHOD *RSA_get_default_method(void);
16 int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
18 RSA_METHOD *RSA_get_method(const RSA *rsa);
20 RSA_METHOD *RSA_PKCS1_SSLeay(void);
22 RSA_METHOD *RSA_null_method(void);
24 int RSA_flags(const RSA *rsa);
26 RSA *RSA_new_method(RSA_METHOD *method);
28
30 An RSA_METHOD specifies the functions that OpenSSL uses for RSA opera‐
31 tions. By modifying the method, alternative implementations such as
32 hardware accelerators may be used. IMPORTANT: See the NOTES section for
33 important information about how these RSA API functions are affected by
34 the use of ENGINE API calls.
35 Initially, the default RSA_METHOD is the OpenSSL internal implementa‐
37 tion, as returned by RSA_PKCS1_SSLeay().
38 RSA_set_default_method() makes meth the default method for all RSA
40 structures created later. NB: This is true only whilst no ENGINE has
41 been set as a default for RSA, so this function is no longer recom‐
42 mended.
43 RSA_get_default_method() returns a pointer to the current default
45 RSA_METHOD. However, the meaningfulness of this result is dependant on
46 whether the ENGINE API is being used, so this function is no longer
47 recommended.
48 RSA_set_method() selects meth to perform all operations using the key
50 rsa. This will replace the RSA_METHOD used by the RSA key and if the
51 previous method was supplied by an ENGINE, the handle to that ENGINE
52 will be released during the change. It is possible to have RSA keys
53 that only work with certain RSA_METHOD implementations (eg. from an
54 ENGINE module that supports embedded hardware-protected keys), and in
55 such cases attempting to change the RSA_METHOD for the key can have
56 unexpected results.
57 RSA_get_method() returns a pointer to the RSA_METHOD being used by rsa.
59 This method may or may not be supplied by an ENGINE implementation, but
60 if it is, the return value can only be guaranteed to be valid as long
61 as the RSA key itself is valid and does not have its implementation
62 changed by RSA_set_method().
63 RSA_flags() returns the flags that are set for rsa's current
65 RSA_METHOD. See the BUGS section.
66 RSA_new_method() allocates and initializes an RSA structure so that
68 engine will be used for the RSA operations. If engine is NULL, the
69 default ENGINE for RSA operations is used, and if no default ENGINE is
70 set, the RSA_METHOD controlled by RSA_set_default_method() is used.
71 RSA_flags() returns the flags that are set for rsa's current method.
73 RSA_new_method() allocates and initializes an RSA structure so that
75 method will be used for the RSA operations. If method is NULL, the
76 default method is used.
77
79 typedef struct rsa_meth_st
80 {
81 /* name of the implementation */
82 const char *name;
83 /* encrypt */
85 int (*rsa_pub_enc)(int flen, unsigned char *from,
86 unsigned char *to, RSA *rsa, int padding);
87 /* verify arbitrary data */
89 int (*rsa_pub_dec)(int flen, unsigned char *from,
90 unsigned char *to, RSA *rsa, int padding);
91 /* sign arbitrary data */
93 int (*rsa_priv_enc)(int flen, unsigned char *from,
94 unsigned char *to, RSA *rsa, int padding);
95 /* decrypt */
97 int (*rsa_priv_dec)(int flen, unsigned char *from,
98 unsigned char *to, RSA *rsa, int padding);
99 /* compute r0 = r0 ^ I mod rsa->n (May be NULL for some
101 implementations) */
102 int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa);
103 /* compute r = a ^ p mod m (May be NULL for some implementations) */
105 int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
106 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
107 /* called at RSA_new */
109 int (*init)(RSA *rsa);
110 /* called at RSA_free */
112 int (*finish)(RSA *rsa);
113 /* RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key
115 * operations, even if p,q,dmp1,dmq1,iqmp
116 * are NULL
117 * RSA_FLAG_SIGN_VER - enable rsa_sign and rsa_verify
118 * RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match
119 */
120 int flags;
121 char *app_data; /* ?? */
123 /* sign. For backward compatibility, this is used only
125 * if (flags & RSA_FLAG_SIGN_VER)
126 */
127 int (*rsa_sign)(int type, unsigned char *m, unsigned int m_len,
128 unsigned char *sigret, unsigned int *siglen, RSA *rsa);
129 /* verify. For backward compatibility, this is used only
131 * if (flags & RSA_FLAG_SIGN_VER)
132 */
133 int (*rsa_verify)(int type, unsigned char *m, unsigned int m_len,
134 unsigned char *sigbuf, unsigned int siglen, RSA *rsa);
135 } RSA_METHOD;
137
139 RSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_method()
140 and RSA_get_method() return pointers to the respective RSA_METHODs.
141 RSA_set_default_method() returns no value.
143 RSA_set_method() returns a pointer to the old RSA_METHOD implementation
145 that was replaced. However, this return value should probably be
146 ignored because if it was supplied by an ENGINE, the pointer could be
147 invalidated at any time if the ENGINE is unloaded (in fact it could be
148 unloaded as a result of the RSA_set_method() function releasing its
149 handle to the ENGINE). For this reason, the return type may be replaced
150 with a void declaration in a future release.
151 RSA_new_method() returns NULL and sets an error code that can be
153 obtained by ERR_get_error(3) if the allocation fails. Otherwise it
154 returns a pointer to the newly allocated structure.
155
157 As of version 0.9.7, RSA_METHOD implementations are grouped together
158 with other algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into
159 ENGINE modules. If a default ENGINE is specified for RSA functionality
160 using an ENGINE API function, that will override any RSA defaults set
161 using the RSA API (ie. RSA_set_default_method()). For this reason, the
162 ENGINE API is the recommended way to control default implementations
163 for use in RSA and other cryptographic algorithms.
164
166 The behaviour of RSA_flags() is a mis-feature that is left as-is for
167 now to avoid creating compatibility problems. RSA functionality, such
168 as the encryption functions, are controlled by the flags value in the
169 RSA key itself, not by the flags value in the RSA_METHOD attached to
170 the RSA key (which is what this function returns). If the flags element
171 of an RSA key is changed, the changes will be honoured by RSA function‐
172 ality but will not be reflected in the return value of the RSA_flags()
173 function - in effect RSA_flags() behaves more like an
174 RSA_default_flags() function (which does not currently exist).
175
177 rsa(3), RSA_new(3)
178
180 RSA_new_method() and RSA_set_default_method() appeared in SSLeay 0.8.
181 RSA_get_default_method(), RSA_set_method() and RSA_get_method() as well
182 as the rsa_sign and rsa_verify components of RSA_METHOD were added in
183 OpenSSL 0.9.4.
184 RSA_set_default_openssl_method() and RSA_get_default_openssl_method()
186 replaced RSA_set_default_method() and RSA_get_default_method() respec‐
187 tively, and RSA_set_method() and RSA_new_method() were altered to use
188 ENGINEs rather than RSA_METHODs during development of the engine ver‐
189 sion of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the
190 ENGINE API was restructured so that this change was reversed, and be‐
191 haviour of the other functions resembled more closely the previous be‐
192 haviour. The behaviour of defaults in the ENGINE API now transparently
193 overrides the behaviour of defaults in the RSA API without requiring
194 changing these function prototypes.
1950.9.8b 2002-09-25 RSA_set_method(3)