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135 .IX Title "RSA_SET_METHOD 3"
136 .TH RSA_SET_METHOD 3 "2021-02-16" "1.1.1j" "OpenSSL"
137 .\" For nroff, turn off justification. Always turn off hyphenation; it makes
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142 RSA_set_default_method, RSA_get_default_method, RSA_set_method, RSA_get_method, RSA_PKCS1_OpenSSL, RSA_flags, RSA_new_method \- select RSA method
144 .IX Header "SYNOPSIS"
146 \& #include <openssl/rsa.h>
148 \& void RSA_set_default_method(const RSA_METHOD *meth);
150 \& RSA_METHOD *RSA_get_default_method(void);
152 \& int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
154 \& RSA_METHOD *RSA_get_method(const RSA *rsa);
156 \& RSA_METHOD *RSA_PKCS1_OpenSSL(void);
158 \& int RSA_flags(const RSA *rsa);
160 \& RSA *RSA_new_method(ENGINE *engine);
163 .IX Header "DESCRIPTION"
164 An \fB\s-1RSA_METHOD\s0\fR specifies the functions that OpenSSL uses for \s-1RSA\s0
165 operations. By modifying the method, alternative implementations such as
166 hardware accelerators may be used. \s-1IMPORTANT:\s0 See the \s-1NOTES\s0 section for
167 important information about how these \s-1RSA API\s0 functions are affected by the
168 use of \fB\s-1ENGINE\s0\fR \s-1API\s0 calls.
170 Initially, the default \s-1RSA_METHOD\s0 is the OpenSSL internal implementation,
171 as returned by \fBRSA_PKCS1_OpenSSL()\fR.
173 \&\fBRSA_set_default_method()\fR makes \fBmeth\fR the default method for all \s-1RSA\s0
174 structures created later.
175 \&\fB\s-1NB\s0\fR: This is true only whilst no \s-1ENGINE\s0 has
176 been set as a default for \s-1RSA,\s0 so this function is no longer recommended.
177 This function is not thread-safe and should not be called at the same time
178 as other OpenSSL functions.
180 \&\fBRSA_get_default_method()\fR returns a pointer to the current default
181 \&\s-1RSA_METHOD.\s0 However, the meaningfulness of this result is dependent on
182 whether the \s-1ENGINE API\s0 is being used, so this function is no longer
185 \&\fBRSA_set_method()\fR selects \fBmeth\fR to perform all operations using the key
186 \&\fBrsa\fR. This will replace the \s-1RSA_METHOD\s0 used by the \s-1RSA\s0 key and if the
187 previous method was supplied by an \s-1ENGINE,\s0 the handle to that \s-1ENGINE\s0 will
188 be released during the change. It is possible to have \s-1RSA\s0 keys that only
189 work with certain \s-1RSA_METHOD\s0 implementations (e.g. from an \s-1ENGINE\s0 module
190 that supports embedded hardware-protected keys), and in such cases
191 attempting to change the \s-1RSA_METHOD\s0 for the key can have unexpected
194 \&\fBRSA_get_method()\fR returns a pointer to the \s-1RSA_METHOD\s0 being used by \fBrsa\fR.
195 This method may or may not be supplied by an \s-1ENGINE\s0 implementation, but if
196 it is, the return value can only be guaranteed to be valid as long as the
197 \&\s-1RSA\s0 key itself is valid and does not have its implementation changed by
198 \&\fBRSA_set_method()\fR.
200 \&\fBRSA_flags()\fR returns the \fBflags\fR that are set for \fBrsa\fR's current
201 \&\s-1RSA_METHOD.\s0 See the \s-1BUGS\s0 section.
203 \&\fBRSA_new_method()\fR allocates and initializes an \s-1RSA\s0 structure so that
204 \&\fBengine\fR will be used for the \s-1RSA\s0 operations. If \fBengine\fR is \s-1NULL,\s0 the
205 default \s-1ENGINE\s0 for \s-1RSA\s0 operations is used, and if no default \s-1ENGINE\s0 is set,
206 the \s-1RSA_METHOD\s0 controlled by \fBRSA_set_default_method()\fR is used.
208 \&\fBRSA_flags()\fR returns the \fBflags\fR that are set for \fBrsa\fR's current method.
210 \&\fBRSA_new_method()\fR allocates and initializes an \fB\s-1RSA\s0\fR structure so that
211 \&\fBmethod\fR will be used for the \s-1RSA\s0 operations. If \fBmethod\fR is \fB\s-1NULL\s0\fR,
212 the default method is used.
213 .SH "THE RSA_METHOD STRUCTURE"
214 .IX Header "THE RSA_METHOD STRUCTURE"
216 \& typedef struct rsa_meth_st
218 \& /* name of the implementation */
222 \& int (*rsa_pub_enc)(int flen, unsigned char *from,
223 \& unsigned char *to, RSA *rsa, int padding);
225 \& /* verify arbitrary data */
226 \& int (*rsa_pub_dec)(int flen, unsigned char *from,
227 \& unsigned char *to, RSA *rsa, int padding);
229 \& /* sign arbitrary data */
230 \& int (*rsa_priv_enc)(int flen, unsigned char *from,
231 \& unsigned char *to, RSA *rsa, int padding);
234 \& int (*rsa_priv_dec)(int flen, unsigned char *from,
235 \& unsigned char *to, RSA *rsa, int padding);
237 \& /* compute r0 = r0 ^ I mod rsa\->n (May be NULL for some implementations) */
238 \& int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa);
240 \& /* compute r = a ^ p mod m (May be NULL for some implementations) */
241 \& int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
242 \& const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
244 \& /* called at RSA_new */
245 \& int (*init)(RSA *rsa);
247 \& /* called at RSA_free */
248 \& int (*finish)(RSA *rsa);
251 \& * RSA_FLAG_EXT_PKEY \- rsa_mod_exp is called for private key
252 \& * operations, even if p,q,dmp1,dmq1,iqmp
254 \& * RSA_METHOD_FLAG_NO_CHECK \- don\*(Aqt check pub/private match
258 \& char *app_data; /* ?? */
260 \& int (*rsa_sign)(int type,
261 \& const unsigned char *m, unsigned int m_length,
262 \& unsigned char *sigret, unsigned int *siglen, const RSA *rsa);
263 \& int (*rsa_verify)(int dtype,
264 \& const unsigned char *m, unsigned int m_length,
265 \& const unsigned char *sigbuf, unsigned int siglen,
267 \& /* keygen. If NULL builtin RSA key generation will be used */
268 \& int (*rsa_keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
273 .IX Header "RETURN VALUES"
274 \&\fBRSA_PKCS1_OpenSSL()\fR, \fBRSA_PKCS1_null_method()\fR, \fBRSA_get_default_method()\fR
275 and \fBRSA_get_method()\fR return pointers to the respective RSA_METHODs.
277 \&\fBRSA_set_default_method()\fR returns no value.
279 \&\fBRSA_set_method()\fR returns a pointer to the old \s-1RSA_METHOD\s0 implementation
280 that was replaced. However, this return value should probably be ignored
281 because if it was supplied by an \s-1ENGINE,\s0 the pointer could be invalidated
282 at any time if the \s-1ENGINE\s0 is unloaded (in fact it could be unloaded as a
283 result of the \fBRSA_set_method()\fR function releasing its handle to the
284 \&\s-1ENGINE\s0). For this reason, the return type may be replaced with a \fBvoid\fR
285 declaration in a future release.
287 \&\fBRSA_new_method()\fR returns \s-1NULL\s0 and sets an error code that can be obtained
288 by \fBERR_get_error\fR\|(3) if the allocation fails. Otherwise
289 it returns a pointer to the newly allocated structure.
292 The behaviour of \fBRSA_flags()\fR is a mis-feature that is left as-is for now
293 to avoid creating compatibility problems. \s-1RSA\s0 functionality, such as the
294 encryption functions, are controlled by the \fBflags\fR value in the \s-1RSA\s0 key
295 itself, not by the \fBflags\fR value in the \s-1RSA_METHOD\s0 attached to the \s-1RSA\s0 key
296 (which is what this function returns). If the flags element of an \s-1RSA\s0 key
297 is changed, the changes will be honoured by \s-1RSA\s0 functionality but will not
298 be reflected in the return value of the \fBRSA_flags()\fR function \- in effect
299 \&\fBRSA_flags()\fR behaves more like an \fBRSA_default_flags()\fR function (which does
300 not currently exist).
302 .IX Header "SEE ALSO"
306 The \fBRSA_null_method()\fR, which was a partial attempt to avoid patent issues,
307 was replaced to always return \s-1NULL\s0 in OpenSSL 1.1.1.
309 .IX Header "COPYRIGHT"
310 Copyright 2000\-2020 The OpenSSL Project Authors. All Rights Reserved.
312 Licensed under the OpenSSL license (the \*(L"License\*(R"). You may not use
313 this file except in compliance with the License. You can obtain a copy
314 in the file \s-1LICENSE\s0 in the source distribution or at
315 <https://www.openssl.org/source/license.html>.