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RSA_set_method(3) OpenSSL RSA_set_method(3)
NAME
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
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/rsa.h>
The following functions have been deprecated since OpenSSL 3.0, and can
be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
version value, see openssl_user_macros(7):
void RSA_set_default_method(const RSA_METHOD *meth);
const RSA_METHOD *RSA_get_default_method(void);
int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
const RSA_METHOD *RSA_get_method(const RSA *rsa);
const RSA_METHOD *RSA_PKCS1_OpenSSL(void);
int RSA_flags(const RSA *rsa);
RSA *RSA_new_method(ENGINE *engine);
DESCRIPTION
All of the functions described on this page are deprecated.
Applications should instead use the OSSL_PROVIDER APIs.
An RSA_METHOD specifies the functions that OpenSSL uses for RSA
operations. By modifying the method, alternative implementations such
as hardware accelerators may be used. IMPORTANT: See the NOTES section
for important information about how these RSA API functions are
affected by the use of ENGINE API calls.
Initially, the default RSA_METHOD is the OpenSSL internal
implementation, as returned by RSA_PKCS1_OpenSSL().
RSA_set_default_method() makes meth the default method for all RSA
structures created later. NB: This is true only whilst no ENGINE has
been set as a default for RSA, so this function is no longer
recommended. This function is not thread-safe and should not be called
at the same time as other OpenSSL functions.
RSA_get_default_method() returns a pointer to the current default
RSA_METHOD. However, the meaningfulness of this result is dependent on
whether the ENGINE API is being used, so this function is no longer
recommended.
RSA_set_method() selects meth to perform all operations using the key
rsa. This will replace the RSA_METHOD used by the RSA key and if the
previous method was supplied by an ENGINE, the handle to that ENGINE
will be released during the change. It is possible to have RSA keys
that only work with certain RSA_METHOD implementations (e.g. from an
ENGINE module that supports embedded hardware-protected keys), and in
such cases attempting to change the RSA_METHOD for the key can have
unexpected results.
RSA_get_method() returns a pointer to the RSA_METHOD being used by rsa.
This method may or may not be supplied by an ENGINE implementation, but
if it is, the return value can only be guaranteed to be valid as long
as the RSA key itself is valid and does not have its implementation
changed by RSA_set_method().
RSA_flags() returns the flags that are set for rsa's current
RSA_METHOD. See the BUGS section.
RSA_new_method() allocates and initializes an RSA structure so that
engine will be used for the RSA operations. If engine is NULL, the
default ENGINE for RSA operations is used, and if no default ENGINE is
set, the RSA_METHOD controlled by RSA_set_default_method() is used.
RSA_flags() returns the flags that are set for rsa's current method.
RSA_new_method() allocates and initializes an RSA structure so that
method will be used for the RSA operations. If method is NULL, the
default method is used.
THE RSA_METHOD STRUCTURE
typedef struct rsa_meth_st
{
/* name of the implementation */
const char *name;
/* encrypt */
int (*rsa_pub_enc)(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
/* verify arbitrary data */
int (*rsa_pub_dec)(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
/* sign arbitrary data */
int (*rsa_priv_enc)(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
/* decrypt */
int (*rsa_priv_dec)(int flen, unsigned char *from,
unsigned char *to, RSA *rsa, int padding);
/* compute r0 = r0 ^ I mod rsa->n (May be NULL for some implementations) */
int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa);
/* compute r = a ^ p mod m (May be NULL for some implementations) */
int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p,
const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
/* called at RSA_new */
int (*init)(RSA *rsa);
/* called at RSA_free */
int (*finish)(RSA *rsa);
/*
* RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key
* operations, even if p,q,dmp1,dmq1,iqmp
* are NULL
* RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match
*/
int flags;
char *app_data; /* ?? */
int (*rsa_sign)(int type,
const unsigned char *m, unsigned int m_length,
unsigned char *sigret, unsigned int *siglen, const RSA *rsa);
int (*rsa_verify)(int dtype,
const unsigned char *m, unsigned int m_length,
const unsigned char *sigbuf, unsigned int siglen,
const RSA *rsa);
/* keygen. If NULL built-in RSA key generation will be used */
int (*rsa_keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
} RSA_METHOD;
RETURN VALUES
RSA_PKCS1_OpenSSL(), RSA_PKCS1_null_method(), RSA_get_default_method()
and RSA_get_method() return pointers to the respective RSA_METHODs.
RSA_set_default_method() returns no value.
RSA_set_method() returns a pointer to the old RSA_METHOD implementation
that was replaced. However, this return value should probably be
ignored because if it was supplied by an ENGINE, the pointer could be
invalidated at any time if the ENGINE is unloaded (in fact it could be
unloaded as a result of the RSA_set_method() function releasing its
handle to the ENGINE). For this reason, the return type may be replaced
with a void declaration in a future release.
RSA_new_method() returns NULL and sets an error code that can be
obtained by ERR_get_error(3) if the allocation fails. Otherwise it
returns a pointer to the newly allocated structure.
BUGS
The behaviour of RSA_flags() is a mis-feature that is left as-is for
now to avoid creating compatibility problems. RSA functionality, such
as the encryption functions, are controlled by the flags value in the
RSA key itself, not by the flags value in the RSA_METHOD attached to
the RSA key (which is what this function returns). If the flags element
of an RSA key is changed, the changes will be honoured by RSA
functionality but will not be reflected in the return value of the
RSA_flags() function - in effect RSA_flags() behaves more like an
RSA_default_flags() function (which does not currently exist).
SEE ALSO
RSA_new(3)
HISTORY
All of these functions were deprecated in OpenSSL 3.0.
The RSA_null_method(), which was a partial attempt to avoid patent
issues, was replaced to always return NULL in OpenSSL 1.1.1.
COPYRIGHT
Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
3.0.12 2023-05-07 RSA_set_method(3)