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RSA_SET_METHOD(3)
Contents
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RSA_set_default_method, RSA_get_default_method,
RSA_set_method, RSA_get_method, RSA_PKCS1_SSLeay,
RSA_null_method, RSA_flags, RSA_new_method - select RSA
method
#include <openssl/rsa.h>
void RSA_set_default_method(const RSA_METHOD *meth);
RSA_METHOD *RSA_get_default_method(void);
int RSA_set_method(RSA *rsa, const RSA_METHOD *meth);
RSA_METHOD *RSA_get_method(const RSA *rsa);
RSA_METHOD *RSA_PKCS1_SSLeay(void);
RSA_METHOD *RSA_null_method(void);
int RSA_flags(const RSA *rsa);
RSA *RSA_new_method(RSA_METHOD *method);
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_SSLeay().
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.
RSA_get_default_method() returns a pointer to the current
default RSA_METHOD. However, the meaningfulness of this
result is dependant 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 (eg. 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 [Toc] [Back] 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_FLAG_SIGN_VER - enable rsa_sign and
rsa_verify
* RSA_METHOD_FLAG_NO_CHECK - don't check pub/private
match
*/
int flags;
char *app_data; /* ?? */
/* sign. For backward compatibility, this is used only
* if (flags & RSA_FLAG_SIGN_VER)
*/
int (*rsa_sign)(int type, unsigned char *m, unsigned int m_len,
unsigned char *sigret, unsigned int *siglen,
RSA *rsa);
/* verify. For backward compatibility, this is used
only
* if (flags & RSA_FLAG_SIGN_VER)
*/
int (*rsa_verify)(int type, unsigned char *m, unsigned int m_len,
unsigned char *sigbuf, unsigned int siglen, RSA
*rsa);
} RSA_METHOD;
RSA_PKCS1_SSLeay(), 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.
As of version 0.9.7, RSA_METHOD implementations are
grouped together with other algorithmic APIs (eg.
DSA_METHOD, EVP_CIPHER, etc) into ENGINE modules. If a
default ENGINE is specified for RSA functionality using an
ENGINE API function, that will override any RSA defaults
set using the RSA API (ie. RSA_set_default_method()). For
this reason, the ENGINE API is the recommended way to control
default implementations for use in RSA and other
cryptographic algorithms.
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).
rsa(3), RSA_new(3)
RSA_new_method() and RSA_set_default_method() appeared in
SSLeay 0.8. RSA_get_default_method(), RSA_set_method()
and RSA_get_method() as well as the rsa_sign and rsa_verify
components of RSA_METHOD were added in OpenSSL 0.9.4.
RSA_set_default_openssl_method() and
RSA_get_default_openssl_method() replaced
RSA_set_default_method() and RSA_get_default_method()
respectively, and RSA_set_method() and RSA_new_method()
were altered to use ENGINEs rather than RSA_METHODs during
development of the engine version of OpenSSL 0.9.6. For
0.9.7, the handling of defaults in the ENGINE API was
restructured so that this change was reversed, and
behaviour of the other functions resembled more closely
the previous behaviour. The behaviour of defaults in the
ENGINE API now transparently overrides the behaviour of
defaults in the RSA API without requiring changing these
function prototypes.
OpenBSD 3.6 2003-05-11 4 [ Back ] |
