=pod

=head1 NAME

RSA_meth_new, RSA_meth_free, RSA_meth_dup, RSA_meth_get0_name,
RSA_meth_set1_name, RSA_meth_get_flags, RSA_meth_set_flags,
RSA_meth_get_app_data, RSA_meth_set_app_data, RSA_meth_get_pub_enc,
RSA_meth_set_pub_enc, RSA_meth_get_pub_dec, RSA_meth_set_pub_dec,
RSA_meth_get_priv_enc, RSA_meth_set_priv_enc, RSA_meth_get_priv_dec,
RSA_meth_set_priv_dec, RSA_meth_get_mod_exp, RSA_meth_set_mod_exp,
RSA_meth_get_bn_mod_exp, RSA_meth_set_bn_mod_exp, RSA_meth_get_init,
RSA_meth_set_init, RSA_meth_get_finish, RSA_meth_set_finish,
RSA_meth_get_sign, RSA_meth_set_sign, RSA_meth_get_verify,
RSA_meth_set_verify, RSA_meth_get_keygen, RSA_meth_set_keygen
- Routines to build up RSA methods

=head1 SYNOPSIS

 #include <openssl/rsa.h>

 RSA_METHOD *RSA_meth_new(const char *name, int flags);
 void RSA_meth_free(RSA_METHOD *meth);
 RSA_METHOD *RSA_meth_dup(const RSA_METHOD *meth);
 const char *RSA_meth_get0_name(const RSA_METHOD *meth);
 int RSA_meth_set1_name(RSA_METHOD *meth, const char *name);
 int RSA_meth_get_flags(RSA_METHOD *meth);
 int RSA_meth_set_flags(RSA_METHOD *meth, int flags);
 void *RSA_meth_get0_app_data(const RSA_METHOD *meth);
 int RSA_meth_set0_app_data(RSA_METHOD *meth, void *app_data);
 int (*RSA_meth_get_pub_enc(const RSA_METHOD *meth))
     (int flen, const unsigned char *from,
      unsigned char *to, RSA *rsa, int padding);
 int RSA_meth_set_pub_enc(RSA_METHOD *rsa,
                          int (*pub_enc) (int flen, const unsigned char *from,
                                          unsigned char *to, RSA *rsa,
                                          int padding));
 int (*RSA_meth_get_pub_dec(const RSA_METHOD *meth))
     (int flen, const unsigned char *from,
      unsigned char *to, RSA *rsa, int padding);
 int RSA_meth_set_pub_dec(RSA_METHOD *rsa,
                          int (*pub_dec) (int flen, const unsigned char *from,
                                          unsigned char *to, RSA *rsa,
                                          int padding));
 int (*RSA_meth_get_priv_enc(const RSA_METHOD *meth))
     (int flen, const unsigned char *from,
      unsigned char *to, RSA *rsa, int padding);
 int RSA_meth_set_priv_enc(RSA_METHOD *rsa,
                           int (*priv_enc) (int flen, const unsigned char *from,
                                            unsigned char *to, RSA *rsa,
                                            int padding));
 int (*RSA_meth_get_priv_dec(const RSA_METHOD *meth))
     (int flen, const unsigned char *from,
      unsigned char *to, RSA *rsa, int padding);
 int RSA_meth_set_priv_dec(RSA_METHOD *rsa,
                           int (*priv_dec) (int flen, const unsigned char *from,
                                            unsigned char *to, RSA *rsa,
                                            int padding));
     /* Can be null */
 int (*RSA_meth_get_mod_exp(const RSA_METHOD *meth))
     (BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx);
 int RSA_meth_set_mod_exp(RSA_METHOD *rsa,
                          int (*mod_exp) (BIGNUM *r0, const BIGNUM *I, RSA *rsa,
                                          BN_CTX *ctx));
     /* Can be null */
 int (*RSA_meth_get_bn_mod_exp(const RSA_METHOD *meth))
     (BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
      const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx);
 int RSA_meth_set_bn_mod_exp(RSA_METHOD *rsa,
                             int (*bn_mod_exp) (BIGNUM *r,
                                                const BIGNUM *a,
                                                const BIGNUM *p,
                                                const BIGNUM *m,
                                                BN_CTX *ctx,
                                                BN_MONT_CTX *m_ctx));
     /* called at new */
 int (*RSA_meth_get_init(const RSA_METHOD *meth)) (RSA *rsa);
 int RSA_meth_set_init(RSA_METHOD *rsa, int (*init) (RSA *rsa));
     /* called at free */
 int (*RSA_meth_get_finish(const RSA_METHOD *meth)) (RSA *rsa);
 int RSA_meth_set_finish(RSA_METHOD *rsa, int (*finish) (RSA *rsa));
 int (*RSA_meth_get_sign(const RSA_METHOD *meth))
     (int type,
      const unsigned char *m, unsigned int m_length,
      unsigned char *sigret, unsigned int *siglen,
      const RSA *rsa);
 int RSA_meth_set_sign(RSA_METHOD *rsa,
                       int (*sign) (int type, const unsigned char *m,
                                    unsigned int m_length,
                                    unsigned char *sigret, unsigned int *siglen,
                                    const RSA *rsa));
 int (*RSA_meth_get_verify(const RSA_METHOD *meth))
     (int dtype, const unsigned char *m,
      unsigned int m_length, const unsigned char *sigbuf,
      unsigned int siglen, const RSA *rsa);
 int RSA_meth_set_verify(RSA_METHOD *rsa,
                         int (*verify) (int dtype, const unsigned char *m,
                                        unsigned int m_length,
                                        const unsigned char *sigbuf,
                                        unsigned int siglen, const RSA *rsa));
 int (*RSA_meth_get_keygen(const RSA_METHOD *meth))
     (RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb);
 int RSA_meth_set_keygen(RSA_METHOD *rsa,
                         int (*keygen) (RSA *rsa, int bits, BIGNUM *e,
                                        BN_GENCB *cb));

=head1 DESCRIPTION

The B<RSA_METHOD> type is a structure used for the provision of custom
RSA implementations. It provides a set of of functions used by OpenSSL
for the implementation of the various RSA capabilities. See the L<rsa>
page for more information.

RSA_meth_new() creates a new B<RSA_METHOD> structure. It should be
given a unique B<name> and a set of B<flags>. The B<name> should be a
NULL terminated string, which will be duplicated and stored in the
B<RSA_METHOD> object. It is the callers responsibility to free the
original string. The flags will be used during the construction of a
new B<RSA> object based on this B<RSA_METHOD>. Any new B<RSA> object
will have those flags set by default.

RSA_meth_dup() creates a duplicate copy of the B<RSA_METHOD> object
passed as a parameter. This might be useful for creating a new
B<RSA_METHOD> based on an existing one, but with some differences.

RSA_meth_free() destroys an B<RSA_METHOD> structure and frees up any
memory associated with it.

RSA_meth_get0_name() will return a pointer to the name of this
RSA_METHOD. This is a pointer to the internal name string and so
should not be freed by the caller. RSA_meth_set1_name() sets the name
of the RSA_METHOD to B<name>. The string is duplicated and the copy is
stored in the RSA_METHOD structure, so the caller remains responsible
for freeing the memory associated with the name.

RSA_meth_get_flags() returns the current value of the flags associated
with this RSA_METHOD. RSA_meth_set_flags() provides the ability to set
these flags.

The functions RSA_meth_get0_app_data() and RSA_meth_set0_app_data()
provide the ability to associate implementation specific data with the
RSA_METHOD. It is the application's responsibility to free this data
before the RSA_METHOD is freed via a call to RSA_meth_free().

RSA_meth_get_sign() and RSA_meth_set_sign() get and set the function
used for creating an RSA signature respectively. This function will be
called in response to the application calling RSA_sign(). The
parameters for the function have the same meaning as for RSA_sign().

RSA_meth_get_verify() and RSA_meth_set_verify() get and set the
function used for verifying an RSA signature respectively. This
function will be called in response to the application calling
RSA_verify(). The parameters for the function have the same meaning as
for RSA_verify().

RSA_meth_get_mod_exp() and RSA_meth_set_mod_exp() get and set the
function used for CRT computations.

RSA_meth_get_bn_mod_exp() and RSA_meth_set_bn_mod_exp() get and set
the function used for CRT computations, specifically the following
value:

 r = a ^ p mod m

Both the mod_exp() and bn_mod_exp() functions are called by the
default OpenSSL method during encryption, decryption, signing and
verification.

RSA_meth_get_init() and RSA_meth_set_init() get and set the function
used for creating a new RSA instance respectively. This function will
be called in response to the application calling RSA_new() (if the
current default RSA_METHOD is this one) or RSA_new_method(). The
RSA_new() and RSA_new_method() functions will allocate the memory for
the new RSA object, and a pointer to this newly allocated structure
will be passed as a parameter to the function. This function may be
NULL.

RSA_meth_get_finish() and RSA_meth_set_finish() get and set the
function used for destroying an instance of an RSA object respectively.
This function will be called in response to the application calling
RSA_free(). A pointer to the RSA to be destroyed is passed as a
parameter. The destroy function should be used for RSA implementation
specific clean up. The memory for the RSA itself should not be freed
by this function. This function may be NULL.

RSA_meth_get_keygen() and RSA_meth_set_keygen() get and set the
function used for generating a new RSA key pair respectively. This
function will be called in response to the application calling
RSA_generate_key(). The parameter for the function has the same
meaning as for RSA_generate_key().

RSA_meth_get_pub_enc(), RSA_meth_set_pub_enc(),
RSA_meth_get_pub_dec(), RSA_meth_set_pub_dec(),
RSA_meth_get_priv_enc(), RSA_meth_set_priv_enc(),
RSA_meth_get_priv_dec(), RSA_meth_set_priv_dec() get and set the
functions used for public and private key encryption and decryption.
These functions will be called in response to the application calling
RSA_public_encrypt(), RSA_private_decrypt(), RSA_private_encrypt() and
RSA_public_decrypt() and take the same parameters as those.


=head1 RETURN VALUES

RSA_meth_new() and RSA_meth_dup() return the newly allocated
RSA_METHOD object or NULL on failure.

RSA_meth_get0_name() and RSA_meth_get_flags() return the name and
flags associated with the RSA_METHOD respectively.

All other RSA_meth_get_*() functions return the appropriate function
pointer that has been set in the RSA_METHOD, or NULL if no such
pointer has yet been set.

RSA_meth_set1_name and all RSA_meth_set_*() functions return 1 on
success or 0 on failure.

=head1 SEE ALSO

L<rsa(3)>, L<RSA_new(3)>, L<RSA_generate_key(3)>, L<RSA_sign(3)>,
L<RSA_set_method(3)>, L<RSA_size(3)>, L<RSA_get0_key(3)>

=head1 HISTORY

The functions described here were added in OpenSSL version 1.1.0.

=cut
