MirOS Manual: RSA_flags(3), RSA_get_default_method(3), RSA_get_default_openssl_method(3), RSA_get_method(3), RSA_new_method(3), RSA_null_method(3), RSA_PKCS1_RSAref(3), RSA_PKCS1_SSLeay(3), RSA_set_default_method(3), RSA_set_default_openssl_method(3), RSA_set_method(3)


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_SSLeay,
     RSA_null_method, RSA_flags, RSA_new_method - select RSA
     method

SYNOPSIS

      #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);

DESCRIPTION

     An RSA_METHOD specifies the functions that OpenSSL uses for
     RSA operations. By modifying the method, alternative imple-
     mentations such as hardware accelerators may be used. IMPOR-
     TANT: 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

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RSA_SET_METHOD(3)            OpenSSL            RSA_SET_METHOD(3)

     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 con-
     trolled 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);

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RSA_SET_METHOD(3)            OpenSSL            RSA_SET_METHOD(3)

          /* 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;

RETURN VALUES

     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.

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RSA_SET_METHOD(3)            OpenSSL            RSA_SET_METHOD(3)

     Otherwise it returns a pointer to the newly allocated struc-
     ture.

NOTES

     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 func-
     tion, 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 imple-
     mentations for use in RSA and other cryptographic algo-
     rithms.

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 con-
     trolled 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(3), RSA_new(3)

HISTORY

     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 com-
     ponents 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 res-
     tructured 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.

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