Manual Pages for UNIX Operating System command usage for man RSA_get_default_method

OpenSSL                                  RSA_set_method(3openssl)



NNNNAAAAMMMMEEEE
     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

SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
      #include 

      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);


DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
     An RRRRSSSSAAAA_MMMMEEEETTTTHHHHOOOODDDD 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
     EEEENNNNGGGGIIIINNNNEEEE API calls.

     Initially, the default RSA_METHOD is the OpenSSL internal
     implementation, as returned by RSA_PKCS1_SSLeay().

     RSA_set_default_method() makes mmmmeeeetttthhhh the default method for
     all RSA structures created later. NNNNBBBB: 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 dependent on whether the ENGINE API is being used,
     so this function is no longer recommended.

     RSA_set_method() selects mmmmeeeetttthhhh to perform all operations
     using the key rrrrssssaaaa. 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



19/Nov/2007            Last change: 0.9.8o                      1






OpenSSL                                  RSA_set_method(3openssl)



     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 rrrrssssaaaa.  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 ffffllllaaaaggggssss that are set for rrrrssssaaaa's current
     RSA_METHOD. See the BUGS section.

     RSA_new_method() allocates and initializes an RSA structure
     so that eeeennnnggggiiiinnnneeee will be used for the RSA operations. If
     eeeennnnggggiiiinnnneeee 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 ffffllllaaaaggggssss that are set for rrrrssssaaaa's current
     method.

     RSA_new_method() allocates and initializes an RRRRSSSSAAAA structure
     so that mmmmeeeetttthhhhoooodddd will be used for the RSA operations. If
     mmmmeeeetttthhhhoooodddd is NNNNUUUULLLLLLLL, the default method is used.

TTTTHHHHEEEE RRRRSSSSAAAA_MMMMEEEETTTTHHHHOOOODDDD SSSSTTTTRRRRUUUUCCCCTTTTUUUURRRREEEE
      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);






19/Nov/2007            Last change: 0.9.8o                      2






OpenSSL                                  RSA_set_method(3openssl)



          /* 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;


RRRREEEETTTTUUUURRRRNNNN VVVVAAAALLLLUUUUEEEESSSS
     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



19/Nov/2007            Last change: 0.9.8o                      3






OpenSSL                                  RSA_set_method(3openssl)



     ENGINE). For this reason, the return type may be replaced
     with a vvvvooooiiiidddd 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.

NNNNOOOOTTTTEEEESSSS
     As of version 0.9.7, RSA_METHOD implementations are grouped
     together with other algorithmic APIs (eg. DSA_METHOD,
     EVP_CIPHER, etc) into EEEENNNNGGGGIIIINNNNEEEE 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.

BBBBUUUUGGGGSSSS
     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 ffffllllaaaaggggssss value in the RSA key itself, not by
     the ffffllllaaaaggggssss 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).

SSSSEEEEEEEE AAAALLLLSSSSOOOO
     rsa(3), RSA_new(3)

HHHHIIIISSSSTTTTOOOORRRRYYYY
     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 EEEENNNNGGGGIIIINNNNEEEEs rather than RRRRSSSSAAAA_MMMMEEEETTTTHHHHOOOODDDDs 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



19/Nov/2007            Last change: 0.9.8o                      4






OpenSSL                                  RSA_set_method(3openssl)



     API without requiring changing these function prototypes.






















































19/Nov/2007            Last change: 0.9.8o                      5