RSA_set_method(3)

     RSA_set_method(3)      0.9.6h (2000-09-14)      RSA_set_method(3)

     NAME
          RSA_set_default_method, RSA_get_default_method,
          RSA_set_method, RSA_get_method, RSA_PKCS1_SSLeay,
          RSA_PKCS1_RSAref, RSA_null_method, RSA_flags, RSA_new_method
          - select RSA method

     SYNOPSIS
           #include <openssl/rsa.h>

           void RSA_set_default_method(RSA_METHOD *meth);

           RSA_METHOD *RSA_get_default_method(void);

           RSA_METHOD *RSA_set_method(RSA *rsa, RSA_METHOD *meth);

           RSA_METHOD *RSA_get_method(RSA *rsa);

           RSA_METHOD *RSA_PKCS1_SSLeay(void);

           RSA_METHOD *RSA_PKCS1_RSAref(void);

           RSA_METHOD *RSA_null_method(void);

           int RSA_flags(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
          implementations such as hardware accelerators may be used.

          Initially, the default is to use the OpenSSL internal
          implementation, unless OpenSSL was configured with the
          "rsaref" or "-DRSA_NULL" options. RSA_PKCS1_SSLeay() returns
          a pointer to that method.

          RSA_PKCS1_RSAref() returns a pointer to a method that uses
          the RSAref library. This is the default method in the
          "rsaref" configuration; the function is not available in
          other configurations.  RSA_null_method() returns a pointer
          to a method that does not support the RSA transformation. It
          is the default if OpenSSL is compiled with "-DRSA_NULL".
          These methods may be useful in the USA because of a patent
          on the RSA cryptosystem.

          RSA_set_default_method() makes meth the default method for
          all RSA structures created later.

          RSA_get_default_method() returns a pointer to the current
          default method.

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     RSA_set_method(3)      0.9.6h (2000-09-14)      RSA_set_method(3)

          RSA_set_method() selects meth for all operations using the
          key rsa.

          RSA_get_method() returns a pointer to the method currently
          selected for rsa.

          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);

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     RSA_set_method(3)      0.9.6h (2000-09-14)      RSA_set_method(3)

               /* 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_RSAref(),
          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 RSA_METHOD
          previously associated with rsa.

          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.

     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
          components of RSA_METHOD were added in OpenSSL 0.9.4.

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