1=pod 2 3=head1 NAME 4 5RSA_set_default_method, RSA_get_default_method, RSA_set_method, 6RSA_get_method, RSA_PKCS1_SSLeay, RSA_null_method, RSA_flags, 7RSA_new_method - select RSA method 8 9=head1 SYNOPSIS 10 11 #include <openssl/rsa.h> 12 13 void RSA_set_default_method(const RSA_METHOD *meth); 14 15 RSA_METHOD *RSA_get_default_method(void); 16 17 int RSA_set_method(RSA *rsa, const RSA_METHOD *meth); 18 19 RSA_METHOD *RSA_get_method(const RSA *rsa); 20 21 RSA_METHOD *RSA_PKCS1_SSLeay(void); 22 23 RSA_METHOD *RSA_null_method(void); 24 25 int RSA_flags(const RSA *rsa); 26 27 RSA *RSA_new_method(RSA_METHOD *method); 28 29=head1 DESCRIPTION 30 31An B<RSA_METHOD> specifies the functions that OpenSSL uses for RSA 32operations. By modifying the method, alternative implementations such as 33hardware accelerators may be used. IMPORTANT: See the NOTES section for 34important information about how these RSA API functions are affected by the 35use of B<ENGINE> API calls. 36 37Initially, the default RSA_METHOD is the OpenSSL internal implementation, 38as returned by RSA_PKCS1_SSLeay(). 39 40RSA_set_default_method() makes B<meth> the default method for all RSA 41structures created later. B<NB>: This is true only whilst no ENGINE has 42been set as a default for RSA, so this function is no longer recommended. 43 44RSA_get_default_method() returns a pointer to the current default 45RSA_METHOD. However, the meaningfulness of this result is dependent on 46whether the ENGINE API is being used, so this function is no longer 47recommended. 48 49RSA_set_method() selects B<meth> to perform all operations using the key 50B<rsa>. This will replace the RSA_METHOD used by the RSA key and if the 51previous method was supplied by an ENGINE, the handle to that ENGINE will 52be released during the change. It is possible to have RSA keys that only 53work with certain RSA_METHOD implementations (eg. from an ENGINE module 54that supports embedded hardware-protected keys), and in such cases 55attempting to change the RSA_METHOD for the key can have unexpected 56results. 57 58RSA_get_method() returns a pointer to the RSA_METHOD being used by B<rsa>. 59This method may or may not be supplied by an ENGINE implementation, but if 60it is, the return value can only be guaranteed to be valid as long as the 61RSA key itself is valid and does not have its implementation changed by 62RSA_set_method(). 63 64RSA_flags() returns the B<flags> that are set for B<rsa>'s current 65RSA_METHOD. See the BUGS section. 66 67RSA_new_method() allocates and initializes an RSA structure so that 68B<engine> will be used for the RSA operations. If B<engine> is NULL, the 69default ENGINE for RSA operations is used, and if no default ENGINE is set, 70the RSA_METHOD controlled by RSA_set_default_method() is used. 71 72RSA_flags() returns the B<flags> that are set for B<rsa>'s current method. 73 74RSA_new_method() allocates and initializes an B<RSA> structure so that 75B<method> will be used for the RSA operations. If B<method> is B<NULL>, 76the default method is used. 77 78=head1 THE RSA_METHOD STRUCTURE 79 80 typedef struct rsa_meth_st 81 { 82 /* name of the implementation */ 83 const char *name; 84 85 /* encrypt */ 86 int (*rsa_pub_enc)(int flen, unsigned char *from, 87 unsigned char *to, RSA *rsa, int padding); 88 89 /* verify arbitrary data */ 90 int (*rsa_pub_dec)(int flen, unsigned char *from, 91 unsigned char *to, RSA *rsa, int padding); 92 93 /* sign arbitrary data */ 94 int (*rsa_priv_enc)(int flen, unsigned char *from, 95 unsigned char *to, RSA *rsa, int padding); 96 97 /* decrypt */ 98 int (*rsa_priv_dec)(int flen, unsigned char *from, 99 unsigned char *to, RSA *rsa, int padding); 100 101 /* compute r0 = r0 ^ I mod rsa->n (May be NULL for some 102 implementations) */ 103 int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa); 104 105 /* compute r = a ^ p mod m (May be NULL for some implementations) */ 106 int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p, 107 const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); 108 109 /* called at RSA_new */ 110 int (*init)(RSA *rsa); 111 112 /* called at RSA_free */ 113 int (*finish)(RSA *rsa); 114 115 /* RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key 116 * operations, even if p,q,dmp1,dmq1,iqmp 117 * are NULL 118 * RSA_FLAG_SIGN_VER - enable rsa_sign and rsa_verify 119 * RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match 120 */ 121 int flags; 122 123 char *app_data; /* ?? */ 124 125 /* sign. For backward compatibility, this is used only 126 * if (flags & RSA_FLAG_SIGN_VER) 127 */ 128 int (*rsa_sign)(int type, unsigned char *m, unsigned int m_len, 129 unsigned char *sigret, unsigned int *siglen, RSA *rsa); 130 131 /* verify. For backward compatibility, this is used only 132 * if (flags & RSA_FLAG_SIGN_VER) 133 */ 134 int (*rsa_verify)(int type, unsigned char *m, unsigned int m_len, 135 unsigned char *sigbuf, unsigned int siglen, RSA *rsa); 136 137 } RSA_METHOD; 138 139=head1 RETURN VALUES 140 141RSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_method() 142and RSA_get_method() return pointers to the respective RSA_METHODs. 143 144RSA_set_default_method() returns no value. 145 146RSA_set_method() returns a pointer to the old RSA_METHOD implementation 147that was replaced. However, this return value should probably be ignored 148because if it was supplied by an ENGINE, the pointer could be invalidated 149at any time if the ENGINE is unloaded (in fact it could be unloaded as a 150result of the RSA_set_method() function releasing its handle to the 151ENGINE). For this reason, the return type may be replaced with a B<void> 152declaration in a future release. 153 154RSA_new_method() returns NULL and sets an error code that can be obtained 155by L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise 156it returns a pointer to the newly allocated structure. 157 158=head1 NOTES 159 160As of version 0.9.7, RSA_METHOD implementations are grouped together with 161other algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into B<ENGINE> 162modules. If a default ENGINE is specified for RSA functionality using an 163ENGINE API function, that will override any RSA defaults set using the RSA 164API (ie. RSA_set_default_method()). For this reason, the ENGINE API is the 165recommended way to control default implementations for use in RSA and other 166cryptographic algorithms. 167 168=head1 BUGS 169 170The behaviour of RSA_flags() is a mis-feature that is left as-is for now 171to avoid creating compatibility problems. RSA functionality, such as the 172encryption functions, are controlled by the B<flags> value in the RSA key 173itself, not by the B<flags> value in the RSA_METHOD attached to the RSA key 174(which is what this function returns). If the flags element of an RSA key 175is changed, the changes will be honoured by RSA functionality but will not 176be reflected in the return value of the RSA_flags() function - in effect 177RSA_flags() behaves more like an RSA_default_flags() function (which does 178not currently exist). 179 180=head1 SEE ALSO 181 182L<rsa(3)|rsa(3)>, L<RSA_new(3)|RSA_new(3)> 183 184=head1 HISTORY 185 186RSA_new_method() and RSA_set_default_method() appeared in SSLeay 0.8. 187RSA_get_default_method(), RSA_set_method() and RSA_get_method() as 188well as the rsa_sign and rsa_verify components of RSA_METHOD were 189added in OpenSSL 0.9.4. 190 191RSA_set_default_openssl_method() and RSA_get_default_openssl_method() 192replaced RSA_set_default_method() and RSA_get_default_method() 193respectively, and RSA_set_method() and RSA_new_method() were altered to use 194B<ENGINE>s rather than B<RSA_METHOD>s during development of the engine 195version of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the ENGINE 196API was restructured so that this change was reversed, and behaviour of the 197other functions resembled more closely the previous behaviour. The 198behaviour of defaults in the ENGINE API now transparently overrides the 199behaviour of defaults in the RSA API without requiring changing these 200function prototypes. 201 202=cut 203