159191Skris=pod 259191Skris 359191Skris=head1 NAME 459191Skris 559191SkrisRSA_set_default_method, RSA_get_default_method, RSA_set_method, 6109998SmarkmRSA_get_method, RSA_PKCS1_SSLeay, RSA_null_method, RSA_flags, 7109998SmarkmRSA_new_method - select RSA method 859191Skris 959191Skris=head1 SYNOPSIS 1059191Skris 1159191Skris #include <openssl/rsa.h> 1259191Skris 13109998Smarkm void RSA_set_default_method(const RSA_METHOD *meth); 1459191Skris 1559191Skris RSA_METHOD *RSA_get_default_method(void); 1659191Skris 17109998Smarkm int RSA_set_method(RSA *rsa, const RSA_METHOD *meth); 1859191Skris 19109998Smarkm RSA_METHOD *RSA_get_method(const RSA *rsa); 2059191Skris 2159191Skris RSA_METHOD *RSA_PKCS1_SSLeay(void); 2259191Skris 2359191Skris RSA_METHOD *RSA_null_method(void); 2459191Skris 25109998Smarkm int RSA_flags(const RSA *rsa); 2659191Skris 2759191Skris RSA *RSA_new_method(RSA_METHOD *method); 2859191Skris 2959191Skris=head1 DESCRIPTION 3059191Skris 3159191SkrisAn B<RSA_METHOD> specifies the functions that OpenSSL uses for RSA 32109998Smarkmoperations. By modifying the method, alternative implementations such as 33109998Smarkmhardware accelerators may be used. IMPORTANT: See the NOTES section for 34109998Smarkmimportant information about how these RSA API functions are affected by the 35109998Smarkmuse of B<ENGINE> API calls. 3659191Skris 37109998SmarkmInitially, the default RSA_METHOD is the OpenSSL internal implementation, 38109998Smarkmas returned by RSA_PKCS1_SSLeay(). 3959191Skris 40109998SmarkmRSA_set_default_method() makes B<meth> the default method for all RSA 41109998Smarkmstructures created later. B<NB>: This is true only whilst no ENGINE has 42109998Smarkmbeen set as a default for RSA, so this function is no longer recommended. 4359191Skris 4459191SkrisRSA_get_default_method() returns a pointer to the current default 45194206SsimonRSA_METHOD. However, the meaningfulness of this result is dependent on 46109998Smarkmwhether the ENGINE API is being used, so this function is no longer 47109998Smarkmrecommended. 4859191Skris 49109998SmarkmRSA_set_method() selects B<meth> to perform all operations using the key 50109998SmarkmB<rsa>. This will replace the RSA_METHOD used by the RSA key and if the 51109998Smarkmprevious method was supplied by an ENGINE, the handle to that ENGINE will 52109998Smarkmbe released during the change. It is possible to have RSA keys that only 53109998Smarkmwork with certain RSA_METHOD implementations (eg. from an ENGINE module 54109998Smarkmthat supports embedded hardware-protected keys), and in such cases 55109998Smarkmattempting to change the RSA_METHOD for the key can have unexpected 56109998Smarkmresults. 5759191Skris 58109998SmarkmRSA_get_method() returns a pointer to the RSA_METHOD being used by B<rsa>. 59109998SmarkmThis method may or may not be supplied by an ENGINE implementation, but if 60109998Smarkmit is, the return value can only be guaranteed to be valid as long as the 61109998SmarkmRSA key itself is valid and does not have its implementation changed by 62109998SmarkmRSA_set_method(). 6359191Skris 64109998SmarkmRSA_flags() returns the B<flags> that are set for B<rsa>'s current 65109998SmarkmRSA_METHOD. See the BUGS section. 66109998Smarkm 67109998SmarkmRSA_new_method() allocates and initializes an RSA structure so that 68109998SmarkmB<engine> will be used for the RSA operations. If B<engine> is NULL, the 69109998Smarkmdefault ENGINE for RSA operations is used, and if no default ENGINE is set, 70109998Smarkmthe RSA_METHOD controlled by RSA_set_default_method() is used. 71109998Smarkm 7259191SkrisRSA_flags() returns the B<flags> that are set for B<rsa>'s current method. 7359191Skris 7459191SkrisRSA_new_method() allocates and initializes an B<RSA> structure so that 7559191SkrisB<method> will be used for the RSA operations. If B<method> is B<NULL>, 7659191Skristhe default method is used. 7759191Skris 7859191Skris=head1 THE RSA_METHOD STRUCTURE 7959191Skris 8059191Skris typedef struct rsa_meth_st 8159191Skris { 8259191Skris /* name of the implementation */ 8359191Skris const char *name; 8459191Skris 8559191Skris /* encrypt */ 8659191Skris int (*rsa_pub_enc)(int flen, unsigned char *from, 8759191Skris unsigned char *to, RSA *rsa, int padding); 8859191Skris 8959191Skris /* verify arbitrary data */ 9059191Skris int (*rsa_pub_dec)(int flen, unsigned char *from, 9159191Skris unsigned char *to, RSA *rsa, int padding); 9259191Skris 9359191Skris /* sign arbitrary data */ 9459191Skris int (*rsa_priv_enc)(int flen, unsigned char *from, 9559191Skris unsigned char *to, RSA *rsa, int padding); 9659191Skris 9759191Skris /* decrypt */ 9859191Skris int (*rsa_priv_dec)(int flen, unsigned char *from, 9959191Skris unsigned char *to, RSA *rsa, int padding); 10059191Skris 10159191Skris /* compute r0 = r0 ^ I mod rsa->n (May be NULL for some 10259191Skris implementations) */ 10359191Skris int (*rsa_mod_exp)(BIGNUM *r0, BIGNUM *I, RSA *rsa); 10459191Skris 10559191Skris /* compute r = a ^ p mod m (May be NULL for some implementations) */ 10659191Skris int (*bn_mod_exp)(BIGNUM *r, BIGNUM *a, const BIGNUM *p, 10759191Skris const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx); 10859191Skris 10959191Skris /* called at RSA_new */ 11059191Skris int (*init)(RSA *rsa); 11159191Skris 11259191Skris /* called at RSA_free */ 11359191Skris int (*finish)(RSA *rsa); 11459191Skris 11559191Skris /* RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key 11659191Skris * operations, even if p,q,dmp1,dmq1,iqmp 11759191Skris * are NULL 11859191Skris * RSA_FLAG_SIGN_VER - enable rsa_sign and rsa_verify 11959191Skris * RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match 12059191Skris */ 12159191Skris int flags; 12259191Skris 12359191Skris char *app_data; /* ?? */ 12459191Skris 12559191Skris /* sign. For backward compatibility, this is used only 12659191Skris * if (flags & RSA_FLAG_SIGN_VER) 12759191Skris */ 128269686Sjkim int (*rsa_sign)(int type, 129269686Sjkim const unsigned char *m, unsigned int m_length, 130269686Sjkim unsigned char *sigret, unsigned int *siglen, const RSA *rsa); 13159191Skris /* verify. For backward compatibility, this is used only 13259191Skris * if (flags & RSA_FLAG_SIGN_VER) 13359191Skris */ 134269686Sjkim int (*rsa_verify)(int dtype, 135269686Sjkim const unsigned char *m, unsigned int m_length, 136269686Sjkim const unsigned char *sigbuf, unsigned int siglen, 137269686Sjkim const RSA *rsa); 138269686Sjkim /* keygen. If NULL builtin RSA key generation will be used */ 139269686Sjkim int (*rsa_keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb); 14059191Skris 14159191Skris } RSA_METHOD; 14259191Skris 14359191Skris=head1 RETURN VALUES 14459191Skris 145109998SmarkmRSA_PKCS1_SSLeay(), RSA_PKCS1_null_method(), RSA_get_default_method() 146109998Smarkmand RSA_get_method() return pointers to the respective RSA_METHODs. 14759191Skris 14859191SkrisRSA_set_default_method() returns no value. 14959191Skris 150109998SmarkmRSA_set_method() returns a pointer to the old RSA_METHOD implementation 151109998Smarkmthat was replaced. However, this return value should probably be ignored 152109998Smarkmbecause if it was supplied by an ENGINE, the pointer could be invalidated 153109998Smarkmat any time if the ENGINE is unloaded (in fact it could be unloaded as a 154109998Smarkmresult of the RSA_set_method() function releasing its handle to the 155109998SmarkmENGINE). For this reason, the return type may be replaced with a B<void> 156109998Smarkmdeclaration in a future release. 15759191Skris 158109998SmarkmRSA_new_method() returns NULL and sets an error code that can be obtained 159109998Smarkmby L<ERR_get_error(3)|ERR_get_error(3)> if the allocation fails. Otherwise 160109998Smarkmit returns a pointer to the newly allocated structure. 16159191Skris 162109998Smarkm=head1 NOTES 163109998Smarkm 164109998SmarkmAs of version 0.9.7, RSA_METHOD implementations are grouped together with 165109998Smarkmother algorithmic APIs (eg. DSA_METHOD, EVP_CIPHER, etc) into B<ENGINE> 166109998Smarkmmodules. If a default ENGINE is specified for RSA functionality using an 167109998SmarkmENGINE API function, that will override any RSA defaults set using the RSA 168109998SmarkmAPI (ie. RSA_set_default_method()). For this reason, the ENGINE API is the 169109998Smarkmrecommended way to control default implementations for use in RSA and other 170109998Smarkmcryptographic algorithms. 171109998Smarkm 172109998Smarkm=head1 BUGS 173109998Smarkm 174109998SmarkmThe behaviour of RSA_flags() is a mis-feature that is left as-is for now 175109998Smarkmto avoid creating compatibility problems. RSA functionality, such as the 176109998Smarkmencryption functions, are controlled by the B<flags> value in the RSA key 177109998Smarkmitself, not by the B<flags> value in the RSA_METHOD attached to the RSA key 178109998Smarkm(which is what this function returns). If the flags element of an RSA key 179109998Smarkmis changed, the changes will be honoured by RSA functionality but will not 180109998Smarkmbe reflected in the return value of the RSA_flags() function - in effect 181109998SmarkmRSA_flags() behaves more like an RSA_default_flags() function (which does 182109998Smarkmnot currently exist). 183109998Smarkm 18459191Skris=head1 SEE ALSO 18559191Skris 18659191SkrisL<rsa(3)|rsa(3)>, L<RSA_new(3)|RSA_new(3)> 18759191Skris 18859191Skris=head1 HISTORY 18959191Skris 19059191SkrisRSA_new_method() and RSA_set_default_method() appeared in SSLeay 0.8. 19159191SkrisRSA_get_default_method(), RSA_set_method() and RSA_get_method() as 19259191Skriswell as the rsa_sign and rsa_verify components of RSA_METHOD were 19359191Skrisadded in OpenSSL 0.9.4. 19459191Skris 195109998SmarkmRSA_set_default_openssl_method() and RSA_get_default_openssl_method() 196109998Smarkmreplaced RSA_set_default_method() and RSA_get_default_method() 197109998Smarkmrespectively, and RSA_set_method() and RSA_new_method() were altered to use 198109998SmarkmB<ENGINE>s rather than B<RSA_METHOD>s during development of the engine 199109998Smarkmversion of OpenSSL 0.9.6. For 0.9.7, the handling of defaults in the ENGINE 200109998SmarkmAPI was restructured so that this change was reversed, and behaviour of the 201109998Smarkmother functions resembled more closely the previous behaviour. The 202109998Smarkmbehaviour of defaults in the ENGINE API now transparently overrides the 203109998Smarkmbehaviour of defaults in the RSA API without requiring changing these 204109998Smarkmfunction prototypes. 205109998Smarkm 20659191Skris=cut 207