1=pod 2 3=head1 NAME 4 5RSA_set_default_method, RSA_get_default_method, RSA_set_method, 6RSA_get_method, RSA_PKCS1_OpenSSL, 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_OpenSSL(void); 22 23 int RSA_flags(const RSA *rsa); 24 25 RSA *RSA_new_method(ENGINE *engine); 26 27=head1 DESCRIPTION 28 29An B<RSA_METHOD> specifies the functions that OpenSSL uses for RSA 30operations. By modifying the method, alternative implementations such as 31hardware accelerators may be used. IMPORTANT: See the NOTES section for 32important information about how these RSA API functions are affected by the 33use of B<ENGINE> API calls. 34 35Initially, the default RSA_METHOD is the OpenSSL internal implementation, 36as returned by RSA_PKCS1_OpenSSL(). 37 38RSA_set_default_method() makes B<meth> the default method for all RSA 39structures created later. 40B<NB>: This is true only whilst no ENGINE has 41been set as a default for RSA, so this function is no longer recommended. 42This function is not thread-safe and should not be called at the same time 43as other OpenSSL functions. 44 45RSA_get_default_method() returns a pointer to the current default 46RSA_METHOD. However, the meaningfulness of this result is dependent on 47whether the ENGINE API is being used, so this function is no longer 48recommended. 49 50RSA_set_method() selects B<meth> to perform all operations using the key 51B<rsa>. This will replace the RSA_METHOD used by the RSA key and if the 52previous method was supplied by an ENGINE, the handle to that ENGINE will 53be released during the change. It is possible to have RSA keys that only 54work with certain RSA_METHOD implementations (eg. from an ENGINE module 55that supports embedded hardware-protected keys), and in such cases 56attempting to change the RSA_METHOD for the key can have unexpected 57results. 58 59RSA_get_method() returns a pointer to the RSA_METHOD being used by B<rsa>. 60This method may or may not be supplied by an ENGINE implementation, but if 61it is, the return value can only be guaranteed to be valid as long as the 62RSA key itself is valid and does not have its implementation changed by 63RSA_set_method(). 64 65RSA_flags() returns the B<flags> that are set for B<rsa>'s current 66RSA_METHOD. See the BUGS section. 67 68RSA_new_method() allocates and initializes an RSA structure so that 69B<engine> will be used for the RSA operations. If B<engine> is NULL, the 70default ENGINE for RSA operations is used, and if no default ENGINE is set, 71the RSA_METHOD controlled by RSA_set_default_method() is used. 72 73RSA_flags() returns the B<flags> that are set for B<rsa>'s current method. 74 75RSA_new_method() allocates and initializes an B<RSA> structure so that 76B<method> will be used for the RSA operations. If B<method> is B<NULL>, 77the default method is used. 78 79=head1 THE RSA_METHOD STRUCTURE 80 81 typedef struct rsa_meth_st 82 { 83 /* name of the implementation */ 84 const char *name; 85 86 /* encrypt */ 87 int (*rsa_pub_enc)(int flen, unsigned char *from, 88 unsigned char *to, RSA *rsa, int padding); 89 90 /* verify arbitrary data */ 91 int (*rsa_pub_dec)(int flen, unsigned char *from, 92 unsigned char *to, RSA *rsa, int padding); 93 94 /* sign arbitrary data */ 95 int (*rsa_priv_enc)(int flen, unsigned char *from, 96 unsigned char *to, RSA *rsa, int padding); 97 98 /* decrypt */ 99 int (*rsa_priv_dec)(int flen, unsigned char *from, 100 unsigned char *to, RSA *rsa, int padding); 101 102 /* compute r0 = r0 ^ I mod rsa->n (May be NULL for some 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 /* 116 * RSA_FLAG_EXT_PKEY - rsa_mod_exp is called for private key 117 * operations, even if p,q,dmp1,dmq1,iqmp 118 * are NULL 119 * RSA_METHOD_FLAG_NO_CHECK - don't check pub/private match 120 */ 121 int flags; 122 123 char *app_data; /* ?? */ 124 125 int (*rsa_sign)(int type, 126 const unsigned char *m, unsigned int m_length, 127 unsigned char *sigret, unsigned int *siglen, const RSA *rsa); 128 int (*rsa_verify)(int dtype, 129 const unsigned char *m, unsigned int m_length, 130 const unsigned char *sigbuf, unsigned int siglen, 131 const RSA *rsa); 132 /* keygen. If NULL builtin RSA key generation will be used */ 133 int (*rsa_keygen)(RSA *rsa, int bits, BIGNUM *e, BN_GENCB *cb); 134 135 } RSA_METHOD; 136 137=head1 RETURN VALUES 138 139RSA_PKCS1_OpenSSL(), RSA_PKCS1_null_method(), RSA_get_default_method() 140and RSA_get_method() return pointers to the respective RSA_METHODs. 141 142RSA_set_default_method() returns no value. 143 144RSA_set_method() returns a pointer to the old RSA_METHOD implementation 145that was replaced. However, this return value should probably be ignored 146because if it was supplied by an ENGINE, the pointer could be invalidated 147at any time if the ENGINE is unloaded (in fact it could be unloaded as a 148result of the RSA_set_method() function releasing its handle to the 149ENGINE). For this reason, the return type may be replaced with a B<void> 150declaration in a future release. 151 152RSA_new_method() returns NULL and sets an error code that can be obtained 153by L<ERR_get_error(3)> if the allocation fails. Otherwise 154it returns a pointer to the newly allocated structure. 155 156=head1 BUGS 157 158The behaviour of RSA_flags() is a mis-feature that is left as-is for now 159to avoid creating compatibility problems. RSA functionality, such as the 160encryption functions, are controlled by the B<flags> value in the RSA key 161itself, not by the B<flags> value in the RSA_METHOD attached to the RSA key 162(which is what this function returns). If the flags element of an RSA key 163is changed, the changes will be honoured by RSA functionality but will not 164be reflected in the return value of the RSA_flags() function - in effect 165RSA_flags() behaves more like an RSA_default_flags() function (which does 166not currently exist). 167 168=head1 SEE ALSO 169 170L<RSA_new(3)> 171 172=head1 HISTORY 173 174The RSA_null_method(), which was a partial attempt to avoid patent issues, 175was replaced to always return NULL in OpenSSL 1.1.1. 176 177=head1 COPYRIGHT 178 179Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved. 180 181Licensed under the OpenSSL license (the "License"). You may not use 182this file except in compliance with the License. You can obtain a copy 183in the file LICENSE in the source distribution or at 184L<https://www.openssl.org/source/license.html>. 185 186=cut 187