xref: /openssl/crypto/rsa/rsa_crpt.c (revision e077455e)
1 /*
2  * Copyright 1995-2020 The OpenSSL Project Authors. All Rights Reserved.
3  *
4  * Licensed under the Apache License 2.0 (the "License").  You may not use
5  * this file except in compliance with the License.  You can obtain a copy
6  * in the file LICENSE in the source distribution or at
7  * https://www.openssl.org/source/license.html
8  */
9 
10 /*
11  * RSA low level APIs are deprecated for public use, but still ok for
12  * internal use.
13  */
14 #include "internal/deprecated.h"
15 
16 #include <stdio.h>
17 #include <openssl/crypto.h>
18 #include "internal/cryptlib.h"
19 #include "crypto/bn.h"
20 #include <openssl/rand.h>
21 #include "rsa_local.h"
22 
RSA_bits(const RSA * r)23 int RSA_bits(const RSA *r)
24 {
25     return BN_num_bits(r->n);
26 }
27 
RSA_size(const RSA * r)28 int RSA_size(const RSA *r)
29 {
30     return BN_num_bytes(r->n);
31 }
32 
RSA_public_encrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)33 int RSA_public_encrypt(int flen, const unsigned char *from, unsigned char *to,
34                        RSA *rsa, int padding)
35 {
36     return rsa->meth->rsa_pub_enc(flen, from, to, rsa, padding);
37 }
38 
RSA_private_encrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)39 int RSA_private_encrypt(int flen, const unsigned char *from,
40                         unsigned char *to, RSA *rsa, int padding)
41 {
42     return rsa->meth->rsa_priv_enc(flen, from, to, rsa, padding);
43 }
44 
RSA_private_decrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)45 int RSA_private_decrypt(int flen, const unsigned char *from,
46                         unsigned char *to, RSA *rsa, int padding)
47 {
48     return rsa->meth->rsa_priv_dec(flen, from, to, rsa, padding);
49 }
50 
RSA_public_decrypt(int flen,const unsigned char * from,unsigned char * to,RSA * rsa,int padding)51 int RSA_public_decrypt(int flen, const unsigned char *from, unsigned char *to,
52                        RSA *rsa, int padding)
53 {
54     return rsa->meth->rsa_pub_dec(flen, from, to, rsa, padding);
55 }
56 
RSA_flags(const RSA * r)57 int RSA_flags(const RSA *r)
58 {
59     return r == NULL ? 0 : r->meth->flags;
60 }
61 
RSA_blinding_off(RSA * rsa)62 void RSA_blinding_off(RSA *rsa)
63 {
64     BN_BLINDING_free(rsa->blinding);
65     rsa->blinding = NULL;
66     rsa->flags &= ~RSA_FLAG_BLINDING;
67     rsa->flags |= RSA_FLAG_NO_BLINDING;
68 }
69 
RSA_blinding_on(RSA * rsa,BN_CTX * ctx)70 int RSA_blinding_on(RSA *rsa, BN_CTX *ctx)
71 {
72     int ret = 0;
73 
74     if (rsa->blinding != NULL)
75         RSA_blinding_off(rsa);
76 
77     rsa->blinding = RSA_setup_blinding(rsa, ctx);
78     if (rsa->blinding == NULL)
79         goto err;
80 
81     rsa->flags |= RSA_FLAG_BLINDING;
82     rsa->flags &= ~RSA_FLAG_NO_BLINDING;
83     ret = 1;
84  err:
85     return ret;
86 }
87 
rsa_get_public_exp(const BIGNUM * d,const BIGNUM * p,const BIGNUM * q,BN_CTX * ctx)88 static BIGNUM *rsa_get_public_exp(const BIGNUM *d, const BIGNUM *p,
89                                   const BIGNUM *q, BN_CTX *ctx)
90 {
91     BIGNUM *ret = NULL, *r0, *r1, *r2;
92 
93     if (d == NULL || p == NULL || q == NULL)
94         return NULL;
95 
96     BN_CTX_start(ctx);
97     r0 = BN_CTX_get(ctx);
98     r1 = BN_CTX_get(ctx);
99     r2 = BN_CTX_get(ctx);
100     if (r2 == NULL)
101         goto err;
102 
103     if (!BN_sub(r1, p, BN_value_one()))
104         goto err;
105     if (!BN_sub(r2, q, BN_value_one()))
106         goto err;
107     if (!BN_mul(r0, r1, r2, ctx))
108         goto err;
109 
110     ret = BN_mod_inverse(NULL, d, r0, ctx);
111  err:
112     BN_CTX_end(ctx);
113     return ret;
114 }
115 
RSA_setup_blinding(RSA * rsa,BN_CTX * in_ctx)116 BN_BLINDING *RSA_setup_blinding(RSA *rsa, BN_CTX *in_ctx)
117 {
118     BIGNUM *e;
119     BN_CTX *ctx;
120     BN_BLINDING *ret = NULL;
121 
122     if (in_ctx == NULL) {
123         if ((ctx = BN_CTX_new_ex(rsa->libctx)) == NULL)
124             return 0;
125     } else {
126         ctx = in_ctx;
127     }
128 
129     BN_CTX_start(ctx);
130     e = BN_CTX_get(ctx);
131     if (e == NULL) {
132         ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
133         goto err;
134     }
135 
136     if (rsa->e == NULL) {
137         e = rsa_get_public_exp(rsa->d, rsa->p, rsa->q, ctx);
138         if (e == NULL) {
139             ERR_raise(ERR_LIB_RSA, RSA_R_NO_PUBLIC_EXPONENT);
140             goto err;
141         }
142     } else {
143         e = rsa->e;
144     }
145 
146     {
147         BIGNUM *n = BN_new();
148 
149         if (n == NULL) {
150             ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
151             goto err;
152         }
153         BN_with_flags(n, rsa->n, BN_FLG_CONSTTIME);
154 
155         ret = BN_BLINDING_create_param(NULL, e, n, ctx, rsa->meth->bn_mod_exp,
156                                        rsa->_method_mod_n);
157         /* We MUST free n before any further use of rsa->n */
158         BN_free(n);
159     }
160     if (ret == NULL) {
161         ERR_raise(ERR_LIB_RSA, ERR_R_BN_LIB);
162         goto err;
163     }
164 
165     BN_BLINDING_set_current_thread(ret);
166 
167  err:
168     BN_CTX_end(ctx);
169     if (ctx != in_ctx)
170         BN_CTX_free(ctx);
171     if (e != rsa->e)
172         BN_free(e);
173 
174     return ret;
175 }
176