395de3d1 |
1 | /* -*-c-*- |
395de3d1 |
2 | * |
3 | * [RSA encryption with padding * |
4 | * (c) 2000 Straylight/Edgeware |
5 | */ |
6 | |
45c0fd36 |
7 | /*----- Licensing notice --------------------------------------------------* |
395de3d1 |
8 | * |
9 | * This file is part of Catacomb. |
10 | * |
11 | * Catacomb is free software; you can redistribute it and/or modify |
12 | * it under the terms of the GNU Library General Public License as |
13 | * published by the Free Software Foundation; either version 2 of the |
14 | * License, or (at your option) any later version. |
45c0fd36 |
15 | * |
395de3d1 |
16 | * Catacomb is distributed in the hope that it will be useful, |
17 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
18 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
19 | * GNU Library General Public License for more details. |
45c0fd36 |
20 | * |
395de3d1 |
21 | * You should have received a copy of the GNU Library General Public |
22 | * License along with Catacomb; if not, write to the Free |
23 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
24 | * MA 02111-1307, USA. |
25 | */ |
26 | |
395de3d1 |
27 | /*----- Header files ------------------------------------------------------*/ |
28 | |
29 | #include <mLib/alloc.h> |
30 | #include <mLib/bits.h> |
31 | #include <mLib/dstr.h> |
32 | |
33 | #include "mp.h" |
34 | #include "mpmont.h" |
35 | #include "rsa.h" |
36 | |
37 | /*----- Public key operations ---------------------------------------------*/ |
38 | |
39 | /* --- @rsa_pubcreate@ --- * |
40 | * |
41 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
42 | * @rsa_pub *rp@ = pointer to RSA public key |
43 | * |
44 | * Returns: --- |
45 | * |
46 | * Use: Initializes an RSA public-key context. |
47 | */ |
48 | |
49 | void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp) |
50 | { |
51 | rd->rp = rp; |
52 | mpmont_create(&rd->mm, rp->n); |
53 | } |
54 | |
55 | /* --- @rsa_pubdestroy@ --- * |
56 | * |
57 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
58 | * |
59 | * Returns: --- |
60 | * |
61 | * Use: Destroys an RSA public-key context. |
62 | */ |
63 | |
64 | void rsa_pubdestroy(rsa_pubctx *rd) |
65 | { |
66 | mpmont_destroy(&rd->mm); |
67 | } |
68 | |
69 | /* --- @rsa_pubop@ --- * |
70 | * |
71 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
72 | * @mp *d@ = destination |
73 | * @mp *p@ = input message |
74 | * |
75 | * Returns: The transformed output message. |
76 | * |
77 | * Use: Performs an RSA public key operation. |
78 | */ |
79 | |
80 | mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p) |
81 | { |
82 | return (mpmont_exp(&rd->mm, d, p, rd->rp->e)); |
83 | } |
84 | |
85 | /* --- @rsa_qpubop@ --- * |
86 | * |
87 | * Arguments: @rsa_pub *rp@ = pointer to RSA parameters |
88 | * @mp *d@ = destination |
89 | * @mp *p@ = input message |
90 | * |
91 | * Returns: Correctly transformed output message. |
92 | * |
93 | * Use: Performs an RSA public key operation. |
94 | */ |
95 | |
96 | mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c) |
97 | { |
98 | rsa_pubctx rd; |
99 | rsa_pubcreate(&rd, rp); |
100 | d = rsa_pubop(&rd, d, c); |
101 | rsa_pubdestroy(&rd); |
102 | return (d); |
103 | } |
104 | |
105 | /*----- Operations with padding -------------------------------------------*/ |
106 | |
107 | /* --- @rsa_encrypt@ --- * |
108 | * |
109 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
b817bfc6 |
110 | * @mp *d@ = proposed destination integer |
395de3d1 |
111 | * @const void *m@ = pointer to input message |
b817bfc6 |
112 | * @size_t msz@ = size of input message |
113 | * @rsa_pad *e@ = encoding procedure |
395de3d1 |
114 | * @void *earg@ = argument pointer for encoding procedure |
115 | * |
b817bfc6 |
116 | * Returns: The encrypted message, as a multiprecision integer, or null |
117 | * on failure. |
395de3d1 |
118 | * |
119 | * Use: Does RSA encryption. |
120 | */ |
121 | |
b817bfc6 |
122 | mp *rsa_encrypt(rsa_pubctx *rp, mp *d, const void *m, size_t msz, |
123 | rsa_pad *e, void *earg) |
395de3d1 |
124 | { |
395de3d1 |
125 | octet *p; |
b817bfc6 |
126 | unsigned long nb = mp_bits(rp->rp->n); |
127 | size_t n = (nb + 7)/8; |
128 | arena *a = d && d->a ? d->a->a : arena_global; |
129 | |
130 | p = x_alloc(a, n); |
131 | d = e(d, m, msz, p, n, nb, earg); |
132 | x_free(a, p); |
133 | return (d ? rsa_pubop(rp, d, d) : 0); |
395de3d1 |
134 | } |
135 | |
136 | /* --- @rsa_verify@ --- * |
137 | * |
b817bfc6 |
138 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key contxt |
139 | * @mp *s@ = the signature, as a multiprecision integer |
140 | * @const void *m@ = pointer to message to verify, or null |
141 | * @size_t msz@ = size of input message |
142 | * @dstr *d@ = pointer to output string, or null |
143 | * @rsa_vfrunpad *e@ = decoding procedure |
395de3d1 |
144 | * @void *earg@ = argument pointer for decoding procedure |
145 | * |
b817bfc6 |
146 | * Returns: The length of the output string if successful (0 if no output |
147 | * was wanted); negative on failure. |
395de3d1 |
148 | * |
b817bfc6 |
149 | * Use: Does RSA signature verification. To use a signature scheme |
150 | * with recovery, pass in @m == 0@ and @d != 0@: the recovered |
151 | * message should appear in @d@. To use a signature scheme with |
152 | * appendix, provide @m != 0@ and @d == 0@; the result should be |
153 | * zero for success. |
395de3d1 |
154 | */ |
155 | |
b817bfc6 |
156 | int rsa_verify(rsa_pubctx *rp, mp *s, const void *m, size_t msz, |
157 | dstr *d, rsa_vrfunpad *e, void *earg) |
395de3d1 |
158 | { |
b817bfc6 |
159 | mp *p = rsa_pubop(rp, MP_NEW, s); |
160 | unsigned long nb = mp_bits(rp->rp->n); |
161 | size_t n = (nb + 7)/8; |
162 | dstr dd = DSTR_INIT; |
395de3d1 |
163 | int rc; |
164 | |
b817bfc6 |
165 | /* --- Decoder protocol --- * |
166 | * |
167 | * We deal with two kinds of decoders: ones with message recovery and ones |
168 | * with appendix. A decoder with recovery will leave a message in the |
169 | * buffer and exit nonzero: we'll check that against @m@ if provided and |
170 | * just leave it otherwise. A decoder with appendix will inspect @m@ and |
171 | * return zero or @-1@ itself. |
172 | */ |
395de3d1 |
173 | |
b817bfc6 |
174 | if (!d) d = ⅆ |
175 | dstr_ensure(d, n); |
176 | rc = e(p, m, msz, (octet *)d->buf + d->len, n, nb, earg); |
177 | if (rc > 0 && m) { |
178 | if (rc != msz || memcmp(d->buf + d->len, m, msz) != 0) |
179 | rc = -1; |
180 | else |
181 | rc = 0; |
182 | } |
183 | if (rc > 0) |
184 | d->len += rc; |
185 | mp_drop(p); |
186 | dstr_destroy(&dd); |
395de3d1 |
187 | return (rc); |
188 | } |
189 | |
190 | /*----- That's all, folks -------------------------------------------------*/ |