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395de3d1 | 1 | /* -*-c-*- |
2 | * | |
395de3d1 | 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 | { | |
791af0ba | 51 | rd->rp = rp; mp_shrink(rp->e); |
395de3d1 | 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 | { | |
791af0ba MW |
82 | mp *e = rd->rp->e; |
83 | unsigned i; | |
84 | ||
85 | if (MP_EQ(e, MP_THREE)) { | |
86 | MP_COPY(p); | |
87 | d = mpmont_mul(&rd->mm, d, p, rd->mm.r2); | |
88 | d = mp_sqr(d, d); d = mpmont_reduce(&rd->mm, d, d); | |
89 | d = mpmont_mul(&rd->mm, d, d, p); | |
90 | MP_DROP(p); | |
91 | return (d); | |
92 | } | |
93 | #if MPW_BITS > 16 | |
94 | if (MP_LEN(e) == 1 && e->v[0] == 65537) | |
95 | #else | |
96 | if (0 && MP_LEN(e) == 2 && e->v[0] == 1 && e->v[1] == (1 << (16 - MPW_BITS))) | |
97 | #endif | |
98 | { | |
99 | MP_COPY(p); | |
100 | d = mpmont_mul(&rd->mm, d, p, rd->mm.r2); | |
101 | for (i = 0; i < 16; i++) | |
102 | { d = mp_sqr(d, d); d = mpmont_reduce(&rd->mm, d, d); } | |
103 | d = mpmont_mul(&rd->mm, d, d, p); | |
104 | MP_DROP(p); | |
105 | return (d); | |
106 | } | |
395de3d1 | 107 | return (mpmont_exp(&rd->mm, d, p, rd->rp->e)); |
108 | } | |
109 | ||
110 | /* --- @rsa_qpubop@ --- * | |
111 | * | |
112 | * Arguments: @rsa_pub *rp@ = pointer to RSA parameters | |
113 | * @mp *d@ = destination | |
114 | * @mp *p@ = input message | |
115 | * | |
116 | * Returns: Correctly transformed output message. | |
117 | * | |
118 | * Use: Performs an RSA public key operation. | |
119 | */ | |
120 | ||
121 | mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c) | |
122 | { | |
123 | rsa_pubctx rd; | |
124 | rsa_pubcreate(&rd, rp); | |
125 | d = rsa_pubop(&rd, d, c); | |
126 | rsa_pubdestroy(&rd); | |
127 | return (d); | |
128 | } | |
129 | ||
130 | /*----- Operations with padding -------------------------------------------*/ | |
131 | ||
132 | /* --- @rsa_encrypt@ --- * | |
133 | * | |
134 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context | |
b817bfc6 | 135 | * @mp *d@ = proposed destination integer |
395de3d1 | 136 | * @const void *m@ = pointer to input message |
b817bfc6 | 137 | * @size_t msz@ = size of input message |
138 | * @rsa_pad *e@ = encoding procedure | |
395de3d1 | 139 | * @void *earg@ = argument pointer for encoding procedure |
140 | * | |
b817bfc6 | 141 | * Returns: The encrypted message, as a multiprecision integer, or null |
142 | * on failure. | |
395de3d1 | 143 | * |
144 | * Use: Does RSA encryption. | |
145 | */ | |
146 | ||
b817bfc6 | 147 | mp *rsa_encrypt(rsa_pubctx *rp, mp *d, const void *m, size_t msz, |
148 | rsa_pad *e, void *earg) | |
395de3d1 | 149 | { |
395de3d1 | 150 | octet *p; |
b817bfc6 | 151 | unsigned long nb = mp_bits(rp->rp->n); |
152 | size_t n = (nb + 7)/8; | |
153 | arena *a = d && d->a ? d->a->a : arena_global; | |
154 | ||
155 | p = x_alloc(a, n); | |
156 | d = e(d, m, msz, p, n, nb, earg); | |
157 | x_free(a, p); | |
158 | return (d ? rsa_pubop(rp, d, d) : 0); | |
395de3d1 | 159 | } |
160 | ||
161 | /* --- @rsa_verify@ --- * | |
162 | * | |
b817bfc6 | 163 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key contxt |
164 | * @mp *s@ = the signature, as a multiprecision integer | |
165 | * @const void *m@ = pointer to message to verify, or null | |
166 | * @size_t msz@ = size of input message | |
167 | * @dstr *d@ = pointer to output string, or null | |
168 | * @rsa_vfrunpad *e@ = decoding procedure | |
395de3d1 | 169 | * @void *earg@ = argument pointer for decoding procedure |
170 | * | |
b817bfc6 | 171 | * Returns: The length of the output string if successful (0 if no output |
172 | * was wanted); negative on failure. | |
395de3d1 | 173 | * |
b817bfc6 | 174 | * Use: Does RSA signature verification. To use a signature scheme |
175 | * with recovery, pass in @m == 0@ and @d != 0@: the recovered | |
176 | * message should appear in @d@. To use a signature scheme with | |
177 | * appendix, provide @m != 0@ and @d == 0@; the result should be | |
178 | * zero for success. | |
395de3d1 | 179 | */ |
180 | ||
b817bfc6 | 181 | int rsa_verify(rsa_pubctx *rp, mp *s, const void *m, size_t msz, |
182 | dstr *d, rsa_vrfunpad *e, void *earg) | |
395de3d1 | 183 | { |
b817bfc6 | 184 | mp *p = rsa_pubop(rp, MP_NEW, s); |
185 | unsigned long nb = mp_bits(rp->rp->n); | |
186 | size_t n = (nb + 7)/8; | |
187 | dstr dd = DSTR_INIT; | |
395de3d1 | 188 | int rc; |
189 | ||
b817bfc6 | 190 | /* --- Decoder protocol --- * |
191 | * | |
192 | * We deal with two kinds of decoders: ones with message recovery and ones | |
193 | * with appendix. A decoder with recovery will leave a message in the | |
194 | * buffer and exit nonzero: we'll check that against @m@ if provided and | |
195 | * just leave it otherwise. A decoder with appendix will inspect @m@ and | |
196 | * return zero or @-1@ itself. | |
197 | */ | |
395de3d1 | 198 | |
b817bfc6 | 199 | if (!d) d = ⅆ |
200 | dstr_ensure(d, n); | |
201 | rc = e(p, m, msz, (octet *)d->buf + d->len, n, nb, earg); | |
202 | if (rc > 0 && m) { | |
203 | if (rc != msz || memcmp(d->buf + d->len, m, msz) != 0) | |
204 | rc = -1; | |
205 | else | |
206 | rc = 0; | |
207 | } | |
208 | if (rc > 0) | |
209 | d->len += rc; | |
210 | mp_drop(p); | |
211 | dstr_destroy(&dd); | |
395de3d1 | 212 | return (rc); |
213 | } | |
214 | ||
215 | /*----- That's all, folks -------------------------------------------------*/ |