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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rsa-pub.c,v 1.3 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * [RSA encryption with padding * |
6 | * (c) 2000 Straylight/Edgeware |
7 | */ |
8 | |
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9 | /*----- Licensing notice --------------------------------------------------* |
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10 | * |
11 | * This file is part of Catacomb. |
12 | * |
13 | * Catacomb is free software; you can redistribute it and/or modify |
14 | * it under the terms of the GNU Library General Public License as |
15 | * published by the Free Software Foundation; either version 2 of the |
16 | * License, or (at your option) any later version. |
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17 | * |
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18 | * Catacomb is distributed in the hope that it will be useful, |
19 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
20 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
21 | * GNU Library General Public License for more details. |
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22 | * |
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23 | * You should have received a copy of the GNU Library General Public |
24 | * License along with Catacomb; if not, write to the Free |
25 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
26 | * MA 02111-1307, USA. |
27 | */ |
28 | |
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29 | /*----- Header files ------------------------------------------------------*/ |
30 | |
31 | #include <mLib/alloc.h> |
32 | #include <mLib/bits.h> |
33 | #include <mLib/dstr.h> |
34 | |
35 | #include "mp.h" |
36 | #include "mpmont.h" |
37 | #include "rsa.h" |
38 | |
39 | /*----- Public key operations ---------------------------------------------*/ |
40 | |
41 | /* --- @rsa_pubcreate@ --- * |
42 | * |
43 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
44 | * @rsa_pub *rp@ = pointer to RSA public key |
45 | * |
46 | * Returns: --- |
47 | * |
48 | * Use: Initializes an RSA public-key context. |
49 | */ |
50 | |
51 | void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp) |
52 | { |
53 | rd->rp = rp; |
54 | mpmont_create(&rd->mm, rp->n); |
55 | } |
56 | |
57 | /* --- @rsa_pubdestroy@ --- * |
58 | * |
59 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
60 | * |
61 | * Returns: --- |
62 | * |
63 | * Use: Destroys an RSA public-key context. |
64 | */ |
65 | |
66 | void rsa_pubdestroy(rsa_pubctx *rd) |
67 | { |
68 | mpmont_destroy(&rd->mm); |
69 | } |
70 | |
71 | /* --- @rsa_pubop@ --- * |
72 | * |
73 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
74 | * @mp *d@ = destination |
75 | * @mp *p@ = input message |
76 | * |
77 | * Returns: The transformed output message. |
78 | * |
79 | * Use: Performs an RSA public key operation. |
80 | */ |
81 | |
82 | mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p) |
83 | { |
84 | return (mpmont_exp(&rd->mm, d, p, rd->rp->e)); |
85 | } |
86 | |
87 | /* --- @rsa_qpubop@ --- * |
88 | * |
89 | * Arguments: @rsa_pub *rp@ = pointer to RSA parameters |
90 | * @mp *d@ = destination |
91 | * @mp *p@ = input message |
92 | * |
93 | * Returns: Correctly transformed output message. |
94 | * |
95 | * Use: Performs an RSA public key operation. |
96 | */ |
97 | |
98 | mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c) |
99 | { |
100 | rsa_pubctx rd; |
101 | rsa_pubcreate(&rd, rp); |
102 | d = rsa_pubop(&rd, d, c); |
103 | rsa_pubdestroy(&rd); |
104 | return (d); |
105 | } |
106 | |
107 | /*----- Operations with padding -------------------------------------------*/ |
108 | |
109 | /* --- @rsa_encrypt@ --- * |
110 | * |
111 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
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112 | * @mp *d@ = proposed destination integer |
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113 | * @const void *m@ = pointer to input message |
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114 | * @size_t msz@ = size of input message |
115 | * @rsa_pad *e@ = encoding procedure |
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116 | * @void *earg@ = argument pointer for encoding procedure |
117 | * |
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118 | * Returns: The encrypted message, as a multiprecision integer, or null |
119 | * on failure. |
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120 | * |
121 | * Use: Does RSA encryption. |
122 | */ |
123 | |
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124 | mp *rsa_encrypt(rsa_pubctx *rp, mp *d, const void *m, size_t msz, |
125 | rsa_pad *e, void *earg) |
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126 | { |
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127 | octet *p; |
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128 | unsigned long nb = mp_bits(rp->rp->n); |
129 | size_t n = (nb + 7)/8; |
130 | arena *a = d && d->a ? d->a->a : arena_global; |
131 | |
132 | p = x_alloc(a, n); |
133 | d = e(d, m, msz, p, n, nb, earg); |
134 | x_free(a, p); |
135 | return (d ? rsa_pubop(rp, d, d) : 0); |
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136 | } |
137 | |
138 | /* --- @rsa_verify@ --- * |
139 | * |
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140 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key contxt |
141 | * @mp *s@ = the signature, as a multiprecision integer |
142 | * @const void *m@ = pointer to message to verify, or null |
143 | * @size_t msz@ = size of input message |
144 | * @dstr *d@ = pointer to output string, or null |
145 | * @rsa_vfrunpad *e@ = decoding procedure |
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146 | * @void *earg@ = argument pointer for decoding procedure |
147 | * |
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148 | * Returns: The length of the output string if successful (0 if no output |
149 | * was wanted); negative on failure. |
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150 | * |
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151 | * Use: Does RSA signature verification. To use a signature scheme |
152 | * with recovery, pass in @m == 0@ and @d != 0@: the recovered |
153 | * message should appear in @d@. To use a signature scheme with |
154 | * appendix, provide @m != 0@ and @d == 0@; the result should be |
155 | * zero for success. |
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156 | */ |
157 | |
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158 | int rsa_verify(rsa_pubctx *rp, mp *s, const void *m, size_t msz, |
159 | dstr *d, rsa_vrfunpad *e, void *earg) |
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160 | { |
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161 | mp *p = rsa_pubop(rp, MP_NEW, s); |
162 | unsigned long nb = mp_bits(rp->rp->n); |
163 | size_t n = (nb + 7)/8; |
164 | dstr dd = DSTR_INIT; |
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165 | int rc; |
166 | |
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167 | /* --- Decoder protocol --- * |
168 | * |
169 | * We deal with two kinds of decoders: ones with message recovery and ones |
170 | * with appendix. A decoder with recovery will leave a message in the |
171 | * buffer and exit nonzero: we'll check that against @m@ if provided and |
172 | * just leave it otherwise. A decoder with appendix will inspect @m@ and |
173 | * return zero or @-1@ itself. |
174 | */ |
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175 | |
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176 | if (!d) d = ⅆ |
177 | dstr_ensure(d, n); |
178 | rc = e(p, m, msz, (octet *)d->buf + d->len, n, nb, earg); |
179 | if (rc > 0 && m) { |
180 | if (rc != msz || memcmp(d->buf + d->len, m, msz) != 0) |
181 | rc = -1; |
182 | else |
183 | rc = 0; |
184 | } |
185 | if (rc > 0) |
186 | d->len += rc; |
187 | mp_drop(p); |
188 | dstr_destroy(&dd); |
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189 | return (rc); |
190 | } |
191 | |
192 | /*----- That's all, folks -------------------------------------------------*/ |