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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: rsa-pub.c,v 1.2 2000/10/08 16:00:32 mdw Exp $ |
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4 | * |
5 | * [RSA encryption with padding * |
6 | * (c) 2000 Straylight/Edgeware |
7 | */ |
8 | |
9 | /*----- Licensing notice --------------------------------------------------* |
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. |
17 | * |
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. |
22 | * |
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 | |
29 | /*----- Revision history --------------------------------------------------* |
30 | * |
31 | * $Log: rsa-pub.c,v $ |
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32 | * Revision 1.2 2000/10/08 16:00:32 mdw |
33 | * Fix compiler warning. |
34 | * |
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35 | * Revision 1.1 2000/07/01 11:23:52 mdw |
36 | * Public-key operations, for symmetry with `rsa-priv.c'. Functions for |
37 | * doing padded RSA encryption and signature verification. |
38 | * |
39 | */ |
40 | |
41 | /*----- Header files ------------------------------------------------------*/ |
42 | |
43 | #include <mLib/alloc.h> |
44 | #include <mLib/bits.h> |
45 | #include <mLib/dstr.h> |
46 | |
47 | #include "mp.h" |
48 | #include "mpmont.h" |
49 | #include "rsa.h" |
50 | |
51 | /*----- Public key operations ---------------------------------------------*/ |
52 | |
53 | /* --- @rsa_pubcreate@ --- * |
54 | * |
55 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
56 | * @rsa_pub *rp@ = pointer to RSA public key |
57 | * |
58 | * Returns: --- |
59 | * |
60 | * Use: Initializes an RSA public-key context. |
61 | */ |
62 | |
63 | void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp) |
64 | { |
65 | rd->rp = rp; |
66 | mpmont_create(&rd->mm, rp->n); |
67 | } |
68 | |
69 | /* --- @rsa_pubdestroy@ --- * |
70 | * |
71 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
72 | * |
73 | * Returns: --- |
74 | * |
75 | * Use: Destroys an RSA public-key context. |
76 | */ |
77 | |
78 | void rsa_pubdestroy(rsa_pubctx *rd) |
79 | { |
80 | mpmont_destroy(&rd->mm); |
81 | } |
82 | |
83 | /* --- @rsa_pubop@ --- * |
84 | * |
85 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
86 | * @mp *d@ = destination |
87 | * @mp *p@ = input message |
88 | * |
89 | * Returns: The transformed output message. |
90 | * |
91 | * Use: Performs an RSA public key operation. |
92 | */ |
93 | |
94 | mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p) |
95 | { |
96 | return (mpmont_exp(&rd->mm, d, p, rd->rp->e)); |
97 | } |
98 | |
99 | /* --- @rsa_qpubop@ --- * |
100 | * |
101 | * Arguments: @rsa_pub *rp@ = pointer to RSA parameters |
102 | * @mp *d@ = destination |
103 | * @mp *p@ = input message |
104 | * |
105 | * Returns: Correctly transformed output message. |
106 | * |
107 | * Use: Performs an RSA public key operation. |
108 | */ |
109 | |
110 | mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c) |
111 | { |
112 | rsa_pubctx rd; |
113 | rsa_pubcreate(&rd, rp); |
114 | d = rsa_pubop(&rd, d, c); |
115 | rsa_pubdestroy(&rd); |
116 | return (d); |
117 | } |
118 | |
119 | /*----- Operations with padding -------------------------------------------*/ |
120 | |
121 | /* --- @rsa_encrypt@ --- * |
122 | * |
123 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
124 | * @const void *m@ = pointer to input message |
125 | * @size_t sz@ = size of input message |
126 | * @dstr *d@ = pointer to output string |
127 | * @rsa_encodeproc e@ = encoding procedure |
128 | * @void *earg@ = argument pointer for encoding procedure |
129 | * |
130 | * Returns: The length of the output string if successful, negative on |
131 | * failure. |
132 | * |
133 | * Use: Does RSA encryption. |
134 | */ |
135 | |
136 | int rsa_encrypt(rsa_pubctx *rp, const void *m, size_t sz, |
137 | dstr *d, rsa_encodeproc e, void *earg) |
138 | { |
139 | mp *x; |
140 | size_t n = mp_octets(rp->rp->n); |
141 | octet *p; |
142 | int rc; |
143 | |
144 | /* --- Sort out some space --- */ |
145 | |
146 | dstr_ensure(d, n); |
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147 | p = (octet *)d->buf + d->len; |
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148 | p[0] = 0; |
149 | |
150 | /* --- Do the packing --- */ |
151 | |
152 | if ((rc = e(m, sz, p, n, earg)) < 0) |
153 | return (rc); |
154 | |
155 | /* --- Do the encryption --- */ |
156 | |
157 | x = mp_loadb(MP_NEWSEC, p, n); |
158 | x = rsa_pubop(rp, x, x); |
159 | mp_storeb(x, p, n); |
160 | d->len += n; |
161 | mp_drop(x); |
162 | return (n); |
163 | } |
164 | |
165 | /* --- @rsa_verify@ --- * |
166 | * |
167 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
168 | * @const void *m@ = pointer to input message |
169 | * @size_t sz@ = size of input message |
170 | * @dstr *d@ = pointer to output string |
171 | * @rsa_decodeproc e@ = decoding procedure |
172 | * @void *earg@ = argument pointer for decoding procedure |
173 | * |
174 | * Returns: The length of the output string if successful, negative on |
175 | * failure. |
176 | * |
177 | * Use: Does RSA signature verification. |
178 | */ |
179 | |
180 | int rsa_verify(rsa_pubctx *rp, const void *m, size_t sz, |
181 | dstr *d, rsa_decodeproc e, void *earg) |
182 | { |
183 | mp *x; |
184 | size_t n = mp_octets(rp->rp->n); |
185 | octet *p; |
186 | int rc; |
187 | |
188 | /* --- Do the exponentiation --- */ |
189 | |
190 | p = x_alloc(d->a, n); |
191 | x = mp_loadb(MP_NEW, m, sz); |
192 | x = rsa_pubop(rp, x, x); |
193 | mp_storeb(x, p, n); |
194 | mp_drop(x); |
195 | |
196 | /* --- Do the decoding --- */ |
197 | |
198 | rc = e(p, n, d, earg); |
199 | x_free(d->a, p); |
200 | return (rc); |
201 | } |
202 | |
203 | /*----- That's all, folks -------------------------------------------------*/ |