395de3d1 |
1 | /* -*-c-*- |
2 | * |
3 | * $Id: rsa-pub.c,v 1.1 2000/07/01 11:23:52 mdw Exp $ |
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 $ |
32 | * Revision 1.1 2000/07/01 11:23:52 mdw |
33 | * Public-key operations, for symmetry with `rsa-priv.c'. Functions for |
34 | * doing padded RSA encryption and signature verification. |
35 | * |
36 | */ |
37 | |
38 | /*----- Header files ------------------------------------------------------*/ |
39 | |
40 | #include <mLib/alloc.h> |
41 | #include <mLib/bits.h> |
42 | #include <mLib/dstr.h> |
43 | |
44 | #include "mp.h" |
45 | #include "mpmont.h" |
46 | #include "rsa.h" |
47 | |
48 | /*----- Public key operations ---------------------------------------------*/ |
49 | |
50 | /* --- @rsa_pubcreate@ --- * |
51 | * |
52 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
53 | * @rsa_pub *rp@ = pointer to RSA public key |
54 | * |
55 | * Returns: --- |
56 | * |
57 | * Use: Initializes an RSA public-key context. |
58 | */ |
59 | |
60 | void rsa_pubcreate(rsa_pubctx *rd, rsa_pub *rp) |
61 | { |
62 | rd->rp = rp; |
63 | mpmont_create(&rd->mm, rp->n); |
64 | } |
65 | |
66 | /* --- @rsa_pubdestroy@ --- * |
67 | * |
68 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
69 | * |
70 | * Returns: --- |
71 | * |
72 | * Use: Destroys an RSA public-key context. |
73 | */ |
74 | |
75 | void rsa_pubdestroy(rsa_pubctx *rd) |
76 | { |
77 | mpmont_destroy(&rd->mm); |
78 | } |
79 | |
80 | /* --- @rsa_pubop@ --- * |
81 | * |
82 | * Arguments: @rsa_pubctx *rd@ = pointer to an RSA public key context |
83 | * @mp *d@ = destination |
84 | * @mp *p@ = input message |
85 | * |
86 | * Returns: The transformed output message. |
87 | * |
88 | * Use: Performs an RSA public key operation. |
89 | */ |
90 | |
91 | mp *rsa_pubop(rsa_pubctx *rd, mp *d, mp *p) |
92 | { |
93 | return (mpmont_exp(&rd->mm, d, p, rd->rp->e)); |
94 | } |
95 | |
96 | /* --- @rsa_qpubop@ --- * |
97 | * |
98 | * Arguments: @rsa_pub *rp@ = pointer to RSA parameters |
99 | * @mp *d@ = destination |
100 | * @mp *p@ = input message |
101 | * |
102 | * Returns: Correctly transformed output message. |
103 | * |
104 | * Use: Performs an RSA public key operation. |
105 | */ |
106 | |
107 | mp *rsa_qpubop(rsa_pub *rp, mp *d, mp *c) |
108 | { |
109 | rsa_pubctx rd; |
110 | rsa_pubcreate(&rd, rp); |
111 | d = rsa_pubop(&rd, d, c); |
112 | rsa_pubdestroy(&rd); |
113 | return (d); |
114 | } |
115 | |
116 | /*----- Operations with padding -------------------------------------------*/ |
117 | |
118 | /* --- @rsa_encrypt@ --- * |
119 | * |
120 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
121 | * @const void *m@ = pointer to input message |
122 | * @size_t sz@ = size of input message |
123 | * @dstr *d@ = pointer to output string |
124 | * @rsa_encodeproc e@ = encoding procedure |
125 | * @void *earg@ = argument pointer for encoding procedure |
126 | * |
127 | * Returns: The length of the output string if successful, negative on |
128 | * failure. |
129 | * |
130 | * Use: Does RSA encryption. |
131 | */ |
132 | |
133 | int rsa_encrypt(rsa_pubctx *rp, const void *m, size_t sz, |
134 | dstr *d, rsa_encodeproc e, void *earg) |
135 | { |
136 | mp *x; |
137 | size_t n = mp_octets(rp->rp->n); |
138 | octet *p; |
139 | int rc; |
140 | |
141 | /* --- Sort out some space --- */ |
142 | |
143 | dstr_ensure(d, n); |
144 | p = d->buf + d->len; |
145 | p[0] = 0; |
146 | |
147 | /* --- Do the packing --- */ |
148 | |
149 | if ((rc = e(m, sz, p, n, earg)) < 0) |
150 | return (rc); |
151 | |
152 | /* --- Do the encryption --- */ |
153 | |
154 | x = mp_loadb(MP_NEWSEC, p, n); |
155 | x = rsa_pubop(rp, x, x); |
156 | mp_storeb(x, p, n); |
157 | d->len += n; |
158 | mp_drop(x); |
159 | return (n); |
160 | } |
161 | |
162 | /* --- @rsa_verify@ --- * |
163 | * |
164 | * Arguments: @rsa_pubctx *rp@ = pointer to an RSA public key context |
165 | * @const void *m@ = pointer to input message |
166 | * @size_t sz@ = size of input message |
167 | * @dstr *d@ = pointer to output string |
168 | * @rsa_decodeproc e@ = decoding procedure |
169 | * @void *earg@ = argument pointer for decoding procedure |
170 | * |
171 | * Returns: The length of the output string if successful, negative on |
172 | * failure. |
173 | * |
174 | * Use: Does RSA signature verification. |
175 | */ |
176 | |
177 | int rsa_verify(rsa_pubctx *rp, const void *m, size_t sz, |
178 | dstr *d, rsa_decodeproc e, void *earg) |
179 | { |
180 | mp *x; |
181 | size_t n = mp_octets(rp->rp->n); |
182 | octet *p; |
183 | int rc; |
184 | |
185 | /* --- Do the exponentiation --- */ |
186 | |
187 | p = x_alloc(d->a, n); |
188 | x = mp_loadb(MP_NEW, m, sz); |
189 | x = rsa_pubop(rp, x, x); |
190 | mp_storeb(x, p, n); |
191 | mp_drop(x); |
192 | |
193 | /* --- Do the decoding --- */ |
194 | |
195 | rc = e(p, n, d, earg); |
196 | x_free(d->a, p); |
197 | return (rc); |
198 | } |
199 | |
200 | /*----- That's all, folks -------------------------------------------------*/ |