d11a0bf7 |
1 | /* -*-c-*- |
2 | * |
8ef2f81d |
3 | * $Id: key-pass.c,v 1.4 2004/03/28 01:58:26 mdw Exp $ |
d11a0bf7 |
4 | * |
5 | * Encrypting keys with passphrases |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
18 | * |
19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
23 | * |
24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: key-pass.c,v $ |
8ef2f81d |
33 | * Revision 1.4 2004/03/28 01:58:26 mdw |
34 | * Ooops, fix all the bugs. |
35 | * |
59b2b448 |
36 | * Revision 1.3 2004/03/27 00:04:19 mdw |
37 | * INCOMPATIBLE CHANGE. Use proper authentication on encrypted keys. |
38 | * |
bbded534 |
39 | * Revision 1.2 2000/06/17 11:26:35 mdw |
40 | * `rand_getgood' is deprecated. |
41 | * |
d11a0bf7 |
42 | * Revision 1.1 1999/12/22 15:47:48 mdw |
43 | * Major key-management revision. |
44 | * |
45 | */ |
46 | |
47 | /*----- Header files ------------------------------------------------------*/ |
48 | |
49 | #include <mLib/dstr.h> |
50 | |
51 | #include "key.h" |
52 | #include "paranoia.h" |
53 | #include "passphrase.h" |
54 | #include "rand.h" |
55 | |
56 | #include "blowfish-cbc.h" |
57 | #include "rmd160.h" |
59b2b448 |
58 | #include "rmd160-mgf.h" |
59 | #include "rmd160-hmac.h" |
d11a0bf7 |
60 | |
61 | /*----- Main code ---------------------------------------------------------*/ |
62 | |
59b2b448 |
63 | /* --- Format --- * |
64 | * |
65 | * Choose a random 160-bit string %$R$%. Take the passphrase %$P$%, and |
66 | * the message %$m$%. Now, compute %$K_E \cat K_T = H(R \cat P)$%, |
67 | * %$y_0 = E_{K_E}(m)$% and %$\tau = T_{K_T}(y_0)$%. The ciphertext is |
68 | * %$y = N \cat \tau \cat y_0$%. |
69 | * |
70 | * This is not the original format. The original format was insecure, and |
71 | * has been replaced incompatibly. |
72 | */ |
73 | |
d11a0bf7 |
74 | /* --- @key_plock@ --- * |
75 | * |
76 | * Arguments: @const char *tag@ = tag to use for passphrase |
77 | * @key_data *k@ = source key data block |
78 | * @key_data *kt@ = target key data block |
79 | * |
80 | * Returns: Zero if successful, nonzero if there was a problem. |
81 | * |
82 | * Use: Locks a key by encrypting it with a passphrase. |
83 | */ |
84 | |
85 | int key_plock(const char *tag, key_data *k, key_data *kt) |
86 | { |
87 | dstr d = DSTR_INIT; |
59b2b448 |
88 | octet b[RMD160_HASHSZ * 2]; |
89 | octet *m; |
90 | size_t msz; |
d11a0bf7 |
91 | char buf[256]; |
92 | |
93 | /* --- Sanity check --- */ |
94 | |
95 | assert(((void)"Key data is already encrypted", |
96 | (k->e & KF_ENCMASK) != KENC_ENCRYPT)); |
97 | |
59b2b448 |
98 | /* --- Format the stuff in the buffer --- */ |
d11a0bf7 |
99 | |
59b2b448 |
100 | DENSURE(&d, RMD160_HASHSZ * 2); |
101 | rand_get(RAND_GLOBAL, d.buf, RMD160_HASHSZ); |
102 | d.len += RMD160_HASHSZ * 2; |
d11a0bf7 |
103 | key_encode(k, &d, 0); |
104 | if (k == kt) |
105 | key_destroy(k); |
59b2b448 |
106 | m = (octet *)d.buf + RMD160_HASHSZ * 2; |
107 | msz = d.len - RMD160_HASHSZ * 2; |
d11a0bf7 |
108 | |
59b2b448 |
109 | /* --- Read the passphrase --- */ |
110 | |
111 | if (passphrase_read(tag, PMODE_VERIFY, buf, sizeof(buf))) { |
112 | dstr_destroy(&d); |
113 | return (-1); |
114 | } |
115 | |
116 | /* --- Hash the passphrase to make a key --- */ |
d11a0bf7 |
117 | |
118 | { |
59b2b448 |
119 | rmd160_mgfctx r; |
120 | rmd160_mgfkeybegin(&r); |
121 | rmd160_mgfkeyadd(&r, d.buf, RMD160_HASHSZ); |
122 | rmd160_mgfkeyadd(&r, buf, strlen(buf)); |
123 | rmd160_mgfencrypt(&r, 0, b, sizeof(b)); |
124 | BURN(r); |
d11a0bf7 |
125 | BURN(buf); |
126 | } |
127 | |
59b2b448 |
128 | /* --- Encrypt the plaintext --- */ |
d11a0bf7 |
129 | |
130 | { |
131 | blowfish_cbcctx c; |
59b2b448 |
132 | blowfish_cbcinit(&c, b, RMD160_HASHSZ, 0); |
133 | blowfish_cbcencrypt(&c, m, m, msz); |
d11a0bf7 |
134 | BURN(c); |
135 | } |
136 | |
59b2b448 |
137 | /* --- MAC the ciphertext --- */ |
138 | |
139 | { |
140 | rmd160_mackey mk; |
141 | rmd160_macctx mc; |
142 | rmd160_hmacinit(&mk, b + RMD160_HASHSZ, RMD160_HASHSZ); |
143 | rmd160_macinit(&mc, &mk); |
144 | rmd160_machash(&mc, m, msz); |
145 | rmd160_macdone(&mc, d.buf + RMD160_HASHSZ); |
146 | BURN(mk); |
147 | BURN(mc); |
148 | } |
149 | |
150 | /* --- Done --- */ |
d11a0bf7 |
151 | |
59b2b448 |
152 | BURN(b); |
d11a0bf7 |
153 | key_encrypted(kt, d.buf, d.len); |
154 | dstr_destroy(&d); |
155 | return (0); |
156 | } |
157 | |
158 | /* --- @key_punlock@ --- * |
159 | * |
160 | * Arguments: @const char *tag@ = tag to use for passphrase |
161 | * @key_data *k@ = source key data block |
162 | * @key_data *kt@ = target key data block |
163 | * |
164 | * Returns: Zero if it worked, nonzero if it didn't. |
165 | * |
166 | * Use: Unlocks a passphrase-locked key. |
167 | */ |
168 | |
169 | int key_punlock(const char *tag, key_data *k, key_data *kt) |
170 | { |
59b2b448 |
171 | octet b[RMD160_HASHSZ * 2]; |
d11a0bf7 |
172 | char buf[256]; |
8ef2f81d |
173 | octet *p = 0; |
d11a0bf7 |
174 | size_t sz; |
175 | |
176 | /* --- Sanity check --- */ |
177 | |
178 | assert(((void)"Key data isn't encrypted", |
179 | (k->e & KF_ENCMASK) == KENC_ENCRYPT)); |
180 | |
8ef2f81d |
181 | /* --- Check the size --- */ |
d11a0bf7 |
182 | |
59b2b448 |
183 | if (k->u.k.sz < RMD160_HASHSZ * 2) |
8ef2f81d |
184 | return (-1); |
59b2b448 |
185 | sz = k->u.k.sz - RMD160_HASHSZ * 2; |
d11a0bf7 |
186 | |
59b2b448 |
187 | /* --- Fetch the passphrase --- */ |
d11a0bf7 |
188 | |
59b2b448 |
189 | if (passphrase_read(tag, PMODE_READ, buf, sizeof(buf))) |
190 | goto fail; |
d11a0bf7 |
191 | |
59b2b448 |
192 | /* --- Hash the passphrase to make a key --- */ |
d11a0bf7 |
193 | |
194 | { |
59b2b448 |
195 | rmd160_mgfctx r; |
196 | rmd160_mgfkeybegin(&r); |
197 | rmd160_mgfkeyadd(&r, k->u.k.k, RMD160_HASHSZ); |
198 | rmd160_mgfkeyadd(&r, buf, strlen(buf)); |
199 | rmd160_mgfencrypt(&r, 0, b, sizeof(b)); |
200 | BURN(r); |
d11a0bf7 |
201 | BURN(buf); |
202 | } |
203 | |
59b2b448 |
204 | /* --- Verify the MAC --- */ |
205 | |
206 | { |
207 | rmd160_mackey mk; |
208 | rmd160_macctx mc; |
209 | rmd160_hmacinit(&mk, b + RMD160_HASHSZ, RMD160_HASHSZ); |
210 | rmd160_macinit(&mc, &mk); |
8ef2f81d |
211 | rmd160_machash(&mc, k->u.k.k + RMD160_HASHSZ * 2, sz); |
212 | rmd160_macdone(&mc, b + RMD160_HASHSZ); |
213 | if (memcmp(b + RMD160_HASHSZ, k->u.k.k + RMD160_HASHSZ, |
214 | RMD160_HASHSZ) != 0) { |
d11a0bf7 |
215 | passphrase_cancel(tag); |
59b2b448 |
216 | goto fail; |
d11a0bf7 |
217 | } |
59b2b448 |
218 | BURN(mk); |
219 | BURN(mc); |
d11a0bf7 |
220 | } |
221 | |
8ef2f81d |
222 | /* --- Allocate a destination buffer --- */ |
223 | |
224 | p = xmalloc(sz); |
225 | |
226 | /* --- Decrypt the key data --- */ |
227 | |
228 | { |
229 | blowfish_cbcctx c; |
230 | blowfish_cbcinit(&c, b, RMD160_HASHSZ, 0); |
231 | blowfish_cbcdecrypt(&c, k->u.k.k + RMD160_HASHSZ * 2, p, sz); |
232 | BURN(c); |
233 | } |
234 | |
d11a0bf7 |
235 | /* --- Decode the key data into the destination buffer --- */ |
236 | |
237 | if (k == kt) { |
238 | key_destroy(k); |
239 | passphrase_cancel(tag); |
240 | } |
59b2b448 |
241 | if (key_decode(p, sz, kt)) |
242 | goto fail; |
d11a0bf7 |
243 | |
244 | /* --- Done --- */ |
245 | |
246 | free(p); |
247 | return (0); |
248 | |
249 | /* --- Tidy up if things went wrong --- */ |
250 | |
59b2b448 |
251 | fail: |
252 | BURN(b); |
d11a0bf7 |
253 | free(p); |
d11a0bf7 |
254 | return (-1); |
255 | } |
256 | |
257 | /*----- That's all, folks -------------------------------------------------*/ |