d11a0bf7 |
1 | /* -*-c-*- |
2 | * |
12ed8a1f |
3 | * $Id$ |
d11a0bf7 |
4 | * |
5 | * Encrypting keys with passphrases |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
45c0fd36 |
10 | /*----- Licensing notice --------------------------------------------------* |
d11a0bf7 |
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. |
45c0fd36 |
18 | * |
d11a0bf7 |
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. |
45c0fd36 |
23 | * |
d11a0bf7 |
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 | |
d11a0bf7 |
30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <mLib/dstr.h> |
33 | |
34 | #include "key.h" |
35 | #include "paranoia.h" |
36 | #include "passphrase.h" |
37 | #include "rand.h" |
38 | |
39 | #include "blowfish-cbc.h" |
40 | #include "rmd160.h" |
59b2b448 |
41 | #include "rmd160-mgf.h" |
42 | #include "rmd160-hmac.h" |
d11a0bf7 |
43 | |
44 | /*----- Main code ---------------------------------------------------------*/ |
45 | |
59b2b448 |
46 | /* --- Format --- * |
47 | * |
48 | * Choose a random 160-bit string %$R$%. Take the passphrase %$P$%, and |
49 | * the message %$m$%. Now, compute %$K_E \cat K_T = H(R \cat P)$%, |
50 | * %$y_0 = E_{K_E}(m)$% and %$\tau = T_{K_T}(y_0)$%. The ciphertext is |
51 | * %$y = N \cat \tau \cat y_0$%. |
52 | * |
53 | * This is not the original format. The original format was insecure, and |
54 | * has been replaced incompatibly. |
55 | */ |
56 | |
1dda051b |
57 | /* --- @key_lock@ --- * |
d11a0bf7 |
58 | * |
ef13e9a4 |
59 | * Arguments: @key_data **kt@ = where to store the destination pointer |
60 | * @key_data *k@ = source key data block or null to use @*kt@ |
1dda051b |
61 | * @const void *e@ = secret to encrypt key with |
62 | * @size_t esz@ = size of the secret |
d11a0bf7 |
63 | * |
1dda051b |
64 | * Returns: --- |
d11a0bf7 |
65 | * |
1dda051b |
66 | * Use: Encrypts a key data block using a secret. |
d11a0bf7 |
67 | */ |
68 | |
ef13e9a4 |
69 | void key_lock(key_data **kt, key_data *k, const void *e, size_t esz) |
d11a0bf7 |
70 | { |
71 | dstr d = DSTR_INIT; |
59b2b448 |
72 | octet b[RMD160_HASHSZ * 2]; |
73 | octet *m; |
74 | size_t msz; |
1dda051b |
75 | rmd160_mgfctx r; |
76 | blowfish_cbcctx c; |
77 | rmd160_mackey mk; |
78 | rmd160_macctx mc; |
d11a0bf7 |
79 | |
80 | /* --- Sanity check --- */ |
81 | |
ef13e9a4 |
82 | if (k) key_incref(k); else k = *kt; |
d11a0bf7 |
83 | assert(((void)"Key data is already encrypted", |
84 | (k->e & KF_ENCMASK) != KENC_ENCRYPT)); |
85 | |
59b2b448 |
86 | /* --- Format the stuff in the buffer --- */ |
d11a0bf7 |
87 | |
59b2b448 |
88 | DENSURE(&d, RMD160_HASHSZ * 2); |
89 | rand_get(RAND_GLOBAL, d.buf, RMD160_HASHSZ); |
90 | d.len += RMD160_HASHSZ * 2; |
d11a0bf7 |
91 | key_encode(k, &d, 0); |
59b2b448 |
92 | m = (octet *)d.buf + RMD160_HASHSZ * 2; |
93 | msz = d.len - RMD160_HASHSZ * 2; |
d11a0bf7 |
94 | |
59b2b448 |
95 | /* --- Hash the passphrase to make a key --- */ |
d11a0bf7 |
96 | |
1dda051b |
97 | rmd160_mgfkeybegin(&r); |
98 | rmd160_mgfkeyadd(&r, d.buf, RMD160_HASHSZ); |
99 | rmd160_mgfkeyadd(&r, e, esz); |
100 | rmd160_mgfencrypt(&r, 0, b, sizeof(b)); |
101 | BURN(r); |
d11a0bf7 |
102 | |
59b2b448 |
103 | /* --- Encrypt the plaintext --- */ |
d11a0bf7 |
104 | |
1dda051b |
105 | blowfish_cbcinit(&c, b, RMD160_HASHSZ, 0); |
106 | blowfish_cbcencrypt(&c, m, m, msz); |
107 | BURN(c); |
d11a0bf7 |
108 | |
59b2b448 |
109 | /* --- MAC the ciphertext --- */ |
110 | |
1dda051b |
111 | rmd160_hmacinit(&mk, b + RMD160_HASHSZ, RMD160_HASHSZ); |
112 | rmd160_macinit(&mc, &mk); |
113 | rmd160_machash(&mc, m, msz); |
114 | rmd160_macdone(&mc, d.buf + RMD160_HASHSZ); |
115 | BURN(mk); |
116 | BURN(mc); |
59b2b448 |
117 | |
118 | /* --- Done --- */ |
d11a0bf7 |
119 | |
59b2b448 |
120 | BURN(b); |
ef13e9a4 |
121 | *kt = key_newencrypted(0, d.buf, d.len); |
122 | key_drop(k); |
d11a0bf7 |
123 | dstr_destroy(&d); |
d11a0bf7 |
124 | } |
125 | |
1dda051b |
126 | /* --- @key_unlock@ --- * |
d11a0bf7 |
127 | * |
ef13e9a4 |
128 | * Arguments: @key_data **kt@ = where to store the destination pointer |
129 | * @key_data *k@ = source key data block or null to use @*kt@ |
1dda051b |
130 | * @const void *e@ = secret to decrypt the block with |
131 | * @size_t esz@ = size of the secret |
d11a0bf7 |
132 | * |
1dda051b |
133 | * Returns: Zero for success, or a @KERR_@ error code. |
d11a0bf7 |
134 | * |
1dda051b |
135 | * Use: Unlocks a key using a secret. |
d11a0bf7 |
136 | */ |
137 | |
ef13e9a4 |
138 | int key_unlock(key_data **kt, key_data *k, const void *e, size_t esz) |
d11a0bf7 |
139 | { |
59b2b448 |
140 | octet b[RMD160_HASHSZ * 2]; |
8ef2f81d |
141 | octet *p = 0; |
1dda051b |
142 | int rc; |
ef13e9a4 |
143 | int drop = 0; |
144 | key_data *kd; |
1dda051b |
145 | rmd160_mgfctx r; |
146 | blowfish_cbcctx c; |
147 | rmd160_mackey mk; |
148 | rmd160_macctx mc; |
d11a0bf7 |
149 | size_t sz; |
150 | |
151 | /* --- Sanity check --- */ |
152 | |
ef13e9a4 |
153 | if (!k) { k = *kt; drop = 1; } |
d11a0bf7 |
154 | assert(((void)"Key data isn't encrypted", |
155 | (k->e & KF_ENCMASK) == KENC_ENCRYPT)); |
156 | |
8ef2f81d |
157 | /* --- Check the size --- */ |
d11a0bf7 |
158 | |
59b2b448 |
159 | if (k->u.k.sz < RMD160_HASHSZ * 2) |
1dda051b |
160 | return (KERR_MALFORMED); |
59b2b448 |
161 | sz = k->u.k.sz - RMD160_HASHSZ * 2; |
d11a0bf7 |
162 | |
59b2b448 |
163 | /* --- Hash the passphrase to make a key --- */ |
d11a0bf7 |
164 | |
1dda051b |
165 | rmd160_mgfkeybegin(&r); |
166 | rmd160_mgfkeyadd(&r, k->u.k.k, RMD160_HASHSZ); |
167 | rmd160_mgfkeyadd(&r, e, esz); |
168 | rmd160_mgfencrypt(&r, 0, b, sizeof(b)); |
169 | BURN(r); |
d11a0bf7 |
170 | |
59b2b448 |
171 | /* --- Verify the MAC --- */ |
172 | |
1dda051b |
173 | rmd160_hmacinit(&mk, b + RMD160_HASHSZ, RMD160_HASHSZ); |
174 | rmd160_macinit(&mc, &mk); |
175 | rmd160_machash(&mc, k->u.k.k + RMD160_HASHSZ * 2, sz); |
176 | rmd160_macdone(&mc, b + RMD160_HASHSZ); |
177 | if (memcmp(b + RMD160_HASHSZ, k->u.k.k + RMD160_HASHSZ, |
178 | RMD160_HASHSZ) != 0) { |
179 | rc = KERR_BADPASS; |
180 | goto fail; |
d11a0bf7 |
181 | } |
1dda051b |
182 | BURN(mk); |
183 | BURN(mc); |
d11a0bf7 |
184 | |
8ef2f81d |
185 | /* --- Allocate a destination buffer --- */ |
186 | |
187 | p = xmalloc(sz); |
188 | |
189 | /* --- Decrypt the key data --- */ |
190 | |
1dda051b |
191 | blowfish_cbcinit(&c, b, RMD160_HASHSZ, 0); |
192 | blowfish_cbcdecrypt(&c, k->u.k.k + RMD160_HASHSZ * 2, p, sz); |
193 | BURN(c); |
8ef2f81d |
194 | |
d11a0bf7 |
195 | /* --- Decode the key data into the destination buffer --- */ |
196 | |
ef13e9a4 |
197 | if ((kd = key_decode(p, sz)) == 0) { |
1dda051b |
198 | rc = KERR_MALFORMED; |
59b2b448 |
199 | goto fail; |
1dda051b |
200 | } |
ef13e9a4 |
201 | *kt = kd; |
d11a0bf7 |
202 | |
203 | /* --- Done --- */ |
204 | |
12ed8a1f |
205 | xfree(p); |
ef13e9a4 |
206 | if (drop) key_drop(k); |
d11a0bf7 |
207 | return (0); |
208 | |
209 | /* --- Tidy up if things went wrong --- */ |
210 | |
59b2b448 |
211 | fail: |
212 | BURN(b); |
12ed8a1f |
213 | xfree(p); |
1dda051b |
214 | return (rc); |
215 | } |
216 | |
217 | /* --- @key_plock@ --- * |
218 | * |
ef13e9a4 |
219 | * Arguments: @key_data **kt@ = where to store the destination pointer |
220 | * @key_data *k@ = source key data block or null to use @*kt@ |
221 | * @const char *tag@ = tag to use for passphrase |
1dda051b |
222 | * |
223 | * Returns: Zero if successful, a @KERR@ error code on failure. |
224 | * |
225 | * Use: Locks a key by encrypting it with a passphrase. |
226 | */ |
227 | |
ef13e9a4 |
228 | int key_plock(key_data **kt, key_data *k, const char *tag) |
1dda051b |
229 | { |
230 | char buf[256]; |
231 | |
232 | if (passphrase_read(tag, PMODE_VERIFY, buf, sizeof(buf))) |
233 | return (KERR_IO); |
234 | key_lock(kt, k, buf, strlen(buf)); |
235 | BURN(buf); |
236 | return (0); |
237 | } |
238 | |
239 | /* --- @key_punlock@ --- * |
240 | * |
ef13e9a4 |
241 | * Arguments: @key_data **kt@ = where to store the destination pointer |
242 | * @key_data *k@ = source key data block or null to use @*kt@ |
243 | * @const char *tag@ = tag to use for passphrase |
1dda051b |
244 | * |
245 | * Returns: Zero if it worked, a @KERR_@ error code on failure. |
246 | * |
247 | * Use: Unlocks a passphrase-locked key. |
248 | */ |
249 | |
ef13e9a4 |
250 | int key_punlock(key_data **kt, key_data *k, const char *tag) |
1dda051b |
251 | { |
252 | char buf[256]; |
253 | int rc; |
254 | |
255 | if (passphrase_read(tag, PMODE_READ, buf, sizeof(buf))) |
256 | return (KERR_IO); |
257 | rc = key_unlock(kt, k, buf, strlen(buf)); |
258 | BURN(buf); |
ef13e9a4 |
259 | if (rc == KERR_BADPASS || !k) |
1dda051b |
260 | passphrase_cancel(tag); |
261 | return (rc); |
d11a0bf7 |
262 | } |
263 | |
264 | /*----- That's all, folks -------------------------------------------------*/ |