| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * $Id: key-pass.c,v 1.2 2000/06/17 11:26:35 mdw Exp $ |
| 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 $ |
| 33 | * Revision 1.2 2000/06/17 11:26:35 mdw |
| 34 | * `rand_getgood' is deprecated. |
| 35 | * |
| 36 | * Revision 1.1 1999/12/22 15:47:48 mdw |
| 37 | * Major key-management revision. |
| 38 | * |
| 39 | */ |
| 40 | |
| 41 | /*----- Header files ------------------------------------------------------*/ |
| 42 | |
| 43 | #include <mLib/dstr.h> |
| 44 | |
| 45 | #include "key.h" |
| 46 | #include "paranoia.h" |
| 47 | #include "passphrase.h" |
| 48 | #include "rand.h" |
| 49 | |
| 50 | #include "blowfish-cbc.h" |
| 51 | #include "rmd160.h" |
| 52 | |
| 53 | /*----- Main code ---------------------------------------------------------*/ |
| 54 | |
| 55 | /* --- @key_plock@ --- * |
| 56 | * |
| 57 | * Arguments: @const char *tag@ = tag to use for passphrase |
| 58 | * @key_data *k@ = source key data block |
| 59 | * @key_data *kt@ = target key data block |
| 60 | * |
| 61 | * Returns: Zero if successful, nonzero if there was a problem. |
| 62 | * |
| 63 | * Use: Locks a key by encrypting it with a passphrase. |
| 64 | */ |
| 65 | |
| 66 | int key_plock(const char *tag, key_data *k, key_data *kt) |
| 67 | { |
| 68 | dstr d = DSTR_INIT; |
| 69 | octet hash[RMD160_HASHSZ]; |
| 70 | char buf[256]; |
| 71 | |
| 72 | /* --- Sanity check --- */ |
| 73 | |
| 74 | assert(((void)"Key data is already encrypted", |
| 75 | (k->e & KF_ENCMASK) != KENC_ENCRYPT)); |
| 76 | |
| 77 | /* --- Read the passphrase --- */ |
| 78 | |
| 79 | if (passphrase_read(tag, PMODE_VERIFY, buf, sizeof(buf))) |
| 80 | return (-1); |
| 81 | |
| 82 | /* --- Extract the key data --- * |
| 83 | * |
| 84 | * On the front, put four random bytes to act as a passphrase salt (which |
| 85 | * remain in the clear), and four zero bytes to be able to spot duff |
| 86 | * passphrases when unlocking. |
| 87 | */ |
| 88 | |
| 89 | DENSURE(&d, 8); |
| 90 | rand_get(RAND_GLOBAL, d.buf, 4); |
| 91 | memset(d.buf + 4, 0, 4); |
| 92 | d.len += 8; |
| 93 | key_encode(k, &d, 0); |
| 94 | if (k == kt) |
| 95 | key_destroy(k); |
| 96 | |
| 97 | /* --- Hash the passphrase into a key --- */ |
| 98 | |
| 99 | { |
| 100 | rmd160_ctx h; |
| 101 | rmd160_init(&h); |
| 102 | rmd160_hash(&h, d.buf, 4); |
| 103 | rmd160_hash(&h, buf, strlen(buf)); |
| 104 | rmd160_done(&h, hash); |
| 105 | BURN(h); |
| 106 | BURN(buf); |
| 107 | } |
| 108 | |
| 109 | /* --- Encrypt the key data --- */ |
| 110 | |
| 111 | { |
| 112 | blowfish_cbcctx c; |
| 113 | blowfish_cbcinit(&c, hash, sizeof(hash), 0); |
| 114 | blowfish_cbcencrypt(&c, d.buf + 4, d.buf + 4, d.len - 4); |
| 115 | BURN(hash); |
| 116 | BURN(c); |
| 117 | } |
| 118 | |
| 119 | /* --- Put the key data back in the key --- */ |
| 120 | |
| 121 | key_encrypted(kt, d.buf, d.len); |
| 122 | dstr_destroy(&d); |
| 123 | return (0); |
| 124 | } |
| 125 | |
| 126 | /* --- @key_punlock@ --- * |
| 127 | * |
| 128 | * Arguments: @const char *tag@ = tag to use for passphrase |
| 129 | * @key_data *k@ = source key data block |
| 130 | * @key_data *kt@ = target key data block |
| 131 | * |
| 132 | * Returns: Zero if it worked, nonzero if it didn't. |
| 133 | * |
| 134 | * Use: Unlocks a passphrase-locked key. |
| 135 | */ |
| 136 | |
| 137 | int key_punlock(const char *tag, key_data *k, key_data *kt) |
| 138 | { |
| 139 | octet hash[RMD160_HASHSZ]; |
| 140 | char buf[256]; |
| 141 | octet *p; |
| 142 | size_t sz; |
| 143 | |
| 144 | /* --- Sanity check --- */ |
| 145 | |
| 146 | assert(((void)"Key data isn't encrypted", |
| 147 | (k->e & KF_ENCMASK) == KENC_ENCRYPT)); |
| 148 | |
| 149 | /* --- Fetch the passphrase --- */ |
| 150 | |
| 151 | if (passphrase_read(tag, PMODE_READ, buf, sizeof(buf))) |
| 152 | goto fail_0; |
| 153 | |
| 154 | /* --- Allocate a destination buffer --- * |
| 155 | * |
| 156 | * Minimum size for a key is four bytes salt, four bytes zeroes, two bytes |
| 157 | * type, and two bytes length, making a total of twelve. |
| 158 | */ |
| 159 | |
| 160 | if (k->u.k.sz < 12) |
| 161 | goto fail_0; |
| 162 | sz = k->u.k.sz - 4; |
| 163 | p = xmalloc(k->u.k.sz); |
| 164 | |
| 165 | /* --- Hash the passphrase --- */ |
| 166 | |
| 167 | { |
| 168 | rmd160_ctx h; |
| 169 | rmd160_init(&h); |
| 170 | rmd160_hash(&h, k->u.k.k, 4); |
| 171 | rmd160_hash(&h, buf, strlen(buf)); |
| 172 | rmd160_done(&h, hash); |
| 173 | BURN(h); |
| 174 | BURN(buf); |
| 175 | } |
| 176 | |
| 177 | /* --- Decrypt the key data --- */ |
| 178 | |
| 179 | { |
| 180 | blowfish_cbcctx c; |
| 181 | blowfish_cbcinit(&c, hash, sizeof(hash), 0); |
| 182 | blowfish_cbcdecrypt(&c, k->u.k.k + 4, p, sz); |
| 183 | BURN(hash); |
| 184 | BURN(c); |
| 185 | if (LOAD32(p) != 0) { |
| 186 | passphrase_cancel(tag); |
| 187 | goto fail_1; |
| 188 | } |
| 189 | } |
| 190 | |
| 191 | /* --- Decode the key data into the destination buffer --- */ |
| 192 | |
| 193 | if (k == kt) { |
| 194 | key_destroy(k); |
| 195 | passphrase_cancel(tag); |
| 196 | } |
| 197 | if (key_decode(p + 4, sz - 4, kt)) |
| 198 | goto fail_1; |
| 199 | |
| 200 | /* --- Done --- */ |
| 201 | |
| 202 | free(p); |
| 203 | return (0); |
| 204 | |
| 205 | /* --- Tidy up if things went wrong --- */ |
| 206 | |
| 207 | fail_1: |
| 208 | free(p); |
| 209 | fail_0: |
| 210 | return (-1); |
| 211 | } |
| 212 | |
| 213 | /*----- That's all, folks -------------------------------------------------*/ |