main.c

   1 /*
   2  * usign - tiny signify replacement
   3  *
   4  * Copyright (C) 2015 Felix Fietkau <nbd@openwrt.org>
   5  *
   6  * Permission to use, copy, modify, and/or distribute this software for any
   7  * purpose with or without fee is hereby granted, provided that the above
   8  * copyright notice and this permission notice appear in all copies.
   9  *
  10  * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
  11  * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
  12  * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
  13  * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  14  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
  15  * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
  16  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  17  */
  18 #include <sys/mman.h>
  19 #include <sys/stat.h>
  20 #include <stdio.h>
  21 #include <stdbool.h>
  22 #include <stdlib.h>
  23 #include <string.h>
  24 #include <getopt.h>
  25 #include <stdint.h>
  26 #include <fcntl.h>
  27 #include <unistd.h>
  28 #include <inttypes.h>
  29
  30 #include "base64.h"
  31 #include "edsign.h"
  32 #include "ed25519.h"
  33
  34 struct pubkey {
  35         char pkalg[2];
  36         uint8_t fingerprint[8];
  37         uint8_t pubkey[EDSIGN_PUBLIC_KEY_SIZE];
  38 };
  39
  40 struct seckey {
  41         char pkalg[2];
  42         char kdfalg[2];
  43         uint32_t kdfrounds;
  44         uint8_t salt[16];
  45         uint8_t checksum[8];
  46         uint8_t fingerprint[8];
  47         uint8_t seckey[64];
  48 };
  49
  50 struct sig {
  51         char pkalg[2];
  52         uint8_t fingerprint[8];
  53         uint8_t sig[EDSIGN_SIGNATURE_SIZE];
  54 };
  55
  56 static const char *pubkeyfile;
  57 static const char *pubkeydir;
  58 static const char *sigfile;
  59 static const char *seckeyfile;
  60 static const char *comment;
  61 static bool quiet;
  62 static enum {
  63         CMD_NONE,
  64         CMD_VERIFY,
  65         CMD_SIGN,
  66         CMD_FINGERPRINT,
  67         CMD_GENERATE,
  68 } cmd = CMD_NONE;
  69
  70 static uint64_t fingerprint_u64(const uint8_t *data)
  71 {
  72         uint64_t val = 0;
  73
  74 #define ADD(_v) val = (val << 8) | _v
  75         ADD(data[0]);
  76         ADD(data[1]);
  77         ADD(data[2]);
  78         ADD(data[3]);
  79         ADD(data[4]);
  80         ADD(data[5]);
  81         ADD(data[6]);
  82         ADD(data[7]);
  83 #undef ADD
  84
  85         return val;
  86 }
  87
  88 static void
  89 file_error(const char *filename, bool _read)
  90 {
  91         if (!quiet || cmd != CMD_VERIFY)
  92                 fprintf(stderr, "Cannot open file '%s' for %s\n", filename,
  93                         _read ? "reading" : "writing");
  94         exit(1);
  95 }
  96
  97 static FILE *
  98 open_file(const char *filename, bool _read)
  99 {
 100         FILE *f;
 101
 102         if (!strcmp(filename, "-"))
 103                 return _read ? stdin : stdout;
 104
 105         f = fopen(filename, _read ? "r" : "w");
 106         if (!f)
 107                 file_error(filename, _read);
 108
 109         return f;
 110 }
 111
 112 static void
 113 get_file(const char *filename, char *buf, int buflen)
 114 {
 115         FILE *f = open_file(filename, true);
 116         int len;
 117
 118         while (1) {
 119                 char *cur = fgets(buf, buflen, f);
 120
 121                 if (!cur) {
 122                         fprintf(stderr, "Premature end of file\n");
 123                         exit(1);
 124                 }
 125
 126                 if (strchr(buf, '\n'))
 127                         break;
 128         }
 129
 130         len = fread(buf, 1, buflen - 1, f);
 131         buf[len] = 0;
 132 }
 133
 134 static bool
 135 get_base64_file(const char *file, void *dest, int size, void *buf, int buflen)
 136 {
 137         get_file(file, buf, buflen - 1);
 138         return b64_decode(buf, dest, size) == size;
 139 }
 140
 141 static void write_file(const char *name, const uint8_t *fingerprint,
 142                        const char *prefix, char *buf)
 143 {
 144         FILE *f;
 145
 146         f = open_file(name, false);
 147         fputs("untrusted comment: ", f);
 148         if (comment)
 149                 fputs(comment, f);
 150         else
 151                 fprintf(f, "%s %"PRIx64, prefix,
 152                         fingerprint_u64(fingerprint));
 153         fprintf(f, "\n%s\n", buf);
 154         fclose(f);
 155 }
 156
 157 static int verify(const char *msgfile)
 158 {
 159         struct pubkey pkey;
 160         struct sig sig;
 161         struct edsign_verify_state vst;
 162         FILE *f;
 163         char buf[512];
 164
 165         f = open_file(msgfile, true);
 166         if (!f) {
 167                 fprintf(stderr, "Cannot open message file\n");
 168                 return 1;
 169         }
 170
 171         if (!get_base64_file(sigfile, &sig, sizeof(sig), buf, sizeof(buf)) ||
 172             memcmp(sig.pkalg, "Ed", 2) != 0) {
 173                 fprintf(stderr, "Failed to decode signature\n");
 174                 return 1;
 175         }
 176
 177         if (!pubkeyfile) {
 178                 snprintf(buf, sizeof(buf), "%s/%"PRIx64, pubkeydir,
 179                          fingerprint_u64(sig.fingerprint));
 180                 pubkeyfile = buf;
 181         }
 182
 183         if (!get_base64_file(pubkeyfile, &pkey, sizeof(pkey), buf, sizeof(buf)) ||
 184             memcmp(pkey.pkalg, "Ed", 2) != 0) {
 185                 fprintf(stderr, "Failed to decode public key\n");
 186                 return 1;
 187         }
 188
 189         edsign_verify_init(&vst, sig.sig, pkey.pubkey);
 190
 191         while (!feof(f)) {
 192                 int len = fread(buf, 1, sizeof(buf), f);
 193                 edsign_verify_add(&vst, buf, len);
 194         }
 195         fclose(f);
 196
 197         if (!edsign_verify(&vst, sig.sig, pkey.pubkey)) {
 198                 if (!quiet)
 199                         fprintf(stderr, "verification failed\n");
 200                 return 1;
 201         }
 202
 203         if (!quiet)
 204                 fprintf(stderr, "OK\n");
 205         return 0;
 206 }
 207
 208 static int sign(const char *msgfile)
 209 {
 210         struct seckey skey;
 211         struct sig sig = {
 212                 .pkalg = "Ed",
 213         };
 214         struct stat st;
 215         char buf[512];
 216         void *pubkey = buf;
 217         long mlen;
 218         void *m;
 219         int mfd;
 220
 221         if (!get_base64_file(seckeyfile, &skey, sizeof(skey), buf, sizeof(buf)) ||
 222             memcmp(skey.pkalg, "Ed", 2) != 0) {
 223                 fprintf(stderr, "Failed to decode secret key\n");
 224                 return 1;
 225         }
 226
 227         if (skey.kdfrounds) {
 228                 fprintf(stderr, "Password protected secret keys are not supported\n");
 229                 return 1;
 230         }
 231
 232         mfd = open(msgfile, O_RDONLY, 0);
 233         if (mfd < 0 || fstat(mfd, &st) < 0 ||
 234                 (m = mmap(0, st.st_size, PROT_READ, MAP_PRIVATE, mfd, 0)) == MAP_FAILED) {
 235                 if (mfd >= 0)
 236                         close(mfd);
 237                 perror("Cannot open message file");
 238                 return 1;
 239         }
 240         mlen = st.st_size;
 241
 242         memcpy(sig.fingerprint, skey.fingerprint, sizeof(sig.fingerprint));
 243         edsign_sec_to_pub(pubkey, skey.seckey);
 244         edsign_sign(sig.sig, pubkey, skey.seckey, m, mlen);
 245         munmap(m, mlen);
 246         close(mfd);
 247
 248         if (b64_encode(&sig, sizeof(sig), buf, sizeof(buf)) < 0)
 249                 return 1;
 250
 251         write_file(sigfile, sig.fingerprint, "signed by key", buf);
 252
 253         return 0;
 254 }
 255
 256 static int fingerprint(void)
 257 {
 258         struct seckey skey;
 259         struct pubkey pkey;
 260         struct sig sig;
 261         char buf[512];
 262         uint8_t *fp;
 263
 264         if (seckeyfile &&
 265             get_base64_file(seckeyfile, &skey, sizeof(skey), buf, sizeof(buf)))
 266                 fp = skey.fingerprint;
 267         else if (pubkeyfile &&
 268                  get_base64_file(pubkeyfile, &pkey, sizeof(pkey), buf, sizeof(buf)))
 269                 fp = pkey.fingerprint;
 270         else if (sigfile &&
 271                  get_base64_file(sigfile, &sig, sizeof(sig), buf, sizeof(buf)))
 272                 fp = sig.fingerprint;
 273         else
 274                 return 1;
 275
 276         fprintf(stdout, "%"PRIx64"\n", fingerprint_u64(fp));
 277         return 0;
 278 }
 279
 280 static int generate(void)
 281 {
 282         struct seckey skey = {
 283                 .pkalg = "Ed",
 284                 .kdfalg = "BK",
 285                 .kdfrounds = 0,
 286         };
 287         struct pubkey pkey = {
 288                 .pkalg = "Ed",
 289         };
 290         struct sha512_state s;
 291         char buf[512];
 292         FILE *f;
 293
 294         f = fopen("/dev/urandom", "r");
 295         if (!f ||
 296             fread(skey.fingerprint, sizeof(skey.fingerprint), 1, f) != 1 ||
 297             fread(skey.seckey, EDSIGN_SECRET_KEY_SIZE, 1, f) != 1 ||
 298             fread(skey.salt, sizeof(skey.salt), 1, f) != 1) {
 299                 fprintf(stderr, "Can't read data from /dev/urandom\n");
 300                 return 1;
 301         }
 302         if (f)
 303                 fclose(f);
 304
 305         ed25519_prepare(skey.seckey);
 306         edsign_sec_to_pub(skey.seckey + 32, skey.seckey);
 307
 308         sha512_init(&s);
 309         sha512_add(&s, skey.seckey, sizeof(skey.seckey));
 310         memcpy(skey.checksum, sha512_final_get(&s), sizeof(skey.checksum));
 311
 312         if (b64_encode(&skey, sizeof(skey), buf, sizeof(buf)) < 0)
 313                 return 1;
 314
 315         write_file(seckeyfile, skey.fingerprint, "private key", buf);
 316
 317         memcpy(pkey.fingerprint, skey.fingerprint, sizeof(pkey.fingerprint));
 318         memcpy(pkey.pubkey, skey.seckey + 32, sizeof(pkey.pubkey));
 319
 320         if (b64_encode(&pkey, sizeof(pkey), buf, sizeof(buf)) < 0)
 321                 return 1;
 322
 323         write_file(pubkeyfile, pkey.fingerprint, "public key", buf);
 324
 325         return 0;
 326 }
 327
 328 static int usage(const char *cmd)
 329 {
 330         fprintf(stderr,
 331                 "Usage: %s <command> <options>\n"
 332                 "Commands:\n"
 333                 "  -V:                  verify (needs at least -m and -p|-P)\n"
 334                 "  -S:                  sign (needs at least -m and -s)\n"
 335                 "  -F:                  print key fingerprint of public/secret key or signature\n"
 336                 "  -G:                  generate a new keypair (needs at least -p and -s)\n"
 337                 "Options:\n"
 338                 "  -c <comment>:        add comment to keys\n"
 339                 "  -m <file>:           message file\n"
 340                 "  -p <file>:           public key file (verify/fingerprint only)\n"
 341                 "  -P <path>:           public key directory (verify only)\n"
 342                 "  -q:                  quiet (do not print verification result, use return code only)\n"
 343                 "  -s <file>:           secret key file (sign/fingerprint only)\n"
 344                 "  -x <file>:           signature file (defaults to <message file>.sig)\n"
 345                 "\n",
 346                 cmd);
 347         return 1;
 348 }
 349
 350 static void set_cmd(const char *prog, int val)
 351 {
 352         if (cmd != CMD_NONE)
 353                 exit(usage(prog));
 354
 355         cmd = val;
 356 }
 357
 358 int main(int argc, char **argv)
 359 {
 360         const char *msgfile = NULL;
 361         int ch;
 362
 363         while ((ch = getopt(argc, argv, "FGSVc:m:P:p:qs:x:")) != -1) {
 364                 switch (ch) {
 365                 case 'V':
 366                         set_cmd(argv[0], CMD_VERIFY);
 367                         break;
 368                 case 'S':
 369                         set_cmd(argv[0], CMD_SIGN);
 370                         break;
 371                 case 'F':
 372                         set_cmd(argv[0], CMD_FINGERPRINT);
 373                         break;
 374                 case 'G':
 375                         set_cmd(argv[0], CMD_GENERATE);
 376                         break;
 377                 case 'c':
 378                         comment = optarg;
 379                         break;
 380                 case 'm':
 381                         msgfile = optarg;
 382                         break;
 383                 case 'P':
 384                         pubkeydir = optarg;
 385                         break;
 386                 case 'p':
 387                         pubkeyfile = optarg;
 388                         break;
 389                 case 's':
 390                         seckeyfile = optarg;
 391                         break;
 392                 case 'x':
 393                         sigfile = optarg;
 394                         break;
 395                 case 'q':
 396                         quiet = true;
 397                         break;
 398                 default:
 399                         return usage(argv[0]);
 400                 }
 401         }
 402
 403         if (!sigfile && msgfile) {
 404                 char *buf = alloca(strlen(msgfile) + 5);
 405
 406                 if (!strcmp(msgfile, "-")) {
 407                         fprintf(stderr, "Need signature file when reading message from stdin\n");
 408                         return 1;
 409                 }
 410
 411                 sprintf(buf, "%s.sig", msgfile);
 412                 sigfile = buf;
 413         }
 414
 415         switch (cmd) {
 416         case CMD_VERIFY:
 417                 if ((!pubkeyfile && !pubkeydir) || !msgfile)
 418                         return usage(argv[0]);
 419                 return verify(msgfile);
 420         case CMD_SIGN:
 421                 if (!seckeyfile || !msgfile || !sigfile)
 422                         return usage(argv[0]);
 423                 return sign(msgfile);
 424         case CMD_FINGERPRINT:
 425                 if (!!seckeyfile + !!pubkeyfile + !!sigfile != 1) {
 426                         fprintf(stderr, "Need one secret/public key or signature\n");
 427                         return usage(argv[0]);
 428                 }
 429                 return fingerprint();
 430         case CMD_GENERATE:
 431                 if (!seckeyfile || !pubkeyfile)
 432                         return usage(argv[0]);
 433                 return generate();
 434         default:
 435                 return usage(argv[0]);
 436         }
 437 }