New test vectors.

[u/mdw/catacomb] / catcrypt.c

/* -*-c-*-
 *
 * $Id: catcrypt.c,v 1.1 2004/04/17 09:58:36 mdw Exp $
 *
 * Command-line encryption tool
 *
 * (c) 2004 Straylight/Edgeware
 */

/*----- Licensing notice --------------------------------------------------* 
 *
 * This file is part of Catacomb.
 *
 * Catacomb is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Library General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 * 
 * Catacomb is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Library General Public License for more details.
 * 
 * You should have received a copy of the GNU Library General Public
 * License along with Catacomb; if not, write to the Free
 * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
 * MA 02111-1307, USA.
 */

/*----- Header files ------------------------------------------------------*/

#include "config.h"

#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <mLib/base64.h>
#include <mLib/dstr.h>
#include <mLib/mdwopt.h>
#include <mLib/quis.h>
#include <mLib/report.h>
#include <mLib/sub.h>

#include "buf.h"
#include "rand.h"
#include "noise.h"
#include "mprand.h"
#include "key.h"
#include "cc.h"

/*----- Utilities ---------------------------------------------------------*/

/* --- @keyreport@ --- *
 *
 * Arguments:   @const char *file@ = filename containing the error
 *              @int line@ = line number in file
 *              @const char *err@ = error text message
 *              @void *p@ = unimportant pointer
 *
 * Returns:     ---
 *
 * Use:         Reports errors during the opening of a key file.
 */

static void keyreport(const char *file, int line, const char *err, void *p)
{
  moan("error in keyring `%s' at line `%s': %s", file, line, err);
}

/*----- Static variables --------------------------------------------------*/

static const char *keyring = "keyring";

/*----- Data format -------------------------------------------------------*/

/* --- Overview --- *
 *
 * The encrypted message is divided into chunks, each preceded by a two-octet
 * length.  The chunks don't need to be large -- the idea is that we can
 * stream the chunks in and out.
 *
 * The first chunk is a header.  It contains the decryption key-id, and maybe
 * the verification key-id if the message is signed.
 *
 * Next comes the key-encapsulation chunk.  This is decrypted in some
 * KEM-specific way to yield a secret hash.  This hash is what is signed if
 * the message is signed.  The hash is expanded using an MGF (or similar) to
 * make a symmetric encryption and MAC key.
 *
 * If the message is signed, there comes a signature chunk.  The signature is
 * on the secret hash.  This means that the recipient can modify the message
 * and still have a valid signature, so it's not useful for proving things to
 * other people; but it also means that the recipient knows that the message
 * is from someone who knows the hash, which limits the possiblities to (a)
 * whoever encrypted the message (good!) and (b) whoever knows the
 * recipient's private key.
 *
 * Then come message chunks.  Each one begins with a MAC over an implicit
 * sequence number and the ciphertext.  The final chunk's ciphertext is
 * empty; no other chunk is empty.  Thus can the correct end-of-file be
 * discerned.
 */

/*----- Chunk I/O ---------------------------------------------------------*/

static void chunk_write(enc *e, buf *b)
{
  octet l[2];
  size_t n = BLEN(b);
  assert(n <= MASK16);
  STORE16(l, n);
  if (e->ops->write(e, l, 2) ||
      e->ops->write(e, BBASE(b), BLEN(b)))
    die(EXIT_FAILURE, "error writing output: %s", strerror(errno));
}

static void chunk_read(enc *e, dstr *d, buf *b)
{
  octet l[2];
  size_t n;

  dstr_reset(d);
  errno = 0;
  if (e->ops->read(e, l, 2) != 2)
    goto err;
  n = LOAD16(l);
  dstr_ensure(d, n);
  if (e->ops->read(e, d->buf, n) != n)
    goto err;
  d->len = n;
  buf_init(b, d->buf, d->len);
  return;

err:
  if (!errno) die(EXIT_FAILURE, "unexpected end-of-file on input");
  else die(EXIT_FAILURE, "error reading input: %s", strerror(errno));
}

/*----- Encryption --------------------------------------------------------*/

static int encrypt(int argc, char *argv[])
{
  const char *of = 0, *kn = "ccrypt";
  FILE *ofp = 0;
  FILE *fp = 0;
  const char *ef = "binary";
  const char *err;
  int i;
  size_t n;
  dstr d = DSTR_INIT;
  octet *tag, *ct;
  buf b;
  size_t seq;
  char bb[16384];
  unsigned f = 0;
  key_file kf;
  key *k;
  kem *km;
  gcipher *cx, *c;
  gmac *m;
  ghash *h;
  const encops *eo;
  enc *e;

#define f_bogus 1u

  for (;;) {
    static const struct option opt[] = {
      { "key",		OPTF_ARGREQ,	0,	'k' },
      { "armour",	0,		0,	'a' },
      { "armor",	0,		0,	'a' },
      { "format", 	OPTF_ARGREQ,	0,	'f' },
      { "output", 	OPTF_ARGREQ,	0,	'o' },
      { 0,		0,		0,	0 }
    };
    i = mdwopt(argc, argv, "k:af:o:", opt, 0, 0, 0);
    if (i < 0) break;
    switch (i) {
      case 'k': kn = optarg; break;
      case 'a': ef = "pem"; break;
      case 'f': ef = optarg; break;
      case 'o': of = optarg; break;
      default: f |= f_bogus; break;
    }
  }
  if (argc - optind > 1 || (f & f_bogus))
    die(EXIT_FAILURE, "Usage: encrypt [-options] [file]");

  if (key_open(&kf, keyring, KOPEN_READ, keyreport, 0))
    die(EXIT_FAILURE, "can't open keyring `%s'", keyring);
  if ((k = key_bytag(&kf, kn)) == 0)
    die(EXIT_FAILURE, "key `%s' not found", kn);

  if ((eo = getenc(ef)) == 0)
    die(EXIT_FAILURE, "encoding `%s' not found", ef);

  if (optind == argc)
    fp = stdin;
  else if (strcmp(argv[optind], "-") == 0) {
    fp = stdin;
    optind++;
  } else if ((fp = fopen(argv[optind], "rb")) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s': %s",
	argv[optind], strerror(errno));
  } else
    optind++;

  if (!of || strcmp(of, "-") == 0)
    ofp = stdout;
  else if ((ofp = fopen(of, eo->wmode)) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s' for output: %s",
	ofp, strerror(errno));
  }

  key_fulltag(k, &d);
  e = initenc(eo, ofp, "CATCRYPT ENCRYPTED MESSAGE", 1);
  km = getkem(k, "ccrypt", 0);
  if ((err = km->ops->check(km)) != 0)
    moan("key `%s' fails check: %s", d.buf, err);

  /* --- Build the header chunk --- */

  dstr_reset(&d);
  dstr_ensure(&d, 256);
  buf_init(&b, d.buf, 256);
  buf_putu32(&b, k->id);
  assert(BOK(&b));
  chunk_write(e, &b);

  /* --- Build the KEM chunk --- */

  dstr_reset(&d);
  if (setupkem(km, &d, &cx, &c, &m))
    die(EXIT_FAILURE, "failed to encapsulate key");
  buf_init(&b, d.buf, d.len);
  BSTEP(&b, d.len);
  chunk_write(e, &b);

  /* --- Now do the main crypto --- */

  assert(GC_CLASS(c)->blksz <= sizeof(bb));
  dstr_ensure(&d, sizeof(bb) + GM_CLASS(m)->hashsz);
  seq = 0;
  for (;;) {
    h = GM_INIT(m);
    STORE32(bb, seq);
    GH_HASH(h, bb, 4);
    seq++;
    if (GC_CLASS(c)->blksz) {
      GC_ENCRYPT(cx, 0, bb, GC_CLASS(c)->blksz);
      GC_SETIV(c, bb);
    }
    n = fread(bb, 1, sizeof(bb), fp);
    if (!n) break;
    buf_init(&b, d.buf, d.sz);
    tag = buf_get(&b, GM_CLASS(m)->hashsz);
    ct = buf_get(&b, n);
    assert(tag); assert(ct);
    GC_ENCRYPT(c, bb, ct, n);
    GH_HASH(h, ct, n);
    GH_DONE(h, tag);
    GH_DESTROY(h);
    chunk_write(e, &b);
  }

  /* --- Final terminator packet --- */

  buf_init(&b, d.buf, d.sz);
  tag = buf_get(&b, GM_CLASS(m)->hashsz);
  assert(tag);
  GH_DONE(h, tag);
  GH_DESTROY(h);
  chunk_write(e, &b);

  /* --- All done --- */

  e->ops->encdone(e);
  GM_DESTROY(m);
  GC_DESTROY(c);
  GC_DESTROY(cx);
  freeenc(e);
  freekem(km);
  if (of) fclose(ofp);
  key_close(&kf);
  dstr_destroy(&d);
  return (0);

#undef f_bogus
}

/*---- Decryption ---------------------------------------------------------*/

static int decrypt(int argc, char *argv[])
{
  const char *of = 0;
  FILE *ofp = 0;
  FILE *fp = 0;
  const char *ef = "binary";
  int i;
  dstr d = DSTR_INIT;
  buf b;
  key_file kf;
  size_t seq;
  uint32 id;
  key *k;
  kem *km;
  gcipher *cx;
  gcipher *c;
  ghash *h;
  gmac *m;
  octet *tag;
  unsigned f = 0;
  const encops *eo;
  enc *e;

#define f_bogus 1u

  for (;;) {
    static const struct option opt[] = {
      { "armour",	0,		0,	'a' },
      { "armor",	0,		0,	'a' },
      { "format", 	OPTF_ARGREQ,	0,	'f' },
      { "output", 	OPTF_ARGREQ,	0,	'o' },
      { 0,		0,		0,	0 }
    };
    i = mdwopt(argc, argv, "af:o:", opt, 0, 0, 0);
    if (i < 0) break;
    switch (i) {
      case 'a': ef = "pem"; break;
      case 'f': ef = optarg; break;
      case 'o': of = optarg; break;
      default: f |= f_bogus; break;
    }
  }
  if (argc - optind > 1 || (f & f_bogus))
    die(EXIT_FAILURE, "Usage: decrypt [-options] [file]");

  if ((eo = getenc(ef)) == 0)
    die(EXIT_FAILURE, "encoding `%s' not found", ef);

  if (optind == argc)
    fp = stdin;
  else if (strcmp(argv[optind], "-") == 0) {
    fp = stdin;
    optind++;
  } else if ((fp = fopen(argv[optind], eo->rmode)) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s': %s",
	argv[optind], strerror(errno));
  } else
    optind++;

  if (key_open(&kf, keyring, KOPEN_READ, keyreport, 0))
    die(EXIT_FAILURE, "can't open keyring `%s'", keyring);

  e = initenc(eo, fp, "CATCRYPT ENCRYPTED MESSAGE", 0);

  /* --- Read the header chunk --- */

  chunk_read(e, &d, &b);
  if (buf_getu32(&b, &id))
    die(EXIT_FAILURE, "malformed header: missing keyid");
  if (BLEFT(&b))
    die(EXIT_FAILURE, "malformed header: junk at end");

  /* --- Find the key --- */

  if ((k = key_byid(&kf, id)) == 0)
    die(EXIT_FAILURE, "key id %08lx not found", (unsigned long)id);
  km = getkem(k, "ccrypt", 1);

  /* --- Read the KEM chunk --- */

  chunk_read(e, &d, &b);
  if (setupkem(km, &d, &cx, &c, &m))
    die(EXIT_FAILURE, "failed to decapsulate key");

  /* --- Now decrypt the main body --- */

  if (!of || strcmp(of, "-") == 0)
    ofp = stdout;
  else if ((ofp = fopen(of, "wb")) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s' for output: %s",
	ofp, strerror(errno));
  }

  seq = 0;
  dstr_ensure(&d, GC_CLASS(c)->blksz);
  dstr_ensure(&d, 4);
  for (;;) {
    if (GC_CLASS(c)->blksz) {
      GC_ENCRYPT(cx, 0, d.buf, GC_CLASS(c)->blksz);
      GC_SETIV(c, d.buf);
    }
    h = GM_INIT(m);
    STORE32(d.buf, seq);
    GH_HASH(h, d.buf, 4);
    seq++;
    chunk_read(e, &d, &b);
    if ((tag = buf_get(&b, GM_CLASS(m)->hashsz)) == 0)
      die(EXIT_FAILURE, "bad ciphertext chunk: no tag");
    GH_HASH(h, BCUR(&b), BLEFT(&b));
    if (memcmp(tag, GH_DONE(h, 0), GM_CLASS(m)->hashsz) != 0)
      die(EXIT_FAILURE, "bad ciphertext chunk: authentication failure");
    if (!BLEFT(&b))
      break;
    GC_DECRYPT(c, BCUR(&b), BCUR(&b), BLEFT(&b));
    if (fwrite(BCUR(&b), 1, BLEFT(&b), ofp) != BLEFT(&b))
      die(EXIT_FAILURE, "error writing output: %s", strerror(errno));
  }

  if (fflush(ofp) || ferror(ofp))
    die(EXIT_FAILURE, "error writing output: %s", strerror(errno));
    
  e->ops->decdone(e);
  freeenc(e);
  GC_DESTROY(c);
  GC_DESTROY(cx);
  GM_DESTROY(m);
  freekem(km);
  if (of) fclose(ofp);
  key_close(&kf);
  dstr_destroy(&d);
  return (0);

#undef f_bogus
}

/*----- Test code ---------------------------------------------------------*/

static int encode(int argc, char *argv[])
{
  const char *of = 0;
  FILE *ofp = 0;
  FILE *fp = 0;
  const char *ef = "binary";
  const char *bd = "MESSAGE";
  int i;
  size_t n;
  char buf[4096];
  unsigned f = 0;
  const encops *eo;
  enc *e;

#define f_bogus 1u

  for (;;) {
    static const struct option opt[] = {
      { "format", 	OPTF_ARGREQ,	0,	'f' },
      { "boundary", 	OPTF_ARGREQ,	0,	'b' },
      { "output", 	OPTF_ARGREQ,	0,	'o' },
      { 0,		0,		0,	0 }
    };
    i = mdwopt(argc, argv, "f:b:o:", opt, 0, 0, 0);
    if (i < 0) break;
    switch (i) {
      case 'f': ef = optarg; break;
      case 'b': bd = optarg; break;
      case 'o': of = optarg; break;
      default: f |= f_bogus; break;
    }
  }
  if (argc - optind > 1 || (f & f_bogus))
    die(EXIT_FAILURE, "Usage: encode [-options] [file]");

  if ((eo = getenc(ef)) == 0)
    die(EXIT_FAILURE, "encoding `%s' not found", ef);

  if (optind == argc)
    fp = stdin;
  else if (strcmp(argv[optind], "-") == 0) {
    fp = stdin;
    optind++;
  } else if ((fp = fopen(argv[optind], "rb")) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s': %s",
	argv[optind], strerror(errno));
  } else
    optind++;

  if (!of || strcmp(of, "-") == 0)
    ofp = stdout;
  else if ((ofp = fopen(of, eo->wmode)) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s' for output: %s",
	ofp, strerror(errno));
  }

  e = initenc(eo, ofp, bd, 1);

  do {
    n = fread(buf, 1, sizeof(buf), fp);
    if (e->ops->write(e, buf, n))
      die(EXIT_FAILURE, "error writing output: %s", strerror(errno));
  } while (n == sizeof(buf));
  e->ops->encdone(e);
  freeenc(e);
  return (0);

#undef f_bogus
}

static int decode(int argc, char *argv[])
{
  const char *of = 0;
  FILE *ofp = 0;
  FILE *fp = 0;
  const char *ef = "binary";
  const char *bd = 0;
  int i;
  char buf[4096];
  unsigned f = 0;
  const encops *eo;
  enc *e;

#define f_bogus 1u

  for (;;) {
    static const struct option opt[] = {
      { "format", 	OPTF_ARGREQ,	0,	'f' },
      { "boundary", 	OPTF_ARGREQ,	0,	'b' },
      { "output", 	OPTF_ARGREQ,	0,	'o' },
      { 0,		0,		0,	0 }
    };
    i = mdwopt(argc, argv, "f:b:o:", opt, 0, 0, 0);
    if (i < 0) break;
    switch (i) {
      case 'f': ef = optarg; break;
      case 'b': bd = optarg; break;
      case 'o': of = optarg; break;
      default: f |= f_bogus; break;
    }
  }
  if (argc - optind > 1 || (f & f_bogus))
    die(EXIT_FAILURE, "Usage: decode [-options] [file]");

  if ((eo = getenc(ef)) == 0)
    die(EXIT_FAILURE, "encoding `%s' not found", ef);

  if (optind == argc)
    fp = stdin;
  else if (strcmp(argv[optind], "-") == 0) {
    fp = stdin;
    optind++;
  } else if ((fp = fopen(argv[optind], eo->rmode)) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s': %s",
	argv[optind], strerror(errno));
  } else
    optind++;

  if (!of || strcmp(of, "-") == 0)
    ofp = stdout;
  else if ((ofp = fopen(of, "wb")) == 0) {
    die(EXIT_FAILURE, "couldn't open file `%s' for output: %s",
	ofp, strerror(errno));
  }

  e = initenc(eo, fp, bd, 0);

  do {
    if ((i = e->ops->read(e, buf, sizeof(buf))) < 0)
      die(EXIT_FAILURE, "error reading input: %s", strerror(errno));
    if (fwrite(buf, 1, i, ofp) < i)
      die(EXIT_FAILURE, "error writing output: %s", strerror(errno));
  } while (i == sizeof(buf));
  e->ops->decdone(e);
  freeenc(e);
  return (0);

#undef f_bogus
}

/*----- Main code ---------------------------------------------------------*/

typedef struct cmd {
  const char *name;
  int (*func)(int /*argc*/, char */*argv*/[]);
  const char *usage;
  const char *help;
} cmd;

static cmd cmdtab[] = {
  { "encode", encode,
    "encode [-f format] [-b label] [-o output] [file]",
    "\
Options:\n\
\n\
-f, --format=FORMAT	Encode to FORMAT.\n\
-b, --boundary=LABEL	PEM boundary is LABEL.\n\
-o, --output=FILE	Write output to FILE.\n\
" },
  { "decode", decode,
    "decode [-f format] [-b label] [-o output] [file]",
    "\
Options:\n\
\n\
-f, --format=FORMAT	Decode from FORMAT.\n\
-b, --boundary=LABEL	PEM boundary is LABEL.\n\
-o, --output=FILE	Write output to FILE.\n\
" },
  { "encrypt", encrypt,
    "encrypt [-a] [-k tag] [f format]] [-o output] [file]",
    "\
Options:\n\
\n\
-a, --armour		Same as `-f pem'.\n\
-f, --format=FORMAT	Encode as FORMAT.\n\
-k, --key=TAG		Use public key named by TAG.\n\
-o, --output=FILE	Write output to FILE.\n\
" },
  { "decrypt", decrypt,
    "decrypt [-t] [-o output] [file]", "\
Options:\n\
\n\
-t, --text		Read PEM-encoded input.\n\
-o, --output=FILE	Write output to FILE.\n\
" },
  { 0, 0, 0 }
};

/* --- @findcmd@ --- *
 *
 * Arguments:	@const char *name@ = a command name
 *
 * Returns:	Pointer to the command structure.
 *
 * Use:		Looks up a command by name.  If the command isn't found, an
 *		error is reported and the program is terminated.
 */

static cmd *findcmd(const char *name)
{
  cmd *c, *chosen = 0;
  size_t sz = strlen(name);

  for (c = cmdtab; c->name; c++) {
    if (strncmp(name, c->name, sz) == 0) {
      if (c->name[sz] == 0) {
	chosen = c;
	break;
      } else if (chosen)
	die(EXIT_FAILURE, "ambiguous command name `%s'", name);
      else
	chosen = c;
    }
  }
  if (!chosen)
    die(EXIT_FAILURE, "unknown command name `%s'", name);
  return (chosen);
}

static void version(FILE *fp)
{
  pquis(fp, "$, Catacomb version " VERSION "\n");
}

static void usage(FILE *fp)
{
  pquis(fp, "Usage: $ [-k keyring] command [args]\n");
}

static void help(FILE *fp, char **argv)
{
  cmd *c;

  if (*argv) {
    c = findcmd(*argv);
    fprintf(fp, "Usage: %s [-k keyring] %s\n", QUIS, c->usage);
    if (c->help) {
      fputc('\n', fp);	
      fputs(c->help, fp);
    }
  } else {
    version(fp);
    fputc('\n', fp);
    usage(fp);
    fputs("\n\
Create and verify signatures on lists of files.\n\
\n", fp);
    for (c = cmdtab; c->name; c++)
      fprintf(fp, "%s\n", c->usage);
  }
}

/* --- @main@ --- *
 *
 * Arguments:	@int argc@ = number of command line arguments
 *		@char *argv[]@ = vector of command line arguments
 *
 * Returns:	Zero if successful, nonzero otherwise.
 *
 * Use:		Signs or verifies signatures on lists of files.  Useful for
 *		ensuring that a distribution is unmolested.
 */

int main(int argc, char *argv[])
{
  unsigned f = 0;

#define f_bogus 1u

  /* --- Initialize the library --- */

  ego(argv[0]);
  sub_init();
  rand_noisesrc(RAND_GLOBAL, &noise_source);
  rand_seed(RAND_GLOBAL, 160);

  /* --- Parse options --- */

  for (;;) {
    static struct option opts[] = {
      { "help",		0,		0,	'h' },
      { "version",	0,		0,	'v' },
      { "usage",	0,		0,	'u' },
      { "keyring",	OPTF_ARGREQ,	0,	'k' },
      { 0,		0,		0,	0 }
    };
    int i = mdwopt(argc, argv, "+hvu k:", opts, 0, 0, 0);
    if (i < 0)
      break;
    switch (i) {
      case 'h':
	help(stdout, argv + optind);
	exit(0);
	break;
      case 'v':
	version(stdout);
	exit(0);
	break;
      case 'u':
	usage(stdout);
	exit(0);
      case 'k':
	keyring = optarg;
	break;
      default:
	f |= f_bogus;
	break;
    }
  }

  argc -= optind;
  argv += optind;
  optind = 0;
  if (f & f_bogus || argc < 1) {
    usage(stderr);
    exit(EXIT_FAILURE);
  }

  /* --- Dispatch to the correct subcommand handler --- */

  return (findcmd(argv[0])->func(argc, argv));

#undef f_bogus
}

/*----- That's all, folks -------------------------------------------------*/