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-rw-r--r--sm/encrypt.c550
1 files changed, 550 insertions, 0 deletions
diff --git a/sm/encrypt.c b/sm/encrypt.c
new file mode 100644
index 000000000..725a81b70
--- /dev/null
+++ b/sm/encrypt.c
@@ -0,0 +1,550 @@
+/* encrypt.c - Encrypt a message
+ * Copyright (C) 2001, 2003 Free Software Foundation, Inc.
+ *
+ * This file is part of GnuPG.
+ *
+ * GnuPG is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * GnuPG 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <time.h>
+#include <assert.h>
+
+#include "gpgsm.h"
+#include <gcrypt.h>
+#include <ksba.h>
+
+#include "keydb.h"
+#include "i18n.h"
+
+
+struct dek_s {
+ const char *algoid;
+ int algo;
+ gcry_cipher_hd_t chd;
+ char key[32];
+ int keylen;
+ char iv[32];
+ int ivlen;
+};
+typedef struct dek_s *DEK;
+
+struct encrypt_cb_parm_s {
+ FILE *fp;
+ DEK dek;
+ int eof_seen;
+ int ready;
+ int readerror;
+ int bufsize;
+ unsigned char *buffer;
+ int buflen;
+};
+
+
+
+
+
+/* initialize the data encryptionkey (session key) */
+static int
+init_dek (DEK dek)
+{
+ int rc=0, mode, i;
+
+ dek->algo = gcry_cipher_map_name (dek->algoid);
+ mode = gcry_cipher_mode_from_oid (dek->algoid);
+ if (!dek->algo || !mode)
+ {
+ log_error ("unsupported algorithm `%s'\n", dek->algoid);
+ return gpg_error (GPG_ERR_UNSUPPORTED_ALGORITHM);
+ }
+
+ dek->keylen = gcry_cipher_get_algo_keylen (dek->algo);
+ if (!dek->keylen || dek->keylen > sizeof (dek->key))
+ return gpg_error (GPG_ERR_BUG);
+
+ dek->ivlen = gcry_cipher_get_algo_blklen (dek->algo);
+ if (!dek->ivlen || dek->ivlen > sizeof (dek->iv))
+ return gpg_error (GPG_ERR_BUG);
+
+ if (dek->keylen < 100/8)
+ { /* make sure we don't use weak keys */
+ log_error ("key length of `%s' too small\n", dek->algoid);
+ return gpg_error (GPG_ERR_UNSUPPORTED_ALGORITHM);
+ }
+
+ rc = gcry_cipher_open (&dek->chd, dek->algo, mode, GCRY_CIPHER_SECURE);
+ if (rc)
+ {
+ log_error ("failed to create cipher context: %s\n", gpg_strerror (rc));
+ return rc;
+ }
+
+ for (i=0; i < 8; i++)
+ {
+ gcry_randomize (dek->key, dek->keylen, GCRY_STRONG_RANDOM );
+ rc = gcry_cipher_setkey (dek->chd, dek->key, dek->keylen);
+ if (gpg_err_code (rc) != GPG_ERR_WEAK_KEY)
+ break;
+ log_info(_("weak key created - retrying\n") );
+ }
+ if (rc)
+ {
+ log_error ("failed to set the key: %s\n", gpg_strerror (rc));
+ gcry_cipher_close (dek->chd);
+ dek->chd = NULL;
+ return rc;
+ }
+
+ gcry_randomize (dek->iv, dek->ivlen, GCRY_STRONG_RANDOM);
+ rc = gcry_cipher_setiv (dek->chd, dek->iv, dek->ivlen);
+ if (rc)
+ {
+ log_error ("failed to set the IV: %s\n", gpg_strerror (rc));
+ gcry_cipher_close (dek->chd);
+ dek->chd = NULL;
+ return rc;
+ }
+
+ return 0;
+}
+
+
+/* Encode the session key. NBITS is the number of bits which should be
+ used for packing the session key. returns: An mpi with the session
+ key (caller must free) */
+static gcry_mpi_t
+encode_session_key (DEK dek, unsigned int nbits)
+{
+ int nframe = (nbits+7) / 8;
+ byte *p;
+ byte *frame;
+ int i,n;
+ gcry_mpi_t a;
+
+ if (dek->keylen + 7 > nframe || !nframe)
+ log_bug ("can't encode a %d bit key in a %d bits frame\n",
+ dek->keylen*8, nbits );
+
+ /* We encode the session key in this way:
+ *
+ * 0 2 RND(n bytes) 0 KEY(k bytes)
+ *
+ * (But how can we store the leading 0 - the external representaion
+ * of MPIs doesn't allow leading zeroes =:-)
+ *
+ * RND are non-zero random bytes.
+ * KEY is the encryption key (session key)
+ */
+
+ frame = gcry_xmalloc_secure (nframe);
+ n = 0;
+ frame[n++] = 0;
+ frame[n++] = 2;
+ i = nframe - 3 - dek->keylen;
+ assert (i > 0);
+ p = gcry_random_bytes_secure (i, GCRY_STRONG_RANDOM);
+ /* replace zero bytes by new values */
+ for (;;)
+ {
+ int j, k;
+ byte *pp;
+
+ /* count the zero bytes */
+ for(j=k=0; j < i; j++ )
+ {
+ if( !p[j] )
+ k++;
+ }
+ if( !k )
+ break; /* okay: no zero bytes */
+
+ k += k/128; /* better get some more */
+ pp = gcry_random_bytes_secure (k, GCRY_STRONG_RANDOM);
+ for (j=0; j < i && k; j++)
+ {
+ if( !p[j] )
+ p[j] = pp[--k];
+ }
+ xfree (pp);
+ }
+ memcpy (frame+n, p, i);
+ xfree (p);
+
+ n += i;
+ frame[n++] = 0;
+ memcpy (frame+n, dek->key, dek->keylen);
+ n += dek->keylen;
+ assert (n == nframe);
+ if (gcry_mpi_scan (&a, GCRYMPI_FMT_USG, frame, n, &nframe) )
+ BUG ();
+ gcry_free(frame);
+
+ return a;
+}
+
+
+
+/* encrypt the DEK under the key contained in CERT and return it as a
+ canonical S-Exp in encval */
+static int
+encrypt_dek (const DEK dek, KsbaCert cert, char **encval)
+{
+ gcry_sexp_t s_ciph, s_data, s_pkey;
+ int rc;
+ KsbaSexp buf;
+ size_t len;
+
+ *encval = NULL;
+
+ /* get the key from the cert */
+ buf = ksba_cert_get_public_key (cert);
+ if (!buf)
+ {
+ log_error ("no public key for recipient\n");
+ return gpg_error (GPG_ERR_NO_PUBKEY);
+ }
+ len = gcry_sexp_canon_len (buf, 0, NULL, NULL);
+ if (!len)
+ {
+ log_error ("libksba did not return a proper S-Exp\n");
+ return gpg_error (GPG_ERR_BUG);
+ }
+ rc = gcry_sexp_sscan (&s_pkey, NULL, buf, len);
+ xfree (buf); buf = NULL;
+ if (rc)
+ {
+ log_error ("gcry_sexp_scan failed: %s\n", gpg_strerror (rc));
+ return rc;
+ }
+
+ /* put the encoded cleartext into a simple list */
+ {
+ /* fixme: actually the pkcs-1 encoding should go into libgcrypt */
+ gcry_mpi_t data = encode_session_key (dek, gcry_pk_get_nbits (s_pkey));
+ if (!data)
+ {
+ gcry_mpi_release (data);
+ return gpg_error (GPG_ERR_GENERAL);
+ }
+ if (gcry_sexp_build (&s_data, NULL, "%m", data))
+ BUG ();
+ gcry_mpi_release (data);
+ }
+
+ /* pass it to libgcrypt */
+ rc = gcry_pk_encrypt (&s_ciph, s_data, s_pkey);
+ gcry_sexp_release (s_data);
+ gcry_sexp_release (s_pkey);
+
+ /* reformat it */
+ len = gcry_sexp_sprint (s_ciph, GCRYSEXP_FMT_CANON, NULL, 0);
+ assert (len);
+ buf = xtrymalloc (len);
+ if (!buf)
+ {
+ gpg_error_t tmperr = OUT_OF_CORE (errno);
+ gcry_sexp_release (s_ciph);
+ return tmperr;
+ }
+ len = gcry_sexp_sprint (s_ciph, GCRYSEXP_FMT_CANON, buf, len);
+ assert (len);
+
+ *encval = buf;
+ return 0;
+}
+
+
+
+/* do the actual encryption */
+static int
+encrypt_cb (void *cb_value, char *buffer, size_t count, size_t *nread)
+{
+ struct encrypt_cb_parm_s *parm = cb_value;
+ int blklen = parm->dek->ivlen;
+ unsigned char *p;
+ size_t n;
+
+ *nread = 0;
+ if (!buffer)
+ return -1; /* not supported */
+
+ if (parm->ready)
+ return -1;
+
+ if (count < blklen)
+ BUG ();
+
+ if (!parm->eof_seen)
+ { /* fillup the buffer */
+ p = parm->buffer;
+ for (n=parm->buflen; n < parm->bufsize; n++)
+ {
+ int c = getc (parm->fp);
+ if (c == EOF)
+ {
+ if (ferror (parm->fp))
+ {
+ parm->readerror = errno;
+ return -1;
+ }
+ parm->eof_seen = 1;
+ break;
+ }
+ p[n] = c;
+ }
+ parm->buflen = n;
+ }
+
+ n = parm->buflen < count? parm->buflen : count;
+ n = n/blklen * blklen;
+ if (n)
+ { /* encrypt the stuff */
+ gcry_cipher_encrypt (parm->dek->chd, buffer, n, parm->buffer, n);
+ *nread = n;
+ /* Who cares about cycles, take the easy way and shift the buffer */
+ parm->buflen -= n;
+ memmove (parm->buffer, parm->buffer+n, parm->buflen);
+ }
+ else if (parm->eof_seen)
+ { /* no complete block but eof: add padding */
+ /* fixme: we should try to do this also in the above code path */
+ int i, npad = blklen - (parm->buflen % blklen);
+ p = parm->buffer;
+ for (n=parm->buflen, i=0; n < parm->bufsize && i < npad; n++, i++)
+ p[n] = npad;
+ gcry_cipher_encrypt (parm->dek->chd, buffer, n, parm->buffer, n);
+ *nread = n;
+ parm->ready = 1;
+ }
+
+ return 0;
+}
+
+
+
+
+/* Perform an encrypt operation.
+
+ Encrypt the data received on DATA-FD and write it to OUT_FP. The
+ recipients are take from the certificate given in recplist; if this
+ is NULL it will be encrypted for a default recipient */
+int
+gpgsm_encrypt (CTRL ctrl, CERTLIST recplist, int data_fd, FILE *out_fp)
+{
+ int rc = 0;
+ Base64Context b64writer = NULL;
+ KsbaError err;
+ KsbaWriter writer;
+ KsbaReader reader = NULL;
+ KsbaCMS cms = NULL;
+ KsbaStopReason stopreason;
+ KEYDB_HANDLE kh = NULL;
+ struct encrypt_cb_parm_s encparm;
+ DEK dek = NULL;
+ int recpno;
+ FILE *data_fp = NULL;
+ CERTLIST cl;
+
+ memset (&encparm, 0, sizeof encparm);
+
+ if (!recplist)
+ {
+ log_error(_("no valid recipients given\n"));
+ gpgsm_status (ctrl, STATUS_NO_RECP, "0");
+ rc = gpg_error (GPG_ERR_NO_PUBKEY);
+ goto leave;
+ }
+
+ kh = keydb_new (0);
+ if (!kh)
+ {
+ log_error (_("failed to allocated keyDB handle\n"));
+ rc = gpg_error (GPG_ERR_GENERAL);
+ goto leave;
+ }
+
+ data_fp = fdopen ( dup (data_fd), "rb");
+ if (!data_fp)
+ {
+ rc = gpg_error (gpg_err_code_from_errno (errno));
+ log_error ("fdopen() failed: %s\n", strerror (errno));
+ goto leave;
+ }
+
+ reader = ksba_reader_new ();
+ if (!reader)
+ rc = KSBA_Out_Of_Core;
+ if (!rc)
+ rc = ksba_reader_set_cb (reader, encrypt_cb, &encparm);
+ if (rc)
+ {
+ rc = map_ksba_err (rc);
+ goto leave;
+ }
+ encparm.fp = data_fp;
+
+ ctrl->pem_name = "ENCRYPTED MESSAGE";
+ rc = gpgsm_create_writer (&b64writer, ctrl, out_fp, &writer);
+ if (rc)
+ {
+ log_error ("can't create writer: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+
+ cms = ksba_cms_new ();
+ if (!cms)
+ {
+ rc = gpg_error (GPG_ERR_ENOMEM);
+ goto leave;
+ }
+
+ err = ksba_cms_set_reader_writer (cms, reader, writer);
+ if (err)
+ {
+ log_debug ("ksba_cms_set_reader_writer failed: %s\n",
+ ksba_strerror (err));
+ rc = map_ksba_err (err);
+ goto leave;
+ }
+
+ /* We are going to create enveloped data with uninterpreted data as
+ inner content */
+ err = ksba_cms_set_content_type (cms, 0, KSBA_CT_ENVELOPED_DATA);
+ if (!err)
+ err = ksba_cms_set_content_type (cms, 1, KSBA_CT_DATA);
+ if (err)
+ {
+ log_debug ("ksba_cms_set_content_type failed: %s\n",
+ ksba_strerror (err));
+ rc = map_ksba_err (err);
+ goto leave;
+ }
+
+ /* create a session key */
+ dek = xtrycalloc (1, sizeof *dek); /* hmmm: should we put it into secmem?*/
+ if (!dek)
+ rc = OUT_OF_CORE (errno);
+ else
+ {
+ dek->algoid = opt.def_cipher_algoid;
+ rc = init_dek (dek);
+ }
+ if (rc)
+ {
+ log_error ("failed to create the session key: %s\n",
+ gpg_strerror (rc));
+ goto leave;
+ }
+
+ err = ksba_cms_set_content_enc_algo (cms, dek->algoid, dek->iv, dek->ivlen);
+ if (err)
+ {
+ log_error ("ksba_cms_set_content_enc_algo failed: %s\n",
+ ksba_strerror (err));
+ rc = map_ksba_err (err);
+ goto leave;
+ }
+
+ encparm.dek = dek;
+ /* Use a ~8k (AES) or ~4k (3DES) buffer */
+ encparm.bufsize = 500 * dek->ivlen;
+ encparm.buffer = xtrymalloc (encparm.bufsize);
+ if (!encparm.buffer)
+ {
+ rc = OUT_OF_CORE (errno);
+ goto leave;
+ }
+
+ /* gather certificates of recipients, encrypt the session key for
+ each and store them in the CMS object */
+ for (recpno = 0, cl = recplist; cl; recpno++, cl = cl->next)
+ {
+ char *encval;
+
+ rc = encrypt_dek (dek, cl->cert, &encval);
+ if (rc)
+ {
+ log_error ("encryption failed for recipient no. %d: %s\n",
+ recpno, gpg_strerror (rc));
+ goto leave;
+ }
+
+ err = ksba_cms_add_recipient (cms, cl->cert);
+ if (err)
+ {
+ log_error ("ksba_cms_add_recipient failed: %s\n",
+ ksba_strerror (err));
+ rc = map_ksba_err (err);
+ xfree (encval);
+ goto leave;
+ }
+
+ err = ksba_cms_set_enc_val (cms, recpno, encval);
+ xfree (encval);
+ if (err)
+ {
+ log_error ("ksba_cms_set_enc_val failed: %s\n",
+ ksba_strerror (err));
+ rc = map_ksba_err (err);
+ goto leave;
+ }
+ }
+
+ /* main control loop for encryption */
+ recpno = 0;
+ do
+ {
+ err = ksba_cms_build (cms, &stopreason);
+ if (err)
+ {
+ log_debug ("ksba_cms_build failed: %s\n", ksba_strerror (err));
+ rc = map_ksba_err (err);
+ goto leave;
+ }
+ }
+ while (stopreason != KSBA_SR_READY);
+
+ if (encparm.readerror)
+ {
+ log_error ("error reading input: %s\n", strerror (encparm.readerror));
+ rc = gpg_error (gpg_err_code_from_errno (encparm.readerror));
+ goto leave;
+ }
+
+
+ rc = gpgsm_finish_writer (b64writer);
+ if (rc)
+ {
+ log_error ("write failed: %s\n", gpg_strerror (rc));
+ goto leave;
+ }
+ log_info ("encrypted data created\n");
+
+ leave:
+ ksba_cms_release (cms);
+ gpgsm_destroy_writer (b64writer);
+ ksba_reader_release (reader);
+ keydb_release (kh);
+ xfree (dek);
+ if (data_fp)
+ fclose (data_fp);
+ xfree (encparm.buffer);
+ return rc;
+}
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