Adding upstream version 2.2.27.upstream/2.2.27upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 497 insertions, 0 deletions

diff --git a/g10/pubkey-enc.c b/g10/pubkey-enc.c
new file mode 100644
index 0000000..30a4bc0
--- /dev/null
+++ b/g10/pubkey-enc.c
@@ -0,0 +1,497 @@
+/* pubkey-enc.c - Process a public key encoded packet.
+ * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2006, 2009,
+ *               2010 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 3 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, see <https://www.gnu.org/licenses/>.
+ */
+
+#include <config.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "gpg.h"
+#include "../common/util.h"
+#include "packet.h"
+#include "keydb.h"
+#include "trustdb.h"
+#include "../common/status.h"
+#include "options.h"
+#include "main.h"
+#include "../common/i18n.h"
+#include "pkglue.h"
+#include "call-agent.h"
+#include "../common/host2net.h"
+#include "../common/compliance.h"
+
+
+static gpg_error_t get_it (ctrl_t ctrl, PKT_pubkey_enc *k,
+                           DEK *dek, PKT_public_key *sk, u32 *keyid);
+
+
+/* Check that the given algo is mentioned in one of the valid user-ids. */
+static int
+is_algo_in_prefs (kbnode_t keyblock, preftype_t type, int algo)
+{
+  kbnode_t k;
+
+  for (k = keyblock; k; k = k->next)
+    {
+      if (k->pkt->pkttype == PKT_USER_ID)
+        {
+          PKT_user_id *uid = k->pkt->pkt.user_id;
+          prefitem_t *prefs = uid->prefs;
+
+          if (uid->created && prefs && !uid->flags.revoked && !uid->flags.expired)
+            {
+              for (; prefs->type; prefs++)
+                if (prefs->type == type && prefs->value == algo)
+                  return 1;
+            }
+        }
+    }
+  return 0;
+}
+
+
+/*
+ * Get the session key from a pubkey enc packet and return it in DEK,
+ * which should have been allocated in secure memory by the caller.
+ */
+gpg_error_t
+get_session_key (ctrl_t ctrl, PKT_pubkey_enc * k, DEK * dek)
+{
+  PKT_public_key *sk = NULL;
+  int rc;
+
+  if (DBG_CLOCK)
+    log_clock ("get_session_key enter");
+
+  rc = openpgp_pk_test_algo2 (k->pubkey_algo, PUBKEY_USAGE_ENC);
+  if (rc)
+    goto leave;
+
+  if ((k->keyid[0] || k->keyid[1]) && !opt.try_all_secrets)
+    {
+      sk = xmalloc_clear (sizeof *sk);
+      sk->pubkey_algo = k->pubkey_algo; /* We want a pubkey with this algo.  */
+      if (!(rc = get_seckey (ctrl, sk, k->keyid)))
+        {
+          /* Check compliance.  */
+          if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_DECRYPTION,
+                                     sk->pubkey_algo, 0,
+                                     sk->pkey, nbits_from_pk (sk), NULL))
+            {
+              log_info (_("key %s is not suitable for decryption"
+                          " in %s mode\n"),
+                        keystr_from_pk (sk),
+                        gnupg_compliance_option_string (opt.compliance));
+              rc = gpg_error (GPG_ERR_PUBKEY_ALGO);
+            }
+          else
+            rc = get_it (ctrl, k, dek, sk, k->keyid);
+        }
+    }
+  else if (opt.skip_hidden_recipients)
+    rc = gpg_error (GPG_ERR_NO_SECKEY);
+  else  /* Anonymous receiver: Try all available secret keys.  */
+    {
+      void *enum_context = NULL;
+      u32 keyid[2];
+
+      for (;;)
+        {
+          sk = xmalloc_clear (sizeof *sk);
+          rc = enum_secret_keys (ctrl, &enum_context, sk);
+          if (rc)
+            {
+              sk = NULL;  /* enum_secret_keys turns SK into a shallow copy! */
+              rc = GPG_ERR_NO_SECKEY;
+              break;
+            }
+          if (sk->pubkey_algo != k->pubkey_algo)
+            continue;
+          if (!(sk->pubkey_usage & PUBKEY_USAGE_ENC))
+            continue;
+          keyid_from_pk (sk, keyid);
+          if (!opt.quiet)
+            log_info (_("anonymous recipient; trying secret key %s ...\n"),
+                      keystr (keyid));
+
+          /* Check compliance.  */
+          if (! gnupg_pk_is_allowed (opt.compliance, PK_USE_DECRYPTION,
+                                     sk->pubkey_algo, 0,
+                                     sk->pkey, nbits_from_pk (sk), NULL))
+            {
+              log_info (_("key %s is not suitable for decryption"
+                          " in %s mode\n"),
+                          keystr_from_pk (sk),
+                          gnupg_compliance_option_string (opt.compliance));
+              continue;
+            }
+
+          rc = get_it (ctrl, k, dek, sk, keyid);
+          if (!rc)
+            {
+              if (!opt.quiet)
+                log_info (_("okay, we are the anonymous recipient.\n"));
+              sk = NULL;
+              break;
+            }
+          else if (gpg_err_code (rc) == GPG_ERR_FULLY_CANCELED)
+            {
+              sk = NULL;
+              break; /* Don't try any more secret keys.  */
+            }
+        }
+      enum_secret_keys (ctrl, &enum_context, NULL);  /* free context */
+    }
+
+ leave:
+  free_public_key (sk);
+  if (DBG_CLOCK)
+    log_clock ("get_session_key leave");
+  return rc;
+}
+
+
+static gpg_error_t
+get_it (ctrl_t ctrl,
+        PKT_pubkey_enc *enc, DEK *dek, PKT_public_key *sk, u32 *keyid)
+{
+  gpg_error_t err;
+  byte *frame = NULL;
+  unsigned int n;
+  size_t nframe;
+  u16 csum, csum2;
+  int padding;
+  gcry_sexp_t s_data;
+  char *desc;
+  char *keygrip;
+  byte fp[MAX_FINGERPRINT_LEN];
+  size_t fpn;
+
+  if (DBG_CLOCK)
+    log_clock ("decryption start");
+
+  /* Get the keygrip.  */
+  err = hexkeygrip_from_pk (sk, &keygrip);
+  if (err)
+    goto leave;
+
+  /* Convert the data to an S-expression.  */
+  if (sk->pubkey_algo == PUBKEY_ALGO_ELGAMAL
+      || sk->pubkey_algo == PUBKEY_ALGO_ELGAMAL_E)
+    {
+      if (!enc->data[0] || !enc->data[1])
+        err = gpg_error (GPG_ERR_BAD_MPI);
+      else
+        err = gcry_sexp_build (&s_data, NULL, "(enc-val(elg(a%m)(b%m)))",
+                               enc->data[0], enc->data[1]);
+    }
+  else if (sk->pubkey_algo == PUBKEY_ALGO_RSA
+           || sk->pubkey_algo == PUBKEY_ALGO_RSA_E)
+    {
+      if (!enc->data[0])
+        err = gpg_error (GPG_ERR_BAD_MPI);
+      else
+        err = gcry_sexp_build (&s_data, NULL, "(enc-val(rsa(a%m)))",
+                               enc->data[0]);
+    }
+  else if (sk->pubkey_algo == PUBKEY_ALGO_ECDH)
+    {
+      if (!enc->data[0] || !enc->data[1])
+        err = gpg_error (GPG_ERR_BAD_MPI);
+      else
+        err = gcry_sexp_build (&s_data, NULL, "(enc-val(ecdh(s%m)(e%m)))",
+                               enc->data[1], enc->data[0]);
+    }
+  else
+    err = gpg_error (GPG_ERR_BUG);
+
+  if (err)
+    goto leave;
+
+  if (sk->pubkey_algo == PUBKEY_ALGO_ECDH)
+    {
+      fingerprint_from_pk (sk, fp, &fpn);
+      log_assert (fpn == 20);
+    }
+
+  /* Decrypt. */
+  desc = gpg_format_keydesc (ctrl, sk, FORMAT_KEYDESC_NORMAL, 1);
+  err = agent_pkdecrypt (NULL, keygrip,
+                         desc, sk->keyid, sk->main_keyid, sk->pubkey_algo,
+                         s_data, &frame, &nframe, &padding);
+  xfree (desc);
+  gcry_sexp_release (s_data);
+  if (err)
+    goto leave;
+
+  /* Now get the DEK (data encryption key) from the frame
+   *
+   * Old versions encode the DEK in this format (msb is left):
+   *
+   *     0  1  DEK(16 bytes)  CSUM(2 bytes)  0  RND(n bytes) 2
+   *
+   * Later versions encode the DEK like this:
+   *
+   *     0  2  RND(n bytes)  0  A  DEK(k bytes)  CSUM(2 bytes)
+   *
+   * (mpi_get_buffer already removed the leading zero).
+   *
+   * RND are non-zero randow bytes.
+   * A   is the cipher algorithm
+   * DEK is the encryption key (session key) with length k
+   * CSUM
+   */
+  if (DBG_CRYPTO)
+    log_printhex (frame, nframe, "DEK frame:");
+  n = 0;
+
+  if (sk->pubkey_algo == PUBKEY_ALGO_ECDH)
+    {
+      gcry_mpi_t shared_mpi;
+      gcry_mpi_t decoded;
+
+      /* At the beginning the frame are the bytes of shared point MPI.  */
+      err = gcry_mpi_scan (&shared_mpi, GCRYMPI_FMT_USG, frame, nframe, NULL);
+      if (err)
+        {
+          err = gpg_error (GPG_ERR_WRONG_SECKEY);
+          goto leave;
+        }
+
+      err = pk_ecdh_decrypt (&decoded, fp, enc->data[1]/*encr data as an MPI*/,
+                             shared_mpi, sk->pkey);
+      mpi_release (shared_mpi);
+      if(err)
+        goto leave;
+
+      xfree (frame);
+      err = gcry_mpi_aprint (GCRYMPI_FMT_USG, &frame, &nframe, decoded);
+      mpi_release (decoded);
+      if (err)
+        goto leave;
+
+      /* Now the frame are the bytes decrypted but padded session key.  */
+      if (!nframe || nframe <= 8
+          || frame[nframe-1] > nframe)
+        {
+          err = gpg_error (GPG_ERR_WRONG_SECKEY);
+          goto leave;
+        }
+      nframe -= frame[nframe-1]; /* Remove padding.  */
+      log_assert (!n); /* (used just below) */
+    }
+  else
+    {
+      if (padding)
+        {
+          if (n + 7 > nframe)
+            {
+              err = gpg_error (GPG_ERR_WRONG_SECKEY);
+              goto leave;
+            }
+
+          /* FIXME: Actually the leading zero is required but due to
+           * the way we encode the output in libgcrypt as an MPI we
+           * are not able to encode that leading zero.  However, when
+           * using a Smartcard we are doing it the right way and
+           * therefore we have to skip the zero.  This should be fixed
+           * in gpg-agent of course. */
+          if (!frame[n])
+            n++;
+
+          if (frame[n] == 1 && frame[nframe - 1] == 2)
+            {
+              log_info (_("old encoding of the DEK is not supported\n"));
+              err = gpg_error (GPG_ERR_CIPHER_ALGO);
+              goto leave;
+            }
+          if (frame[n] != 2) /* Something went wrong.  */
+            {
+              err = gpg_error (GPG_ERR_WRONG_SECKEY);
+              goto leave;
+            }
+          for (n++; n < nframe && frame[n]; n++) /* Skip the random bytes.  */
+            ;
+          n++; /* Skip the zero byte.  */
+        }
+    }
+
+  if (n + 4 > nframe)
+    {
+      err = gpg_error (GPG_ERR_WRONG_SECKEY);
+      goto leave;
+    }
+
+  dek->keylen = nframe - (n + 1) - 2;
+  dek->algo = frame[n++];
+  err = openpgp_cipher_test_algo (dek->algo);
+  if (err)
+    {
+      if (!opt.quiet && gpg_err_code (err) == GPG_ERR_CIPHER_ALGO)
+        {
+          log_info (_("cipher algorithm %d%s is unknown or disabled\n"),
+                    dek->algo,
+                    dek->algo == CIPHER_ALGO_IDEA ? " (IDEA)" : "");
+        }
+      dek->algo = 0;
+      goto leave;
+    }
+  if (dek->keylen != openpgp_cipher_get_algo_keylen (dek->algo))
+    {
+      err = gpg_error (GPG_ERR_WRONG_SECKEY);
+      goto leave;
+    }
+
+  /* Copy the key to DEK and compare the checksum.  */
+  csum = buf16_to_u16 (frame+nframe-2);
+  memcpy (dek->key, frame + n, dek->keylen);
+  for (csum2 = 0, n = 0; n < dek->keylen; n++)
+    csum2 += dek->key[n];
+  if (csum != csum2)
+    {
+      err = gpg_error (GPG_ERR_WRONG_SECKEY);
+      goto leave;
+    }
+  if (DBG_CLOCK)
+    log_clock ("decryption ready");
+  if (DBG_CRYPTO)
+    log_printhex (dek->key, dek->keylen, "DEK is:");
+
+  /* Check that the algo is in the preferences and whether it has
+   * expired.  Also print a status line with the key's fingerprint.  */
+  {
+    PKT_public_key *pk = NULL;
+    PKT_public_key *mainpk = NULL;
+    KBNODE pkb = get_pubkeyblock (ctrl, keyid);
+
+    if (!pkb)
+      {
+        err = -1;
+        log_error ("oops: public key not found for preference check\n");
+      }
+    else if (pkb->pkt->pkt.public_key->selfsigversion > 3
+             && dek->algo != CIPHER_ALGO_3DES
+             && !opt.quiet
+             && !is_algo_in_prefs (pkb, PREFTYPE_SYM, dek->algo))
+      log_info (_("WARNING: cipher algorithm %s not found in recipient"
+                  " preferences\n"), openpgp_cipher_algo_name (dek->algo));
+
+    if (!err)
+      {
+        kbnode_t k;
+        int first = 1;
+
+        for (k = pkb; k; k = k->next)
+          {
+            if (k->pkt->pkttype == PKT_PUBLIC_KEY
+                || k->pkt->pkttype == PKT_PUBLIC_SUBKEY)
+              {
+                u32 aki[2];
+
+                if (first)
+                  {
+                    first = 0;
+                    mainpk = k->pkt->pkt.public_key;
+                  }
+
+                keyid_from_pk (k->pkt->pkt.public_key, aki);
+                if (aki[0] == keyid[0] && aki[1] == keyid[1])
+                  {
+                    pk = k->pkt->pkt.public_key;
+                    break;
+                  }
+              }
+          }
+        if (!pk)
+          BUG ();
+        if (pk->expiredate && pk->expiredate <= make_timestamp ())
+          {
+            log_info (_("Note: secret key %s expired at %s\n"),
+                      keystr (keyid), asctimestamp (pk->expiredate));
+          }
+      }
+
+    if (pk && pk->flags.revoked)
+      {
+        log_info (_("Note: key has been revoked"));
+        log_printf ("\n");
+        show_revocation_reason (ctrl, pk, 1);
+      }
+
+    if (is_status_enabled () && pk && mainpk)
+      {
+        char pkhex[MAX_FINGERPRINT_LEN*2+1];
+        char mainpkhex[MAX_FINGERPRINT_LEN*2+1];
+
+        hexfingerprint (pk, pkhex, sizeof pkhex);
+        hexfingerprint (mainpk, mainpkhex, sizeof mainpkhex);
+
+        /* Note that we do not want to create a trustdb just for
+         * getting the ownertrust: If there is no trustdb there can't
+         * be ulitmately trusted key anyway and thus the ownertrust
+         * value is irrelevant.  */
+        write_status_printf (STATUS_DECRYPTION_KEY, "%s %s %c",
+                             pkhex, mainpkhex,
+                             get_ownertrust_info (ctrl, mainpk, 1));
+
+      }
+
+    release_kbnode (pkb);
+    err = 0;
+  }
+
+ leave:
+  xfree (frame);
+  xfree (keygrip);
+  return err;
+}
+
+
+/*
+ * Get the session key from the given string.
+ * String is supposed to be formatted as this:
+ *  <algo-id>:<even-number-of-hex-digits>
+ */
+gpg_error_t
+get_override_session_key (DEK *dek, const char *string)
+{
+  const char *s;
+  int i;
+
+  if (!string)
+    return GPG_ERR_BAD_KEY;
+  dek->algo = atoi (string);
+  if (dek->algo < 1)
+    return GPG_ERR_BAD_KEY;
+  if (!(s = strchr (string, ':')))
+    return GPG_ERR_BAD_KEY;
+  s++;
+  for (i = 0; i < DIM (dek->key) && *s; i++, s += 2)
+    {
+      int c = hextobyte (s);
+      if (c == -1)
+        return GPG_ERR_BAD_KEY;
+      dek->key[i] = c;
+    }
+  if (*s)
+    return GPG_ERR_BAD_KEY;
+  dek->keylen = i;
+  return 0;
+}