This commit was manufactured by cvs2svn to create branch

'GNUPG-1-9-BRANCH'.

1 files changed, 307 insertions, 0 deletions

diff --git a/g10/pubkey-enc.c b/g10/pubkey-enc.c
new file mode 100644
index 000000000..1c52ce4de
--- /dev/null
+++ b/g10/pubkey-enc.c
@@ -0,0 +1,307 @@
+/* pubkey-enc.c -  public key encoded packet handling
+ * Copyright (C) 1998, 1999, 2000, 2001, 2002 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 <assert.h>
+#include "util.h"
+#include "memory.h"
+#include "packet.h"
+#include "mpi.h"
+#include "keydb.h"
+#include "trustdb.h"
+#include "cipher.h"
+#include "status.h"
+#include "options.h"
+#include "main.h"
+#include "i18n.h"
+
+static int get_it( PKT_pubkey_enc *k,
+		   DEK *dek, PKT_secret_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 keyblock, preftype_t type, int algo )
+{
+    KBNODE 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->is_revoked && !uid->is_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.
+ */
+int
+get_session_key( PKT_pubkey_enc *k, DEK *dek )
+{
+    PKT_secret_key *sk = NULL;
+    int rc;
+
+    rc = check_pubkey_algo2 (k->pubkey_algo, PUBKEY_USAGE_ENC);
+    if( rc )
+	goto leave;
+
+    if( (k->keyid[0] || k->keyid[1]) && !opt.try_all_secrets ) {
+	sk = m_alloc_clear( sizeof *sk );
+	sk->pubkey_algo = k->pubkey_algo; /* we want a pubkey with this algo*/
+	if( !(rc = get_seckey( sk, k->keyid )) )
+	    rc = get_it( k, dek, sk, k->keyid );
+    }
+    else { /* anonymous receiver: Try all available secret keys */
+	void *enum_context = NULL;
+	u32 keyid[2];
+	char *p;
+
+	for(;;) {
+	    if( sk )
+		free_secret_key( sk );
+	    sk = m_alloc_clear( sizeof *sk );
+	    rc=enum_secret_keys( &enum_context, sk, 1, 0);
+	    if( rc ) {
+		rc = G10ERR_NO_SECKEY;
+		break;
+	    }
+	    if( sk->pubkey_algo != k->pubkey_algo )
+		continue;
+	    keyid_from_sk( sk, keyid );
+	    log_info(_("anonymous recipient; trying secret key %08lX ...\n"),
+                     (ulong)keyid[1] );
+
+	    if(!opt.try_all_secrets && !is_status_enabled())
+	      {
+		p=get_last_passphrase();
+		set_next_passphrase(p);
+		m_free(p);
+	      }
+
+	    rc = check_secret_key( sk, opt.try_all_secrets?1:-1 ); /* ask
+								      only
+								      once */
+	    if( !rc )
+		rc = get_it( k, dek, sk, keyid );
+	    if( !rc ) {
+		log_info(_("okay, we are the anonymous recipient.\n") );
+		break;
+	    }
+	}
+	enum_secret_keys( &enum_context, NULL, 0, 0 ); /* free context */
+    }
+
+  leave:
+    if( sk )
+	free_secret_key( sk );
+    return rc;
+}
+
+
+static int
+get_it( PKT_pubkey_enc *enc, DEK *dek, PKT_secret_key *sk, u32 *keyid )
+{
+    int rc;
+    MPI plain_dek  = NULL;
+    byte *frame = NULL;
+    unsigned n, nframe;
+    u16 csum, csum2;
+
+    rc = pubkey_decrypt(sk->pubkey_algo, &plain_dek, enc->data, sk->skey );
+    if( rc )
+	goto leave;
+    frame = mpi_get_buffer( plain_dek, &nframe, NULL );
+    mpi_free( plain_dek ); plain_dek = NULL;
+
+    /* Now get the DEK (data encryption key) from the frame
+     *
+     * Old versions encode the DEK in 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_CIPHER )
+	log_hexdump("DEK frame:", frame, nframe );
+    n=0;
+    if( n + 7 > nframe )
+	{ rc = G10ERR_WRONG_SECKEY; goto leave; }
+    if( frame[n] == 1 && frame[nframe-1] == 2 ) {
+	log_info(_("old encoding of the DEK is not supported\n"));
+	rc = G10ERR_CIPHER_ALGO;
+	goto leave;
+    }
+    if( frame[n] != 2 )  /* somethink is wrong */
+	{ rc = G10ERR_WRONG_SECKEY; goto leave; }
+    for(n++; n < nframe && frame[n]; n++ ) /* skip the random bytes */
+	;
+    n++; /* and the zero byte */
+    if( n + 4 > nframe )
+	{ rc = G10ERR_WRONG_SECKEY; goto leave; }
+
+    dek->keylen = nframe - (n+1) - 2;
+    dek->algo = frame[n++];
+    if( dek->algo ==  CIPHER_ALGO_IDEA )
+	write_status(STATUS_RSA_OR_IDEA);
+    rc = check_cipher_algo( dek->algo );
+    if( rc ) {
+	if( !opt.quiet && rc == G10ERR_CIPHER_ALGO ) {
+	    log_info(_("cipher algorithm %d%s is unknown or disabled\n"),
+                     dek->algo, dek->algo == CIPHER_ALGO_IDEA? " (IDEA)":"");
+	    if(dek->algo==CIPHER_ALGO_IDEA)
+	      idea_cipher_warn(0);
+	}
+	dek->algo = 0;
+	goto leave;
+    }
+    if( (dek->keylen*8) != cipher_get_keylen( dek->algo ) ) {
+	rc = G10ERR_WRONG_SECKEY;
+	goto leave;
+    }
+
+    /* copy the key to DEK and compare the checksum */
+    csum  = frame[nframe-2] << 8;
+    csum |= frame[nframe-1];
+    memcpy( dek->key, frame+n, dek->keylen );
+    for( csum2=0, n=0; n < dek->keylen; n++ )
+	csum2 += dek->key[n];
+    if( csum != csum2 ) {
+	rc = G10ERR_WRONG_SECKEY;
+	goto leave;
+    }
+    if( DBG_CIPHER )
+	log_hexdump("DEK is:", dek->key, dek->keylen );
+    /* check that the algo is in the preferences and whether it has expired */
+    {
+	PKT_public_key *pk = NULL;
+        KBNODE pkb = get_pubkeyblock (keyid);
+
+	if( !pkb ) {
+            rc = -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
+	    && !is_algo_in_prefs( pkb, PREFTYPE_SYM, dek->algo ) ) {
+	    /* Don't print a note while we are not on verbose mode,
+	     * the cipher is blowfish and the preferences have twofish
+	     * listed */
+	    if( opt.verbose || dek->algo != CIPHER_ALGO_BLOWFISH
+		|| !is_algo_in_prefs( pkb, PREFTYPE_SYM, CIPHER_ALGO_TWOFISH))
+		log_info(_(
+		    "NOTE: cipher algorithm %d not found in preferences\n"),
+								 dek->algo );
+	}
+
+        if (!rc) {
+            KBNODE k;
+            
+            for (k=pkb; k; k = k->next) {
+                if (k->pkt->pkttype == PKT_PUBLIC_KEY 
+                    || k->pkt->pkttype == PKT_PUBLIC_SUBKEY){
+                    u32 aki[2];
+        	    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 %08lX expired at %s\n"),
+                         (ulong)keyid[1], asctimestamp( pk->expiredate) );
+            }
+        }
+
+        if ( pk &&  pk->is_revoked ) {
+            log_info( _("NOTE: key has been revoked") );
+            putc( '\n', log_stream() );
+            show_revocation_reason( pk, 1 );
+        }
+
+	release_kbnode (pkb);
+	rc = 0;
+    }
+
+
+  leave:
+    mpi_free(plain_dek);
+    m_free(frame);
+    return rc;
+}
+
+
+/****************
+ * Get the session key from the given string.
+ * String is supposed to be formatted as this:
+ *  <algo-id>:<even-number-of-hex-digits>
+ */
+int
+get_override_session_key( DEK *dek, const char *string )
+{
+    const char *s;
+    int i;
+
+    if ( !string )
+	return G10ERR_BAD_KEY;
+    dek->algo = atoi(string);
+    if ( dek->algo < 1 )
+	return G10ERR_BAD_KEY;
+    if ( !(s = strchr ( string, ':' )) )
+	return G10ERR_BAD_KEY;
+    s++;
+    for(i=0; i < DIM(dek->key) && *s; i++, s +=2 ) {
+	int c = hextobyte ( s );
+	if (c == -1)
+	    return G10ERR_BAD_KEY;
+	dek->key[i] = c;
+    }
+    if ( *s )
+	return G10ERR_BAD_KEY;
+    dek->keylen = i;
+    return 0;
+}
+