See ChangeLog: Mon Jan 24 13:04:28 CET 2000 Werner Koch
[gnupg.git] / g10 / seckey-cert.c
index 4e1a384..10f7092 100644 (file)
@@ -1,14 +1,14 @@
-/* seckey-cert.c -  secret key certifucate packet handling
- *     Copyright (c) 1997 by Werner Koch (dd9jn)
+/* seckey-cert.c -  secret key certificate packet handling
+ *     Copyright (C) 1998, 1999 Free Software Foundation, Inc.
  *
- * This file is part of G10.
+ * This file is part of GnuPG.
  *
- * G10 is free software; you can redistribute it and/or modify
+ * 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.
  *
- * G10 is distributed in the hope that it will be useful,
+ * 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.
 #include <stdlib.h>
 #include <string.h>
 #include <assert.h>
+
+#include <gcrypt.h>
 #include "util.h"
-#include "memory.h"
 #include "packet.h"
-#include "mpi.h"
 #include "keydb.h"
-#include "cipher.h"
+#include "main.h"
+#include "options.h"
+#include "i18n.h"
+#include "status.h"
 
-#if  BLOWFISH_BLOCKSIZE != 8
-  #error unsupportted blocksize
-#endif
 
-static u16
-checksum( byte *p )
+static int
+do_check( PKT_secret_key *sk )
 {
-    u16 n, a;
+    byte *buffer;
+    u16 csum=0;
+    int i, res;
+    unsigned nbytes;
 
-    n = *p++ << 8;
-    n |= *p++;
-    for(a=0; n; n-- )
-       a += *p++;
-    return a;
-}
+    if( sk->is_protected ) { /* remove the protection */
+       DEK *dek = NULL;
+       u32 keyid[4]; /* 4! because we need two of them */
+       GCRY_CIPHER_HD cipher_hd=NULL;
+       PKT_secret_key *save_sk;
 
+       if( sk->protect.algo == GCRY_CIPHER_NONE )
+           BUG();
+       if( openpgp_cipher_test_algo( sk->protect.algo ) ) {
+           log_info(_("protection algorithm %d is not supported\n"),
+                       sk->protect.algo );
+           return G10ERR_CIPHER_ALGO;
+       }
+       keyid_from_sk( sk, keyid );
+       keyid[2] = keyid[3] = 0;
+       if( !sk->is_primary ) {
+           PKT_secret_key *sk2 = gcry_xcalloc( 1, sizeof *sk2 );
+           if( !get_primary_seckey( sk2, keyid ) )
+               keyid_from_sk( sk2, keyid+2 );
+           free_secret_key( sk2 );
+       }
+       dek = passphrase_to_dek( keyid, sk->pubkey_algo, sk->protect.algo,
+                                &sk->protect.s2k, 0 );
+       if( !(cipher_hd = gcry_cipher_open( sk->protect.algo,
+                                     GCRY_CIPHER_MODE_CFB,
+                                     GCRY_CIPHER_SECURE
+                                     | (sk->protect.algo >= 100 ?
+                                          0 : GCRY_CIPHER_ENABLE_SYNC) ) )
+                                   ) {
+           BUG();
+       }
 
+       if( gcry_cipher_setkey( cipher_hd, dek->key, dek->keylen ) )
+           log_fatal("set key failed: %s\n", gcry_strerror(-1) );
+       gcry_free(dek);
+       save_sk = copy_secret_key( NULL, sk );
+       if( gcry_cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen ))
+           log_fatal("set IV failed: %s\n", gcry_strerror(-1) );
+       csum = 0;
+       if( sk->version >= 4 ) {
+           size_t ndata;
+           unsigned int ndatabits;
+           byte *p, *data;
 
-static int
-check_elg( PKT_seckey_cert *cert )
-{
-    byte iv[8];
-    byte *mpibuf;
-    u16 n;
-    MPI temp_mpi;
-    int res;
-    u32 keyid[2];
-    ELG_secret_key skey;
-
-    if( cert->d.elg.is_protected ) { /* remove the protection */
-       DEK *dek = NULL;
-       BLOWFISH_context *blowfish_ctx=NULL;
-
-       switch( cert->d.elg.protect_algo ) {
-         case CIPHER_ALGO_NONE: log_bug(NULL); break;
-         case CIPHER_ALGO_BLOWFISH:
-           keyid_from_skc( cert, keyid );
-           dek = get_passphrase_hash( keyid, NULL );
-           m_free(dek); /* pw is in secure memory, so m_free() burns it */
-           memset( iv, 0, BLOWFISH_BLOCKSIZE );
-           blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
-           blowfish_setiv( blowfish_ctx, iv );
-           blowfish_decode_cfb( blowfish_ctx,
-                                cert->d.elg.protect.blowfish.iv,
-                                cert->d.elg.protect.blowfish.iv, 8 );
-           cert->d.elg.calc_csum = 0;
-           mpibuf = (byte*)cert->d.elg.x;
-           n = ((mpibuf[0] << 8) | mpibuf[1])-2;
-           blowfish_decode_cfb( blowfish_ctx, mpibuf+4, mpibuf+4, n );
-           cert->d.elg.calc_csum += checksum( mpibuf );
-           cert->d.elg.x = mpi_decode_buffer( mpibuf );
-           m_free( mpibuf );
-           m_free( blowfish_ctx );
-           cert->d.elg.is_protected = 0;
-           /* now let's see wether we have used the right passphrase */
-           if( cert->d.elg.calc_csum != cert->d.elg.csum )
-               return G10ERR_BAD_PASS;
-
-           skey.p = cert->d.elg.p;
-           skey.g = cert->d.elg.g;
-           skey.y = cert->d.elg.y;
-           skey.x = cert->d.elg.x;
-           res = elg_check_secret_key( &skey );
-           memset( &skey, 0, sizeof skey );
-           if( !res )
-               return G10ERR_BAD_PASS;
-           break;
+           i = pubkey_get_npkey(sk->pubkey_algo);
+           assert( gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
+           p = gcry_mpi_get_opaque( sk->skey[i], &ndatabits );
+           ndata = (ndatabits+7)/8;
+           data = gcry_xmalloc_secure( ndata );
+           gcry_cipher_decrypt( cipher_hd, data, ndata, p, ndata );
+           mpi_release( sk->skey[i] ); sk->skey[i] = NULL ;
+           p = data;
+           if( ndata < 2 ) {
+               log_error("not enough bytes for checksum\n");
+               sk->csum = 0;
+               csum = 1;
+           }
+           else {
+               csum = checksum( data, ndata-2);
+               sk->csum = data[ndata-2] << 8 | data[ndata-1];
+           }
+           /* must check it here otherwise the mpi_read_xx would fail
+            * because the length may have an arbitrary value */
+           if( sk->csum == csum ) {
+               for( ; i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
+                   nbytes = ndata;
+                   assert( gcry_is_secure( p ) );
+                   res = gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_PGP,
+                                                            p, &nbytes);
+                   if( res )
+                       log_bug("gcry_mpi_scan failed in do_check: rc=%d\n", res);
 
-         default:
-           return G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
+                   ndata -= nbytes;
+                   p += nbytes;
+               }
+           }
+           gcry_free(data);
        }
+       else {
+           for(i=pubkey_get_npkey(sk->pubkey_algo);
+                   i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
+               size_t ndata;
+               unsigned int ndatabits;
+               byte *p, *data;
+
+               assert( gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
+               p = gcry_mpi_get_opaque( sk->skey[i], &ndatabits );
+               ndata = (ndatabits+7)/8;
+               data = gcry_xmalloc_secure( ndata );
+               gcry_cipher_sync( cipher_hd );
+               gcry_cipher_decrypt( cipher_hd, data, ndata, p, ndata );
+               mpi_release( sk->skey[i] ); sk->skey[i] = NULL ;
+
+               res = gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_USG,
+                                    data, &ndata );
+               if( res )
+                   log_bug("gcry_mpi_scan failed in do_check: rc=%d\n", res);
+
+               csum += checksum_mpi( sk->skey[i] );
+               gcry_free( buffer );
+           }
+       }
+       gcry_cipher_close( cipher_hd );
+       /* now let's see whether we have used the right passphrase */
+       if( csum != sk->csum ) {
+           copy_secret_key( sk, save_sk );
+           free_secret_key( save_sk );
+           return G10ERR_BAD_PASS;
+       }
+       /* the checksum may fail, so we also check the key itself */
+       res = pubkey_check_secret_key( sk->pubkey_algo, sk->skey );
+       if( res ) {
+           copy_secret_key( sk, save_sk );
+           free_secret_key( save_sk );
+           return G10ERR_BAD_PASS;
+       }
+       free_secret_key( save_sk );
+       sk->is_protected = 0;
     }
-    /* must check the checksum here, because we didn't do it when
-     * parsing an unprotected certificate */
-    if( cert->d.elg.calc_csum != cert->d.elg.csum ) {
-       log_error("checksum in secret key certificate is wrong\n");
-       log_debug("stored csum=%04hx calculated csum=%04hx\n",
-                  cert->d.elg.csum, cert->d.elg.calc_csum );
-       return G10ERR_CHECKSUM;
+    else { /* not protected, assume it is okay if the checksum is okay */
+       csum = 0;
+       for(i=pubkey_get_npkey(sk->pubkey_algo);
+               i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
+           csum += checksum_mpi( sk->skey[i] );
+       }
+       if( csum != sk->csum )
+           return G10ERR_CHECKSUM;
     }
+
     return 0;
 }
 
 
-#ifdef HAVE_RSA_CIPHER
-static int
-check_rsa( PKT_seckey_cert *cert )
+
+/****************
+ * Check the secret key
+ * Ask up to 3 (or n) times for a correct passphrase
+ */
+int
+check_secret_key( PKT_secret_key *sk, int n )
 {
-    byte iv[8];
-    byte *mpibuf;
-    u16 n;
-    MPI temp_mpi;
-    int res;
-    u32 keyid[2];
-
-    if( cert->d.rsa.is_protected ) { /* remove the protection */
-       DEK *dek = NULL;
-       BLOWFISH_context *blowfish_ctx=NULL;
+    int rc = G10ERR_BAD_PASS;
+    int i;
 
-       switch( cert->d.rsa.protect_algo ) {
-         case CIPHER_ALGO_NONE:
-           log_bug("unprotect seckey_cert is flagged protected\n");
-           break;
-         case CIPHER_ALGO_BLOWFISH:
-           keyid_from_skc( cert, keyid );
-           dek = get_passphrase_hash( keyid, NULL );
-
-           m_free(dek); /* pw is in secure memory, so m_free() burns it */
-           memset( iv, 0, BLOWFISH_BLOCKSIZE );
-           blowfish_ctx = m_alloc_secure( sizeof *blowfish_ctx );
-           blowfish_setiv( blowfish_ctx, iv );
-           blowfish_decode_cfb( blowfish_ctx,
-                                cert->d.rsa.protect.blowfish.iv,
-                                cert->d.rsa.protect.blowfish.iv, 8 );
-           cert->d.rsa.calc_csum = 0;
-         #define X(a) do {                                             \
-                   mpibuf = (byte*)cert->d.rsa.rsa_##a;                \
-                   n = ((mpibuf[0] << 8) | mpibuf[1])-2;               \
-                   blowfish_decode_cfb( blowfish_ctx,                  \
-                                        mpibuf+4, mpibuf+4, n );       \
-                   cert->d.rsa.calc_csum += checksum( mpibuf );        \
-                   cert->d.rsa.rsa_##a = mpi_decode_buffer( mpibuf );  \
-                   m_free( mpibuf );                                   \
-               } while(0)
-           X(d);
-           X(p);
-           X(q);
-           X(u);
-         #undef X
-           m_free( blowfish_ctx );
-           cert->d.rsa.is_protected = 0;
-         #if 0
-           #define X(a) do { printf("\tRSA " #a ": ");                   \
-                             mpi_print(stdout, cert->d.rsa.rsa_##a, 1 ); \
-                             putchar('\n');                              \
-                           } while(0)
-           X(n); X(e); X(d); X(p); X(q); X(u);
-           #undef X
-         #endif
-           /* now let's see wether we have used the right passphrase */
-           if( cert->d.rsa.calc_csum != cert->d.rsa.csum )
-               return G10ERR_BAD_PASS;
-           temp_mpi = mpi_alloc(40);
-           mpi_mul(temp_mpi, cert->d.rsa.rsa_p, cert->d.rsa.rsa_q );
-           res = mpi_cmp( temp_mpi, cert->d.rsa.rsa_n );
-           mpi_free(temp_mpi);
-           if( res )
-               return G10ERR_BAD_PASS;
-           break;
+    if( n < 1 )
+       n = opt.batch? 1 : 3; /* use the default value */
 
-         default:
-           return G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
+    for(i=0; i < n && rc == G10ERR_BAD_PASS; i++ ) {
+       if( i )
+           log_info(_("Invalid passphrase; please try again ...\n"));
+       rc = do_check( sk );
+       if( rc == G10ERR_BAD_PASS && is_status_enabled() ) {
+           u32 kid[2];
+           char buf[50];
+
+           keyid_from_sk( sk, kid );
+           sprintf(buf, "%08lX%08lX", (ulong)kid[0], (ulong)kid[1]);
+           write_status_text( STATUS_BAD_PASSPHRASE, buf );
        }
+       if( have_static_passphrase() )
+           break;
     }
-    /* must check the checksum here, because we didn't do it when
-     * parsing an unprotected certificate */
-    if( cert->d.rsa.calc_csum != cert->d.rsa.csum ) {
-       log_error("checksum in secret key certificate is wrong\n");
-       log_debug("stored csum=%04hx calculated csum=%04hx\n",
-                  cert->d.rsa.csum, cert->d.rsa.calc_csum );
-       return G10ERR_CHECKSUM;
-    }
-    return 0;
+
+    if( !rc )
+       write_status( STATUS_GOOD_PASSPHRASE );
+
+    return rc;
 }
-#endif /*HAVE_RSA_CIPHER*/
 
+/****************
+ * check whether the secret key is protected.
+ * Returns: 0 not protected, -1 on error or the protection algorithm
+ */
+int
+is_secret_key_protected( PKT_secret_key *sk )
+{
+    return sk->is_protected? sk->protect.algo : 0;
+}
 
 
 
 /****************
- * Check the secret key certificate
+ * Protect the secret key with the passphrase from DEK
  */
 int
-check_secret_key( PKT_seckey_cert *cert )
+protect_secret_key( PKT_secret_key *sk, DEK *dek )
 {
-    if( cert->pubkey_algo == PUBKEY_ALGO_ELGAMAL )
-       return check_elg( cert );
-  #ifdef HAVE_RSA_CIPHER
-    else if( cert->pubkey_algo == PUBKEY_ALGO_RSA )
-       return check_rsa( cert );
-  #endif
-    else
-       return G10ERR_PUBKEY_ALGO;
+    int i,j, rc = 0;
+    byte *buffer;
+    unsigned nbytes;
+    u16 csum;
+
+    if( !dek )
+       return 0;
+
+    if( !sk->is_protected ) { /* okay, apply the protection */
+       GCRY_CIPHER_HD cipher_hd=NULL;
+
+       if( openpgp_cipher_test_algo( sk->protect.algo ) )
+           rc = G10ERR_CIPHER_ALGO; /* unsupport protection algorithm */
+       else {
+           print_cipher_algo_note( sk->protect.algo );
+           if( !(cipher_hd = gcry_cipher_open( sk->protect.algo,
+                                         GCRY_CIPHER_MODE_CFB,
+                                         GCRY_CIPHER_SECURE
+                                         | (sk->protect.algo >= 100 ?
+                                             0 : GCRY_CIPHER_ENABLE_SYNC) ))
+                                        ) {
+               BUG();
+           }
+
+
+           rc = gcry_cipher_setkey( cipher_hd, dek->key, dek->keylen );
+           if( rc == GCRYERR_WEAK_KEY ) {
+               log_info(_("WARNING: Weak key detected"
+                          " - please change passphrase again.\n"));
+               rc = 0;
+           }
+           else if( rc )
+               BUG();
+
+           /* set the IV length */
+           {   int blocksize = gcry_cipher_get_algo_blklen( sk->protect.algo );
+               if( blocksize != 8 && blocksize != 16 )
+                   log_fatal("unsupported blocksize %d\n", blocksize );
+               sk->protect.ivlen = blocksize;
+           }
+
+           assert( sk->protect.ivlen <= DIM(sk->protect.iv) );
+           gcry_randomize(sk->protect.iv, sk->protect.ivlen,
+                                                       GCRY_STRONG_RANDOM);
+           gcry_cipher_setiv( cipher_hd, sk->protect.iv, sk->protect.ivlen );
+           #warning FIXME: replace set/get buffer
+           if( sk->version >= 4 ) {
+             #define NMPIS (GNUPG_MAX_NSKEY - GNUPG_MAX_NPKEY)
+               byte *bufarr[NMPIS];
+               unsigned narr[NMPIS];
+               unsigned nbits[NMPIS];
+               int ndata=0;
+               byte *p, *data;
+
+               for(j=0, i = pubkey_get_npkey(sk->pubkey_algo);
+                       i < pubkey_get_nskey(sk->pubkey_algo); i++, j++ ) {
+                   assert( !gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
+
+                   if( gcry_mpi_aprint( GCRYMPI_FMT_USG, (char*)bufarr+j,
+                                                         narr+j, sk->skey[i]))
+                       BUG();
+
+                   nbits[j]  = gcry_mpi_get_nbits( sk->skey[i] );
+                   ndata += narr[j] + 2;
+               }
+               for( ; j < NMPIS; j++ )
+                   bufarr[j] = NULL;
+               ndata += 2; /* for checksum */
+
+               data = gcry_xmalloc_secure( ndata );
+               p = data;
+               for(j=0; j < NMPIS && bufarr[j]; j++ ) {
+                   p[0] = nbits[j] >> 8 ;
+                   p[1] = nbits[j];
+                   p += 2;
+                   memcpy(p, bufarr[j], narr[j] );
+                   p += narr[j];
+                   gcry_free(bufarr[j]);
+               }
+             #undef NMPIS
+               csum = checksum( data, ndata-2);
+               sk->csum = csum;
+               *p++ =  csum >> 8;
+               *p++ =  csum;
+               assert( p == data+ndata );
+               gcry_cipher_encrypt( cipher_hd, data, ndata, NULL, 0 );
+               for(i = pubkey_get_npkey(sk->pubkey_algo);
+                       i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
+                   mpi_release( sk->skey[i] );
+                   sk->skey[i] = NULL;
+               }
+               i = pubkey_get_npkey(sk->pubkey_algo);
+               sk->skey[i] = gcry_mpi_set_opaque(NULL, data, ndata*8 );
+           }
+           else {
+               /* NOTE: we always recalculate the checksum because there
+                * are some test releases which calculated it wrong */
+              #warning FIXME:  Replace this code
+               csum = 0;
+               for(i=pubkey_get_npkey(sk->pubkey_algo);
+                       i < pubkey_get_nskey(sk->pubkey_algo); i++ ) {
+                   csum += checksum_mpi( sk->skey[i] );
+
+                   if( gcry_mpi_aprint( GCRYMPI_FMT_USG,
+                                        &buffer, &nbytes, sk->skey[i] ) )
+                       BUG();
+
+                   gcry_cipher_sync( cipher_hd );
+                   assert( !gcry_mpi_get_flag( sk->skey[i], GCRYMPI_FLAG_OPAQUE ) );
+                   gcry_cipher_encrypt( cipher_hd, buffer, nbytes, NULL, 0 );
+                   gcry_mpi_release( sk->skey[i] );
+                   if( gcry_mpi_scan( &sk->skey[i], GCRYMPI_FMT_USG,
+                                      buffer,&nbytes ) )
+                       BUG();
+
+                   gcry_free( buffer );
+               }
+               sk->csum = csum;
+           }
+           sk->is_protected = 1;
+           gcry_cipher_close( cipher_hd );
+       }
+    }
+    return rc;
 }