See ChangeLog: Fri Jul 14 19:38:23 CEST 2000 Werner Koch

1 files changed, 35 insertions, 14 deletions

diff --git a/g10/cipher.c b/g10/cipher.c
index 8fc0d3815..cad6ff664 100644
--- a/g10/cipher.c
+++ b/g10/cipher.c
@@ -1,5 +1,5 @@
 /* cipher.c - En-/De-ciphering filter
- *	Copyright (C) 1998,1999 Free Software Foundation, Inc.
+ *	Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
  *
  * This file is part of GnuPG.
  *
@@ -33,6 +33,7 @@
 #include "packet.h"
 #include "options.h"
 #include "main.h"
+#include "status.h"
 
 
 #define MIN_PARTIAL_SIZE 512
@@ -44,10 +45,18 @@ write_header( cipher_filter_context_t *cfx, IOBUF a )
     PACKET pkt;
     PKT_encrypted ed;
     byte temp[18];
-    int blocksize;
-    unsigned nprefix;
-    int use_mdc = opt.force_mdc;
+    unsigned int blocksize;
+    unsigned int nprefix;
     int rc;
+    int use_mdc = opt.force_mdc;
+
+    blocksize = gcry_cipher_get_algo_blklen( cfx->dek->algo );
+    if( blocksize < 8 || blocksize > 16 )
+	log_fatal("unsupported blocksize %u\n", blocksize );
+    if( blocksize != 8 )
+	use_mdc = 1;  /* enable it for all modern ciphers */
+    if( opt.rfc2440 )
+	use_mdc = 0;  /* override - rfc2440 does not know about MDC */
 
     memset( &ed, 0, sizeof ed );
     ed.len = cfx->datalen;
@@ -55,18 +64,16 @@ write_header( cipher_filter_context_t *cfx, IOBUF a )
     if( use_mdc ) {
 	ed.mdc_method = GCRY_MD_SHA1;
 	cfx->mdc_hash = gcry_md_open( GCRY_MD_SHA1, 0 );
-	/*should we check the function works, or is it better to provide
-	  a flag which makes the function die itself ?? FIXME */
-	/*md_start_debug( cfx->mdc_hash, "mdccreat" );*/
+	if( !cfx->mdc_hash )
+	    BUG();
+	if ( DBG_HASHING )
+	    gcry_md_start_debug( cfx->mdc_hash, "creatmdc" );
     }
     init_packet( &pkt );
     pkt.pkttype = use_mdc? PKT_ENCRYPTED_MDC : PKT_ENCRYPTED;
     pkt.pkt.encrypted = &ed;
     if( build_packet( a, &pkt ))
 	log_bug("build_packet(ENCR_DATA) failed\n");
-    blocksize = gcry_cipher_get_algo_blklen( cfx->dek->algo );
-    if( blocksize < 8 || blocksize > 16 )
-	log_fatal("unsupported blocksize %d\n", blocksize );
     nprefix = blocksize;
     gcry_randomize( temp, nprefix, GCRY_STRONG_RANDOM );
     temp[nprefix] = temp[nprefix-2];
@@ -75,7 +82,7 @@ write_header( cipher_filter_context_t *cfx, IOBUF a )
     if( !(cfx->cipher_hd = gcry_cipher_open( cfx->dek->algo,
 				       GCRY_CIPHER_MODE_CFB,
 				       GCRY_CIPHER_SECURE
-				       | (cfx->dek->algo >= 100 ?
+				       | ((use_mdc || cfx->dek->algo >= 100) ?
 					     0 : GCRY_CIPHER_ENABLE_SYNC)))
 				     ) {
 	/* we should never get an error here cause we already checked, that
@@ -83,6 +90,7 @@ write_header( cipher_filter_context_t *cfx, IOBUF a )
 	BUG();
     }
 
+
 /*   log_hexdump( "thekey", cfx->dek->key, cfx->dek->keylen );*/
     rc = gcry_cipher_setkey( cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen );
     if( !rc )
@@ -99,6 +107,7 @@ write_header( cipher_filter_context_t *cfx, IOBUF a )
 	log_fatal("encrypt failed: %s\n", gcry_strerror(rc) );
     iobuf_write(a, temp, nprefix+2);
     cfx->header=1;
+
 }
 
 
@@ -120,6 +129,7 @@ cipher_filter( void *opaque, int control,
     else if( control == IOBUFCTRL_FLUSH ) { /* encrypt */
 	assert(a);
 	if( !cfx->header ) {
+	    write_status( STATUS_BEGIN_ENCRYPTION );
 	    write_header( cfx, a );
 	}
 	if( cfx->mdc_hash )
@@ -134,15 +144,26 @@ cipher_filter( void *opaque, int control,
 	if( cfx->mdc_hash ) {
 	    byte *hash;
 	    int hashlen = gcry_md_get_algo_dlen( gcry_md_get_algo( cfx->mdc_hash ) );
+	    byte temp[22];
+
+	    assert( hashlen == 20 );
+	    /* we must hash the prefix of the MDC packet here */
+	    temp[0] = 0xd3;
+	    temp[1] = 0x14;
+	    gcry_md_putc( cfx->mdc_hash, temp[0] );
+	    gcry_md_putc( cfx->mdc_hash, temp[1] );
+
 	    hash = gcry_md_read( cfx->mdc_hash, 0 );
-	    rc = gcry_cipher_encrypt( cfx->cipher_hd, hash, hashlen, NULL, 0 );
+	    memcpy(temp+2, hash, 20);
+	    rc = gcry_cipher_encrypt( cfx->cipher_hd, temp, 22, NULL, 0 );
 	    if( rc )
 		log_fatal("encrypt failed: %s\n", gcry_strerror(rc) );
-	    if( iobuf_write( a, hash, hashlen ) )
-		rc = GPGERR_WRITE_FILE;
 	    gcry_md_close( cfx->mdc_hash ); cfx->mdc_hash = NULL;
+	    if( iobuf_write( a, temp, 22 ) )
+		log_error("writing MDC packet failed\n" );
 	}
 	gcry_cipher_close(cfx->cipher_hd);
+	write_status( STATUS_END_ENCRYPTION );
     }
     else if( control == IOBUFCTRL_DESC ) {
 	*(char**)buf = "cipher_filter";