diff options
Diffstat (limited to 'g10/cipher.c')
| -rw-r--r-- | g10/cipher.c | 31 |
1 files changed, 22 insertions, 9 deletions
diff --git a/g10/cipher.c b/g10/cipher.c index b270a4aee..0bed51300 100644 --- a/g10/cipher.c +++ b/g10/cipher.c @@ -49,22 +49,27 @@ write_header( cipher_filter_context_t *cfx, IOBUF a ) unsigned nprefix; int use_mdc = opt.force_mdc; + blocksize = cipher_get_blocksize( 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; ed.new_ctb = !ed.len && !opt.rfc1991; if( use_mdc ) { ed.mdc_method = DIGEST_ALGO_SHA1; cfx->mdc_hash = md_open( DIGEST_ALGO_SHA1, 0 ); - /*md_start_debug( cfx->mdc_hash, "mdccreat" );*/ + /*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 = cipher_get_blocksize( cfx->dek->algo ); - if( blocksize < 8 || blocksize > 16 ) - log_fatal("unsupported blocksize %u\n", blocksize ); nprefix = blocksize; randomize_buffer( temp, nprefix, 1 ); temp[nprefix] = temp[nprefix-2]; @@ -75,8 +80,6 @@ write_header( cipher_filter_context_t *cfx, IOBUF a ) cipher_setkey( cfx->cipher_hd, cfx->dek->key, cfx->dek->keylen ); cipher_setiv( cfx->cipher_hd, NULL, 0 ); /* log_hexdump( "prefix", temp, nprefix+2 ); */ - if( cfx->mdc_hash ) - md_write( cfx->mdc_hash, temp, nprefix+2 ); cipher_encrypt( cfx->cipher_hd, temp, temp, nprefix+2); cipher_sync( cfx->cipher_hd ); iobuf_write(a, temp, nprefix+2); @@ -115,12 +118,22 @@ cipher_filter( void *opaque, int control, if( cfx->mdc_hash ) { byte *hash; int hashlen = md_digest_length( 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; + md_putc( cfx->mdc_hash, temp[0] ); + md_putc( cfx->mdc_hash, temp[1] ); + md_final( cfx->mdc_hash ); hash = md_read( cfx->mdc_hash, 0 ); - cipher_encrypt( cfx->cipher_hd, hash, hash, hashlen ); - if( iobuf_write( a, hash, hashlen ) ) - rc = G10ERR_WRITE_FILE; + memcpy(temp+2, hash, 20); + cipher_encrypt( cfx->cipher_hd, temp, temp, 22 ); md_close( cfx->mdc_hash ); cfx->mdc_hash = NULL; + if( iobuf_write( a, temp, 22 ) ) + log_error("writing MDC packet failed\n" ); } cipher_close(cfx->cipher_hd); write_status( STATUS_END_ENCRYPTION ); |