1 /* keyblob.h - Defs to describe a keyblob
2 * Copyright (C) 2009 Free Software Foundation, Inc.
4 * This file is part of GnuPG.
6 * GnuPG is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 3 of the License, or
9 * (at your option) any later version.
11 * GnuPG is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, see <https://www.gnu.org/licenses/>.
23 /* The setup area (header block) is the actual core of G13. Here is
26 u8 Packet type. Value is 61 (0x3d).
27 u8 Constant value 255 (0xff).
28 u32 Length of the following structure
29 b10 Value: "GnuPG/G13\x00".
30 u8 Version. Value is 1.
33 u8 OS Flag: 0 = unspecified, 1 = Linux
34 u32 Length of the entire header. This includes all bytes
35 starting at the packet type and ending with the last
36 padding byte of the header.
37 u8 Number of copies of this header (1..255).
38 u8 Number of copies of this header at the end of the
39 container (usually 0).
41 n bytes: OpenPGP encrypted and optionally signed keyblob.
42 n bytes: CMS encrypted and optionally signed keyblob. Such a CMS
43 packet will be enclosed in a private flagged OpenPGP
44 packet. Either the OpenPGP encrypted packet as described
45 above, the CMS encrypted or both packets must exist. The
46 encapsulation packet has this structure:
47 u8 Packet type. Value is 61 (0x3d).
48 u8 Constant value 255 (0xff).
49 u32 Length of the following structure
50 b10 Value: "GnuPG/CMS\x00".
51 b(n) Regular CMS structure.
52 n bytes: Padding. The structure resembles an OpenPGP packet.
53 u8 Packet type. Value is 61 (0x3d).
54 u8 Constant value 255 (0xff).
55 u32 Length of the following structure
56 b10 Value: "GnuPG/PAD\x00".
58 (repeat the above value
59 or if the remaining N < 10, all 0x00).
60 Given this structure the minimum padding is 16 bytes.
62 n bytes: File system container.
63 (optionally followed by copies on the header).
67 #define KEYBLOB_TAG_BLOBVERSION 0
68 /* This tag is used to describe the version of the keyblob. It must
69 be the first tag in a keyblob and may only occur once. Its value
70 is a single byte giving the blob version. The only defined version
73 #define KEYBLOB_TAG_CONTTYPE 1
74 /* This tag gives the type of the container. The value is a two byte
75 big endian integer giving the type of the container as described by
76 the CONTTYPE_ constants. */
78 #define KEYBLOB_TAG_DETACHED 2
79 /* Indicates that the actual storage is not in the same file as the
80 keyblob. If a value is given it is expected to be the GUID of the
83 #define KEYBLOB_TAG_CREATED 3
84 /* This is an ISO 8601 time string with the date the container was
87 #define KEYBLOB_TAG_CONT_NSEC 7
88 /* Number of 512-byte sectors of the entire container including all
89 copies of the setup area. */
91 #define KEYBLOB_TAG_ENC_NSEC 8
92 #define KEYBLOB_TAG_ENC_OFF 9
93 /* Number of 512-byte sectors used for the encrypted data and its
94 start offset in 512-byte sectors from the begin of the container.
95 Note that these information can also be deduced from the
96 unencrypted part of the setup area. */
98 #define KEYBLOB_TAG_ALGOSTR 10
99 /* For a dm-crypt container this is the used algorithm string. For
100 example: "aes-cbc-essiv:sha256". */
102 #define KEYBLOB_TAG_KEYNO 16
103 /* This tag indicates a new key. The value is a 4 byte big endian
104 integer giving the key number. If the container type does only
105 need one key this key number should be 0. */
107 #define KEYBLOB_TAG_ENCALGO 17
108 /* Describes the algorithm of the key. It must follow a KEYNO tag.
109 The value is a 2 byte big endian algorithm number. The algorithm
110 numbers used are those from Libgcrypt (e.g. AES 128 is described by
111 the value 7). This tag is optional. */
113 #define KEYBLOB_TAG_ENCKEY 18
114 /* This tag gives the actual encryption key. It must follow a KEYNO
115 tag. The value is the plain key. */
117 #define KEYBLOB_TAG_MACALGO 19
118 /* Describes the MAC algorithm. It must follow a KEYNO tag. The
119 value is a 2 byte big endian algorithm number describing the MAC
120 algorithm with a value of 1 indicating HMAC. It is followed by
121 data specific to the MAC algorithm. In case of HMAC this data is a
122 2 byte big endian integer with the Libgcrypt algorithm id of the
125 #define KEYBLOB_TAG_MACKEY 20
126 /* This tag gives the actual MACing key. It must follow a KEYNO tag.
127 The value is the key used for MACing. */
130 #define KEYBLOB_TAG_HDRCOPY 21
131 /* The value of this tag is a copy of the setup area prefix header
132 block (packet 61 with marker "GnuPG/G13\x00". We use it to allow
133 signing of that cleartext data. */
135 #define KEYBLOB_TAG_FILLER 0xffff
136 /* This tag may be used for alignment and padding purposes. The value
141 #define CONTTYPE_ENCFS 1
142 /* A EncFS based backend. This requires a whole directory which
143 includes the encrypted files. Metadata is not encrypted. */
145 #define CONTTYPE_DM_CRYPT 2
146 /* A DM-Crypt based backend. */
149 #define CONTTYPE_TRUECRYPT 21571
150 /* A Truecrypt (www.truecrypt.org) based container. Due to the design
151 of truecrypt this requires a second datafile because it is not
152 possible to prepend a truecrypt container with our keyblob. */
157 gpg_error_t g13_is_container (ctrl_t ctrl, const char *filename);
158 gpg_error_t g13_keyblob_read (const char *filename,
159 void **r_enckeyblob, size_t *r_enckeybloblen);
162 #endif /*G13_KEYBLOB_H*/