1/* Asymmetric Public-key cryptography key type interface
2 *
3 * See Documentation/security/asymmetric-keys.txt
4 *
5 * Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
6 * Written by David Howells (dhowells@redhat.com)
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public Licence
10 * as published by the Free Software Foundation; either version
11 * 2 of the Licence, or (at your option) any later version.
12 */
13
14#ifndef _KEYS_ASYMMETRIC_TYPE_H
15#define _KEYS_ASYMMETRIC_TYPE_H
16
17#include <linux/key-type.h>
18
19extern struct key_type key_type_asymmetric;
20
21/*
22 * The key payload is four words.  The asymmetric-type key uses them as
23 * follows:
24 */
25enum asymmetric_payload_bits {
26	asym_crypto,
27	asym_subtype,
28	asym_key_ids,
29};
30
31/*
32 * Identifiers for an asymmetric key ID.  We have three ways of looking up a
33 * key derived from an X.509 certificate:
34 *
35 * (1) Serial Number & Issuer.  Non-optional.  This is the only valid way to
36 *     map a PKCS#7 signature to an X.509 certificate.
37 *
38 * (2) Issuer & Subject Unique IDs.  Optional.  These were the original way to
39 *     match X.509 certificates, but have fallen into disuse in favour of (3).
40 *
41 * (3) Auth & Subject Key Identifiers.  Optional.  SKIDs are only provided on
42 *     CA keys that are intended to sign other keys, so don't appear in end
43 *     user certificates unless forced.
44 *
45 * We could also support an PGP key identifier, which is just a SHA1 sum of the
46 * public key and certain parameters, but since we don't support PGP keys at
47 * the moment, we shall ignore those.
48 *
49 * What we actually do is provide a place where binary identifiers can be
50 * stashed and then compare against them when checking for an id match.
51 */
52struct asymmetric_key_id {
53	unsigned short	len;
54	unsigned char	data[];
55};
56
57struct asymmetric_key_ids {
58	void		*id[2];
59};
60
61extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
62				   const struct asymmetric_key_id *kid2);
63
64extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
65				      const struct asymmetric_key_id *kid2);
66
67extern struct asymmetric_key_id *asymmetric_key_generate_id(const void *val_1,
68							    size_t len_1,
69							    const void *val_2,
70							    size_t len_2);
71static inline
72const struct asymmetric_key_ids *asymmetric_key_ids(const struct key *key)
73{
74	return key->payload.data[asym_key_ids];
75}
76
77/*
78 * The payload is at the discretion of the subtype.
79 */
80
81#endif /* _KEYS_ASYMMETRIC_TYPE_H */
82