include/keys/asymmetric-type.h

   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
  19 extern 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  */
  25 enum 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  */
  52 struct asymmetric_key_id {
  53         unsigned short  len;
  54         unsigned char   data[];
  55 };
  56
  57 struct asymmetric_key_ids {
  58         void            *id[2];
  59 };
  60
  61 extern bool asymmetric_key_id_same(const struct asymmetric_key_id *kid1,
  62                                    const struct asymmetric_key_id *kid2);
  63
  64 extern bool asymmetric_key_id_partial(const struct asymmetric_key_id *kid1,
  65                                       const struct asymmetric_key_id *kid2);
  66
  67 extern 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);
  71 static inline
  72 const 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 */