linux/include/crypto/public_key.h
David Howells 4ae71c1dce KEYS: Provide signature verification with an asymmetric key
Provide signature verification using an asymmetric-type key to indicate the
public key to be used.

The API is a single function that can be found in crypto/public_key.h:

	int verify_signature(const struct key *key,
			     const struct public_key_signature *sig)

The first argument is the appropriate key to be used and the second argument
is the parsed signature data:

	struct public_key_signature {
		u8 *digest;
		u16 digest_size;
		enum pkey_hash_algo pkey_hash_algo : 8;
		union {
			MPI mpi[2];
			struct {
				MPI s;		/* m^d mod n */
			} rsa;
			struct {
				MPI r;
				MPI s;
			} dsa;
		};
	};

This should be filled in prior to calling the function.  The hash algorithm
should already have been called and the hash finalised and the output should
be in a buffer pointed to by the 'digest' member.

Any extra data to be added to the hash by the hash format (eg. PGP) should
have been added by the caller prior to finalising the hash.

It is assumed that the signature is made up of a number of MPI values.  If an
algorithm becomes available for which this is not the case, the above structure
will have to change.

It is also assumed that it will have been checked that the signature algorithm
matches the key algorithm.

Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2012-10-08 13:50:15 +10:30

108 lines
2.5 KiB
C

/* Asymmetric public-key algorithm definitions
*
* See Documentation/crypto/asymmetric-keys.txt
*
* Copyright (C) 2012 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#ifndef _LINUX_PUBLIC_KEY_H
#define _LINUX_PUBLIC_KEY_H
#include <linux/mpi.h>
enum pkey_algo {
PKEY_ALGO_DSA,
PKEY_ALGO_RSA,
PKEY_ALGO__LAST
};
extern const char *const pkey_algo[PKEY_ALGO__LAST];
enum pkey_hash_algo {
PKEY_HASH_MD4,
PKEY_HASH_MD5,
PKEY_HASH_SHA1,
PKEY_HASH_RIPE_MD_160,
PKEY_HASH_SHA256,
PKEY_HASH_SHA384,
PKEY_HASH_SHA512,
PKEY_HASH_SHA224,
PKEY_HASH__LAST
};
extern const char *const pkey_hash_algo[PKEY_HASH__LAST];
enum pkey_id_type {
PKEY_ID_PGP, /* OpenPGP generated key ID */
PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */
PKEY_ID_TYPE__LAST
};
extern const char *const pkey_id_type[PKEY_ID_TYPE__LAST];
/*
* Cryptographic data for the public-key subtype of the asymmetric key type.
*
* Note that this may include private part of the key as well as the public
* part.
*/
struct public_key {
const struct public_key_algorithm *algo;
u8 capabilities;
#define PKEY_CAN_ENCRYPT 0x01
#define PKEY_CAN_DECRYPT 0x02
#define PKEY_CAN_SIGN 0x04
#define PKEY_CAN_VERIFY 0x08
enum pkey_id_type id_type : 8;
union {
MPI mpi[5];
struct {
MPI p; /* DSA prime */
MPI q; /* DSA group order */
MPI g; /* DSA group generator */
MPI y; /* DSA public-key value = g^x mod p */
MPI x; /* DSA secret exponent (if present) */
} dsa;
struct {
MPI n; /* RSA public modulus */
MPI e; /* RSA public encryption exponent */
MPI d; /* RSA secret encryption exponent (if present) */
MPI p; /* RSA secret prime (if present) */
MPI q; /* RSA secret prime (if present) */
} rsa;
};
};
extern void public_key_destroy(void *payload);
/*
* Public key cryptography signature data
*/
struct public_key_signature {
u8 *digest;
u8 digest_size; /* Number of bytes in digest */
u8 nr_mpi; /* Occupancy of mpi[] */
enum pkey_hash_algo pkey_hash_algo : 8;
union {
MPI mpi[2];
struct {
MPI s; /* m^d mod n */
} rsa;
struct {
MPI r;
MPI s;
} dsa;
};
};
struct key;
extern int verify_signature(const struct key *key,
const struct public_key_signature *sig);
#endif /* _LINUX_PUBLIC_KEY_H */