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authentication: More documentation

This commit is contained in:
Harald Welte 2012-07-18 19:47:56 +02:00
parent a9e4a1402b
commit 007a71e332
2 changed files with 81 additions and 20 deletions
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44
include/osmocom/crypt/auth.h
View File

@ -1,11 +1,17 @@
#ifndef _OSMOCRYPTO_AUTH_H
#define _OSMOCRYPTO_AUTH_H
/*! \addtogroup auth
* @{
*/
/*! \file auth.h */
#include <stdint.h>
#include <osmocom/core/linuxlist.h>
/*! \brief Authentication Type */
/*! \brief Authentication Type (GSM/UMTS) */
enum osmo_sub_auth_type {
OSMO_AUTH_TYPE_NONE = 0x00,
OSMO_AUTH_TYPE_GSM = 0x01,
@ -29,42 +35,44 @@ struct osmo_sub_auth_data {
enum osmo_auth_algo algo;
union {
struct {
uint8_t opc[16];
uint8_t k[16];
uint8_t opc[16]; /*!< operator invariant value */
uint8_t k[16]; /*!< secret key of the subscriber */
uint8_t amf[2];
uint64_t sqn;
int opc_is_op;
uint64_t sqn; /*!< sequence number */
int opc_is_op; /*!< is the OPC field OPC (0) or OP (1) ? */
} umts;
struct {
uint8_t ki[16];
uint8_t ki[16]; /*!< secret key */
} gsm;
} u;
};
/* data structure describing a computed auth vector, generated by AuC */
struct osmo_auth_vector {
uint8_t rand[16];
uint8_t autn[16];
uint8_t ck[16];
uint8_t ik[16];
uint8_t res[16];
uint8_t res_len;
uint8_t kc[8];
uint8_t sres[4];
uint8_t rand[16]; /*!< random challenge */
uint8_t autn[16]; /*!< authentication nonce */
uint8_t ck[16]; /*!< ciphering key */
uint8_t ik[16]; /*!< integrity key */
uint8_t res[16]; /*!< authentication result */
uint8_t res_len; /*!< length (in bytes) of res */
uint8_t kc[8]; /*!< Kc for GSM encryption (A5) */
uint8_t sres[4]; /*!< authentication result for GSM */
uint32_t auth_types; /*!< bitmask of OSMO_AUTH_TYPE_* */
};
/* \brief An implementation of an authentication algorithm */
struct osmo_auth_impl {
struct llist_head list;
enum osmo_auth_algo algo;
const char *name;
unsigned int priority;
enum osmo_auth_algo algo; /*!< algorithm we implement */
const char *name; /*!< name of the implementation */
unsigned int priority; /*!< priority value (resp. othe implementations */
/*! \brief callback for generate authentication vectors */
int (*gen_vec)(struct osmo_auth_vector *vec,
struct osmo_sub_auth_data *aud,
const uint8_t *_rand);
/* \brief callback for generationg auth vectors + re-sync */
int (*gen_vec_auts)(struct osmo_auth_vector *vec,
struct osmo_sub_auth_data *aud,
const uint8_t *rand_auts, const uint8_t *auts,
@ -89,3 +97,5 @@ const char *osmo_auth_alg_name(enum osmo_auth_algo alg);
enum osmo_auth_algo osmo_auth_alg_parse(const char *name);
#endif /* _OSMOCRYPTO_AUTH_H */
/* @} */

57
src/gsm/auth_core.c
View File

@ -1,6 +1,6 @@
/* GSM/GPRS/3G authentication core infrastructure */
/* (C) 2010-2011 by Harald Welte <laforge@gnumonks.org>
/* (C) 2010-2012 by Harald Welte <laforge@gnumonks.org>
*
* All Rights Reserved
*
@ -30,11 +30,23 @@
#include <osmocom/crypt/auth.h>
/*! \addtogroup auth
* @{
*/
/* \file auth_core.c
*/
static LLIST_HEAD(osmo_auths);
static struct osmo_auth_impl *selected_auths[_OSMO_AUTH_ALG_NUM];
/* register a cipher with the core */
/*! \brief Register an authentication algorithm implementation with the core
* \param[in] impl Structure describing implementation and it's callbacks
*
* This function is called by an authentication implementation plugin to
* register itself with the authentication core.
*/
int osmo_auth_register(struct osmo_auth_impl *impl)
{
if (impl->algo >= ARRAY_SIZE(selected_auths))
@ -50,13 +62,23 @@ int osmo_auth_register(struct osmo_auth_impl *impl)
return 0;
}
/* load all available GPRS cipher plugins */
/*! \brief Load all available authentication plugins from the given path
* \param[in] path Path name of the directory containing the plugins
*
* This function will load all plugins contained in the specified path.
*/
int osmo_auth_load(const char *path)
{
/* load all plugins available from path */
return osmo_plugin_load_all(path);
}
/*! \brief Determine if a given authentication algorithm is supported
* \param[in] algo Algorithm which should be checked
*
* This function is used by an application to determine at runtime if a
* given authentication algorithm is supported or not.
*/
int osmo_auth_supported(enum osmo_auth_algo algo)
{
if (algo >= ARRAY_SIZE(selected_auths))
@ -68,6 +90,17 @@ int osmo_auth_supported(enum osmo_auth_algo algo)
return 0;
}
/*! \brief Generate authentication vector
* \param[out] vec Generated authentication vector
* \param[in] aud Subscriber-specific key material
* \param[in] rand Random challenge to be used
*
* This function performs the core cryptographic function of the AUC,
* computing authentication triples/quintuples based on the permanent
* subscriber data and a random value. The result is what is forwarded
* by the AUC via HLR and VLR to the MSC which will then be able to
* invoke authentication with the MS
*/
int osmo_auth_gen_vec(struct osmo_auth_vector *vec,
struct osmo_sub_auth_data *aud,
const uint8_t *_rand)
@ -87,6 +120,20 @@ int osmo_auth_gen_vec(struct osmo_auth_vector *vec,
return 0;
}
/*! \brief Generate authentication vector and re-sync sequence
* \param[out] vec Generated authentication vector
* \param[in] aud Subscriber-specific key material
* \param[in] rand_auts RAND value sent by the SIM/MS
* \param[in] auts AUTS value sent by the SIM/MS
* \param[in] rand Random challenge to be used to generate vector
*
* This function performs a special variant of the core cryptographic
* function of the AUC: computing authentication triples/quintuples
* based on the permanent subscriber data, a random value as well as the
* AUTS and RAND values returned by the SIM/MS. This special variant is
* needed if the sequence numbers between MS and AUC have for some
* reason become diffrent.
*/
int osmo_auth_gen_vec_auts(struct osmo_auth_vector *vec,
struct osmo_sub_auth_data *aud,
const uint8_t *rand_auts, const uint8_t *auts,
@ -110,12 +157,16 @@ static const struct value_string auth_alg_vals[] = {
{ 0, NULL }
};
/*! \brief Get human-readable name of authentication algorithm */
const char *osmo_auth_alg_name(enum osmo_auth_algo alg)
{
return get_value_string(auth_alg_vals, alg);
}
/*! \brief Parse human-readable name of authentication algorithm */
enum osmo_auth_algo osmo_auth_alg_parse(const char *name)
{
return get_string_value(auth_alg_vals, name);
}
/*! @} */