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Make C4 function globally available 

This function perform 64 -> 128 bit key expansion which useful for
converting between UMTS CK and GSM Kc, A5/3 and A5/4, GEA3 and GEA4
keys.

Change-Id: I5a6c6deef6027cd6af144c9062d4c9166be26904
Related: OS#1582
This commit is contained in:
Max 2016-06-27 18:12:49 +02:00 committed by Harald Welte
parent b897c42993
commit ceae123752
3 changed files with 5 additions and 5 deletions
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2
include/osmocom/crypt/auth.h
View File

@ -91,7 +91,7 @@ int osmo_auth_register(struct osmo_auth_impl *impl);
int osmo_auth_load(const char *path);
int osmo_auth_supported(enum osmo_auth_algo algo);
void osmo_c4(uint8_t *ck, const uint8_t *kc);
const char *osmo_auth_alg_name(enum osmo_auth_algo alg);
enum osmo_auth_algo osmo_auth_alg_parse(const char *name);

4
src/gsm/a5.c
View File

@ -40,6 +40,7 @@
#include <osmocom/gsm/a5.h>
#include <osmocom/gsm/kasumi.h>
#include <osmocom/crypt/auth.h>
/* Somme OS (like Nuttx) don't have ENOTSUP */
#ifndef ENOTSUP
@ -95,8 +96,7 @@ void
_a5_3(const uint8_t *key, uint32_t fn, ubit_t *dl, ubit_t *ul, bool fn_correct)
{
uint8_t ck[16];
memcpy(ck, key, 8);
memcpy(ck + 8, key, 8);
osmo_c4(ck, key);
/* internal function require 128 bit key so we expand by concatenating supplied 64 bit key */
_a5_4(ck, fn, dl, ul, fn_correct);
}

4
src/gsm/auth_core.c
View File

@ -106,7 +106,7 @@ static inline void c5_function(uint8_t *ik, const uint8_t *kc)
}
/* C4 function to derive UMTS CK from GSM Kc */
static inline void c4_function(uint8_t *ck, const uint8_t *kc)
void osmo_c4(uint8_t *ck, const uint8_t *kc)
{
memcpy(ck, kc, 8);
memcpy(ck+8, kc, 8);
@ -125,7 +125,7 @@ int osmo_auth_3g_from_2g(struct osmo_auth_vector *vec)
if ((vec->auth_types & OSMO_AUTH_TYPE_GSM) &&
!(vec->auth_types & OSMO_AUTH_TYPE_UMTS)) {
c5_function(vec->ik, vec->kc);
c4_function(vec->ck, vec->kc);
osmo_c4(vec->ck, vec->kc);
/* We cannot actually set OSMO_AUTH_TYPE_UMTS as we have no
* AUTN and no RES, and thus can only perform GSM
* authentication with this tuple.