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owe: updated to use ell ECDH/ECC API's

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This commit is contained in:
James Prestwood 2018-12-12 09:14:17 -08:00 committed by Denis Kenzior
parent 82ac1e0ba5
commit e11c157478
1 changed files with 47 additions and 33 deletions
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80
src/owe.c
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@ -23,17 +23,23 @@
#include <ell/ell.h>
#include "crypto.h"
#include "ecc.h"
#include "ecdh.h"
#include "ie.h"
#include "handshake.h"
#include "owe.h"
#include "mpdu.h"
/*
* TODO: Once other groups are added, this will need to be dynamic. OWE does
* support retries with different groups, but this is not yet implemented since
* only group 19 is supported.
*/
#define OWE_DEFAULT_GROUP 19
struct owe_sm {
struct handshake_state *hs;
uint8_t private[32];
uint64_t public_key[NUM_ECC_DIGITS * 2];
const struct l_ecc_curve *curve;
struct l_ecc_scalar *private;
struct l_ecc_point *public_key;
owe_tx_authenticate_func_t auth_tx;
owe_tx_associate_func_t assoc_tx;
@ -48,31 +54,26 @@ struct owe_sm *owe_sm_new(struct handshake_state *hs,
{
struct owe_sm *owe = l_new(struct owe_sm, 1);
memset(owe->public_key, 0, sizeof(owe->public_key));
owe->hs = hs;
owe->auth_tx = auth;
owe->assoc_tx = assoc;
owe->user_data = user_data;
owe->complete = complete;
owe->curve = l_ecc_curve_get(OWE_DEFAULT_GROUP);
if (!ecdh_generate_key_pair(owe->private, 32, owe->public_key, 64)) {
if (!l_ecdh_generate_key_pair(owe->curve, &owe->private,
&owe->public_key)) {
l_free(owe);
return NULL;
}
/*
* Store our own public key in BE ordering since all future uses
* will need it.
*/
ecc_native2be(owe->public_key);
ecc_native2be(owe->public_key + 4);
return owe;
}
void owe_sm_free(struct owe_sm *owe)
{
memset(owe->private, 0, sizeof(owe->private));
l_ecc_scalar_free(owe->private);
l_ecc_point_free(owe->public_key);
l_free(owe);
}
@ -84,9 +85,10 @@ void owe_start(struct owe_sm *owe)
void owe_rx_authenticate(struct owe_sm *owe)
{
uint8_t buf[37];
uint8_t buf[5 + L_ECC_SCALAR_MAX_BYTES];
struct iovec iov[3];
int iov_elems = 0;
size_t len;
/*
* RFC 8110 Section 4.3
@ -102,10 +104,11 @@ void owe_rx_authenticate(struct owe_sm *owe)
* 802.11 association request.
*/
buf[0] = IE_TYPE_EXTENSION;
buf[1] = 35; /* length */
buf[2] = IE_TYPE_OWE_DH_PARAM - 256;
l_put_le16(19, buf + 3); /* group */
memcpy(buf + 5, owe->public_key, 32);
l_put_le16(OWE_DEFAULT_GROUP, buf + 3); /* group */
len = l_ecc_point_get_x(owe->public_key, buf + 5,
L_ECC_SCALAR_MAX_BYTES);
buf[1] = 3 + len; /* length */
iov[iov_elems].iov_base = (void *) buf;
iov[iov_elems].iov_len = buf[1] + 2;
@ -120,31 +123,41 @@ void owe_rx_authenticate(struct owe_sm *owe)
static bool owe_compute_keys(struct owe_sm *owe, const void *public_key,
size_t pub_len)
{
uint64_t shared_secret[4];
struct l_ecc_scalar *shared_secret;
uint8_t ss_buf[L_ECC_SCALAR_MAX_BYTES];
uint8_t prk[32];
uint8_t pmk[32];
uint8_t pmkid[16];
uint8_t key[32 + 32 + 2];
uint64_t public_native[4];
struct iovec iov[2];
struct l_checksum *sha;
struct l_ecc_point *other_public;
memcpy(public_native, public_key, 32);
ecc_be2native(public_native);
/* z = F(DH(x, Y)) */
if (!ecdh_generate_shared_secret(owe->private, public_native, pub_len,
shared_secret, 32))
other_public = l_ecc_point_from_data(owe->curve,
L_ECC_POINT_TYPE_COMPLIANT,
public_key, pub_len);
if (!other_public) {
l_error("AP public key was not valid");
return false;
}
memcpy(key, owe->public_key, 32);
if (!l_ecdh_generate_shared_secret(owe->curve, owe->private,
other_public, &shared_secret)) {
return false;
}
l_ecc_point_free(other_public);
l_ecc_scalar_get_data(shared_secret, ss_buf, sizeof(ss_buf));
l_ecc_scalar_free(shared_secret);
l_ecc_point_get_x(owe->public_key, key, sizeof(key));
memcpy(key + 32, public_key, 32);
l_put_le16(19, key + 64);
ecc_native2be(shared_secret);
l_put_le16(OWE_DEFAULT_GROUP, key + 64);
/* prk = HKDF-extract(C | A | group, z) */
if (!hkdf_extract_sha256(key, 66, 1, prk, shared_secret, 32))
if (!hkdf_extract_sha256(key, 66, 1, prk, ss_buf, 32))
goto failed;
/* PMK = HKDF-expand(prk, "OWE Key Generation", n) */
@ -155,7 +168,7 @@ static bool owe_compute_keys(struct owe_sm *owe, const void *public_key,
sha = l_checksum_new(L_CHECKSUM_SHA256);
/* PMKID = Truncate-128(Hash(C | A)) */
iov[0].iov_base = owe->public_key;
iov[0].iov_base = key; /* first 32 bytes of key are owe->public_key */
iov[0].iov_len = 32;
iov[1].iov_base = (void *) public_key;
iov[1].iov_len = 32;
@ -172,7 +185,8 @@ static bool owe_compute_keys(struct owe_sm *owe, const void *public_key,
return true;
failed:
memset(shared_secret, 0, sizeof(shared_secret));
memset(ss_buf, 0, sizeof(ss_buf));
l_ecc_scalar_free(shared_secret);
return false;
}