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component/bt: Fixed the vulnerability released by Bluetooth org when using public key not check in the process of ECDH encryption.

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This commit is contained in:
yulong 2018-08-13 15:33:42 +08:00
parent 516d9f0eae
commit 7aa29a0dbb
3 changed files with 44 additions and 0 deletions
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2
components/bt/bluedroid/stack/smp/include/p_256_ecc_pp.h
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@ -58,6 +58,8 @@ extern elliptic_curve_t curve_p256;
void ECC_PointMult_Bin_NAF(Point *q, Point *p, DWORD *n, uint32_t keyLength);
bool ECC_CheckPointIsInElliCur_P256(Point *p);
#define ECC_PointMult(q, p, n, keyLength) ECC_PointMult_Bin_NAF(q, p, n, keyLength)
void p_256_init_curve(UINT32 keyLength);

35
components/bt/bluedroid/stack/smp/p_256_ecc_pp.c
View file

@ -240,4 +240,39 @@ void ECC_PointMult_Bin_NAF(Point *q, Point *p, DWORD *n, uint32_t keyLength)
multiprecision_mersenns_mult_mod(q->y, q->y, q->z, keyLength);
}
bool ECC_CheckPointIsInElliCur_P256(Point *p)
{
/* y^2 % q */
DWORD y_y_q[KEY_LENGTH_DWORDS_P256] = {0x0};
/* x^2 % q */
DWORD x_x_q[KEY_LENGTH_DWORDS_P256] = {0x0};
/* x % q */
DWORD x_q[KEY_LENGTH_DWORDS_P256] = {0x0};
/* x^2, To prevent overflow, the length of the x square here needs to
be expanded to two times the original one. */
DWORD x_x[2*KEY_LENGTH_DWORDS_P256] = {0x0};
/* y_y_q =(p->y)^2(mod q) */
multiprecision_mersenns_squa_mod(y_y_q, p->y, KEY_LENGTH_DWORDS_P256);
/* Calculate the value of p->x square, x_x = (p->x)^2 */
multiprecision_mult(x_x, p->x, p->x, KEY_LENGTH_DWORDS_P256);
/* The function of the elliptic curve is y^2 = x^3 - 3x + b (mod q) ==>
y^2 = (x^2 - 3)*x + b (mod q),
so we calculate the x^2 - 3 value here */
x_x[0] -= 3;
/* Using math relations. (a*b) % q = ((a%q)*(b%q)) % q ==>
(x^2 - 3)*x = (((x^2 - 3) % q) * x % q) % q */
multiprecision_fast_mod_P256(x_x_q, x_x);
/* x_x = x_x_q * x_q */
multiprecision_mult(x_x, x_x_q, p->x, KEY_LENGTH_DWORDS_P256);
/* x_q = x_x % q */
multiprecision_fast_mod_P256(x_q, x_x);
/* Save the result in x_x_q */
multiprecision_add_mod(x_x_q, x_q, curve_p256.b, KEY_LENGTH_DWORDS_P256);
/* compare the y_y_q and x_x_q, see if they are on a given elliptic curve. */
if (multiprecision_compare(y_y_q, x_x_q, KEY_LENGTH_DWORDS_P256)) {
return false;
} else {
return true;
}
}

7
components/bt/bluedroid/stack/smp/smp_act.c
View file

@ -22,6 +22,7 @@
#include "btm_int.h"
#include "l2c_api.h"
#include "smp_int.h"
#include "p_256_ecc_pp.h"
//#include "utils/include/bt_utils.h"
#if SMP_INCLUDED == TRUE
@ -668,6 +669,12 @@ void smp_process_pairing_public_key(tSMP_CB *p_cb, tSMP_INT_DATA *p_data)
STREAM_TO_ARRAY(p_cb->peer_publ_key.x, p, BT_OCTET32_LEN);
STREAM_TO_ARRAY(p_cb->peer_publ_key.y, p, BT_OCTET32_LEN);
/* In order to prevent the x and y coordinates of the public key from being modified,
we need to check whether the x and y coordinates are on the given elliptic curve. */
if (!ECC_CheckPointIsInElliCur_P256((Point *)&p_cb->peer_publ_key)) {
SMP_TRACE_ERROR("%s, Invalid Public key.", __func__);
smp_sm_event(p_cb, SMP_AUTH_CMPL_EVT, &reason);
}
p_cb->flags |= SMP_PAIR_FLAG_HAVE_PEER_PUBL_KEY;
smp_wait_for_both_public_keys(p_cb, NULL);