diff options
Diffstat (limited to 'package/network/services/hostapd/patches/084-EAP-pwd-Derive-the-y-coordinate-for-PWE-with-own-imp.patch')
| -rw-r--r-- | package/network/services/hostapd/patches/084-EAP-pwd-Derive-the-y-coordinate-for-PWE-with-own-imp.patch | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/package/network/services/hostapd/patches/084-EAP-pwd-Derive-the-y-coordinate-for-PWE-with-own-imp.patch b/package/network/services/hostapd/patches/084-EAP-pwd-Derive-the-y-coordinate-for-PWE-with-own-imp.patch new file mode 100644 index 0000000000..c5ddddcec3 --- /dev/null +++ b/package/network/services/hostapd/patches/084-EAP-pwd-Derive-the-y-coordinate-for-PWE-with-own-imp.patch @@ -0,0 +1,108 @@ +From 603cd880e7f90595482658a7136fa6a7be5cb485 Mon Sep 17 00:00:00 2001 +From: Jouni Malinen <j@w1.fi> +Date: Fri, 7 Jan 2022 18:52:27 +0200 +Subject: [PATCH 4/4] EAP-pwd: Derive the y coordinate for PWE with own + implementation + +The crypto_ec_point_solve_y_coord() wrapper function might not use +constant time operations in the crypto library and as such, could leak +side channel information about the password that is used to generate the +PWE in the hunting and pecking loop. As such, calculate the two possible +y coordinate values and pick the correct one to use with constant time +selection. + +Signed-off-by: Jouni Malinen <j@w1.fi> +--- + src/eap_common/eap_pwd_common.c | 46 ++++++++++++++++++++++++++------- + 1 file changed, 36 insertions(+), 10 deletions(-) + +--- a/src/eap_common/eap_pwd_common.c ++++ b/src/eap_common/eap_pwd_common.c +@@ -127,7 +127,8 @@ int compute_password_element(EAP_PWD_gro + u8 qr_or_qnr_bin[MAX_ECC_PRIME_LEN]; + u8 x_bin[MAX_ECC_PRIME_LEN]; + u8 prime_bin[MAX_ECC_PRIME_LEN]; +- struct crypto_bignum *tmp2 = NULL; ++ u8 x_y[2 * MAX_ECC_PRIME_LEN]; ++ struct crypto_bignum *tmp2 = NULL, *y = NULL; + struct crypto_hash *hash; + unsigned char pwe_digest[SHA256_MAC_LEN], *prfbuf = NULL, ctr; + int ret = 0, res; +@@ -139,6 +140,7 @@ int compute_password_element(EAP_PWD_gro + u8 found_ctr = 0, is_odd = 0; + int cmp_prime; + unsigned int in_range; ++ unsigned int is_eq; + + if (grp->pwe) + return -1; +@@ -151,11 +153,6 @@ int compute_password_element(EAP_PWD_gro + if (crypto_bignum_to_bin(prime, prime_bin, sizeof(prime_bin), + primebytelen) < 0) + return -1; +- grp->pwe = crypto_ec_point_init(grp->group); +- if (!grp->pwe) { +- wpa_printf(MSG_INFO, "EAP-pwd: unable to create bignums"); +- goto fail; +- } + + if ((prfbuf = os_malloc(primebytelen)) == NULL) { + wpa_printf(MSG_INFO, "EAP-pwd: unable to malloc space for prf " +@@ -261,10 +258,37 @@ int compute_password_element(EAP_PWD_gro + */ + crypto_bignum_deinit(x_candidate, 1); + x_candidate = crypto_bignum_init_set(x_bin, primebytelen); +- if (!x_candidate || +- crypto_ec_point_solve_y_coord(grp->group, grp->pwe, x_candidate, +- is_odd) != 0) { +- wpa_printf(MSG_INFO, "EAP-pwd: Could not solve for y"); ++ if (!x_candidate) ++ goto fail; ++ ++ /* y = sqrt(x^3 + ax + b) mod p ++ * if LSB(y) == LSB(pwd-seed): PWE = (x, y) ++ * else: PWE = (x, p - y) ++ * ++ * Calculate y and the two possible values for PWE and after that, ++ * use constant time selection to copy the correct alternative. ++ */ ++ y = crypto_ec_point_compute_y_sqr(grp->group, x_candidate); ++ if (!y || ++ dragonfly_sqrt(grp->group, y, y) < 0 || ++ crypto_bignum_to_bin(y, x_y, MAX_ECC_PRIME_LEN, primebytelen) < 0 || ++ crypto_bignum_sub(prime, y, y) < 0 || ++ crypto_bignum_to_bin(y, x_y + MAX_ECC_PRIME_LEN, ++ MAX_ECC_PRIME_LEN, primebytelen) < 0) { ++ wpa_printf(MSG_DEBUG, "SAE: Could not solve y"); ++ goto fail; ++ } ++ ++ /* Constant time selection of the y coordinate from the two ++ * options */ ++ is_eq = const_time_eq(is_odd, x_y[primebytelen - 1] & 0x01); ++ const_time_select_bin(is_eq, x_y, x_y + MAX_ECC_PRIME_LEN, ++ primebytelen, x_y + primebytelen); ++ os_memcpy(x_y, x_bin, primebytelen); ++ wpa_hexdump_key(MSG_DEBUG, "EAP-pwd: PWE", x_y, 2 * primebytelen); ++ grp->pwe = crypto_ec_point_from_bin(grp->group, x_y); ++ if (!grp->pwe) { ++ wpa_printf(MSG_DEBUG, "EAP-pwd: Could not generate PWE"); + goto fail; + } + +@@ -289,6 +313,7 @@ int compute_password_element(EAP_PWD_gro + /* cleanliness and order.... */ + crypto_bignum_deinit(x_candidate, 1); + crypto_bignum_deinit(tmp2, 1); ++ crypto_bignum_deinit(y, 1); + crypto_bignum_deinit(qr, 1); + crypto_bignum_deinit(qnr, 1); + bin_clear_free(prfbuf, primebytelen); +@@ -296,6 +321,7 @@ int compute_password_element(EAP_PWD_gro + os_memset(qnr_bin, 0, sizeof(qnr_bin)); + os_memset(qr_or_qnr_bin, 0, sizeof(qr_or_qnr_bin)); + os_memset(pwe_digest, 0, sizeof(pwe_digest)); ++ forced_memzero(x_y, sizeof(x_y)); + + return ret; + } |