DPP: Move PKEX z derivation on Responder to earlier phase
K and z can be derived already based on information available at the time the PKEX Exchange Request is being processed, so move these there from the PKEX Commit-Reveal Request processing since that matches the DPP tech spec description close and allows PKEX exchange to be aborted earlier if anything unexpected happens. Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>
This commit is contained in:
Jouni Malinen
Jouni Malinen
parent
578c9ea1ab
commit
d05c82c4d0
1 changed files with 93 additions and 90 deletions
183
src/common/dpp.c
183
src/common/dpp.c
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@ -5752,6 +5752,65 @@ fail:
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}
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static int dpp_pkex_derive_z(const u8 *mac_init, const u8 *mac_resp,
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const u8 *Mx, size_t Mx_len,
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const u8 *Nx, size_t Nx_len,
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const char *code,
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const u8 *Kx, size_t Kx_len,
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u8 *z, unsigned int hash_len)
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{
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u8 salt[DPP_MAX_HASH_LEN], prk[DPP_MAX_HASH_LEN];
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int res;
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u8 *info, *pos;
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size_t info_len;
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/* z = HKDF(<>, MAC-Initiator | MAC-Responder | M.x | N.x | code, K.x)
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*/
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/* HKDF-Extract(<>, IKM=K.x) */
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os_memset(salt, 0, hash_len);
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if (dpp_hmac(hash_len, salt, hash_len, Kx, Kx_len, prk) < 0)
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return -1;
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wpa_hexdump_key(MSG_DEBUG, "DPP: PRK = HKDF-Extract(<>, IKM)",
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prk, hash_len);
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info_len = 2 * ETH_ALEN + Mx_len + Nx_len + os_strlen(code);
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info = os_malloc(info_len);
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if (!info)
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return -1;
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pos = info;
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os_memcpy(pos, mac_init, ETH_ALEN);
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pos += ETH_ALEN;
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os_memcpy(pos, mac_resp, ETH_ALEN);
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pos += ETH_ALEN;
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os_memcpy(pos, Mx, Mx_len);
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pos += Mx_len;
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os_memcpy(pos, Nx, Nx_len);
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pos += Nx_len;
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os_memcpy(pos, code, os_strlen(code));
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/* HKDF-Expand(PRK, info, L) */
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if (hash_len == 32)
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res = hmac_sha256_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else if (hash_len == 48)
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res = hmac_sha384_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else if (hash_len == 64)
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res = hmac_sha512_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else
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res = -1;
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os_free(info);
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os_memset(prk, 0, hash_len);
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if (res < 0)
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return -1;
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wpa_hexdump_key(MSG_DEBUG, "DPP: z = HKDF-Expand(PRK, info, L)",
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z, hash_len);
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return 0;
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}
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struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
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struct dpp_bootstrap_info *bi,
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const u8 *own_mac,
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@ -5772,6 +5831,10 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
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EC_KEY *Y_ec = NULL, *X_ec = NULL;;
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const EC_POINT *Y_point;
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BIGNUM *Nx = NULL, *Ny = NULL;
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u8 Kx[DPP_MAX_SHARED_SECRET_LEN];
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size_t Kx_len;
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int res;
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EVP_PKEY_CTX *ctx = NULL;
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if (bi->pkex_t >= PKEX_COUNTER_T_LIMIT) {
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wpa_msg(msg_ctx, MSG_INFO, DPP_EVENT_FAIL
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@ -5914,9 +5977,37 @@ struct dpp_pkex * dpp_pkex_rx_exchange_req(void *msg_ctx,
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if (!pkex->exchange_resp)
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goto fail;
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/* K = y * X' */
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ctx = EVP_PKEY_CTX_new(pkex->y, NULL);
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if (!ctx ||
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EVP_PKEY_derive_init(ctx) != 1 ||
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EVP_PKEY_derive_set_peer(ctx, pkex->x) != 1 ||
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EVP_PKEY_derive(ctx, NULL, &Kx_len) != 1 ||
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Kx_len > DPP_MAX_SHARED_SECRET_LEN ||
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EVP_PKEY_derive(ctx, Kx, &Kx_len) != 1) {
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wpa_printf(MSG_ERROR,
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"DPP: Failed to derive ECDH shared secret: %s",
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ERR_error_string(ERR_get_error(), NULL));
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goto fail;
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}
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wpa_hexdump_key(MSG_DEBUG, "DPP: ECDH shared secret (K.x)",
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Kx, Kx_len);
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/* z = HKDF(<>, MAC-Initiator | MAC-Responder | M.x | N.x | code, K.x)
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*/
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res = dpp_pkex_derive_z(pkex->peer_mac, pkex->own_mac,
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pkex->Mx, curve->prime_len,
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pkex->Nx, curve->prime_len, pkex->code,
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Kx, Kx_len, pkex->z, curve->hash_len);
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os_memset(Kx, 0, Kx_len);
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if (res < 0)
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goto fail;
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pkex->exchange_done = 1;
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out:
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EVP_PKEY_CTX_free(ctx);
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BN_CTX_free(bnctx);
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EC_POINT_free(Qi);
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EC_POINT_free(Qr);
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@ -5938,65 +6029,6 @@ fail:
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}
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static int dpp_pkex_derive_z(const u8 *mac_init, const u8 *mac_resp,
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const u8 *Mx, size_t Mx_len,
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const u8 *Nx, size_t Nx_len,
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const char *code,
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const u8 *Kx, size_t Kx_len,
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u8 *z, unsigned int hash_len)
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{
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u8 salt[DPP_MAX_HASH_LEN], prk[DPP_MAX_HASH_LEN];
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int res;
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u8 *info, *pos;
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size_t info_len;
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/* z = HKDF(<>, MAC-Initiator | MAC-Responder | M.x | N.x | code, K.x)
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*/
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/* HKDF-Extract(<>, IKM=K.x) */
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os_memset(salt, 0, hash_len);
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if (dpp_hmac(hash_len, salt, hash_len, Kx, Kx_len, prk) < 0)
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return -1;
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wpa_hexdump_key(MSG_DEBUG, "DPP: PRK = HKDF-Extract(<>, IKM)",
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prk, hash_len);
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info_len = 2 * ETH_ALEN + Mx_len + Nx_len + os_strlen(code);
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info = os_malloc(info_len);
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if (!info)
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return -1;
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pos = info;
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os_memcpy(pos, mac_init, ETH_ALEN);
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pos += ETH_ALEN;
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os_memcpy(pos, mac_resp, ETH_ALEN);
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pos += ETH_ALEN;
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os_memcpy(pos, Mx, Mx_len);
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pos += Mx_len;
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os_memcpy(pos, Nx, Nx_len);
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pos += Nx_len;
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os_memcpy(pos, code, os_strlen(code));
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/* HKDF-Expand(PRK, info, L) */
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if (hash_len == 32)
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res = hmac_sha256_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else if (hash_len == 48)
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res = hmac_sha384_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else if (hash_len == 64)
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res = hmac_sha512_kdf(prk, hash_len, NULL, info, info_len,
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z, hash_len);
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else
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res = -1;
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os_free(info);
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os_memset(prk, 0, hash_len);
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if (res < 0)
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return -1;
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wpa_hexdump_key(MSG_DEBUG, "DPP: z = HKDF-Expand(PRK, info, L)",
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z, hash_len);
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return 0;
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}
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static struct wpabuf *
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dpp_pkex_build_commit_reveal_req(struct dpp_pkex *pkex,
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const struct wpabuf *A_pub, const u8 *u)
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@ -6394,8 +6426,8 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
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{
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const struct dpp_curve_params *curve = pkex->own_bi->curve;
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EVP_PKEY_CTX *ctx = NULL;
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size_t Jx_len, Kx_len, Lx_len;
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u8 Jx[DPP_MAX_SHARED_SECRET_LEN], Kx[DPP_MAX_SHARED_SECRET_LEN];
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size_t Jx_len, Lx_len;
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u8 Jx[DPP_MAX_SHARED_SECRET_LEN];
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u8 Lx[DPP_MAX_SHARED_SECRET_LEN];
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const u8 *wrapped_data, *b_key, *peer_u;
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u16 wrapped_data_len, b_key_len, peer_u_len = 0;
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@ -6407,39 +6439,11 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
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struct wpabuf *msg = NULL, *A_pub = NULL, *X_pub = NULL, *Y_pub = NULL;
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struct wpabuf *B_pub = NULL;
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u8 u[DPP_MAX_HASH_LEN], v[DPP_MAX_HASH_LEN];
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int res;
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if (!pkex->exchange_done || pkex->failed ||
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pkex->t >= PKEX_COUNTER_T_LIMIT)
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goto fail;
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/* K = y * X' */
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ctx = EVP_PKEY_CTX_new(pkex->y, NULL);
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if (!ctx ||
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EVP_PKEY_derive_init(ctx) != 1 ||
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EVP_PKEY_derive_set_peer(ctx, pkex->x) != 1 ||
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EVP_PKEY_derive(ctx, NULL, &Kx_len) != 1 ||
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Kx_len > DPP_MAX_SHARED_SECRET_LEN ||
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EVP_PKEY_derive(ctx, Kx, &Kx_len) != 1) {
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wpa_printf(MSG_ERROR,
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"DPP: Failed to derive ECDH shared secret: %s",
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ERR_error_string(ERR_get_error(), NULL));
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goto fail;
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}
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wpa_hexdump_key(MSG_DEBUG, "DPP: ECDH shared secret (K.x)",
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Kx, Kx_len);
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/* z = HKDF(<>, MAC-Initiator | MAC-Responder | M.x | N.x | code, K.x)
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*/
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res = dpp_pkex_derive_z(pkex->peer_mac, pkex->own_mac,
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pkex->Mx, curve->prime_len,
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pkex->Nx, curve->prime_len, pkex->code,
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Kx, Kx_len, pkex->z, curve->hash_len);
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os_memset(Kx, 0, Kx_len);
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if (res < 0)
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goto fail;
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wrapped_data = dpp_get_attr(buf, buflen, DPP_ATTR_WRAPPED_DATA,
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&wrapped_data_len);
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if (!wrapped_data || wrapped_data_len < AES_BLOCK_SIZE) {
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@ -6496,7 +6500,6 @@ struct wpabuf * dpp_pkex_rx_commit_reveal_req(struct dpp_pkex *pkex,
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pkex->peer_bootstrap_key);
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/* ECDH: J' = y * A' */
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EVP_PKEY_CTX_free(ctx);
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ctx = EVP_PKEY_CTX_new(pkex->y, NULL);
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if (!ctx ||
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EVP_PKEY_derive_init(ctx) != 1 ||
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