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https://git.kernel.org/pub/scm/network/wireless/iwd.git
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dpp-util: Introduce dpp-util, and add crypto operations
This commit is contained in:
James Prestwood
Denis Kenzior
parent
bc36aca98e
commit
cdf05183b9
@ -248,6 +248,7 @@ src_iwd_SOURCES = src/main.c linux/nl80211.h src/iwd.h src/missing.h \
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src/band.h src/band.c \
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src/sysfs.h src/sysfs.c \
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src/offchannel.h src/offchannel.c \
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src/dpp-util.h src/dpp-util.c \
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$(eap_sources) \
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$(builtin_sources)
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260
src/dpp-util.c
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260
src/dpp-util.c
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/*
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*
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* Wireless daemon for Linux
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*
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* Copyright (C) 2021 Intel Corporation. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <stdio.h>
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#include <errno.h>
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#include <ell/ell.h>
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#include "src/dpp-util.h"
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#include "src/util.h"
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#include "src/crypto.h"
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/*
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* EasyConnect 2.0 Table 3. Key and Nonce Length Dependency on Prime Length
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*/
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static enum l_checksum_type dpp_sha_from_key_len(size_t len)
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{
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if (len == 32)
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return L_CHECKSUM_SHA256;
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else if (len == 48)
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return L_CHECKSUM_SHA384;
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else if (len == 64)
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return L_CHECKSUM_SHA512;
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else
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return L_CHECKSUM_NONE;
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}
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size_t dpp_nonce_len_from_key_len(size_t len)
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{
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if (len == 32)
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return 16;
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else if (len == 48)
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return 24;
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else if (len == 64)
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return 32;
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else
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return 0;
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}
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/*
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* 3.2.2
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* H()
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*/
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bool dpp_hash(enum l_checksum_type type, uint8_t *out, unsigned int num, ...)
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{
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struct l_checksum *sha = l_checksum_new(type);
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size_t hsize = l_checksum_digest_length(type);
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unsigned int i;
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va_list va;
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va_start(va, num);
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for (i = 0; i < num; i++) {
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void *data = va_arg(va, void *);
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size_t len = va_arg(va, size_t);
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l_checksum_update(sha, data, len);
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}
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va_end(va);
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l_checksum_get_digest(sha, out, hsize);
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l_checksum_free(sha);
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return true;
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}
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/*
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* 3.2.2
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*
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* HKDF is defined as:
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*
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* key = HKDF(salt, info, ikm)
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* = HKDF-Expand(HKDF-Extract(salt, ikm), info, len)
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*
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* Note: A NULL 'salt' means a zero'ed buffer and 'salt_len' should still be
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* set for this zero'ed buffer length.
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*/
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static bool dpp_hkdf(enum l_checksum_type sha, const void *salt,
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size_t salt_len, const char *info, const void *ikm,
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size_t ikm_len, void *out, size_t out_len)
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{
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uint8_t tmp[64];
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uint8_t zero_salt[64] = { 0 };
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size_t hash_len = l_checksum_digest_length(sha);
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if (!salt)
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salt = zero_salt;
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if (!hkdf_extract(sha, salt, salt_len, 1, tmp,
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ikm, ikm_len))
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return false;
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return hkdf_expand(sha, tmp, hash_len, info, out, out_len);
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}
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bool dpp_derive_r_auth(const void *i_nonce, const void *r_nonce,
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size_t nonce_len, struct l_ecc_point *i_proto,
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struct l_ecc_point *r_proto,
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struct l_ecc_point *r_boot,
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void *r_auth)
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{
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uint64_t pix[L_ECC_MAX_DIGITS];
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uint64_t prx[L_ECC_MAX_DIGITS];
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uint64_t brx[L_ECC_MAX_DIGITS];
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size_t keys_len;
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uint8_t zero = 0;
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enum l_checksum_type type;
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keys_len = l_ecc_point_get_x(i_proto, pix, sizeof(pix));
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l_ecc_point_get_x(r_proto, prx, sizeof(prx));
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l_ecc_point_get_x(r_boot, brx, sizeof(brx));
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type = dpp_sha_from_key_len(keys_len);
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/*
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* R-auth = H(I-nonce | R-nonce | PI.x | PR.x | [ BI.x | ] BR.x | 0)
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*/
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return dpp_hash(type, r_auth, 6, i_nonce, nonce_len, r_nonce, nonce_len,
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pix, keys_len, prx, keys_len, brx, keys_len, &zero, 1);
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}
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bool dpp_derive_i_auth(const void *r_nonce, const void *i_nonce,
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size_t nonce_len, struct l_ecc_point *r_proto,
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struct l_ecc_point *i_proto,
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struct l_ecc_point *r_boot, void *i_auth)
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{
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uint64_t prx[L_ECC_MAX_DIGITS];
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uint64_t pix[L_ECC_MAX_DIGITS];
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uint64_t brx[L_ECC_MAX_DIGITS];
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size_t keys_len;
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uint8_t one = 1;
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enum l_checksum_type type;
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keys_len = l_ecc_point_get_x(r_proto, prx, sizeof(prx));
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l_ecc_point_get_x(i_proto, pix, sizeof(pix));
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l_ecc_point_get_x(r_boot, brx, sizeof(brx));
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type = dpp_sha_from_key_len(keys_len);
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/*
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* I-auth = H(R-nonce | I-nonce | PR.x | PI.x | BR.x | [ BI.x | ] 1)
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*/
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return dpp_hash(type, i_auth, 6, r_nonce, nonce_len, i_nonce, nonce_len,
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prx, keys_len, pix, keys_len, brx, keys_len, &one, 1);
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}
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/*
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* Derives key k1. This returns the intermediate secret M.x used in deriving
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* key ke.
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*/
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struct l_ecc_scalar *dpp_derive_k1(const struct l_ecc_point *i_proto_public,
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const struct l_ecc_scalar *boot_private,
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void *k1)
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{
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struct l_ecc_scalar *m;
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uint64_t mx_bytes[L_ECC_MAX_DIGITS];
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ssize_t key_len;
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enum l_checksum_type sha;
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if (!l_ecdh_generate_shared_secret(boot_private, i_proto_public, &m))
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return NULL;
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key_len = l_ecc_scalar_get_data(m, mx_bytes, sizeof(mx_bytes));
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sha = dpp_sha_from_key_len(key_len);
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if (!dpp_hkdf(sha, NULL, key_len, "first intermediate key", mx_bytes,
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key_len, k1, key_len)) {
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l_ecc_scalar_free(m);
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return NULL;
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}
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return m;
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}
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/*
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* Derives key k2. This returns the intermediate secret N.x used in deriving
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* key ke.
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*/
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struct l_ecc_scalar *dpp_derive_k2(const struct l_ecc_point *i_proto_public,
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const struct l_ecc_scalar *proto_private,
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void *k2)
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{
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struct l_ecc_scalar *n;
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uint64_t nx_bytes[L_ECC_MAX_DIGITS];
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ssize_t key_len;
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enum l_checksum_type sha;
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if (!l_ecdh_generate_shared_secret(proto_private, i_proto_public, &n))
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return NULL;
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key_len = l_ecc_scalar_get_data(n, nx_bytes, sizeof(nx_bytes));
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sha = dpp_sha_from_key_len(key_len);
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if (!dpp_hkdf(sha, NULL, key_len, "second intermediate key", nx_bytes,
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key_len, k2, key_len)) {
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l_ecc_scalar_free(n);
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return NULL;
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}
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return n;
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}
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bool dpp_derive_ke(const uint8_t *i_nonce, const uint8_t *r_nonce,
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struct l_ecc_scalar *m, struct l_ecc_scalar *n,
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void *ke)
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{
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uint8_t nonces[32 + 32];
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size_t nonce_len;
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uint64_t mx_bytes[L_ECC_MAX_DIGITS];
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uint64_t nx_bytes[L_ECC_MAX_DIGITS];
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uint64_t bk[L_ECC_MAX_DIGITS];
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ssize_t key_len;
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enum l_checksum_type sha;
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key_len = l_ecc_scalar_get_data(m, mx_bytes, sizeof(mx_bytes));
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l_ecc_scalar_get_data(n, nx_bytes, sizeof(nx_bytes));
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nonce_len = dpp_nonce_len_from_key_len(key_len);
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sha = dpp_sha_from_key_len(key_len);
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memcpy(nonces, i_nonce, nonce_len);
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memcpy(nonces + nonce_len, r_nonce, nonce_len);
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/* bk = HKDF-Extract(I-nonce | R-nonce, M.x | N.x [ | L.x]) */
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if (!hkdf_extract(sha, nonces, nonce_len * 2, 2, bk, mx_bytes,
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key_len, nx_bytes, key_len))
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return false;
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/* ke = HKDF-Expand(bk, "DPP Key", length) */
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return hkdf_expand(sha, bk, key_len, "DPP Key", ke, key_len);
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}
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46
src/dpp-util.h
Normal file
46
src/dpp-util.h
Normal file
@ -0,0 +1,46 @@
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/*
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*
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* Wireless daemon for Linux
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*
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* Copyright (C) 2021 Intel Corporation. All rights reserved.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*
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*/
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struct l_ecc_point;
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struct l_ecc_scalar;
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size_t dpp_nonce_len_from_key_len(size_t len);
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bool dpp_hash(enum l_checksum_type type, uint8_t *out, unsigned int num, ...);
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bool dpp_derive_r_auth(const void *i_nonce, const void *r_nonce,
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size_t nonce_len, struct l_ecc_point *i_proto,
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struct l_ecc_point *r_proto,
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struct l_ecc_point *r_boot,
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void *r_auth);
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bool dpp_derive_i_auth(const void *r_nonce, const void *i_nonce,
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size_t nonce_len, struct l_ecc_point *r_proto,
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struct l_ecc_point *i_proto,
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struct l_ecc_point *r_boot, void *i_auth);
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struct l_ecc_scalar *dpp_derive_k1(const struct l_ecc_point *i_proto_public,
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const struct l_ecc_scalar *boot_private,
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void *k1);
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struct l_ecc_scalar *dpp_derive_k2(const struct l_ecc_point *i_proto_public,
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const struct l_ecc_scalar *proto_private,
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void *k2);
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bool dpp_derive_ke(const uint8_t *i_nonce, const uint8_t *r_nonce,
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struct l_ecc_scalar *m, struct l_ecc_scalar *n,
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void *ke);
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