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/*
* Copyright (C) 2018 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "stack/crypto_toolbox/crypto_toolbox.h"
#include "stack/crypto_toolbox/aes.h"
#include <algorithm>
#include <base/logging.h>
#include <base/strings/string_number_conversions.h>
using base::HexEncode;
namespace crypto_toolbox {
Octet16 h6(const Octet16& w, std::array<uint8_t, 4> keyid) {
return aes_cmac(w, keyid.data(), keyid.size());
}
Octet16 h7(const Octet16& salt, const Octet16& w) {
return aes_cmac(salt, w.data(), w.size());
}
Octet16 f4(const uint8_t* u, const uint8_t* v, const Octet16& x, uint8_t z) {
constexpr size_t msg_len = BT_OCTET32_LEN /* U size */ +
BT_OCTET32_LEN /* V size */ + 1 /* Z size */;
DVLOG(2) << "U=" << HexEncode(u, BT_OCTET32_LEN)
<< ", V=" << HexEncode(v, BT_OCTET32_LEN)
<< ", X=" << HexEncode(x.data(), x.size()) << ", Z=" << std::hex
<< +z;
std::array<uint8_t, msg_len> msg;
auto it = msg.begin();
it = std::copy(&z, &z + 1, it);
it = std::copy(v, v + BT_OCTET32_LEN, it);
it = std::copy(u, u + BT_OCTET32_LEN, it);
return aes_cmac(x, msg.data(), msg.size());
}
/** helper for f5 */
static Octet16 calculate_mac_key_or_ltk(const Octet16& t, uint8_t counter,
uint8_t* key_id, const Octet16& n1,
const Octet16& n2, uint8_t* a1,
uint8_t* a2, uint8_t* length) {
constexpr size_t msg_len = 1 /* Counter size */ + 4 /* keyID size */ +
OCTET16_LEN /* N1 size */ +
OCTET16_LEN /* N2 size */ + 7 /* A1 size*/ +
7 /* A2 size*/ + 2 /* Length size */;
std::array<uint8_t, msg_len> msg;
auto it = msg.begin();
it = std::copy(length, length + 2, it);
it = std::copy(a2, a2 + 7, it);
it = std::copy(a1, a1 + 7, it);
it = std::copy(n2.begin(), n2.end(), it);
it = std::copy(n1.begin(), n1.end(), it);
it = std::copy(key_id, key_id + 4, it);
it = std::copy(&counter, &counter + 1, it);
return aes_cmac(t, msg.data(), msg.size());
}
void f5(const uint8_t* w, const Octet16& n1, const Octet16& n2, uint8_t* a1,
uint8_t* a2, Octet16* mac_key, Octet16* ltk) {
DVLOG(2) << __func__ << "W=" << HexEncode(w, BT_OCTET32_LEN)
<< ", N1=" << HexEncode(n1.data(), n1.size())
<< ", N2=" << HexEncode(n2.data(), n2.size())
<< ", A1=" << HexEncode(a1, 7) << ", A2=" << HexEncode(a2, 7);
const Octet16 salt{0xBE, 0x83, 0x60, 0x5A, 0xDB, 0x0B, 0x37, 0x60,
0x38, 0xA5, 0xF5, 0xAA, 0x91, 0x83, 0x88, 0x6C};
Octet16 t = aes_cmac(salt, w, BT_OCTET32_LEN);
DVLOG(2) << "T=" << HexEncode(t.data(), t.size());
uint8_t key_id[4] = {0x65, 0x6c, 0x74, 0x62}; /* 0x62746c65 */
uint8_t length[2] = {0x00, 0x01}; /* 0x0100 */
*mac_key = calculate_mac_key_or_ltk(t, 0, key_id, n1, n2, a1, a2, length);
*ltk = calculate_mac_key_or_ltk(t, 1, key_id, n1, n2, a1, a2, length);
DVLOG(2) << "mac_key=" << HexEncode(mac_key->data(), mac_key->size());
DVLOG(2) << "ltk=" << HexEncode(ltk->data(), ltk->size());
}
Octet16 f6(const Octet16& w, const Octet16& n1, const Octet16& n2,
const Octet16& r, uint8_t* iocap, uint8_t* a1, uint8_t* a2) {
const uint8_t msg_len = OCTET16_LEN /* N1 size */ +
OCTET16_LEN /* N2 size */ + OCTET16_LEN /* R size */ +
3 /* IOcap size */ + 7 /* A1 size*/
+ 7 /* A2 size*/;
DVLOG(2) << __func__ << "W=" << HexEncode(w.data(), w.size())
<< ", N1=" << HexEncode(n1.data(), n1.size())
<< ", N2=" << HexEncode(n2.data(), n2.size())
<< ", R=" << HexEncode(r.data(), r.size())
<< ", IOcap=" << HexEncode(iocap, 3) << ", A1=" << HexEncode(a1, 7)
<< ", A2=" << HexEncode(a2, 7);
std::array<uint8_t, msg_len> msg;
auto it = msg.begin();
it = std::copy(a2, a2 + 7, it);
it = std::copy(a1, a1 + 7, it);
it = std::copy(iocap, iocap + 3, it);
it = std::copy(r.begin(), r.end(), it);
it = std::copy(n2.begin(), n2.end(), it);
it = std::copy(n1.begin(), n1.end(), it);
return aes_cmac(w, msg.data(), msg.size());
}
uint32_t g2(const uint8_t* u, const uint8_t* v, const Octet16& x,
const Octet16& y) {
constexpr size_t msg_len = BT_OCTET32_LEN /* U size */ +
BT_OCTET32_LEN /* V size */
+ OCTET16_LEN /* Y size */;
DVLOG(2) << __func__ << "U=" << HexEncode(u, BT_OCTET32_LEN)
<< ", V=" << HexEncode(v, BT_OCTET32_LEN)
<< ", X=" << HexEncode(x.data(), x.size())
<< ", Y=" << HexEncode(y.data(), y.size());
std::array<uint8_t, msg_len> msg;
auto it = msg.begin();
it = std::copy(y.begin(), y.end(), it);
it = std::copy(v, v + BT_OCTET32_LEN, it);
it = std::copy(u, u + BT_OCTET32_LEN, it);
Octet16 cmac = aes_cmac(x, msg.data(), msg.size());
/* vres = cmac mod 2**32 mod 10**6 */
uint32_t vres;
uint8_t* p = cmac.data();
STREAM_TO_UINT32(vres, p);
vres = vres % 1000000;
return vres;
}
Octet16 ltk_to_link_key(const Octet16& ltk, bool use_h7) {
Octet16 ilk; /* intermidiate link key */
if (use_h7) {
constexpr Octet16 salt{0x31, 0x70, 0x6D, 0x74, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
ilk = h7(salt, ltk);
} else {
/* "tmp1" mapping to extended ASCII, little endian*/
constexpr std::array<uint8_t, 4> keyID_tmp1 = {0x31, 0x70, 0x6D, 0x74};
ilk = h6(ltk, keyID_tmp1);
}
/* "lebr" mapping to extended ASCII, little endian */
constexpr std::array<uint8_t, 4> keyID_lebr = {0x72, 0x62, 0x65, 0x6c};
return h6(ilk, keyID_lebr);
}
Octet16 link_key_to_ltk(const Octet16& link_key, bool use_h7) {
Octet16 iltk; /* intermidiate long term key */
if (use_h7) {
constexpr Octet16 salt{0x32, 0x70, 0x6D, 0x74, 0x00, 0x00, 0x00, 0x00,
0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00};
iltk = h7(salt, link_key);
} else {
/* "tmp2" mapping to extended ASCII, little endian */
constexpr std::array<uint8_t, 4> keyID_tmp2 = {0x32, 0x70, 0x6D, 0x74};
iltk = h6(link_key, keyID_tmp2);
}
/* "brle" mapping to extended ASCII, little endian */
constexpr std::array<uint8_t, 4> keyID_brle = {0x65, 0x6c, 0x72, 0x62};
return h6(iltk, keyID_brle);
}
} // namespace crypto_toolbox