1 /*
2 * Copyright (c) 2017, The OpenThread Authors.
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 * 3. Neither the name of the copyright holder nor the
13 * names of its contributors may be used to endorse or promote products
14 * derived from this software without specific prior written permission.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26 * POSSIBILITY OF SUCH DAMAGE.
27 */
28
29 /**
30 * @file
31 * This file implements the generating pskc function.
32 */
33
34 #include "utils/pskc.hpp"
35
36 #include "common/code_utils.hpp"
37 #include "common/logging.hpp"
38
39 namespace otbr {
40 namespace Psk {
41
SetSalt(const uint8_t * aExtPanId,const char * aNetworkName)42 void Pskc::SetSalt(const uint8_t *aExtPanId, const char *aNetworkName)
43 {
44 const char *saltPrefix = "Thread";
45 int cur = 0;
46 int ret = kPskcStatus_Ok;
47 int remainingSpace = 0;
48 int networkNameLen = 0;
49
50 if (strlen(saltPrefix) + OT_EXTENDED_PAN_ID_LENGTH + strlen(aNetworkName) >= sizeof(mSalt))
51 {
52 otbrLogWarning("Network name too long; will be truncated.");
53 }
54
55 memset(mSalt, 0, sizeof(mSalt));
56 memcpy(mSalt, saltPrefix, strlen(saltPrefix));
57 cur += strlen(saltPrefix);
58
59 memcpy(mSalt + cur, aExtPanId, OT_EXTENDED_PAN_ID_LENGTH);
60 cur += OT_EXTENDED_PAN_ID_LENGTH;
61
62 VerifyOrExit(strlen(aNetworkName) > 0, ret = kPskcStatus_InvalidArgument);
63
64 remainingSpace = sizeof(mSalt) - cur;
65 if (remainingSpace > 0)
66 {
67 networkNameLen = std::min(static_cast<int>(strlen(aNetworkName)), remainingSpace);
68 memcpy(mSalt + cur, aNetworkName, networkNameLen);
69 cur += networkNameLen;
70 }
71
72 mSaltLen = static_cast<uint16_t>(cur);
73
74 exit:
75 if (ret != kPskcStatus_Ok)
76 {
77 otbrLogErr("ExtPanId or NetworkName is nullptr");
78 }
79 return;
80 }
81
ComputePskc(const uint8_t * aExtPanId,const char * aNetworkName,const char * aPassphrase)82 const uint8_t *Pskc::ComputePskc(const uint8_t *aExtPanId, const char *aNetworkName, const char *aPassphrase)
83 {
84 uint32_t blockCounter = 0;
85 uint16_t useLen = 0;
86 uint16_t prfBlockLen = MBEDTLS_CIPHER_BLKSIZE_MAX;
87 uint8_t prfInput[OT_PBKDF2_SALT_MAX_LENGTH + 4];
88 uint8_t prfOutput[MBEDTLS_CIPHER_BLKSIZE_MAX];
89 uint8_t keyBlock[MBEDTLS_CIPHER_BLKSIZE_MAX];
90 uint16_t keyLen = OT_PSKC_LENGTH;
91 uint8_t *pskc = mPskc;
92
93 SetSalt(aExtPanId, aNetworkName);
94
95 while (keyLen)
96 {
97 memcpy(prfInput, mSalt, mSaltLen);
98
99 blockCounter++;
100 prfInput[mSaltLen + 0] = (uint8_t)(blockCounter >> 24);
101 prfInput[mSaltLen + 1] = (uint8_t)(blockCounter >> 16);
102 prfInput[mSaltLen + 2] = (uint8_t)(blockCounter >> 8);
103 prfInput[mSaltLen + 3] = (uint8_t)(blockCounter);
104 // Calculate U_1
105 mbedtls_aes_cmac_prf_128(reinterpret_cast<const uint8_t *>(aPassphrase), strlen(aPassphrase), prfInput,
106 mSaltLen + 4, prfOutput);
107 memcpy(keyBlock, prfOutput, prfBlockLen);
108
109 for (uint32_t i = 1; i < OT_ITERATION_COUNTS; i++)
110 {
111 memcpy(prfInput, prfOutput, prfBlockLen);
112
113 // Calculate U_i
114 mbedtls_aes_cmac_prf_128(reinterpret_cast<const uint8_t *>(aPassphrase), strlen(aPassphrase), prfInput,
115 prfBlockLen, prfOutput);
116
117 // xor
118 for (uint32_t j = 0; j < prfBlockLen; j++)
119 {
120 keyBlock[j] ^= prfOutput[j];
121 }
122 }
123
124 useLen = (keyLen < prfBlockLen) ? keyLen : prfBlockLen;
125 memcpy(pskc, keyBlock, useLen);
126 pskc += useLen;
127 keyLen -= useLen;
128 }
129 return mPskc;
130 }
131
132 } // namespace Psk
133 } // namespace otbr
134