1 /* Microsoft Reference Implementation for TPM 2.0
2 *
3 * The copyright in this software is being made available under the BSD License,
4 * included below. This software may be subject to other third party and
5 * contributor rights, including patent rights, and no such rights are granted
6 * under this license.
7 *
8 * Copyright (c) Microsoft Corporation
9 *
10 * All rights reserved.
11 *
12 * BSD License
13 *
14 * Redistribution and use in source and binary forms, with or without modification,
15 * are permitted provided that the following conditions are met:
16 *
17 * Redistributions of source code must retain the above copyright notice, this list
18 * of conditions and the following disclaimer.
19 *
20 * Redistributions in binary form must reproduce the above copyright notice, this
21 * list of conditions and the following disclaimer in the documentation and/or
22 * other materials provided with the distribution.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ""AS IS""
25 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
27 * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR
28 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
29 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
30 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON
31 * ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
32 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
33 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
34 */
35 //** Introduction
36 // In some implementations of the TPM, the hardware can provide a secret
37 // value to the TPM. This secret value is statistically unique to the
38 // instance of the TPM. Typical uses of this value are to provide
39 // personalization to the random number generation and as a shared secret
40 // between the TPM and the manufacturer.
41
42 //** Includes
43 #include "Platform.h"
44
45 const char notReallyUnique[] =
46 "This is not really a unique value. A real unique value should"
47 " be generated by the platform.";
48
49 //** _plat__GetUnique()
50 // This function is used to access the platform-specific unique value.
51 // This function places the unique value in the provided buffer ('b')
52 // and returns the number of bytes transferred. The function will not
53 // copy more data than 'bSize'.
54 // NOTE: If a platform unique value has unequal distribution of uniqueness
55 // and 'bSize' is smaller than the size of the unique value, the 'bSize'
56 // portion with the most uniqueness should be returned.
57 LIB_EXPORT uint32_t
_plat__GetUnique(uint32_t which,uint32_t bSize,unsigned char * b)58 _plat__GetUnique(
59 uint32_t which, // authorities (0) or details
60 uint32_t bSize, // size of the buffer
61 unsigned char *b // output buffer
62 )
63 {
64 const char *from = notReallyUnique;
65 uint32_t retVal = 0;
66
67 if(which == 0) // the authorities value
68 {
69 for(retVal = 0;
70 *from != 0 && retVal < bSize;
71 retVal++)
72 {
73 *b++ = *from++;
74 }
75 }
76 else
77 {
78 #define uSize sizeof(notReallyUnique)
79 b = &b[((bSize < uSize) ? bSize : uSize) - 1];
80 for(retVal = 0;
81 *from != 0 && retVal < bSize;
82 retVal++)
83 {
84 *b-- = *from++;
85 }
86 }
87 return retVal;
88 }