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1 | /* -*-c-*- |
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2 | * |
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3 | * FIPS140 randomness tests |
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4 | * |
5 | * (c) 2000 Straylight/Edgeware |
6 | */ |
7 | |
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8 | /*----- Licensing notice --------------------------------------------------* |
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9 | * |
10 | * This file is part of Catacomb. |
11 | * |
12 | * Catacomb is free software; you can redistribute it and/or modify |
13 | * it under the terms of the GNU Library General Public License as |
14 | * published by the Free Software Foundation; either version 2 of the |
15 | * License, or (at your option) any later version. |
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16 | * |
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17 | * Catacomb is distributed in the hope that it will be useful, |
18 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
20 | * GNU Library General Public License for more details. |
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21 | * |
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22 | * You should have received a copy of the GNU Library General Public |
23 | * License along with Catacomb; if not, write to the Free |
24 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
25 | * MA 02111-1307, USA. |
26 | */ |
27 | |
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28 | /*----- Header files ------------------------------------------------------*/ |
29 | |
30 | #include <mLib/bits.h> |
31 | |
32 | #include "fipstest.h" |
33 | |
34 | /*----- Main code ---------------------------------------------------------*/ |
35 | |
36 | /* --- @monobit@ --- * |
37 | * |
38 | * Arguments: @const octet *p@ = pointer to buffer |
39 | * |
40 | * Returns: Zero if OK, @FIPSTEST_MONOBIT@ on failure. |
41 | * |
42 | * Use: Performs the monobit test on a buffer of data. If %$n_1$% is |
43 | * the number of 1 bits in the buffer, then the monobit test is |
44 | * passed when %$9654 < n_1 < 10346$%. |
45 | */ |
46 | |
47 | static unsigned monobit(const octet *p) |
48 | { |
49 | unsigned n1 = 0; |
50 | unsigned i, j; |
51 | |
52 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
53 | octet x = p[i]; |
54 | for (j = 0; j < 8; j++) { |
55 | if (x & 1) |
56 | n1++; |
57 | x >>= 1; |
58 | } |
59 | } |
60 | |
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61 | if (9725 >= n1 || n1 >= 10275) |
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62 | return (FIPSTEST_MONOBIT); |
63 | return (0); |
64 | } |
65 | |
66 | /* --- @poker@ --- * |
67 | * |
68 | * Arguments: @const octet *p@ = pointer to buffer |
69 | * |
70 | * Returns: Zero if OK, @FIPSTEST_POKER@ on failure. |
71 | * |
72 | * Use: Performs the poker test on a buffer of data. The buffer is |
73 | * divided into 4-bit nibbles %$x_i$%. If |
74 | * %$f(x) = \sum_{x_i = x} 1$% is the frequency of each nibble, |
75 | * then the test is passed if |
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76 | * %$2.16 < 16/5000 \sum_i f(i)^2 - 5000 < 46.17$%. |
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77 | */ |
78 | |
79 | static unsigned poker(const octet *p) |
80 | { |
81 | unsigned long f[16] = { 0 }; |
82 | unsigned i; |
83 | unsigned long q = 0; |
84 | |
85 | /* --- Compute the frequencies --- */ |
86 | |
87 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
88 | octet x = p[i]; |
89 | f[x & 0xf]++; |
90 | f[(x >> 4) & 0xf]++; |
91 | } |
92 | |
93 | /* --- Now do the comparison --- * |
94 | * |
95 | * This can be simplified. Multiply through the inequality by 5000 and |
96 | * we get %$5150 < 16 \sum_i f(i)^2 - 5000^2 < 287000$%. |
97 | */ |
98 | |
99 | for (i = 0; i < 16; i++) |
100 | q += f[i] * f[i]; |
101 | q <<= 4; |
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102 | q -= 5000ul * 5000ul; |
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103 | |
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104 | if (10800 >= q || q >= 230850) |
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105 | return (FIPSTEST_POKER); |
106 | return (0); |
107 | } |
108 | |
109 | /* --- @runs@ --- * |
110 | * |
111 | * Arguments: @const octet *p@ = pointer to buffer |
112 | * |
113 | * Returns: Zero for success, @FIPSTEST_RUNS@ or @FIPSTEST_LONGRUNS@ on |
114 | * failure. |
115 | * |
116 | * Use: Performs the runs and long runs tests. The frequency of each |
117 | * `run', or sequence of equal bits, is counted and tested. |
118 | */ |
119 | |
120 | static unsigned runs(const octet *p) |
121 | { |
122 | unsigned rc = 0; |
123 | unsigned i, j; |
124 | unsigned r = 0; |
125 | unsigned bb = 0; |
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126 | unsigned f[2][6] = { { 0 } }; |
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127 | |
128 | /* --- Count the run lengths --- */ |
129 | |
130 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
131 | octet x = p[i]; |
132 | for (j = 0; j < 8; j++) { |
133 | unsigned b = x & 1; |
134 | x >>= 1; |
135 | if (b == bb) |
136 | r++; |
137 | else { |
138 | if (r) { |
139 | if (r >= 34) |
140 | rc |= FIPSTEST_LONGRUNS; |
141 | if (r > 6) |
142 | r = 6; |
143 | f[bb][r - 1]++; |
144 | } |
145 | r = 1; |
146 | bb = b; |
147 | } |
148 | } |
149 | } |
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150 | |
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151 | if (r >= 26) |
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152 | rc |= FIPSTEST_LONGRUNS; |
153 | if (r > 6) |
154 | r = 6; |
155 | f[bb][r - 1]++; |
156 | |
157 | /* --- Check the results --- */ |
158 | |
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159 | if (2343 > f[0][0] || f[0][0] > 2657 || 2343 > f[1][0] || f[1][0] > 2657 || |
160 | 1135 > f[0][1] || f[0][1] > 1365 || 1135 > f[1][1] || f[1][1] > 1365 || |
161 | 542 > f[0][2] || f[0][2] > 708 || 542 > f[1][2] || f[1][2] > 708 || |
162 | 251 > f[0][3] || f[0][3] > 373 || 251 > f[1][3] || f[1][3] > 373 || |
163 | 111 > f[0][4] || f[0][4] > 201 || 111 > f[1][4] || f[1][4] > 201 || |
164 | 111 > f[0][5] || f[0][5] > 201 || 111 > f[1][5] || f[1][5] > 201) |
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165 | rc |= FIPSTEST_RUNS; |
166 | |
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167 | return (rc); |
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168 | } |
169 | |
170 | /* --- @fipstest@ --- * |
171 | * |
172 | * Arguments: @const octet *p@ = pointer to a buffer of @FIPSTEST_BUFSZ@ |
173 | * bytes |
174 | * |
175 | * Returns: Zero if OK, or a bitmask of failed tests. |
176 | * |
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177 | * Use: Performs the FIPS140 randomness tests on a block of data. |
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178 | */ |
179 | |
180 | unsigned fipstest(const octet *p) |
181 | { |
182 | unsigned rc = 0; |
183 | rc |= monobit(p); |
184 | rc |= poker(p); |
185 | rc |= runs(p); |
186 | return (rc); |
187 | } |
188 | |
189 | /*----- That's all, folks -------------------------------------------------*/ |