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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: fipstest.c,v 1.4 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
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5 | * FIPS140 randomness tests |
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6 | * |
7 | * (c) 2000 Straylight/Edgeware |
8 | */ |
9 | |
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10 | /*----- Licensing notice --------------------------------------------------* |
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11 | * |
12 | * This file is part of Catacomb. |
13 | * |
14 | * Catacomb is free software; you can redistribute it and/or modify |
15 | * it under the terms of the GNU Library General Public License as |
16 | * published by the Free Software Foundation; either version 2 of the |
17 | * License, or (at your option) any later version. |
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18 | * |
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19 | * Catacomb is distributed in the hope that it will be useful, |
20 | * but WITHOUT ANY WARRANTY; without even the implied warranty of |
21 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
22 | * GNU Library General Public License for more details. |
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23 | * |
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24 | * You should have received a copy of the GNU Library General Public |
25 | * License along with Catacomb; if not, write to the Free |
26 | * Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, |
27 | * MA 02111-1307, USA. |
28 | */ |
29 | |
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30 | /*----- Header files ------------------------------------------------------*/ |
31 | |
32 | #include <mLib/bits.h> |
33 | |
34 | #include "fipstest.h" |
35 | |
36 | /*----- Main code ---------------------------------------------------------*/ |
37 | |
38 | /* --- @monobit@ --- * |
39 | * |
40 | * Arguments: @const octet *p@ = pointer to buffer |
41 | * |
42 | * Returns: Zero if OK, @FIPSTEST_MONOBIT@ on failure. |
43 | * |
44 | * Use: Performs the monobit test on a buffer of data. If %$n_1$% is |
45 | * the number of 1 bits in the buffer, then the monobit test is |
46 | * passed when %$9654 < n_1 < 10346$%. |
47 | */ |
48 | |
49 | static unsigned monobit(const octet *p) |
50 | { |
51 | unsigned n1 = 0; |
52 | unsigned i, j; |
53 | |
54 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
55 | octet x = p[i]; |
56 | for (j = 0; j < 8; j++) { |
57 | if (x & 1) |
58 | n1++; |
59 | x >>= 1; |
60 | } |
61 | } |
62 | |
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63 | if (9725 >= n1 || n1 >= 10275) |
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64 | return (FIPSTEST_MONOBIT); |
65 | return (0); |
66 | } |
67 | |
68 | /* --- @poker@ --- * |
69 | * |
70 | * Arguments: @const octet *p@ = pointer to buffer |
71 | * |
72 | * Returns: Zero if OK, @FIPSTEST_POKER@ on failure. |
73 | * |
74 | * Use: Performs the poker test on a buffer of data. The buffer is |
75 | * divided into 4-bit nibbles %$x_i$%. If |
76 | * %$f(x) = \sum_{x_i = x} 1$% is the frequency of each nibble, |
77 | * then the test is passed if |
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78 | * %$2.16 < 16/5000 \sum_i f(i)^2 - 5000 < 46.17$%. |
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79 | */ |
80 | |
81 | static unsigned poker(const octet *p) |
82 | { |
83 | unsigned long f[16] = { 0 }; |
84 | unsigned i; |
85 | unsigned long q = 0; |
86 | |
87 | /* --- Compute the frequencies --- */ |
88 | |
89 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
90 | octet x = p[i]; |
91 | f[x & 0xf]++; |
92 | f[(x >> 4) & 0xf]++; |
93 | } |
94 | |
95 | /* --- Now do the comparison --- * |
96 | * |
97 | * This can be simplified. Multiply through the inequality by 5000 and |
98 | * we get %$5150 < 16 \sum_i f(i)^2 - 5000^2 < 287000$%. |
99 | */ |
100 | |
101 | for (i = 0; i < 16; i++) |
102 | q += f[i] * f[i]; |
103 | q <<= 4; |
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104 | q -= 5000ul * 5000ul; |
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105 | |
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106 | if (10800 >= q || q >= 230850) |
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107 | return (FIPSTEST_POKER); |
108 | return (0); |
109 | } |
110 | |
111 | /* --- @runs@ --- * |
112 | * |
113 | * Arguments: @const octet *p@ = pointer to buffer |
114 | * |
115 | * Returns: Zero for success, @FIPSTEST_RUNS@ or @FIPSTEST_LONGRUNS@ on |
116 | * failure. |
117 | * |
118 | * Use: Performs the runs and long runs tests. The frequency of each |
119 | * `run', or sequence of equal bits, is counted and tested. |
120 | */ |
121 | |
122 | static unsigned runs(const octet *p) |
123 | { |
124 | unsigned rc = 0; |
125 | unsigned i, j; |
126 | unsigned r = 0; |
127 | unsigned bb = 0; |
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128 | unsigned f[2][6] = { { 0 } }; |
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129 | |
130 | /* --- Count the run lengths --- */ |
131 | |
132 | for (i = 0; i < FIPSTEST_BUFSZ; i++) { |
133 | octet x = p[i]; |
134 | for (j = 0; j < 8; j++) { |
135 | unsigned b = x & 1; |
136 | x >>= 1; |
137 | if (b == bb) |
138 | r++; |
139 | else { |
140 | if (r) { |
141 | if (r >= 34) |
142 | rc |= FIPSTEST_LONGRUNS; |
143 | if (r > 6) |
144 | r = 6; |
145 | f[bb][r - 1]++; |
146 | } |
147 | r = 1; |
148 | bb = b; |
149 | } |
150 | } |
151 | } |
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152 | |
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153 | if (r >= 26) |
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154 | rc |= FIPSTEST_LONGRUNS; |
155 | if (r > 6) |
156 | r = 6; |
157 | f[bb][r - 1]++; |
158 | |
159 | /* --- Check the results --- */ |
160 | |
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161 | if (2343 > f[0][0] || f[0][0] > 2657 || 2343 > f[1][0] || f[1][0] > 2657 || |
162 | 1135 > f[0][1] || f[0][1] > 1365 || 1135 > f[1][1] || f[1][1] > 1365 || |
163 | 542 > f[0][2] || f[0][2] > 708 || 542 > f[1][2] || f[1][2] > 708 || |
164 | 251 > f[0][3] || f[0][3] > 373 || 251 > f[1][3] || f[1][3] > 373 || |
165 | 111 > f[0][4] || f[0][4] > 201 || 111 > f[1][4] || f[1][4] > 201 || |
166 | 111 > f[0][5] || f[0][5] > 201 || 111 > f[1][5] || f[1][5] > 201) |
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167 | rc |= FIPSTEST_RUNS; |
168 | |
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169 | return (rc); |
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170 | } |
171 | |
172 | /* --- @fipstest@ --- * |
173 | * |
174 | * Arguments: @const octet *p@ = pointer to a buffer of @FIPSTEST_BUFSZ@ |
175 | * bytes |
176 | * |
177 | * Returns: Zero if OK, or a bitmask of failed tests. |
178 | * |
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179 | * Use: Performs the FIPS140 randomness tests on a block of data. |
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180 | */ |
181 | |
182 | unsigned fipstest(const octet *p) |
183 | { |
184 | unsigned rc = 0; |
185 | rc |= monobit(p); |
186 | rc |= poker(p); |
187 | rc |= runs(p); |
188 | return (rc); |
189 | } |
190 | |
191 | /*----- That's all, folks -------------------------------------------------*/ |