Commit | Line | Data |
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7809fc3d | 1 | /* -*-c-*- |
2 | * | |
7809fc3d | 3 | * General block cipher utilities |
4 | * | |
5 | * (c) 2000 Straylight/Edgeware | |
6 | */ | |
7 | ||
45c0fd36 | 8 | /*----- Licensing notice --------------------------------------------------* |
7809fc3d | 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. | |
45c0fd36 | 16 | * |
7809fc3d | 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. | |
45c0fd36 | 21 | * |
7809fc3d | 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 | ||
7809fc3d | 28 | /*----- Header files ------------------------------------------------------*/ |
29 | ||
30 | #include <assert.h> | |
31 | ||
32 | #include "gcipher.h" | |
33 | ||
34 | /*----- Main code ---------------------------------------------------------*/ | |
35 | ||
36 | /* --- @keysz@ --- * | |
37 | * | |
38 | * Arguments: @size_t sz@ = a proposed key size, or zero | |
39 | * @const octet *ksz@ = pointer to key size table | |
40 | * | |
41 | * Returns: See below. | |
42 | * | |
43 | * Use: Returns a sensible key size. If @sz@ is nonzero, it is | |
44 | * interpreted as an amount (in bytes) of key material which the | |
45 | * caller has available, and the return value is either the | |
46 | * largest allowable key size less than or equal to the caller's | |
47 | * size, or zero if there is no valid key length small enough. | |
48 | * If @sz@ is zero, the function returns a `recommended' key | |
49 | * size. | |
50 | */ | |
51 | ||
52 | size_t keysz(size_t sz, const octet *ksz) | |
53 | { | |
c77f9bb9 MW |
54 | unsigned op = ksz[0]&KSZ_OPMASK; |
55 | unsigned wd = (ksz[0]&KSZ_16BIT) ? 2 : 1; | |
56 | unsigned t, u, v; | |
57 | ||
58 | ksz++; | |
0588f9b2 | 59 | #define ARG(i) (wd == 1 ? ksz[i] : LOAD16(ksz + 2*i)) |
7809fc3d | 60 | if (sz == 0) |
c77f9bb9 MW |
61 | return (ARG(0)); |
62 | else switch (op) { | |
63 | case KSZ_ANY: return (sz); | |
7809fc3d | 64 | case KSZ_RANGE: |
c77f9bb9 MW |
65 | t = ARG(1); u = ARG(2); v = ARG(3); |
66 | if (v) sz -= sz%v; | |
67 | if (sz < t) return (0); | |
68 | if (u && sz > u) return (u); | |
7809fc3d | 69 | return (sz); |
c77f9bb9 MW |
70 | case KSZ_SET: |
71 | u = 0; | |
72 | for (;;) { | |
73 | t = ARG(0); ksz += wd; if (!t) break; | |
74 | if (sz >= t && u < t) u = t; | |
7809fc3d | 75 | } |
c77f9bb9 | 76 | return (u); |
7809fc3d | 77 | } |
c77f9bb9 | 78 | #undef ARG |
7809fc3d | 79 | |
80 | assert(((void)"bad key size table", 0)); | |
81 | return (0); | |
82 | } | |
83 | ||
778b9e26 MW |
84 | /* --- @keysz_pad@ --- * |
85 | * | |
86 | * Arguments: @size_t sz@ = a proposed key size | |
87 | * @const octet *ksz@ = pointer to key size table | |
88 | * | |
89 | * Returns: A key size, at least as large as @sz@, or zero if no such | |
90 | * size is available. | |
91 | */ | |
92 | ||
93 | size_t keysz_pad(size_t sz, const octet *ksz) | |
94 | { | |
95 | unsigned op = ksz[0]&KSZ_OPMASK; | |
96 | unsigned wd = (ksz[0]&KSZ_16BIT) ? 2 : 1; | |
97 | unsigned t, u, v; | |
98 | ||
99 | ksz++; | |
100 | #define ARG(i) (wd == 1 ? ksz[i] : LOAD16(ksz + 2*i)) | |
101 | switch (op) { | |
102 | case KSZ_ANY: return (sz); | |
103 | case KSZ_RANGE: | |
104 | t = ARG(1); u = ARG(2); v = ARG(3); | |
105 | if (v) { sz += v - 1; sz -= sz%v; } | |
106 | if (u && sz > u) return (0); | |
107 | if (sz < t) return (t); | |
108 | return (sz); | |
109 | case KSZ_SET: | |
110 | u = 0; | |
111 | for (;;) { | |
112 | t = ARG(0); ksz += wd; if (!t) break; | |
113 | if (sz <= t && (!u || u > t)) u = t; | |
114 | } | |
115 | return (u); | |
116 | } | |
117 | #undef ARG | |
118 | ||
119 | assert(((void)"bad key size table", 0)); | |
120 | return (0); | |
121 | } | |
122 | ||
7809fc3d | 123 | /*----- That's all, folks -------------------------------------------------*/ |