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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: ofb.h,v 1.3 2000/06/17 11:48:24 mdw Exp $ |
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4 | * |
5 | * Output feedback for block ciphers |
6 | * |
7 | * (c) 1999 Straylight/Edgeware |
8 | */ |
9 | |
10 | /*----- Licensing notice --------------------------------------------------* |
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. |
18 | * |
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. |
23 | * |
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 | |
30 | /*----- Revision history --------------------------------------------------* |
31 | * |
32 | * $Log: ofb.h,v $ |
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33 | * Revision 1.3 2000/06/17 11:48:24 mdw |
34 | * Change buffer offset to be unsigned. |
35 | * |
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36 | * Revision 1.2 1999/12/10 23:16:40 mdw |
37 | * Split mode macros into interface and implementation. |
38 | * |
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39 | * Revision 1.1 1999/09/03 08:41:12 mdw |
40 | * Initial import. |
41 | * |
42 | */ |
43 | |
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44 | #ifndef CATACOMB_OFB_H |
45 | #define CATACOMB_OFB_H |
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46 | |
47 | #ifdef __cplusplus |
48 | extern "C" { |
49 | #endif |
50 | |
51 | /*----- Header files ------------------------------------------------------*/ |
52 | |
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53 | #include <stddef.h> |
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54 | |
55 | #include <mLib/bits.h> |
56 | |
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57 | #ifndef CATACOMB_GCIPHER_H |
58 | # include "gcipher.h" |
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59 | #endif |
60 | |
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61 | #ifndef CATACOMB_GRAND_H |
62 | # include "grand.h" |
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63 | #endif |
64 | |
65 | /*----- Macros ------------------------------------------------------------*/ |
66 | |
67 | /* --- @OFB_DECL@ --- * |
68 | * |
69 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
70 | * |
71 | * Use: Makes declarations for output feedback mode. |
72 | */ |
73 | |
74 | #define OFB_DECL(PRE, pre) \ |
75 | \ |
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76 | /* --- Output feedback context --- */ \ |
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77 | \ |
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78 | typedef struct pre##_ofbctx { \ |
79 | pre##_ctx ctx; /* Underlying cipher context */ \ |
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80 | unsigned off; /* Current offset in buffer */ \ |
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81 | octet iv[PRE##_BLKSZ]; /* Output buffer and IV */ \ |
82 | } pre##_ofbctx; \ |
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83 | \ |
84 | /* --- @pre_ofbgetiv@ --- * \ |
85 | * \ |
86 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
87 | * @void *iv#@ = pointer to output data block \ |
88 | * \ |
89 | * Returns: --- \ |
90 | * \ |
91 | * Use: Reads the currently set IV. Reading and setting an IV \ |
92 | * is not transparent to the cipher. It will add a `step' \ |
93 | * which must be matched by a similar operation during \ |
94 | * decryption. \ |
95 | */ \ |
96 | \ |
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97 | extern void pre##_ofbgetiv(const pre##_ofbctx */*ctx*/, \ |
98 | void */*iv*/); \ |
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99 | \ |
100 | /* --- @pre_ofbsetiv@ --- * \ |
101 | * \ |
102 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
103 | * @cnost void *iv@ = pointer to IV to set \ |
104 | * \ |
105 | * Returns: --- \ |
106 | * \ |
107 | * Use: Sets the IV to use for subsequent encryption. \ |
108 | */ \ |
109 | \ |
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110 | extern void pre##_ofbsetiv(pre##_ofbctx */*ctx*/, \ |
111 | const void */*iv*/); \ |
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112 | \ |
113 | /* --- @pre_ofbbdry@ --- * \ |
114 | * \ |
115 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
116 | * \ |
117 | * Returns: --- \ |
118 | * \ |
119 | * Use: Inserts a boundary during encryption. Successful \ |
120 | * decryption must place a similar boundary. \ |
121 | */ \ |
122 | \ |
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123 | extern void pre##_ofbbdry(pre##_ofbctx */*ctx*/); \ |
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124 | \ |
125 | /* --- @pre_ofbsetkey@ --- * \ |
126 | * \ |
127 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
128 | * @const pre_ctx *k@ = pointer to cipher context \ |
129 | * \ |
130 | * Returns: --- \ |
131 | * \ |
132 | * Use: Sets the OFB context to use a different cipher key. \ |
133 | */ \ |
134 | \ |
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135 | extern void pre##_ofbsetkey(pre##_ofbctx */*ctx*/, \ |
136 | const pre##_ctx */*k*/); \ |
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137 | \ |
138 | /* --- @pre_ofbinit@ --- * \ |
139 | * \ |
140 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
141 | * @const void *key@ = pointer to the key buffer \ |
142 | * @size_t sz@ = size of the key \ |
143 | * @const void *iv@ = pointer to initialization vector \ |
144 | * \ |
145 | * Returns: --- \ |
146 | * \ |
147 | * Use: Initializes a OFB context ready for use. You should \ |
148 | * ensure that the IV chosen is unique: reusing an IV will \ |
149 | * compromise the security of the entire plaintext. This \ |
150 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
151 | * and @pre_ofbsetiv@. \ |
152 | */ \ |
153 | \ |
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154 | extern void pre##_ofbinit(pre##_ofbctx */*ctx*/, \ |
155 | const void */*key*/, size_t /*sz*/, \ |
156 | const void */*iv*/); \ |
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157 | \ |
158 | /* --- @pre_ofbencrypt@ --- * \ |
159 | * \ |
160 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
161 | * @const void *src@ = pointer to source data \ |
162 | * @void *dest@ = pointer to destination data \ |
163 | * @size_t sz@ = size of block to be encrypted \ |
164 | * \ |
165 | * Returns: --- \ |
166 | * \ |
167 | * Use: Encrypts or decrypts a block with a block cipher in OFB \ |
168 | * mode: encryption and decryption are the same in OFB. \ |
169 | * The destination may be null to just churn the feedback \ |
170 | * round for a bit. The source may be null to use the \ |
171 | * cipher as a random data generator. \ |
172 | */ \ |
173 | \ |
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174 | extern void pre##_ofbencrypt(pre##_ofbctx */*ctx*/, \ |
175 | const void */*src*/, void */*dest*/, \ |
176 | size_t /*sz*/); \ |
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177 | \ |
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178 | /* --- @pre_ofbrand@ --- * \ |
179 | * \ |
180 | * Arguments: @const void *k@ = pointer to key material \ |
181 | * @size_t sz@ = size of key material \ |
182 | * \ |
183 | * Returns: Pointer to generic random number generator interface. \ |
184 | * \ |
185 | * Use: Creates a random number interface wrapper around an \ |
186 | * OFB-mode block cipher. \ |
187 | */ \ |
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188 | \ |
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189 | extern grand *pre##_ofbrand(const void */*k*/, size_t /*sz*/); \ |
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190 | \ |
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191 | /* --- Generic cipher interface --- */ \ |
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192 | \ |
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193 | extern const gccipher pre##_ofb; |
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194 | |
195 | /*----- That's all, folks -------------------------------------------------*/ |
196 | |
197 | #ifdef __cplusplus |
198 | } |
199 | #endif |
200 | |
201 | #endif |