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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: ofb.h,v 1.4 2001/06/17 00:10:51 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 1.4 2001/06/17 00:10:51 mdw |
34 | * Typesetting fixes |
35 | * |
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36 | * Revision 1.3 2000/06/17 11:48:24 mdw |
37 | * Change buffer offset to be unsigned. |
38 | * |
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39 | * Revision 1.2 1999/12/10 23:16:40 mdw |
40 | * Split mode macros into interface and implementation. |
41 | * |
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42 | * Revision 1.1 1999/09/03 08:41:12 mdw |
43 | * Initial import. |
44 | * |
45 | */ |
46 | |
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47 | #ifndef CATACOMB_OFB_H |
48 | #define CATACOMB_OFB_H |
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49 | |
50 | #ifdef __cplusplus |
51 | extern "C" { |
52 | #endif |
53 | |
54 | /*----- Header files ------------------------------------------------------*/ |
55 | |
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56 | #include <stddef.h> |
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57 | |
58 | #include <mLib/bits.h> |
59 | |
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60 | #ifndef CATACOMB_GCIPHER_H |
61 | # include "gcipher.h" |
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62 | #endif |
63 | |
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64 | #ifndef CATACOMB_GRAND_H |
65 | # include "grand.h" |
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66 | #endif |
67 | |
68 | /*----- Macros ------------------------------------------------------------*/ |
69 | |
70 | /* --- @OFB_DECL@ --- * |
71 | * |
72 | * Arguments: @PRE@, @pre@ = prefixes for block cipher definitions |
73 | * |
74 | * Use: Makes declarations for output feedback mode. |
75 | */ |
76 | |
77 | #define OFB_DECL(PRE, pre) \ |
78 | \ |
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79 | /* --- Output feedback context --- */ \ |
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80 | \ |
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81 | typedef struct pre##_ofbctx { \ |
82 | pre##_ctx ctx; /* Underlying cipher context */ \ |
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83 | unsigned off; /* Current offset in buffer */ \ |
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84 | octet iv[PRE##_BLKSZ]; /* Output buffer and IV */ \ |
85 | } pre##_ofbctx; \ |
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86 | \ |
87 | /* --- @pre_ofbgetiv@ --- * \ |
88 | * \ |
89 | * Arguments: @const pre_ofbctx *ctx@ = pointer to OFB context block \ |
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90 | * @void *iv@ = pointer to output data block \ |
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91 | * \ |
92 | * Returns: --- \ |
93 | * \ |
94 | * Use: Reads the currently set IV. Reading and setting an IV \ |
95 | * is not transparent to the cipher. It will add a `step' \ |
96 | * which must be matched by a similar operation during \ |
97 | * decryption. \ |
98 | */ \ |
99 | \ |
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100 | extern void pre##_ofbgetiv(const pre##_ofbctx */*ctx*/, \ |
101 | void */*iv*/); \ |
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102 | \ |
103 | /* --- @pre_ofbsetiv@ --- * \ |
104 | * \ |
105 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
106 | * @cnost void *iv@ = pointer to IV to set \ |
107 | * \ |
108 | * Returns: --- \ |
109 | * \ |
110 | * Use: Sets the IV to use for subsequent encryption. \ |
111 | */ \ |
112 | \ |
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113 | extern void pre##_ofbsetiv(pre##_ofbctx */*ctx*/, \ |
114 | const void */*iv*/); \ |
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115 | \ |
116 | /* --- @pre_ofbbdry@ --- * \ |
117 | * \ |
118 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
119 | * \ |
120 | * Returns: --- \ |
121 | * \ |
122 | * Use: Inserts a boundary during encryption. Successful \ |
123 | * decryption must place a similar boundary. \ |
124 | */ \ |
125 | \ |
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126 | extern void pre##_ofbbdry(pre##_ofbctx */*ctx*/); \ |
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127 | \ |
128 | /* --- @pre_ofbsetkey@ --- * \ |
129 | * \ |
130 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
131 | * @const pre_ctx *k@ = pointer to cipher context \ |
132 | * \ |
133 | * Returns: --- \ |
134 | * \ |
135 | * Use: Sets the OFB context to use a different cipher key. \ |
136 | */ \ |
137 | \ |
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138 | extern void pre##_ofbsetkey(pre##_ofbctx */*ctx*/, \ |
139 | const pre##_ctx */*k*/); \ |
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140 | \ |
141 | /* --- @pre_ofbinit@ --- * \ |
142 | * \ |
143 | * Arguments: @pre_ofbctx *ctx@ = pointer to cipher context \ |
144 | * @const void *key@ = pointer to the key buffer \ |
145 | * @size_t sz@ = size of the key \ |
146 | * @const void *iv@ = pointer to initialization vector \ |
147 | * \ |
148 | * Returns: --- \ |
149 | * \ |
150 | * Use: Initializes a OFB context ready for use. You should \ |
151 | * ensure that the IV chosen is unique: reusing an IV will \ |
152 | * compromise the security of the entire plaintext. This \ |
153 | * is equivalent to calls to @pre_init@, @pre_ofbsetkey@ \ |
154 | * and @pre_ofbsetiv@. \ |
155 | */ \ |
156 | \ |
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157 | extern void pre##_ofbinit(pre##_ofbctx */*ctx*/, \ |
158 | const void */*key*/, size_t /*sz*/, \ |
159 | const void */*iv*/); \ |
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160 | \ |
161 | /* --- @pre_ofbencrypt@ --- * \ |
162 | * \ |
163 | * Arguments: @pre_ofbctx *ctx@ = pointer to OFB context block \ |
164 | * @const void *src@ = pointer to source data \ |
165 | * @void *dest@ = pointer to destination data \ |
166 | * @size_t sz@ = size of block to be encrypted \ |
167 | * \ |
168 | * Returns: --- \ |
169 | * \ |
170 | * Use: Encrypts or decrypts a block with a block cipher in OFB \ |
171 | * mode: encryption and decryption are the same in OFB. \ |
172 | * The destination may be null to just churn the feedback \ |
173 | * round for a bit. The source may be null to use the \ |
174 | * cipher as a random data generator. \ |
175 | */ \ |
176 | \ |
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177 | extern void pre##_ofbencrypt(pre##_ofbctx */*ctx*/, \ |
178 | const void */*src*/, void */*dest*/, \ |
179 | size_t /*sz*/); \ |
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180 | \ |
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181 | /* --- @pre_ofbrand@ --- * \ |
182 | * \ |
183 | * Arguments: @const void *k@ = pointer to key material \ |
184 | * @size_t sz@ = size of key material \ |
185 | * \ |
186 | * Returns: Pointer to generic random number generator interface. \ |
187 | * \ |
188 | * Use: Creates a random number interface wrapper around an \ |
189 | * OFB-mode block cipher. \ |
190 | */ \ |
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191 | \ |
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192 | extern grand *pre##_ofbrand(const void */*k*/, size_t /*sz*/); \ |
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193 | \ |
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194 | /* --- Generic cipher interface --- */ \ |
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195 | \ |
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196 | extern const gccipher pre##_ofb; |
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197 | |
198 | /*----- That's all, folks -------------------------------------------------*/ |
199 | |
200 | #ifdef __cplusplus |
201 | } |
202 | #endif |
203 | |
204 | #endif |