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1 | /* -*-c-*- |
2 | * |
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3 | * $Id: cfb.h,v 1.5 2004/04/08 01:36:15 mdw Exp $ |
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4 | * |
5 | * Ciphertext feedback for block ciphers |
6 | * |
7 | * (c) 1999 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 | #ifndef CATACOMB_CFB_H |
31 | #define CATACOMB_CFB_H |
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32 | |
33 | #ifdef __cplusplus |
34 | extern "C" { |
35 | #endif |
36 | |
37 | /*----- Header files ------------------------------------------------------*/ |
38 | |
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39 | #include <stddef.h> |
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40 | |
41 | #include <mLib/bits.h> |
42 | |
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43 | #ifndef CATACOMB_GCIPHER_H |
44 | # include "gcipher.h" |
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45 | #endif |
46 | |
47 | /*----- Data structures ---------------------------------------------------*/ |
48 | |
49 | /* --- @CFB_DECL@ --- * |
50 | * |
51 | * Arguments: @PRE@, @pre@ = prefixes for the underlying block cipher |
52 | * |
53 | * Use: Creates declarations for CFB mode. |
54 | */ |
55 | |
56 | #define CFB_DECL(PRE, pre) \ |
57 | \ |
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58 | /* --- Ciphertext feedback context --- */ \ |
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59 | \ |
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60 | typedef struct pre##_cfbctx { \ |
61 | pre##_ctx ctx; /* Underlying cipher context */ \ |
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62 | unsigned off; /* Offset into @iv@ buffer */ \ |
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63 | octet iv[PRE##_BLKSZ]; /* Previous ciphertext or IV */ \ |
64 | } pre##_cfbctx; \ |
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65 | \ |
66 | /* --- @pre_cfbgetiv@ --- * \ |
67 | * \ |
68 | * Arguments: @const pre_cfbctx *ctx@ = pointer to CFB context block \ |
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69 | * @void *iv@ = pointer to output data block \ |
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70 | * \ |
71 | * Returns: --- \ |
72 | * \ |
73 | * Use: Reads the currently set IV. Reading and setting an IV \ |
74 | * is not transparent to the cipher. It will add a `step' \ |
75 | * which must be matched by a similar operation during \ |
76 | * decryption. \ |
77 | */ \ |
78 | \ |
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79 | extern void pre##_cfbgetiv(const pre##_cfbctx */*ctx*/, \ |
80 | void */*iv*/); \ |
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81 | \ |
82 | /* --- @pre_cfbsetiv@ --- * \ |
83 | * \ |
84 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
85 | * @cnost void *iv@ = pointer to IV to set \ |
86 | * \ |
87 | * Returns: --- \ |
88 | * \ |
89 | * Use: Sets the IV to use for subsequent encryption. \ |
90 | */ \ |
91 | \ |
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92 | extern void pre##_cfbsetiv(pre##_cfbctx */*ctx*/, \ |
93 | const void */*iv*/); \ |
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94 | \ |
95 | /* --- @pre_cfbbdry@ --- * \ |
96 | * \ |
97 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
98 | * \ |
99 | * Returns: --- \ |
100 | * \ |
101 | * Use: Inserts a boundary during encryption. Successful \ |
102 | * decryption must place a similar boundary. \ |
103 | */ \ |
104 | \ |
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105 | extern void pre##_cfbbdry(pre##_cfbctx */*ctx*/); \ |
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106 | \ |
107 | /* --- @pre_cfbsetkey@ --- * \ |
108 | * \ |
109 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
110 | * @const pre_ctx *k@ = pointer to cipher context \ |
111 | * \ |
112 | * Returns: --- \ |
113 | * \ |
114 | * Use: Sets the CFB context to use a different cipher key. \ |
115 | */ \ |
116 | \ |
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117 | extern void pre##_cfbsetkey(pre##_cfbctx */*ctx*/, \ |
118 | const pre##_ctx */*k*/); \ |
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119 | \ |
120 | /* --- @pre_cfbinit@ --- * \ |
121 | * \ |
122 | * Arguments: @pre_cfbctx *ctx@ = pointer to cipher context \ |
123 | * @const void *key@ = pointer to the key buffer \ |
124 | * @size_t sz@ = size of the key \ |
125 | * @const void *iv@ = pointer to initialization vector \ |
126 | * \ |
127 | * Returns: --- \ |
128 | * \ |
129 | * Use: Initializes a CFB context ready for use. You should \ |
130 | * ensure that the IV chosen is unique: reusing an IV will \ |
131 | * compromise the security of at least the first block \ |
132 | * encrypted. This is equivalent to calls to @pre_init@, \ |
133 | * @pre_cfbsetkey@ and @pre_cfbsetiv@. \ |
134 | */ \ |
135 | \ |
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136 | extern void pre##_cfbinit(pre##_cfbctx */*ctx*/, \ |
137 | const void */*key*/, size_t /*sz*/, \ |
138 | const void */*iv*/); \ |
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139 | \ |
140 | /* --- @pre_cfbencrypt@ --- * \ |
141 | * \ |
142 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB context block \ |
143 | * @const void *src@ = pointer to source data \ |
144 | * @void *dest@ = pointer to destination data \ |
145 | * @size_t sz@ = size of block to be encrypted \ |
146 | * \ |
147 | * Returns: --- \ |
148 | * \ |
149 | * Use: Encrypts a block with a block cipher in CFB mode. The \ |
150 | * input block may be arbitrary in size. CFB mode is not \ |
151 | * sensitive to block boundaries. \ |
152 | */ \ |
153 | \ |
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154 | extern void pre##_cfbencrypt(pre##_cfbctx */*ctx*/, \ |
155 | const void */*src*/, void */*dest*/, \ |
156 | size_t /*sz*/); \ |
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157 | \ |
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158 | /* --- @pre_cfbencrypt@ --- * \ |
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159 | * \ |
160 | * Arguments: @pre_cfbctx *ctx@ = pointer to CFB 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 | * \ |
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167 | * Use: Decrypts a block with a block cipher in CFB mode. The \ |
168 | * input block may be arbitrary in size. CFB mode is not \ |
169 | * sensitive to block boundaries. \ |
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170 | */ \ |
171 | \ |
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172 | extern void pre##_cfbdecrypt(pre##_cfbctx */*ctx*/, \ |
173 | const void */*src*/, void */*dest*/, \ |
174 | size_t /*sz*/); \ |
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175 | \ |
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176 | /* --- Generic cipher interface --- */ \ |
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177 | \ |
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178 | extern const gccipher pre##_cfb; |
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179 | |
180 | /*----- That's all, folks -------------------------------------------------*/ |
181 | |
182 | #ifdef __cplusplus |
183 | } |
184 | #endif |
185 | |
186 | #endif |