| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * The MGF mask generation function |
| 4 | * |
| 5 | * (c) 2000 Straylight/Edgeware |
| 6 | */ |
| 7 | |
| 8 | /*----- Licensing notice --------------------------------------------------* |
| 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. |
| 16 | * |
| 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. |
| 21 | * |
| 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 | |
| 28 | /*----- Notes on the MGF-1 mask generating function -----------------------* |
| 29 | * |
| 30 | * The idea of a mask-generating function is that given an input of arbitrary |
| 31 | * size, it can emit a pseudorandom output `mask' of arbitrary size. This is |
| 32 | * used in PKCS#1 OAEP (RFC2437). My recommendation would be to use a decent |
| 33 | * stream cipher instead, like RC4 or SEAL. MGF-1 isn't very fast. |
| 34 | */ |
| 35 | |
| 36 | #ifndef CATACOMB_MGF_H |
| 37 | #define CATACOMB_MGF_H |
| 38 | |
| 39 | #ifdef __cplusplus |
| 40 | extern "C" { |
| 41 | #endif |
| 42 | |
| 43 | /*----- Header files ------------------------------------------------------*/ |
| 44 | |
| 45 | #include <mLib/bits.h> |
| 46 | |
| 47 | #ifndef CATACOMB_GCIPHER_H |
| 48 | # include "gcipher.h" |
| 49 | #endif |
| 50 | |
| 51 | #ifndef CATACOMB_GRAND_H |
| 52 | # include "grand.h" |
| 53 | #endif |
| 54 | |
| 55 | /*----- Macros ------------------------------------------------------------*/ |
| 56 | |
| 57 | #define MGF_DECL(PRE, pre) \ |
| 58 | \ |
| 59 | /* --- An MGF generation context --- */ \ |
| 60 | \ |
| 61 | typedef struct pre##_mgfctx { \ |
| 62 | pre##_ctx k; /* Underlying key context */ \ |
| 63 | uint32 c; /* Counter */ \ |
| 64 | octet b[PRE##_HASHSZ]; /* Output buffer */ \ |
| 65 | unsigned off; /* Size of buffered data */ \ |
| 66 | } pre##_mgfctx; \ |
| 67 | \ |
| 68 | /* --- Other useful constants --- */ \ |
| 69 | \ |
| 70 | extern const octet pre##_mgfkeysz[]; \ |
| 71 | \ |
| 72 | /* --- @pre_mgfkeybegin@, @pre_mgfkeyadd@ --- * \ |
| 73 | * \ |
| 74 | * Arguments: @pre_mgfctx *k@ = pointer to context to initialize \ |
| 75 | * @const void *p@ = pointer to data to contribute \ |
| 76 | * @size_t sz@ = size of data to contribute \ |
| 77 | * \ |
| 78 | * Returns: --- \ |
| 79 | * \ |
| 80 | * Use: A multi-step keying procedure for initializing an MGF \ |
| 81 | * context. The data is contributed to a hashing context \ |
| 82 | * which is then used for mask generation. If you only \ |
| 83 | * have a fixed buffer, you can save a lot of effort by \ |
| 84 | * simply calling @pre_mgfinit@. \ |
| 85 | */ \ |
| 86 | \ |
| 87 | extern void pre##_mgfkeybegin(pre##_mgfctx */*k*/); \ |
| 88 | extern void pre##_mgfkeyadd(pre##_mgfctx */*k*/, \ |
| 89 | const void */*p*/, size_t /*sz*/); \ |
| 90 | \ |
| 91 | /* ---- @pre_mgfinit@ --- * \ |
| 92 | * \ |
| 93 | * Arguments: @pre_mgfctx *k@ = pointer to context to initialize \ |
| 94 | * @const void *p@ = pointer to data to contribute \ |
| 95 | * @size_t sz@ = size of data to contribute \ |
| 96 | * \ |
| 97 | * Returns: --- \ |
| 98 | * \ |
| 99 | * Use: A simpler interface to initialization if all of your \ |
| 100 | * keying material is in one place. \ |
| 101 | */ \ |
| 102 | \ |
| 103 | extern void pre##_mgfinit(pre##_mgfctx */*k*/, \ |
| 104 | const void */*p*/, size_t /*sz*/); \ |
| 105 | \ |
| 106 | /* --- @pre_mgfencrypt@ --- * \ |
| 107 | * \ |
| 108 | * Arguments: @pre_mgfctx *k@ = pointer to masking context \ |
| 109 | * @const void *s@ = pointer to source buffer \ |
| 110 | * @void *d@ = pointer to destination buffer \ |
| 111 | * @size_t sz@ = size of buffers \ |
| 112 | * \ |
| 113 | * Returns: --- \ |
| 114 | * \ |
| 115 | * Use: Outputs pseudorandom data, or masks an input buffer. \ |
| 116 | * \ |
| 117 | * If @s@ is nonzero, the source material is exclusive- \ |
| 118 | * orred with the generated mask. If @d@ is zero, the \ |
| 119 | * generator is simply spun around for a while, which \ |
| 120 | * isn't very useful. \ |
| 121 | */ \ |
| 122 | \ |
| 123 | extern void pre##_mgfencrypt(pre##_mgfctx */*k*/, const void */*s*/, \ |
| 124 | void */*d*/, size_t /*sz*/); \ |
| 125 | \ |
| 126 | /* --- @pre_mgfsetindex@ --- * \ |
| 127 | * \ |
| 128 | * Arguments: @pre_mgfctx *k@ = pointer to masking context \ |
| 129 | * @uint32 *c@ = new index to set \ |
| 130 | * \ |
| 131 | * Returns: --- \ |
| 132 | * \ |
| 133 | * Use: Sets a new index. This may be used to step around the \ |
| 134 | * output stream in a rather crude way. \ |
| 135 | */ \ |
| 136 | \ |
| 137 | extern void pre##_mgfsetindex(pre##_mgfctx */*k*/, uint32 /*c*/); \ |
| 138 | \ |
| 139 | /* --- @pre_mgfrand@ --- * \ |
| 140 | * \ |
| 141 | * Arguments: @const void *k@ = pointer to key material \ |
| 142 | * @size_t sz@ = size of key material \ |
| 143 | * \ |
| 144 | * Returns: Pointer to a generic random number generator instance. \ |
| 145 | * \ |
| 146 | * Use: Creates a random number interface wrapper around an \ |
| 147 | * MGF-1-mode hash function. \ |
| 148 | */ \ |
| 149 | \ |
| 150 | extern grand *pre##_mgfrand(const void */*k*/, size_t /*sz*/); \ |
| 151 | \ |
| 152 | /* --- Generic cipher interface --- */ \ |
| 153 | \ |
| 154 | extern const gccipher pre##_mgf; |
| 155 | |
| 156 | /*----- That's all, folks -------------------------------------------------*/ |
| 157 | |
| 158 | #ifdef __cplusplus |
| 159 | } |
| 160 | #endif |
| 161 | |
| 162 | #endif |