| 1 | /* -*-c-*- |
| 2 | * |
| 3 | * The Tiny Encryption Algorithm |
| 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 | /*----- Header files ------------------------------------------------------*/ |
| 29 | |
| 30 | #include <mLib/bits.h> |
| 31 | |
| 32 | #include "blkc.h" |
| 33 | #include "gcipher.h" |
| 34 | #include "paranoia.h" |
| 35 | #include "tea.h" |
| 36 | |
| 37 | /*----- Global variables --------------------------------------------------*/ |
| 38 | |
| 39 | const octet tea_keysz[] = { KSZ_RANGE, TEA_KEYSZ, 0, 16, 1 }; |
| 40 | |
| 41 | /*----- Main code ---------------------------------------------------------*/ |
| 42 | |
| 43 | /* --- @tea_init@ --- * |
| 44 | * |
| 45 | * Arguments: @tea_ctx *k@ = pointer to key block |
| 46 | * @const void *buf@ = pointer to key buffer |
| 47 | * @size_t sz@ = size of key material |
| 48 | * |
| 49 | * Returns: --- |
| 50 | * |
| 51 | * Use: Initializes a TEA key buffer. The key buffer must be 16 |
| 52 | * bytes long. |
| 53 | */ |
| 54 | |
| 55 | void tea_init(tea_ctx *k, const void *buf, size_t sz) |
| 56 | { |
| 57 | octet kb[16]; |
| 58 | const octet *p; |
| 59 | |
| 60 | KSZ_ASSERT(tea, sz); |
| 61 | if (sz >= sizeof(kb)) |
| 62 | p = buf; |
| 63 | else { |
| 64 | memcpy(kb, buf, sz); |
| 65 | memset(kb + sz, 0, sizeof(kb) - sz); |
| 66 | p = kb; |
| 67 | } |
| 68 | |
| 69 | k->ka = LOAD32(p + 0); k->kb = LOAD32(p + 4); |
| 70 | k->kc = LOAD32(p + 8); k->kd = LOAD32(p + 12); |
| 71 | k->r = 32; |
| 72 | |
| 73 | if (p == kb) |
| 74 | BURN(kb); |
| 75 | } |
| 76 | |
| 77 | /* --- @tea_eblk@, @tea_dblk@ --- * |
| 78 | * |
| 79 | * Arguments: @const tea_ctx *k@ = pointer to key block |
| 80 | * @const uint32 s[2]@ = pointer to source block |
| 81 | * @uint32 d[2]@ = pointer to teatination block |
| 82 | * |
| 83 | * Returns: --- |
| 84 | * |
| 85 | * Use: Low-level block encryption and decryption. |
| 86 | */ |
| 87 | |
| 88 | #define DELTA 0x9e3779b9 |
| 89 | |
| 90 | void tea_eblk(const tea_ctx *k, const uint32 *s, uint32 *d) |
| 91 | { |
| 92 | uint32 y = s[0], z = s[1]; |
| 93 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd; |
| 94 | uint32 n = 0; |
| 95 | unsigned i; |
| 96 | |
| 97 | for (i = 0; i < k->r; i++) { |
| 98 | n += DELTA; |
| 99 | y = U32(y + (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb))); |
| 100 | z = U32(z + (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd))); |
| 101 | } |
| 102 | d[0] = y; d[1] = z; |
| 103 | } |
| 104 | |
| 105 | void tea_dblk(const tea_ctx *k, const uint32 *s, uint32 *d) |
| 106 | { |
| 107 | uint32 y = s[0], z = s[1]; |
| 108 | uint32 ka = k->ka, kb = k->kb, kc = k->kc, kd = k->kd; |
| 109 | uint32 n = DELTA * k->r; |
| 110 | unsigned i; |
| 111 | |
| 112 | for (i = 0; i < k->r; i++) { |
| 113 | z = U32(z - (((y << 4) + kc) ^ (y + n) ^ ((y >> 5) + kd))); |
| 114 | y = U32(y - (((z << 4) + ka) ^ (z + n) ^ ((z >> 5) + kb))); |
| 115 | n -= DELTA; |
| 116 | } |
| 117 | d[0] = y; d[1] = z; |
| 118 | } |
| 119 | |
| 120 | BLKC_TEST(TEA, tea) |
| 121 | |
| 122 | /*----- That's all, folks -------------------------------------------------*/ |