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Diffstat (limited to 'trunk/main/aestab.c')
| -rw-r--r-- | trunk/main/aestab.c | 236 |
1 files changed, 236 insertions, 0 deletions
diff --git a/trunk/main/aestab.c b/trunk/main/aestab.c new file mode 100644 index 000000000..b134d22d8 --- /dev/null +++ b/trunk/main/aestab.c @@ -0,0 +1,236 @@ +/* + --------------------------------------------------------------------------- + Copyright (c) 2003, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK. + All rights reserved. + + LICENSE TERMS + + The free distribution and use of this software in both source and binary + form is allowed (with or without changes) provided that: + + 1. distributions of this source code include the above copyright + notice, this list of conditions and the following disclaimer; + + 2. distributions in binary form include the above copyright + notice, this list of conditions and the following disclaimer + in the documentation and/or other associated materials; + + 3. the copyright holder's name is not used to endorse products + built using this software without specific written permission. + + ALTERNATIVELY, provided that this notice is retained in full, this product + may be distributed under the terms of the GNU General Public License (GPL), + in which case the provisions of the GPL apply INSTEAD OF those given above. + + DISCLAIMER + + This software is provided 'as is' with no explicit or implied warranties + in respect of its properties, including, but not limited to, correctness + and/or fitness for purpose. + --------------------------------------------------------------------------- + Issue Date: 26/08/2003 + +*/ + +#if defined(__cplusplus) +extern "C" +{ +#endif + +#ifndef HAVE_CRYPTO + +#define DO_TABLES + +#include "aesopt.h" + +#if defined(FIXED_TABLES) + +/* implemented in case of wrong call for fixed tables */ + +void gen_tabs(void) +{ +} + +#else /* dynamic table generation */ + +#if !defined(FF_TABLES) + +/* Generate the tables for the dynamic table option + + It will generally be sensible to use tables to compute finite + field multiplies and inverses but where memory is scarse this + code might sometimes be better. But it only has effect during + initialisation so its pretty unimportant in overall terms. +*/ + +/* return 2 ^ (n - 1) where n is the bit number of the highest bit + set in x with x in the range 1 < x < 0x00000200. This form is + used so that locals within fi can be bytes rather than words +*/ + +static aes_08t hibit(const aes_32t x) +{ aes_08t r = (aes_08t)((x >> 1) | (x >> 2)); + + r |= (r >> 2); + r |= (r >> 4); + return (r + 1) >> 1; +} + +/* return the inverse of the finite field element x */ + +static aes_08t fi(const aes_08t x) +{ aes_08t p1 = x, p2 = BPOLY, n1 = hibit(x), n2 = 0x80, v1 = 1, v2 = 0; + + if(x < 2) return x; + + for(;;) + { + if(!n1) return v1; + + while(n2 >= n1) + { + n2 /= n1; p2 ^= p1 * n2; v2 ^= v1 * n2; n2 = hibit(p2); + } + + if(!n2) return v2; + + while(n1 >= n2) + { + n1 /= n2; p1 ^= p2 * n1; v1 ^= v2 * n1; n1 = hibit(p1); + } + } +} + +#endif + +/* The forward and inverse affine transformations used in the S-box */ + +#define fwd_affine(x) \ + (w = (aes_32t)x, w ^= (w<<1)^(w<<2)^(w<<3)^(w<<4), 0x63^(aes_08t)(w^(w>>8))) + +#define inv_affine(x) \ + (w = (aes_32t)x, w = (w<<1)^(w<<3)^(w<<6), 0x05^(aes_08t)(w^(w>>8))) + +static int init = 0; + +void gen_tabs(void) +{ aes_32t i, w; + +#if defined(FF_TABLES) + + aes_08t pow[512], log[256]; + + if(init) return; + /* log and power tables for GF(2^8) finite field with + WPOLY as modular polynomial - the simplest primitive + root is 0x03, used here to generate the tables + */ + + i = 0; w = 1; + do + { + pow[i] = (aes_08t)w; + pow[i + 255] = (aes_08t)w; + log[w] = (aes_08t)i++; + w ^= (w << 1) ^ (w & 0x80 ? WPOLY : 0); + } + while (w != 1); + +#else + if(init) return; +#endif + + for(i = 0, w = 1; i < RC_LENGTH; ++i) + { + t_set(r,c)[i] = bytes2word(w, 0, 0, 0); + w = f2(w); + } + + for(i = 0; i < 256; ++i) + { aes_08t b; + + b = fwd_affine(fi((aes_08t)i)); + w = bytes2word(f2(b), b, b, f3(b)); + +#ifdef SBX_SET + t_set(s,box)[i] = b; +#endif + +#ifdef FT1_SET /* tables for a normal encryption round */ + t_set(f,n)[i] = w; +#endif +#ifdef FT4_SET + t_set(f,n)[0][i] = w; + t_set(f,n)[1][i] = upr(w,1); + t_set(f,n)[2][i] = upr(w,2); + t_set(f,n)[3][i] = upr(w,3); +#endif + w = bytes2word(b, 0, 0, 0); + +#ifdef FL1_SET /* tables for last encryption round (may also */ + t_set(f,l)[i] = w; /* be used in the key schedule) */ +#endif +#ifdef FL4_SET + t_set(f,l)[0][i] = w; + t_set(f,l)[1][i] = upr(w,1); + t_set(f,l)[2][i] = upr(w,2); + t_set(f,l)[3][i] = upr(w,3); +#endif + +#ifdef LS1_SET /* table for key schedule if t_set(f,l) above is */ + t_set(l,s)[i] = w; /* not of the required form */ +#endif +#ifdef LS4_SET + t_set(l,s)[0][i] = w; + t_set(l,s)[1][i] = upr(w,1); + t_set(l,s)[2][i] = upr(w,2); + t_set(l,s)[3][i] = upr(w,3); +#endif + + b = fi(inv_affine((aes_08t)i)); + w = bytes2word(fe(b), f9(b), fd(b), fb(b)); + +#ifdef IM1_SET /* tables for the inverse mix column operation */ + t_set(i,m)[b] = w; +#endif +#ifdef IM4_SET + t_set(i,m)[0][b] = w; + t_set(i,m)[1][b] = upr(w,1); + t_set(i,m)[2][b] = upr(w,2); + t_set(i,m)[3][b] = upr(w,3); +#endif + +#ifdef ISB_SET + t_set(i,box)[i] = b; +#endif +#ifdef IT1_SET /* tables for a normal decryption round */ + t_set(i,n)[i] = w; +#endif +#ifdef IT4_SET + t_set(i,n)[0][i] = w; + t_set(i,n)[1][i] = upr(w,1); + t_set(i,n)[2][i] = upr(w,2); + t_set(i,n)[3][i] = upr(w,3); +#endif + w = bytes2word(b, 0, 0, 0); +#ifdef IL1_SET /* tables for last decryption round */ + t_set(i,l)[i] = w; +#endif +#ifdef IL4_SET + t_set(i,l)[0][i] = w; + t_set(i,l)[1][i] = upr(w,1); + t_set(i,l)[2][i] = upr(w,2); + t_set(i,l)[3][i] = upr(w,3); +#endif + } + init = 1; +} + +#endif + +#endif /* !HAVE_CRYPTO */ + +#if defined(__cplusplus) +} +#endif + |