2 ---------------------------------------------------------------------------
3 Copyright (c) 2003, Dr Brian Gladman <brg@gladman.me.uk>, Worcester, UK.
8 The free distribution and use of this software in both source and binary
9 form is allowed (with or without changes) provided that:
11 1. distributions of this source code include the above copyright
12 notice, this list of conditions and the following disclaimer;
14 2. distributions in binary form include the above copyright
15 notice, this list of conditions and the following disclaimer
16 in the documentation and/or other associated materials;
18 3. the copyright holder's name is not used to endorse products
19 built using this software without specific written permission.
21 ALTERNATIVELY, provided that this notice is retained in full, this product
22 may be distributed under the terms of the GNU General Public License (GPL),
23 in which case the provisions of the GPL apply INSTEAD OF those given above.
27 This software is provided 'as is' with no explicit or implied warranties
28 in respect of its properties, including, but not limited to, correctness
29 and/or fitness for purpose.
30 ---------------------------------------------------------------------------
31 Issue Date: 26/08/2003
35 #if defined(__cplusplus)
44 #if defined(FIXED_TABLES)
46 /* implemented in case of wrong call for fixed tables */
52 #else /* dynamic table generation */
54 #if !defined(FF_TABLES)
56 /* Generate the tables for the dynamic table option
58 It will generally be sensible to use tables to compute finite
59 field multiplies and inverses but where memory is scarse this
60 code might sometimes be better. But it only has effect during
61 initialisation so its pretty unimportant in overall terms.
64 /* return 2 ^ (n - 1) where n is the bit number of the highest bit
65 set in x with x in the range 1 < x < 0x00000200. This form is
66 used so that locals within fi can be bytes rather than words
69 static aes_08t
hibit(const aes_32t x
)
70 { aes_08t r
= (aes_08t
)((x
>> 1) | (x
>> 2));
77 /* return the inverse of the finite field element x */
79 static aes_08t
fi(const aes_08t x
)
80 { aes_08t p1
= x
, p2
= BPOLY
, n1
= hibit(x
), n2
= 0x80, v1
= 1, v2
= 0;
90 n2
/= n1
; p2
^= p1
* n2
; v2
^= v1
* n2
; n2
= hibit(p2
);
97 n1
/= n2
; p1
^= p2
* n1
; v1
^= v2
* n1
; n1
= hibit(p1
);
104 /* The forward and inverse affine transformations used in the S-box */
106 #define fwd_affine(x) \
107 (w = (aes_32t)x, w ^= (w<<1)^(w<<2)^(w<<3)^(w<<4), 0x63^(aes_08t)(w^(w>>8)))
109 #define inv_affine(x) \
110 (w = (aes_32t)x, w = (w<<1)^(w<<3)^(w<<6), 0x05^(aes_08t)(w^(w>>8)))
117 #if defined(FF_TABLES)
119 aes_08t pow
[512], log
[256];
122 /* log and power tables for GF(2^8) finite field with
123 WPOLY as modular polynomial - the simplest primitive
124 root is 0x03, used here to generate the tables
131 pow
[i
+ 255] = (aes_08t
)w
;
132 log
[w
] = (aes_08t
)i
++;
133 w
^= (w
<< 1) ^ (w
& 0x80 ? WPOLY
: 0);
141 for(i
= 0, w
= 1; i
< RC_LENGTH
; ++i
)
143 t_set(r
,c
)[i
] = bytes2word(w
, 0, 0, 0);
147 for(i
= 0; i
< 256; ++i
)
150 b
= fwd_affine(fi((aes_08t
)i
));
151 w
= bytes2word(f2(b
), b
, b
, f3(b
));
157 #ifdef FT1_SET /* tables for a normal encryption round */
161 t_set(f
,n
)[0][i
] = w
;
162 t_set(f
,n
)[1][i
] = upr(w
,1);
163 t_set(f
,n
)[2][i
] = upr(w
,2);
164 t_set(f
,n
)[3][i
] = upr(w
,3);
166 w
= bytes2word(b
, 0, 0, 0);
168 #ifdef FL1_SET /* tables for last encryption round (may also */
169 t_set(f
,l
)[i
] = w
; /* be used in the key schedule) */
172 t_set(f
,l
)[0][i
] = w
;
173 t_set(f
,l
)[1][i
] = upr(w
,1);
174 t_set(f
,l
)[2][i
] = upr(w
,2);
175 t_set(f
,l
)[3][i
] = upr(w
,3);
178 #ifdef LS1_SET /* table for key schedule if t_set(f,l) above is */
179 t_set(l
,s
)[i
] = w
; /* not of the required form */
182 t_set(l
,s
)[0][i
] = w
;
183 t_set(l
,s
)[1][i
] = upr(w
,1);
184 t_set(l
,s
)[2][i
] = upr(w
,2);
185 t_set(l
,s
)[3][i
] = upr(w
,3);
188 b
= fi(inv_affine((aes_08t
)i
));
189 w
= bytes2word(fe(b
), f9(b
), fd(b
), fb(b
));
191 #ifdef IM1_SET /* tables for the inverse mix column operation */
195 t_set(i
,m
)[0][b
] = w
;
196 t_set(i
,m
)[1][b
] = upr(w
,1);
197 t_set(i
,m
)[2][b
] = upr(w
,2);
198 t_set(i
,m
)[3][b
] = upr(w
,3);
204 #ifdef IT1_SET /* tables for a normal decryption round */
208 t_set(i
,n
)[0][i
] = w
;
209 t_set(i
,n
)[1][i
] = upr(w
,1);
210 t_set(i
,n
)[2][i
] = upr(w
,2);
211 t_set(i
,n
)[3][i
] = upr(w
,3);
213 w
= bytes2word(b
, 0, 0, 0);
214 #ifdef IL1_SET /* tables for last decryption round */
218 t_set(i
,l
)[0][i
] = w
;
219 t_set(i
,l
)[1][i
] = upr(w
,1);
220 t_set(i
,l
)[2][i
] = upr(w
,2);
221 t_set(i
,l
)[3][i
] = upr(w
,3);
229 #if defined(__cplusplus)