359 lines
12 KiB
C++
359 lines
12 KiB
C++
/*
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* Byte-oriented AES-256 implementation.
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* All lookup tables replaced with 'on the fly' calculations.
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*
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* Copyright (c) 2007-2009 Ilya O. Levin, http://www.literatecode.com
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* Other contributors: Hal Finney
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "aes256.h"
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#define F(x) (((x)<<1) ^ ((((x)>>7) & 1) * 0x1b))
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#define FD(x) (((x) >> 1) ^ (((x) & 1) ? 0x8d : 0))
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// #define BACK_TO_TABLES
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#ifdef BACK_TO_TABLES
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const uint8_t sbox[256] = {
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0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5,
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0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0,
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0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc,
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0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a,
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0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0,
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0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b,
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0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85,
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0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5,
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0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17,
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0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88,
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0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c,
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0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9,
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0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6,
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0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e,
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0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94,
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0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68,
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0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16
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};
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const uint8_t sboxinv[256] = {
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0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38,
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0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
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0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87,
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0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
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0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d,
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0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
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0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2,
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0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
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0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16,
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0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
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0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda,
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0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
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0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a,
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0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
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0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02,
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0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
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0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea,
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0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
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0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85,
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0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
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0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89,
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0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
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0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20,
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0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
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0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31,
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0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
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0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d,
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0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
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0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0,
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0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
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0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26,
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0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d
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};
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#define rj_sbox(x) sbox[(x)]
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#define rj_sbox_inv(x) sboxinv[(x)]
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#else /* tableless subroutines */
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/* -------------------------------------------------------------------------- */
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uint8_t gf_alog(uint8_t x) // calculate anti-logarithm gen 3
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{
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uint8_t atb = 1, z;
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while (x--) {z = atb; atb <<= 1; if (z & 0x80) atb^= 0x1b; atb ^= z;}
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return atb;
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} /* gf_alog */
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/* -------------------------------------------------------------------------- */
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uint8_t gf_log(uint8_t x) // calculate logarithm gen 3
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{
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uint8_t atb = 1, i = 0, z;
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do {
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if (atb == x) break;
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z = atb; atb <<= 1; if (z & 0x80) atb^= 0x1b; atb ^= z;
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} while (++i > 0);
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return i;
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} /* gf_log */
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/* -------------------------------------------------------------------------- */
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uint8_t gf_mulinv(uint8_t x) // calculate multiplicative inverse
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{
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return (x) ? gf_alog(255 - gf_log(x)) : 0;
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} /* gf_mulinv */
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/* -------------------------------------------------------------------------- */
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uint8_t rj_sbox(uint8_t x)
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{
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uint8_t y, sb;
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sb = y = gf_mulinv(x);
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y = (y<<1)|(y>>7); sb ^= y; y = (y<<1)|(y>>7); sb ^= y;
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y = (y<<1)|(y>>7); sb ^= y; y = (y<<1)|(y>>7); sb ^= y;
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return (sb ^ 0x63);
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} /* rj_sbox */
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/* -------------------------------------------------------------------------- */
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uint8_t rj_sbox_inv(uint8_t x)
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{
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uint8_t y, sb;
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y = x ^ 0x63;
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sb = y = (y<<1)|(y>>7);
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y = (y<<2)|(y>>6); sb ^= y; y = (y<<3)|(y>>5); sb ^= y;
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return gf_mulinv(sb);
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} /* rj_sbox_inv */
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#endif
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/* -------------------------------------------------------------------------- */
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uint8_t rj_xtime(uint8_t x)
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{
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return (x & 0x80) ? ((x << 1) ^ 0x1b) : (x << 1);
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} /* rj_xtime */
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/* -------------------------------------------------------------------------- */
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void aes_subBytes(uint8_t *buf)
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{
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register uint8_t i = 16;
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while (i--) buf[i] = rj_sbox(buf[i]);
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} /* aes_subBytes */
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/* -------------------------------------------------------------------------- */
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void aes_subBytes_inv(uint8_t *buf)
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{
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register uint8_t i = 16;
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while (i--) buf[i] = rj_sbox_inv(buf[i]);
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} /* aes_subBytes_inv */
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/* -------------------------------------------------------------------------- */
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void aes_addRoundKey(uint8_t *buf, uint8_t *key)
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{
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register uint8_t i = 16;
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while (i--) buf[i] ^= key[i];
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} /* aes_addRoundKey */
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/* -------------------------------------------------------------------------- */
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void aes_addRoundKey_cpy(uint8_t *buf, uint8_t *key, uint8_t *cpk)
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{
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register uint8_t i = 16;
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while (i--) buf[i] ^= (cpk[i] = key[i]), cpk[16+i] = key[16 + i];
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} /* aes_addRoundKey_cpy */
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/* -------------------------------------------------------------------------- */
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void aes_shiftRows(uint8_t *buf)
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{
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register uint8_t i, j; /* to make it potentially parallelable :) */
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i = buf[1]; buf[1] = buf[5]; buf[5] = buf[9]; buf[9] = buf[13]; buf[13] = i;
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i = buf[10]; buf[10] = buf[2]; buf[2] = i;
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j = buf[3]; buf[3] = buf[15]; buf[15] = buf[11]; buf[11] = buf[7]; buf[7] = j;
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j = buf[14]; buf[14] = buf[6]; buf[6] = j;
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} /* aes_shiftRows */
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/* -------------------------------------------------------------------------- */
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void aes_shiftRows_inv(uint8_t *buf)
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{
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register uint8_t i, j; /* same as above :) */
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i = buf[1]; buf[1] = buf[13]; buf[13] = buf[9]; buf[9] = buf[5]; buf[5] = i;
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i = buf[2]; buf[2] = buf[10]; buf[10] = i;
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j = buf[3]; buf[3] = buf[7]; buf[7] = buf[11]; buf[11] = buf[15]; buf[15] = j;
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j = buf[6]; buf[6] = buf[14]; buf[14] = j;
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} /* aes_shiftRows_inv */
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/* -------------------------------------------------------------------------- */
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void aes_mixColumns(uint8_t *buf)
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{
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register uint8_t i, a, b, c, d, e;
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for (i = 0; i < 16; i += 4)
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{
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a = buf[i]; b = buf[i + 1]; c = buf[i + 2]; d = buf[i + 3];
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e = a ^ b ^ c ^ d;
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buf[i] ^= e ^ rj_xtime(a^b); buf[i+1] ^= e ^ rj_xtime(b^c);
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buf[i+2] ^= e ^ rj_xtime(c^d); buf[i+3] ^= e ^ rj_xtime(d^a);
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}
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} /* aes_mixColumns */
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/* -------------------------------------------------------------------------- */
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void aes_mixColumns_inv(uint8_t *buf)
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{
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register uint8_t i, a, b, c, d, e, x, y, z;
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for (i = 0; i < 16; i += 4)
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{
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a = buf[i]; b = buf[i + 1]; c = buf[i + 2]; d = buf[i + 3];
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e = a ^ b ^ c ^ d;
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z = rj_xtime(e);
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x = e ^ rj_xtime(rj_xtime(z^a^c)); y = e ^ rj_xtime(rj_xtime(z^b^d));
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buf[i] ^= x ^ rj_xtime(a^b); buf[i+1] ^= y ^ rj_xtime(b^c);
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buf[i+2] ^= x ^ rj_xtime(c^d); buf[i+3] ^= y ^ rj_xtime(d^a);
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}
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} /* aes_mixColumns_inv */
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/* -------------------------------------------------------------------------- */
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void aes_expandEncKey(uint8_t *k, uint8_t *rc)
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{
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register uint8_t i;
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k[0] ^= rj_sbox(k[29]) ^ (*rc);
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k[1] ^= rj_sbox(k[30]);
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k[2] ^= rj_sbox(k[31]);
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k[3] ^= rj_sbox(k[28]);
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*rc = F( *rc);
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for(i = 4; i < 16; i += 4) k[i] ^= k[i-4], k[i+1] ^= k[i-3],
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k[i+2] ^= k[i-2], k[i+3] ^= k[i-1];
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k[16] ^= rj_sbox(k[12]);
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k[17] ^= rj_sbox(k[13]);
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k[18] ^= rj_sbox(k[14]);
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k[19] ^= rj_sbox(k[15]);
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for(i = 20; i < 32; i += 4) k[i] ^= k[i-4], k[i+1] ^= k[i-3],
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k[i+2] ^= k[i-2], k[i+3] ^= k[i-1];
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} /* aes_expandEncKey */
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/* -------------------------------------------------------------------------- */
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void aes_expandDecKey(uint8_t *k, uint8_t *rc)
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{
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uint8_t i;
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for(i = 28; i > 16; i -= 4) k[i+0] ^= k[i-4], k[i+1] ^= k[i-3],
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k[i+2] ^= k[i-2], k[i+3] ^= k[i-1];
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k[16] ^= rj_sbox(k[12]);
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k[17] ^= rj_sbox(k[13]);
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k[18] ^= rj_sbox(k[14]);
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k[19] ^= rj_sbox(k[15]);
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for(i = 12; i > 0; i -= 4) k[i+0] ^= k[i-4], k[i+1] ^= k[i-3],
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k[i+2] ^= k[i-2], k[i+3] ^= k[i-1];
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*rc = FD(*rc);
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k[0] ^= rj_sbox(k[29]) ^ (*rc);
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k[1] ^= rj_sbox(k[30]);
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k[2] ^= rj_sbox(k[31]);
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k[3] ^= rj_sbox(k[28]);
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} /* aes_expandDecKey */
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/* -------------------------------------------------------------------------- */
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void aes256_init(aes256_context *ctx, uint8_t *k)
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{
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uint8_t rcon = 1;
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register uint8_t i;
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for (i = 0; i < sizeof(ctx->key); i++) ctx->enckey[i] = ctx->deckey[i] = k[i];
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for (i = 8;--i;) aes_expandEncKey(ctx->deckey, &rcon);
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} /* aes256_init */
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/* -------------------------------------------------------------------------- */
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void aes256_done(aes256_context *ctx)
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{
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register uint8_t i;
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for (i = 0; i < sizeof(ctx->key); i++)
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ctx->key[i] = ctx->enckey[i] = ctx->deckey[i] = 0;
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} /* aes256_done */
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/* -------------------------------------------------------------------------- */
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void aes256_encrypt_ecb(aes256_context *ctx, uint8_t *buf)
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{
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uint8_t i, rcon;
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aes_addRoundKey_cpy(buf, ctx->enckey, ctx->key);
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for(i = 1, rcon = 1; i < 14; ++i)
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{
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aes_subBytes(buf);
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aes_shiftRows(buf);
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aes_mixColumns(buf);
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if( i & 1 ) aes_addRoundKey( buf, &ctx->key[16]);
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else aes_expandEncKey(ctx->key, &rcon), aes_addRoundKey(buf, ctx->key);
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}
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aes_subBytes(buf);
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aes_shiftRows(buf);
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aes_expandEncKey(ctx->key, &rcon);
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aes_addRoundKey(buf, ctx->key);
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} /* aes256_encrypt */
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/* -------------------------------------------------------------------------- */
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void aes256_decrypt_ecb(aes256_context *ctx, uint8_t *buf)
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{
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uint8_t i, rcon;
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aes_addRoundKey_cpy(buf, ctx->deckey, ctx->key);
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aes_shiftRows_inv(buf);
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aes_subBytes_inv(buf);
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for (i = 14, rcon = 0x80; --i;)
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{
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if( ( i & 1 ) )
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{
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aes_expandDecKey(ctx->key, &rcon);
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aes_addRoundKey(buf, &ctx->key[16]);
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}
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else aes_addRoundKey(buf, ctx->key);
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aes_mixColumns_inv(buf);
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aes_shiftRows_inv(buf);
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aes_subBytes_inv(buf);
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}
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aes_addRoundKey( buf, ctx->key);
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} /* aes256_decrypt */
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