b713136a00
The CBC initialization vector is passed as a const pointer, and then cast to a non-const pointer to store it in the aes state struct. This cast can easily be avoided by changing the struct field into a const pointer.
614 lines
21 KiB
C
614 lines
21 KiB
C
/*
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This is free and unencumbered software released into the public domain.
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Anyone is free to copy, modify, publish, use, compile, sell, or
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distribute this software, either in source code form or as a compiled
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binary, for any purpose, commercial or non-commercial, and by any
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means.
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In jurisdictions that recognize copyright laws, the author or authors
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of this software dedicate any and all copyright interest in the
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software to the public domain. We make this dedication for the benefit
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of the public at large and to the detriment of our heirs and
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successors. We intend this dedication to be an overt act of
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relinquishment in perpetuity of all present and future rights to this
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software under copyright law.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
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OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
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ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
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OTHER DEALINGS IN THE SOFTWARE.
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For more information, please refer to <http://unlicense.org/>
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This is an implementation of the AES128 algorithm, specifically ECB and CBC mode.
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The implementation is verified against the test vectors in:
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National Institute of Standards and Technology Special Publication 800-38A 2001 ED
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ECB-AES128
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----------
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plain-text:
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6bc1bee22e409f96e93d7e117393172a
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ae2d8a571e03ac9c9eb76fac45af8e51
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30c81c46a35ce411e5fbc1191a0a52ef
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f69f2445df4f9b17ad2b417be66c3710
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key:
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2b7e151628aed2a6abf7158809cf4f3c
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resulting cipher
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3ad77bb40d7a3660a89ecaf32466ef97
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f5d3d58503b9699de785895a96fdbaaf
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43b1cd7f598ece23881b00e3ed030688
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7b0c785e27e8ad3f8223207104725dd4
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NOTE: String length must be evenly divisible by 16byte (str_len % 16 == 0)
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You should pad the end of the string with zeros if this is not the case.
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*/
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/*****************************************************************************/
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/* Includes: */
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/*****************************************************************************/
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#include <string.h> // CBC mode, for memset
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#include "aes.h"
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/*****************************************************************************/
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/* Defines: */
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/*****************************************************************************/
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// The number of columns comprising a state in AES. This is a constant in AES. Value=4
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#define Nb 4
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// The number of 32 bit words in a key.
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#define Nk 4
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// Key length in bytes [128 bit]
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#define KEYLEN 16
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// The number of rounds in AES Cipher.
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#define Nr 10
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// jcallan@github points out that declaring Multiply as a function
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// reduces code size considerably with the Keil ARM compiler.
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// See this link for more information: https://github.com/kokke/tiny-AES128-C/pull/3
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#ifndef MULTIPLY_AS_A_FUNCTION
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#define MULTIPLY_AS_A_FUNCTION 0
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#endif
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/*****************************************************************************/
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/* Private variables: */
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/*****************************************************************************/
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// state - array holding the intermediate results during decryption.
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typedef uint8_t state_t[4][4];
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typedef struct aes_state_t {
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state_t* state;
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// The array that stores the round keys.
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uint8_t RoundKey[176];
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// The Key input to the AES Program
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const uint8_t* Key;
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#if defined(CBC) && CBC
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// Initial Vector used only for CBC mode
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const uint8_t* Iv;
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#endif
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} aes_state_t;
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// The lookup-tables are marked const so they can be placed in read-only storage instead of RAM
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// The numbers below can be computed dynamically trading ROM for RAM -
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// This can be useful in (embedded) bootloader applications, where ROM is often limited.
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static const uint8_t sbox[256] = {
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//0 1 2 3 4 5 6 7 8 9 A B C D E F
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0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16 };
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static const uint8_t rsbox[256] =
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{ 0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
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0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
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0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
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0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
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0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
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0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
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0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
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0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
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0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
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0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
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0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
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0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
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0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
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0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
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0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
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0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d };
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// The round constant word array, Rcon[i], contains the values given by
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// x to th e power (i-1) being powers of x (x is denoted as {02}) in the field GF(2^8)
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// Note that i starts at 1, not 0).
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static const uint8_t Rcon[255] = {
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0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a,
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0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39,
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0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a,
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0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8,
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0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef,
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0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc,
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0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b,
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0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3,
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0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94,
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0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20,
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0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63, 0xc6, 0x97, 0x35,
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0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd, 0x61, 0xc2, 0x9f,
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0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb, 0x8d, 0x01, 0x02, 0x04,
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0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36, 0x6c, 0xd8, 0xab, 0x4d, 0x9a, 0x2f, 0x5e, 0xbc, 0x63,
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0xc6, 0x97, 0x35, 0x6a, 0xd4, 0xb3, 0x7d, 0xfa, 0xef, 0xc5, 0x91, 0x39, 0x72, 0xe4, 0xd3, 0xbd,
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0x61, 0xc2, 0x9f, 0x25, 0x4a, 0x94, 0x33, 0x66, 0xcc, 0x83, 0x1d, 0x3a, 0x74, 0xe8, 0xcb };
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/*****************************************************************************/
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/* Private functions: */
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/*****************************************************************************/
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static uint8_t getSBoxValue(uint8_t num)
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{
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return sbox[num];
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}
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static uint8_t getSBoxInvert(uint8_t num)
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{
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return rsbox[num];
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}
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// This function produces Nb(Nr+1) round keys. The round keys are used in each round to decrypt the states.
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static void KeyExpansion(aes_state_t *state)
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{
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uint32_t i, j, k;
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uint8_t tempa[4]; // Used for the column/row operations
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// The first round key is the key itself.
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for(i = 0; i < Nk; ++i)
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{
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state->RoundKey[(i * 4) + 0] = state->Key[(i * 4) + 0];
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state->RoundKey[(i * 4) + 1] = state->Key[(i * 4) + 1];
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state->RoundKey[(i * 4) + 2] = state->Key[(i * 4) + 2];
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state->RoundKey[(i * 4) + 3] = state->Key[(i * 4) + 3];
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}
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// All other round keys are found from the previous round keys.
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for(; (i < (Nb * (Nr + 1))); ++i)
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{
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for(j = 0; j < 4; ++j)
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{
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tempa[j]=state->RoundKey[(i-1) * 4 + j];
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}
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if (i % Nk == 0)
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{
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// This function rotates the 4 bytes in a word to the left once.
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// [a0,a1,a2,a3] becomes [a1,a2,a3,a0]
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// Function RotWord()
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{
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k = tempa[0];
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tempa[0] = tempa[1];
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tempa[1] = tempa[2];
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tempa[2] = tempa[3];
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tempa[3] = k;
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}
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// SubWord() is a function that takes a four-byte input word and
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// applies the S-box to each of the four bytes to produce an output word.
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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tempa[0] = tempa[0] ^ Rcon[i/Nk];
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}
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else if (Nk > 6 && i % Nk == 4)
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{
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// Function Subword()
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{
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tempa[0] = getSBoxValue(tempa[0]);
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tempa[1] = getSBoxValue(tempa[1]);
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tempa[2] = getSBoxValue(tempa[2]);
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tempa[3] = getSBoxValue(tempa[3]);
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}
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}
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state->RoundKey[i * 4 + 0] = state->RoundKey[(i - Nk) * 4 + 0] ^ tempa[0];
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state->RoundKey[i * 4 + 1] = state->RoundKey[(i - Nk) * 4 + 1] ^ tempa[1];
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state->RoundKey[i * 4 + 2] = state->RoundKey[(i - Nk) * 4 + 2] ^ tempa[2];
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state->RoundKey[i * 4 + 3] = state->RoundKey[(i - Nk) * 4 + 3] ^ tempa[3];
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}
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}
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// This function adds the round key to state.
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// The round key is added to the state by an XOR function.
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static void AddRoundKey(aes_state_t *state, uint8_t round)
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{
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uint8_t i,j;
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for(i=0;i<4;++i)
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{
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for(j = 0; j < 4; ++j)
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{
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(*state->state)[i][j] ^= state->RoundKey[round * Nb * 4 + i * Nb + j];
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}
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}
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}
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// The SubBytes Function Substitutes the values in the
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// state matrix with values in an S-box.
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static void SubBytes(aes_state_t *state)
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{
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uint8_t i, j;
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for(i = 0; i < 4; ++i)
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{
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for(j = 0; j < 4; ++j)
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{
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(*state->state)[j][i] = getSBoxValue((*state->state)[j][i]);
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}
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}
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}
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// The ShiftRows() function shifts the rows in the state to the left.
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// Each row is shifted with different offset.
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// Offset = Row number. So the first row is not shifted.
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static void ShiftRows(aes_state_t *state)
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{
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uint8_t temp;
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// Rotate first row 1 columns to left
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temp = (*state->state)[0][1];
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(*state->state)[0][1] = (*state->state)[1][1];
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(*state->state)[1][1] = (*state->state)[2][1];
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(*state->state)[2][1] = (*state->state)[3][1];
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(*state->state)[3][1] = temp;
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// Rotate second row 2 columns to left
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temp = (*state->state)[0][2];
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(*state->state)[0][2] = (*state->state)[2][2];
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(*state->state)[2][2] = temp;
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temp = (*state->state)[1][2];
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(*state->state)[1][2] = (*state->state)[3][2];
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(*state->state)[3][2] = temp;
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// Rotate third row 3 columns to left
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temp = (*state->state)[0][3];
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(*state->state)[0][3] = (*state->state)[3][3];
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(*state->state)[3][3] = (*state->state)[2][3];
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(*state->state)[2][3] = (*state->state)[1][3];
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(*state->state)[1][3] = temp;
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}
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static uint8_t xtime(uint8_t x)
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{
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return ((x<<1) ^ (((x>>7) & 1) * 0x1b));
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}
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// MixColumns function mixes the columns of the state matrix
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static void MixColumns(aes_state_t *state)
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{
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uint8_t i;
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uint8_t Tmp,Tm,t;
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for(i = 0; i < 4; ++i)
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{
|
|
t = (*state->state)[i][0];
|
|
Tmp = (*state->state)[i][0] ^ (*state->state)[i][1] ^ (*state->state)[i][2] ^ (*state->state)[i][3] ;
|
|
Tm = (*state->state)[i][0] ^ (*state->state)[i][1] ; Tm = xtime(Tm); (*state->state)[i][0] ^= Tm ^ Tmp ;
|
|
Tm = (*state->state)[i][1] ^ (*state->state)[i][2] ; Tm = xtime(Tm); (*state->state)[i][1] ^= Tm ^ Tmp ;
|
|
Tm = (*state->state)[i][2] ^ (*state->state)[i][3] ; Tm = xtime(Tm); (*state->state)[i][2] ^= Tm ^ Tmp ;
|
|
Tm = (*state->state)[i][3] ^ t ; Tm = xtime(Tm); (*state->state)[i][3] ^= Tm ^ Tmp ;
|
|
}
|
|
}
|
|
|
|
// Multiply is used to multiply numbers in the field GF(2^8)
|
|
#if MULTIPLY_AS_A_FUNCTION
|
|
static uint8_t Multiply(uint8_t x, uint8_t y)
|
|
{
|
|
return (((y & 1) * x) ^
|
|
((y>>1 & 1) * xtime(x)) ^
|
|
((y>>2 & 1) * xtime(xtime(x))) ^
|
|
((y>>3 & 1) * xtime(xtime(xtime(x)))) ^
|
|
((y>>4 & 1) * xtime(xtime(xtime(xtime(x))))));
|
|
}
|
|
#else
|
|
#define Multiply(x, y) \
|
|
( ((y & 1) * x) ^ \
|
|
((y>>1 & 1) * xtime(x)) ^ \
|
|
((y>>2 & 1) * xtime(xtime(x))) ^ \
|
|
((y>>3 & 1) * xtime(xtime(xtime(x)))) ^ \
|
|
((y>>4 & 1) * xtime(xtime(xtime(xtime(x)))))) \
|
|
|
|
#endif
|
|
|
|
// MixColumns function mixes the columns of the state matrix.
|
|
// The method used to multiply may be difficult to understand for the inexperienced.
|
|
// Please use the references to gain more information.
|
|
static void InvMixColumns(aes_state_t *state)
|
|
{
|
|
int i;
|
|
uint8_t a,b,c,d;
|
|
for(i=0;i<4;++i)
|
|
{
|
|
a = (*state->state)[i][0];
|
|
b = (*state->state)[i][1];
|
|
c = (*state->state)[i][2];
|
|
d = (*state->state)[i][3];
|
|
|
|
(*state->state)[i][0] = Multiply(a, 0x0e) ^ Multiply(b, 0x0b) ^ Multiply(c, 0x0d) ^ Multiply(d, 0x09);
|
|
(*state->state)[i][1] = Multiply(a, 0x09) ^ Multiply(b, 0x0e) ^ Multiply(c, 0x0b) ^ Multiply(d, 0x0d);
|
|
(*state->state)[i][2] = Multiply(a, 0x0d) ^ Multiply(b, 0x09) ^ Multiply(c, 0x0e) ^ Multiply(d, 0x0b);
|
|
(*state->state)[i][3] = Multiply(a, 0x0b) ^ Multiply(b, 0x0d) ^ Multiply(c, 0x09) ^ Multiply(d, 0x0e);
|
|
}
|
|
}
|
|
|
|
|
|
// The SubBytes Function Substitutes the values in the
|
|
// state matrix with values in an S-box.
|
|
static void InvSubBytes(aes_state_t *state)
|
|
{
|
|
uint8_t i,j;
|
|
for(i=0;i<4;++i)
|
|
{
|
|
for(j=0;j<4;++j)
|
|
{
|
|
(*state->state)[j][i] = getSBoxInvert((*state->state)[j][i]);
|
|
}
|
|
}
|
|
}
|
|
|
|
static void InvShiftRows(aes_state_t *state)
|
|
{
|
|
uint8_t temp;
|
|
|
|
// Rotate first row 1 columns to right
|
|
temp=(*state->state)[3][1];
|
|
(*state->state)[3][1]=(*state->state)[2][1];
|
|
(*state->state)[2][1]=(*state->state)[1][1];
|
|
(*state->state)[1][1]=(*state->state)[0][1];
|
|
(*state->state)[0][1]=temp;
|
|
|
|
// Rotate second row 2 columns to right
|
|
temp=(*state->state)[0][2];
|
|
(*state->state)[0][2]=(*state->state)[2][2];
|
|
(*state->state)[2][2]=temp;
|
|
|
|
temp=(*state->state)[1][2];
|
|
(*state->state)[1][2]=(*state->state)[3][2];
|
|
(*state->state)[3][2]=temp;
|
|
|
|
// Rotate third row 3 columns to right
|
|
temp=(*state->state)[0][3];
|
|
(*state->state)[0][3]=(*state->state)[1][3];
|
|
(*state->state)[1][3]=(*state->state)[2][3];
|
|
(*state->state)[2][3]=(*state->state)[3][3];
|
|
(*state->state)[3][3]=temp;
|
|
}
|
|
|
|
|
|
// Cipher is the main function that encrypts the PlainText.
|
|
static void Cipher(aes_state_t *state)
|
|
{
|
|
uint8_t round = 0;
|
|
|
|
// Add the First round key to the state before starting the rounds.
|
|
AddRoundKey(state, 0);
|
|
|
|
// There will be Nr rounds.
|
|
// The first Nr-1 rounds are identical.
|
|
// These Nr-1 rounds are executed in the loop below.
|
|
for(round = 1; round < Nr; ++round)
|
|
{
|
|
SubBytes(state);
|
|
ShiftRows(state);
|
|
MixColumns(state);
|
|
AddRoundKey(state, round);
|
|
}
|
|
|
|
// The last round is given below.
|
|
// The MixColumns function is not here in the last round.
|
|
SubBytes(state);
|
|
ShiftRows(state);
|
|
AddRoundKey(state, Nr);
|
|
}
|
|
|
|
static void InvCipher(aes_state_t *state)
|
|
{
|
|
uint8_t round=0;
|
|
|
|
// Add the First round key to the state before starting the rounds.
|
|
AddRoundKey(state, Nr);
|
|
|
|
// There will be Nr rounds.
|
|
// The first Nr-1 rounds are identical.
|
|
// These Nr-1 rounds are executed in the loop below.
|
|
for(round=Nr-1;round>0;round--)
|
|
{
|
|
InvShiftRows(state);
|
|
InvSubBytes(state);
|
|
AddRoundKey(state, round);
|
|
InvMixColumns(state);
|
|
}
|
|
|
|
// The last round is given below.
|
|
// The MixColumns function is not here in the last round.
|
|
InvShiftRows(state);
|
|
InvSubBytes(state);
|
|
AddRoundKey(state, 0);
|
|
}
|
|
|
|
static void BlockCopy(uint8_t* output, uint8_t* input)
|
|
{
|
|
uint8_t i;
|
|
for (i=0;i<KEYLEN;++i)
|
|
{
|
|
output[i] = input[i];
|
|
}
|
|
}
|
|
|
|
|
|
|
|
/*****************************************************************************/
|
|
/* Public functions: */
|
|
/*****************************************************************************/
|
|
#if defined(ECB) && ECB
|
|
|
|
|
|
void AES128_ECB_encrypt(uint8_t* input, const uint8_t* key, uint8_t* output)
|
|
{
|
|
aes_state_t state;
|
|
// Copy input to output, and work in-memory on output
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
|
|
state.Key = key;
|
|
KeyExpansion(&state);
|
|
|
|
// The next function call encrypts the PlainText with the Key using AES algorithm.
|
|
Cipher(&state);
|
|
}
|
|
|
|
void AES128_ECB_decrypt(uint8_t* input, const uint8_t* key, uint8_t *output)
|
|
{
|
|
aes_state_t state;
|
|
// Copy input to output, and work in-memory on output
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
|
|
// The KeyExpansion routine must be called before encryption.
|
|
state.Key = key;
|
|
KeyExpansion(&state);
|
|
|
|
InvCipher(&state);
|
|
}
|
|
|
|
|
|
#endif // #if defined(ECB) && ECB
|
|
|
|
|
|
|
|
|
|
|
|
#if defined(CBC) && CBC
|
|
|
|
|
|
static void XorWithIv(aes_state_t *state, uint8_t* buf)
|
|
{
|
|
uint8_t i;
|
|
for(i = 0; i < KEYLEN; ++i)
|
|
{
|
|
buf[i] ^= state->Iv[i];
|
|
}
|
|
}
|
|
|
|
void AES128_CBC_encrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
|
|
{
|
|
intptr_t i;
|
|
uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */
|
|
aes_state_t state;
|
|
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
|
|
// Skip the key expansion if key is passed as 0
|
|
if(0 != key)
|
|
{
|
|
state.Key = key;
|
|
KeyExpansion(&state);
|
|
}
|
|
|
|
if(iv != 0)
|
|
{
|
|
state.Iv = iv;
|
|
}
|
|
|
|
for(i = 0; i < length; i += KEYLEN)
|
|
{
|
|
XorWithIv(&state, input);
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
Cipher(&state);
|
|
state.Iv = output;
|
|
input += KEYLEN;
|
|
output += KEYLEN;
|
|
}
|
|
|
|
if(remainders)
|
|
{
|
|
BlockCopy(output, input);
|
|
memset(output + remainders, 0, KEYLEN - remainders); /* add 0-padding */
|
|
state.state = (state_t*)output;
|
|
Cipher(&state);
|
|
}
|
|
}
|
|
|
|
void AES128_CBC_decrypt_buffer(uint8_t* output, uint8_t* input, uint32_t length, const uint8_t* key, const uint8_t* iv)
|
|
{
|
|
intptr_t i;
|
|
uint8_t remainders = length % KEYLEN; /* Remaining bytes in the last non-full block */
|
|
aes_state_t state;
|
|
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
|
|
// Skip the key expansion if key is passed as 0
|
|
if(0 != key)
|
|
{
|
|
state.Key = key;
|
|
KeyExpansion(&state);
|
|
}
|
|
|
|
// If iv is passed as 0, we continue to encrypt without re-setting the Iv
|
|
if(iv != 0)
|
|
{
|
|
state.Iv = iv;
|
|
}
|
|
|
|
for(i = 0; i < length; i += KEYLEN)
|
|
{
|
|
BlockCopy(output, input);
|
|
state.state = (state_t*)output;
|
|
InvCipher(&state);
|
|
XorWithIv(&state, output);
|
|
state.Iv = input;
|
|
input += KEYLEN;
|
|
output += KEYLEN;
|
|
}
|
|
|
|
if(remainders)
|
|
{
|
|
BlockCopy(output, input);
|
|
memset(output+remainders, 0, KEYLEN - remainders); /* add 0-padding */
|
|
state.state = (state_t*)output;
|
|
InvCipher(&state);
|
|
}
|
|
}
|
|
|
|
|
|
#endif // #if defined(CBC) && CBC
|
|
|
|
|