// advanced encryption standard
// Original author: Karl Malbrain, [email protected]
// Ported to Atmel AVR by: Jiri Pittner, [email protected]
//
/*
This work, including the source code, documentation
and related data, is placed into the public domain.

The original author is Karl Malbrain.

THIS SOFTWARE IS PROVIDED AS-IS WITHOUT WARRANTY
OF ANY KIND, NOT EVEN THE IMPLIED WARRANTY OF
MERCHANTABILITY. THE AUTHOR OF THIS SOFTWARE,
ASSUMES _NO_ RESPONSIBILITY FOR ANY CONSEQUENCE
RESULTING FROM THE USE, MODIFICATION, OR
REDISTRIBUTION OF THIS SOFTWARE.
*/

#include <stdlib.h>
#include <string.h>

#include <avr/pgmspace.h> //tables have to reside in flash memory


// AES only supports Nb=4
#define Nb 4			// number of columns in the state & expanded key

#define Nk 4			// number of columns in a key
#define Nr 10			// number of rounds in encryption

#define Sbox(i) (pgm_read_byte(&P_Sbox[i]))
const unsigned char P_Sbox[256] __attribute__ ((__progmem__)) = {		// forward s-box
0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16};

#define InvSbox(i) (pgm_read_byte(&P_InvSbox[i]))
const unsigned char P_InvSbox[256] __attribute__ ((__progmem__)) = {	// inverse s-box
0x52, 0x09, 0x6a, 0xd5, 0x30, 0x36, 0xa5, 0x38, 0xbf, 0x40, 0xa3, 0x9e, 0x81, 0xf3, 0xd7, 0xfb,
0x7c, 0xe3, 0x39, 0x82, 0x9b, 0x2f, 0xff, 0x87, 0x34, 0x8e, 0x43, 0x44, 0xc4, 0xde, 0xe9, 0xcb,
0x54, 0x7b, 0x94, 0x32, 0xa6, 0xc2, 0x23, 0x3d, 0xee, 0x4c, 0x95, 0x0b, 0x42, 0xfa, 0xc3, 0x4e,
0x08, 0x2e, 0xa1, 0x66, 0x28, 0xd9, 0x24, 0xb2, 0x76, 0x5b, 0xa2, 0x49, 0x6d, 0x8b, 0xd1, 0x25,
0x72, 0xf8, 0xf6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xd4, 0xa4, 0x5c, 0xcc, 0x5d, 0x65, 0xb6, 0x92,
0x6c, 0x70, 0x48, 0x50, 0xfd, 0xed, 0xb9, 0xda, 0x5e, 0x15, 0x46, 0x57, 0xa7, 0x8d, 0x9d, 0x84,
0x90, 0xd8, 0xab, 0x00, 0x8c, 0xbc, 0xd3, 0x0a, 0xf7, 0xe4, 0x58, 0x05, 0xb8, 0xb3, 0x45, 0x06,
0xd0, 0x2c, 0x1e, 0x8f, 0xca, 0x3f, 0x0f, 0x02, 0xc1, 0xaf, 0xbd, 0x03, 0x01, 0x13, 0x8a, 0x6b,
0x3a, 0x91, 0x11, 0x41, 0x4f, 0x67, 0xdc, 0xea, 0x97, 0xf2, 0xcf, 0xce, 0xf0, 0xb4, 0xe6, 0x73,
0x96, 0xac, 0x74, 0x22, 0xe7, 0xad, 0x35, 0x85, 0xe2, 0xf9, 0x37, 0xe8, 0x1c, 0x75, 0xdf, 0x6e,
0x47, 0xf1, 0x1a, 0x71, 0x1d, 0x29, 0xc5, 0x89, 0x6f, 0xb7, 0x62, 0x0e, 0xaa, 0x18, 0xbe, 0x1b,
0xfc, 0x56, 0x3e, 0x4b, 0xc6, 0xd2, 0x79, 0x20, 0x9a, 0xdb, 0xc0, 0xfe, 0x78, 0xcd, 0x5a, 0xf4,
0x1f, 0xdd, 0xa8, 0x33, 0x88, 0x07, 0xc7, 0x31, 0xb1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xec, 0x5f,
0x60, 0x51, 0x7f, 0xa9, 0x19, 0xb5, 0x4a, 0x0d, 0x2d, 0xe5, 0x7a, 0x9f, 0x93, 0xc9, 0x9c, 0xef,
0xa0, 0xe0, 0x3b, 0x4d, 0xae, 0x2a, 0xf5, 0xb0, 0xc8, 0xeb, 0xbb, 0x3c, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2b, 0x04, 0x7e, 0xba, 0x77, 0xd6, 0x26, 0xe1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0c, 0x7d};

// combined Xtimes2[Sbox[]]
#define Xtime2Sbox(i) (pgm_read_byte(&P_Xtime2Sbox[i]))
const unsigned char P_Xtime2Sbox[256] __attribute__ ((__progmem__)) = {
0xc6, 0xf8, 0xee, 0xf6, 0xff, 0xd6, 0xde, 0x91, 0x60, 0x02, 0xce, 0x56, 0xe7, 0xb5, 0x4d, 0xec, 
0x8f, 0x1f, 0x89, 0xfa, 0xef, 0xb2, 0x8e, 0xfb, 0x41, 0xb3, 0x5f, 0x45, 0x23, 0x53, 0xe4, 0x9b, 
0x75, 0xe1, 0x3d, 0x4c, 0x6c, 0x7e, 0xf5, 0x83, 0x68, 0x51, 0xd1, 0xf9, 0xe2, 0xab, 0x62, 0x2a, 
0x08, 0x95, 0x46, 0x9d, 0x30, 0x37, 0x0a, 0x2f, 0x0e, 0x24, 0x1b, 0xdf, 0xcd, 0x4e, 0x7f, 0xea, 
0x12, 0x1d, 0x58, 0x34, 0x36, 0xdc, 0xb4, 0x5b, 0xa4, 0x76, 0xb7, 0x7d, 0x52, 0xdd, 0x5e, 0x13, 
0xa6, 0xb9, 0x00, 0xc1, 0x40, 0xe3, 0x79, 0xb6, 0xd4, 0x8d, 0x67, 0x72, 0x94, 0x98, 0xb0, 0x85, 
0xbb, 0xc5, 0x4f, 0xed, 0x86, 0x9a, 0x66, 0x11, 0x8a, 0xe9, 0x04, 0xfe, 0xa0, 0x78, 0x25, 0x4b, 
0xa2, 0x5d, 0x80, 0x05, 0x3f, 0x21, 0x70, 0xf1, 0x63, 0x77, 0xaf, 0x42, 0x20, 0xe5, 0xfd, 0xbf, 
0x81, 0x18, 0x26, 0xc3, 0xbe, 0x35, 0x88, 0x2e, 0x93, 0x55, 0xfc, 0x7a, 0xc8, 0xba, 0x32, 0xe6, 
0xc0, 0x19, 0x9e, 0xa3, 0x44, 0x54, 0x3b, 0x0b, 0x8c, 0xc7, 0x6b, 0x28, 0xa7, 0xbc, 0x16, 0xad, 
0xdb, 0x64, 0x74, 0x14, 0x92, 0x0c, 0x48, 0xb8, 0x9f, 0xbd, 0x43, 0xc4, 0x39, 0x31, 0xd3, 0xf2, 
0xd5, 0x8b, 0x6e, 0xda, 0x01, 0xb1, 0x9c, 0x49, 0xd8, 0xac, 0xf3, 0xcf, 0xca, 0xf4, 0x47, 0x10, 
0x6f, 0xf0, 0x4a, 0x5c, 0x38, 0x57, 0x73, 0x97, 0xcb, 0xa1, 0xe8, 0x3e, 0x96, 0x61, 0x0d, 0x0f, 
0xe0, 0x7c, 0x71, 0xcc, 0x90, 0x06, 0xf7, 0x1c, 0xc2, 0x6a, 0xae, 0x69, 0x17, 0x99, 0x3a, 0x27, 
0xd9, 0xeb, 0x2b, 0x22, 0xd2, 0xa9, 0x07, 0x33, 0x2d, 0x3c, 0x15, 0xc9, 0x87, 0xaa, 0x50, 0xa5, 
0x03, 0x59, 0x09, 0x1a, 0x65, 0xd7, 0x84, 0xd0, 0x82, 0x29, 0x5a, 0x1e, 0x7b, 0xa8, 0x6d, 0x2c 
};

// combined Xtimes3[Sbox[]]
#define Xtime3Sbox(i) (pgm_read_byte(&P_Xtime3Sbox[i]))
const unsigned char P_Xtime3Sbox[256] __attribute__ ((__progmem__)) = {
0xa5, 0x84, 0x99, 0x8d, 0x0d, 0xbd, 0xb1, 0x54, 0x50, 0x03, 0xa9, 0x7d, 0x19, 0x62, 0xe6, 0x9a, 
0x45, 0x9d, 0x40, 0x87, 0x15, 0xeb, 0xc9, 0x0b, 0xec, 0x67, 0xfd, 0xea, 0xbf, 0xf7, 0x96, 0x5b, 
0xc2, 0x1c, 0xae, 0x6a, 0x5a, 0x41, 0x02, 0x4f, 0x5c, 0xf4, 0x34, 0x08, 0x93, 0x73, 0x53, 0x3f, 
0x0c, 0x52, 0x65, 0x5e, 0x28, 0xa1, 0x0f, 0xb5, 0x09, 0x36, 0x9b, 0x3d, 0x26, 0x69, 0xcd, 0x9f, 
0x1b, 0x9e, 0x74, 0x2e, 0x2d, 0xb2, 0xee, 0xfb, 0xf6, 0x4d, 0x61, 0xce, 0x7b, 0x3e, 0x71, 0x97, 
0xf5, 0x68, 0x00, 0x2c, 0x60, 0x1f, 0xc8, 0xed, 0xbe, 0x46, 0xd9, 0x4b, 0xde, 0xd4, 0xe8, 0x4a, 
0x6b, 0x2a, 0xe5, 0x16, 0xc5, 0xd7, 0x55, 0x94, 0xcf, 0x10, 0x06, 0x81, 0xf0, 0x44, 0xba, 0xe3, 
0xf3, 0xfe, 0xc0, 0x8a, 0xad, 0xbc, 0x48, 0x04, 0xdf, 0xc1, 0x75, 0x63, 0x30, 0x1a, 0x0e, 0x6d, 
0x4c, 0x14, 0x35, 0x2f, 0xe1, 0xa2, 0xcc, 0x39, 0x57, 0xf2, 0x82, 0x47, 0xac, 0xe7, 0x2b, 0x95, 
0xa0, 0x98, 0xd1, 0x7f, 0x66, 0x7e, 0xab, 0x83, 0xca, 0x29, 0xd3, 0x3c, 0x79, 0xe2, 0x1d, 0x76, 
0x3b, 0x56, 0x4e, 0x1e, 0xdb, 0x0a, 0x6c, 0xe4, 0x5d, 0x6e, 0xef, 0xa6, 0xa8, 0xa4, 0x37, 0x8b, 
0x32, 0x43, 0x59, 0xb7, 0x8c, 0x64, 0xd2, 0xe0, 0xb4, 0xfa, 0x07, 0x25, 0xaf, 0x8e, 0xe9, 0x18, 
0xd5, 0x88, 0x6f, 0x72, 0x24, 0xf1, 0xc7, 0x51, 0x23, 0x7c, 0x9c, 0x21, 0xdd, 0xdc, 0x86, 0x85, 
0x90, 0x42, 0xc4, 0xaa, 0xd8, 0x05, 0x01, 0x12, 0xa3, 0x5f, 0xf9, 0xd0, 0x91, 0x58, 0x27, 0xb9, 
0x38, 0x13, 0xb3, 0x33, 0xbb, 0x70, 0x89, 0xa7, 0xb6, 0x22, 0x92, 0x20, 0x49, 0xff, 0x78, 0x7a, 
0x8f, 0xf8, 0x80, 0x17, 0xda, 0x31, 0xc6, 0xb8, 0xc3, 0xb0, 0x77, 0x11, 0xcb, 0xfc, 0xd6, 0x3a 
};

// modular multiplication tables
// based on:

// Xtime2[x] = (x & 0x80 ? 0x1b : 0) ^ (x + x)
// Xtime3[x] = x^Xtime2[x];

#define Xtime2(i) (pgm_read_byte(&P_Xtime2[i]))
const unsigned char P_Xtime2[256] __attribute__ ((__progmem__)) = {
0x00, 0x02, 0x04, 0x06, 0x08, 0x0a, 0x0c, 0x0e, 0x10, 0x12, 0x14, 0x16, 0x18, 0x1a, 0x1c, 0x1e, 
0x20, 0x22, 0x24, 0x26, 0x28, 0x2a, 0x2c, 0x2e, 0x30, 0x32, 0x34, 0x36, 0x38, 0x3a, 0x3c, 0x3e, 
0x40, 0x42, 0x44, 0x46, 0x48, 0x4a, 0x4c, 0x4e, 0x50, 0x52, 0x54, 0x56, 0x58, 0x5a, 0x5c, 0x5e, 
0x60, 0x62, 0x64, 0x66, 0x68, 0x6a, 0x6c, 0x6e, 0x70, 0x72, 0x74, 0x76, 0x78, 0x7a, 0x7c, 0x7e, 
0x80, 0x82, 0x84, 0x86, 0x88, 0x8a, 0x8c, 0x8e, 0x90, 0x92, 0x94, 0x96, 0x98, 0x9a, 0x9c, 0x9e, 
0xa0, 0xa2, 0xa4, 0xa6, 0xa8, 0xaa, 0xac, 0xae, 0xb0, 0xb2, 0xb4, 0xb6, 0xb8, 0xba, 0xbc, 0xbe, 
0xc0, 0xc2, 0xc4, 0xc6, 0xc8, 0xca, 0xcc, 0xce, 0xd0, 0xd2, 0xd4, 0xd6, 0xd8, 0xda, 0xdc, 0xde, 
0xe0, 0xe2, 0xe4, 0xe6, 0xe8, 0xea, 0xec, 0xee, 0xf0, 0xf2, 0xf4, 0xf6, 0xf8, 0xfa, 0xfc, 0xfe, 
0x1b, 0x19, 0x1f, 0x1d, 0x13, 0x11, 0x17, 0x15, 0x0b, 0x09, 0x0f, 0x0d, 0x03, 0x01, 0x07, 0x05, 
0x3b, 0x39, 0x3f, 0x3d, 0x33, 0x31, 0x37, 0x35, 0x2b, 0x29, 0x2f, 0x2d, 0x23, 0x21, 0x27, 0x25, 
0x5b, 0x59, 0x5f, 0x5d, 0x53, 0x51, 0x57, 0x55, 0x4b, 0x49, 0x4f, 0x4d, 0x43, 0x41, 0x47, 0x45, 
0x7b, 0x79, 0x7f, 0x7d, 0x73, 0x71, 0x77, 0x75, 0x6b, 0x69, 0x6f, 0x6d, 0x63, 0x61, 0x67, 0x65, 
0x9b, 0x99, 0x9f, 0x9d, 0x93, 0x91, 0x97, 0x95, 0x8b, 0x89, 0x8f, 0x8d, 0x83, 0x81, 0x87, 0x85, 
0xbb, 0xb9, 0xbf, 0xbd, 0xb3, 0xb1, 0xb7, 0xb5, 0xab, 0xa9, 0xaf, 0xad, 0xa3, 0xa1, 0xa7, 0xa5, 
0xdb, 0xd9, 0xdf, 0xdd, 0xd3, 0xd1, 0xd7, 0xd5, 0xcb, 0xc9, 0xcf, 0xcd, 0xc3, 0xc1, 0xc7, 0xc5, 
0xfb, 0xf9, 0xff, 0xfd, 0xf3, 0xf1, 0xf7, 0xf5, 0xeb, 0xe9, 0xef, 0xed, 0xe3, 0xe1, 0xe7, 0xe5}; 

#define Xtime9(i) (pgm_read_byte(&P_Xtime9[i]))
const unsigned char P_Xtime9[256] __attribute__ ((__progmem__)) = {
0x00, 0x09, 0x12, 0x1b, 0x24, 0x2d, 0x36, 0x3f, 0x48, 0x41, 0x5a, 0x53, 0x6c, 0x65, 0x7e, 0x77, 
0x90, 0x99, 0x82, 0x8b, 0xb4, 0xbd, 0xa6, 0xaf, 0xd8, 0xd1, 0xca, 0xc3, 0xfc, 0xf5, 0xee, 0xe7, 
0x3b, 0x32, 0x29, 0x20, 0x1f, 0x16, 0x0d, 0x04, 0x73, 0x7a, 0x61, 0x68, 0x57, 0x5e, 0x45, 0x4c, 
0xab, 0xa2, 0xb9, 0xb0, 0x8f, 0x86, 0x9d, 0x94, 0xe3, 0xea, 0xf1, 0xf8, 0xc7, 0xce, 0xd5, 0xdc, 
0x76, 0x7f, 0x64, 0x6d, 0x52, 0x5b, 0x40, 0x49, 0x3e, 0x37, 0x2c, 0x25, 0x1a, 0x13, 0x08, 0x01, 
0xe6, 0xef, 0xf4, 0xfd, 0xc2, 0xcb, 0xd0, 0xd9, 0xae, 0xa7, 0xbc, 0xb5, 0x8a, 0x83, 0x98, 0x91, 
0x4d, 0x44, 0x5f, 0x56, 0x69, 0x60, 0x7b, 0x72, 0x05, 0x0c, 0x17, 0x1e, 0x21, 0x28, 0x33, 0x3a, 
0xdd, 0xd4, 0xcf, 0xc6, 0xf9, 0xf0, 0xeb, 0xe2, 0x95, 0x9c, 0x87, 0x8e, 0xb1, 0xb8, 0xa3, 0xaa, 
0xec, 0xe5, 0xfe, 0xf7, 0xc8, 0xc1, 0xda, 0xd3, 0xa4, 0xad, 0xb6, 0xbf, 0x80, 0x89, 0x92, 0x9b, 
0x7c, 0x75, 0x6e, 0x67, 0x58, 0x51, 0x4a, 0x43, 0x34, 0x3d, 0x26, 0x2f, 0x10, 0x19, 0x02, 0x0b, 
0xd7, 0xde, 0xc5, 0xcc, 0xf3, 0xfa, 0xe1, 0xe8, 0x9f, 0x96, 0x8d, 0x84, 0xbb, 0xb2, 0xa9, 0xa0, 
0x47, 0x4e, 0x55, 0x5c, 0x63, 0x6a, 0x71, 0x78, 0x0f, 0x06, 0x1d, 0x14, 0x2b, 0x22, 0x39, 0x30, 
0x9a, 0x93, 0x88, 0x81, 0xbe, 0xb7, 0xac, 0xa5, 0xd2, 0xdb, 0xc0, 0xc9, 0xf6, 0xff, 0xe4, 0xed, 
0x0a, 0x03, 0x18, 0x11, 0x2e, 0x27, 0x3c, 0x35, 0x42, 0x4b, 0x50, 0x59, 0x66, 0x6f, 0x74, 0x7d, 
0xa1, 0xa8, 0xb3, 0xba, 0x85, 0x8c, 0x97, 0x9e, 0xe9, 0xe0, 0xfb, 0xf2, 0xcd, 0xc4, 0xdf, 0xd6, 
0x31, 0x38, 0x23, 0x2a, 0x15, 0x1c, 0x07, 0x0e, 0x79, 0x70, 0x6b, 0x62, 0x5d, 0x54, 0x4f, 0x46};

#define XtimeB(i) (pgm_read_byte(&P_XtimeB[i]))
const unsigned char P_XtimeB[256] __attribute__ ((__progmem__)) = {
0x00, 0x0b, 0x16, 0x1d, 0x2c, 0x27, 0x3a, 0x31, 0x58, 0x53, 0x4e, 0x45, 0x74, 0x7f, 0x62, 0x69, 
0xb0, 0xbb, 0xa6, 0xad, 0x9c, 0x97, 0x8a, 0x81, 0xe8, 0xe3, 0xfe, 0xf5, 0xc4, 0xcf, 0xd2, 0xd9, 
0x7b, 0x70, 0x6d, 0x66, 0x57, 0x5c, 0x41, 0x4a, 0x23, 0x28, 0x35, 0x3e, 0x0f, 0x04, 0x19, 0x12, 
0xcb, 0xc0, 0xdd, 0xd6, 0xe7, 0xec, 0xf1, 0xfa, 0x93, 0x98, 0x85, 0x8e, 0xbf, 0xb4, 0xa9, 0xa2, 
0xf6, 0xfd, 0xe0, 0xeb, 0xda, 0xd1, 0xcc, 0xc7, 0xae, 0xa5, 0xb8, 0xb3, 0x82, 0x89, 0x94, 0x9f, 
0x46, 0x4d, 0x50, 0x5b, 0x6a, 0x61, 0x7c, 0x77, 0x1e, 0x15, 0x08, 0x03, 0x32, 0x39, 0x24, 0x2f, 
0x8d, 0x86, 0x9b, 0x90, 0xa1, 0xaa, 0xb7, 0xbc, 0xd5, 0xde, 0xc3, 0xc8, 0xf9, 0xf2, 0xef, 0xe4, 
0x3d, 0x36, 0x2b, 0x20, 0x11, 0x1a, 0x07, 0x0c, 0x65, 0x6e, 0x73, 0x78, 0x49, 0x42, 0x5f, 0x54, 
0xf7, 0xfc, 0xe1, 0xea, 0xdb, 0xd0, 0xcd, 0xc6, 0xaf, 0xa4, 0xb9, 0xb2, 0x83, 0x88, 0x95, 0x9e, 
0x47, 0x4c, 0x51, 0x5a, 0x6b, 0x60, 0x7d, 0x76, 0x1f, 0x14, 0x09, 0x02, 0x33, 0x38, 0x25, 0x2e, 
0x8c, 0x87, 0x9a, 0x91, 0xa0, 0xab, 0xb6, 0xbd, 0xd4, 0xdf, 0xc2, 0xc9, 0xf8, 0xf3, 0xee, 0xe5, 
0x3c, 0x37, 0x2a, 0x21, 0x10, 0x1b, 0x06, 0x0d, 0x64, 0x6f, 0x72, 0x79, 0x48, 0x43, 0x5e, 0x55, 
0x01, 0x0a, 0x17, 0x1c, 0x2d, 0x26, 0x3b, 0x30, 0x59, 0x52, 0x4f, 0x44, 0x75, 0x7e, 0x63, 0x68, 
0xb1, 0xba, 0xa7, 0xac, 0x9d, 0x96, 0x8b, 0x80, 0xe9, 0xe2, 0xff, 0xf4, 0xc5, 0xce, 0xd3, 0xd8, 
0x7a, 0x71, 0x6c, 0x67, 0x56, 0x5d, 0x40, 0x4b, 0x22, 0x29, 0x34, 0x3f, 0x0e, 0x05, 0x18, 0x13, 
0xca, 0xc1, 0xdc, 0xd7, 0xe6, 0xed, 0xf0, 0xfb, 0x92, 0x99, 0x84, 0x8f, 0xbe, 0xb5, 0xa8, 0xa3}; 

#define XtimeD(i) (pgm_read_byte(&P_XtimeD[i]))
const unsigned char P_XtimeD[256] __attribute__ ((__progmem__)) = {
0x00, 0x0d, 0x1a, 0x17, 0x34, 0x39, 0x2e, 0x23, 0x68, 0x65, 0x72, 0x7f, 0x5c, 0x51, 0x46, 0x4b, 
0xd0, 0xdd, 0xca, 0xc7, 0xe4, 0xe9, 0xfe, 0xf3, 0xb8, 0xb5, 0xa2, 0xaf, 0x8c, 0x81, 0x96, 0x9b, 
0xbb, 0xb6, 0xa1, 0xac, 0x8f, 0x82, 0x95, 0x98, 0xd3, 0xde, 0xc9, 0xc4, 0xe7, 0xea, 0xfd, 0xf0, 
0x6b, 0x66, 0x71, 0x7c, 0x5f, 0x52, 0x45, 0x48, 0x03, 0x0e, 0x19, 0x14, 0x37, 0x3a, 0x2d, 0x20, 
0x6d, 0x60, 0x77, 0x7a, 0x59, 0x54, 0x43, 0x4e, 0x05, 0x08, 0x1f, 0x12, 0x31, 0x3c, 0x2b, 0x26, 
0xbd, 0xb0, 0xa7, 0xaa, 0x89, 0x84, 0x93, 0x9e, 0xd5, 0xd8, 0xcf, 0xc2, 0xe1, 0xec, 0xfb, 0xf6, 
0xd6, 0xdb, 0xcc, 0xc1, 0xe2, 0xef, 0xf8, 0xf5, 0xbe, 0xb3, 0xa4, 0xa9, 0x8a, 0x87, 0x90, 0x9d, 
0x06, 0x0b, 0x1c, 0x11, 0x32, 0x3f, 0x28, 0x25, 0x6e, 0x63, 0x74, 0x79, 0x5a, 0x57, 0x40, 0x4d, 
0xda, 0xd7, 0xc0, 0xcd, 0xee, 0xe3, 0xf4, 0xf9, 0xb2, 0xbf, 0xa8, 0xa5, 0x86, 0x8b, 0x9c, 0x91, 
0x0a, 0x07, 0x10, 0x1d, 0x3e, 0x33, 0x24, 0x29, 0x62, 0x6f, 0x78, 0x75, 0x56, 0x5b, 0x4c, 0x41, 
0x61, 0x6c, 0x7b, 0x76, 0x55, 0x58, 0x4f, 0x42, 0x09, 0x04, 0x13, 0x1e, 0x3d, 0x30, 0x27, 0x2a, 
0xb1, 0xbc, 0xab, 0xa6, 0x85, 0x88, 0x9f, 0x92, 0xd9, 0xd4, 0xc3, 0xce, 0xed, 0xe0, 0xf7, 0xfa, 
0xb7, 0xba, 0xad, 0xa0, 0x83, 0x8e, 0x99, 0x94, 0xdf, 0xd2, 0xc5, 0xc8, 0xeb, 0xe6, 0xf1, 0xfc, 
0x67, 0x6a, 0x7d, 0x70, 0x53, 0x5e, 0x49, 0x44, 0x0f, 0x02, 0x15, 0x18, 0x3b, 0x36, 0x21, 0x2c, 
0x0c, 0x01, 0x16, 0x1b, 0x38, 0x35, 0x22, 0x2f, 0x64, 0x69, 0x7e, 0x73, 0x50, 0x5d, 0x4a, 0x47, 
0xdc, 0xd1, 0xc6, 0xcb, 0xe8, 0xe5, 0xf2, 0xff, 0xb4, 0xb9, 0xae, 0xa3, 0x80, 0x8d, 0x9a, 0x97}; 

#define XtimeE(i) (pgm_read_byte(&P_XtimeE[i]))
const unsigned char P_XtimeE[256] __attribute__ ((__progmem__)) = {
0x00, 0x0e, 0x1c, 0x12, 0x38, 0x36, 0x24, 0x2a, 0x70, 0x7e, 0x6c, 0x62, 0x48, 0x46, 0x54, 0x5a, 
0xe0, 0xee, 0xfc, 0xf2, 0xd8, 0xd6, 0xc4, 0xca, 0x90, 0x9e, 0x8c, 0x82, 0xa8, 0xa6, 0xb4, 0xba, 
0xdb, 0xd5, 0xc7, 0xc9, 0xe3, 0xed, 0xff, 0xf1, 0xab, 0xa5, 0xb7, 0xb9, 0x93, 0x9d, 0x8f, 0x81, 
0x3b, 0x35, 0x27, 0x29, 0x03, 0x0d, 0x1f, 0x11, 0x4b, 0x45, 0x57, 0x59, 0x73, 0x7d, 0x6f, 0x61, 
0xad, 0xa3, 0xb1, 0xbf, 0x95, 0x9b, 0x89, 0x87, 0xdd, 0xd3, 0xc1, 0xcf, 0xe5, 0xeb, 0xf9, 0xf7, 
0x4d, 0x43, 0x51, 0x5f, 0x75, 0x7b, 0x69, 0x67, 0x3d, 0x33, 0x21, 0x2f, 0x05, 0x0b, 0x19, 0x17, 
0x76, 0x78, 0x6a, 0x64, 0x4e, 0x40, 0x52, 0x5c, 0x06, 0x08, 0x1a, 0x14, 0x3e, 0x30, 0x22, 0x2c, 
0x96, 0x98, 0x8a, 0x84, 0xae, 0xa0, 0xb2, 0xbc, 0xe6, 0xe8, 0xfa, 0xf4, 0xde, 0xd0, 0xc2, 0xcc, 
0x41, 0x4f, 0x5d, 0x53, 0x79, 0x77, 0x65, 0x6b, 0x31, 0x3f, 0x2d, 0x23, 0x09, 0x07, 0x15, 0x1b, 
0xa1, 0xaf, 0xbd, 0xb3, 0x99, 0x97, 0x85, 0x8b, 0xd1, 0xdf, 0xcd, 0xc3, 0xe9, 0xe7, 0xf5, 0xfb, 
0x9a, 0x94, 0x86, 0x88, 0xa2, 0xac, 0xbe, 0xb0, 0xea, 0xe4, 0xf6, 0xf8, 0xd2, 0xdc, 0xce, 0xc0, 
0x7a, 0x74, 0x66, 0x68, 0x42, 0x4c, 0x5e, 0x50, 0x0a, 0x04, 0x16, 0x18, 0x32, 0x3c, 0x2e, 0x20, 
0xec, 0xe2, 0xf0, 0xfe, 0xd4, 0xda, 0xc8, 0xc6, 0x9c, 0x92, 0x80, 0x8e, 0xa4, 0xaa, 0xb8, 0xb6, 
0x0c, 0x02, 0x10, 0x1e, 0x34, 0x3a, 0x28, 0x26, 0x7c, 0x72, 0x60, 0x6e, 0x44, 0x4a, 0x58, 0x56, 
0x37, 0x39, 0x2b, 0x25, 0x0f, 0x01, 0x13, 0x1d, 0x47, 0x49, 0x5b, 0x55, 0x7f, 0x71, 0x63, 0x6d, 
0xd7, 0xd9, 0xcb, 0xc5, 0xef, 0xe1, 0xf3, 0xfd, 0xa7, 0xa9, 0xbb, 0xb5, 0x9f, 0x91, 0x83, 0x8d}; 

// exchanges columns in each of 4 rows
// row0 - unchanged, row1- shifted left 1, 
// row2 - shifted left 2 and row3 - shifted left 3
void ShiftRows (unsigned char *state)
{
unsigned char tmp;

	// just substitute row 0
	state[0] = Sbox(state[0]), state[4] = Sbox(state[4]);
	state[8] = Sbox(state[8]), state[12] = Sbox(state[12]);

	// rotate row 1
	tmp = Sbox(state[1]), state[1] = Sbox(state[5]);
	state[5] = Sbox(state[9]), state[9] = Sbox(state[13]), state[13] = tmp;

	// rotate row 2
	tmp = Sbox(state[2]), state[2] = Sbox(state[10]), state[10] = tmp;
	tmp = Sbox(state[6]), state[6] = Sbox(state[14]), state[14] = tmp;

	// rotate row 3
	tmp = Sbox(state[15]), state[15] = Sbox(state[11]);
	state[11] = Sbox(state[7]), state[7] = Sbox(state[3]), state[3] = tmp;
}

// restores columns in each of 4 rows
// row0 - unchanged, row1- shifted right 1, 
// row2 - shifted right 2 and row3 - shifted right 3
void InvShiftRows (unsigned char *state)
{
unsigned char tmp;

	// restore row 0
	state[0] = InvSbox(state[0]), state[4] = InvSbox(state[4]);
	state[8] = InvSbox(state[8]), state[12] = InvSbox(state[12]);

	// restore row 1
	tmp = InvSbox(state[13]), state[13] = InvSbox(state[9]);
	state[9] = InvSbox(state[5]), state[5] = InvSbox(state[1]), state[1] = tmp;

	// restore row 2
	tmp = InvSbox(state[2]), state[2] = InvSbox(state[10]), state[10] = tmp;
	tmp = InvSbox(state[6]), state[6] = InvSbox(state[14]), state[14] = tmp;

	// restore row 3
	tmp = InvSbox(state[3]), state[3] = InvSbox(state[7]);
	state[7] = InvSbox(state[11]), state[11] = InvSbox(state[15]), state[15] = tmp;
}

// recombine and mix each row in a column
void MixSubColumns (unsigned char *state)
{
unsigned char tmp[4 * Nb];

	// mixing column 0
	tmp[0] = Xtime2Sbox(state[0]) ^ Xtime3Sbox(state[5]) ^ Sbox(state[10]) ^ Sbox(state[15]);
	tmp[1] = Sbox(state[0]) ^ Xtime2Sbox(state[5]) ^ Xtime3Sbox(state[10]) ^ Sbox(state[15]);
	tmp[2] = Sbox(state[0]) ^ Sbox(state[5]) ^ Xtime2Sbox(state[10]) ^ Xtime3Sbox(state[15]);
	tmp[3] = Xtime3Sbox(state[0]) ^ Sbox(state[5]) ^ Sbox(state[10]) ^ Xtime2Sbox(state[15]);

	// mixing column 1
	tmp[4] = Xtime2Sbox(state[4]) ^ Xtime3Sbox(state[9]) ^ Sbox(state[14]) ^ Sbox(state[3]);
	tmp[5] = Sbox(state[4]) ^ Xtime2Sbox(state[9]) ^ Xtime3Sbox(state[14]) ^ Sbox(state[3]);
	tmp[6] = Sbox(state[4]) ^ Sbox(state[9]) ^ Xtime2Sbox(state[14]) ^ Xtime3Sbox(state[3]);
	tmp[7] = Xtime3Sbox(state[4]) ^ Sbox(state[9]) ^ Sbox(state[14]) ^ Xtime2Sbox(state[3]);

	// mixing column 2
	tmp[8] = Xtime2Sbox(state[8]) ^ Xtime3Sbox(state[13]) ^ Sbox(state[2]) ^ Sbox(state[7]);
	tmp[9] = Sbox(state[8]) ^ Xtime2Sbox(state[13]) ^ Xtime3Sbox(state[2]) ^ Sbox(state[7]);
	tmp[10]  = Sbox(state[8]) ^ Sbox(state[13]) ^ Xtime2Sbox(state[2]) ^ Xtime3Sbox(state[7]);
	tmp[11]  = Xtime3Sbox(state[8]) ^ Sbox(state[13]) ^ Sbox(state[2]) ^ Xtime2Sbox(state[7]);

	// mixing column 3
	tmp[12] = Xtime2Sbox(state[12]) ^ Xtime3Sbox(state[1]) ^ Sbox(state[6]) ^ Sbox(state[11]);
	tmp[13] = Sbox(state[12]) ^ Xtime2Sbox(state[1]) ^ Xtime3Sbox(state[6]) ^ Sbox(state[11]);
	tmp[14] = Sbox(state[12]) ^ Sbox(state[1]) ^ Xtime2Sbox(state[6]) ^ Xtime3Sbox(state[11]);
	tmp[15] = Xtime3Sbox(state[12]) ^ Sbox(state[1]) ^ Sbox(state[6]) ^ Xtime2Sbox(state[11]);

	memcpy (state, tmp, sizeof(tmp));
}

// restore and un-mix each row in a column
void InvMixSubColumns (unsigned char *state)
{
unsigned char tmp[4 * Nb];
int i;

	// restore column 0
	tmp[0] = XtimeE(state[0]) ^ XtimeB(state[1]) ^ XtimeD(state[2]) ^ Xtime9(state[3]);
	tmp[5] = Xtime9(state[0]) ^ XtimeE(state[1]) ^ XtimeB(state[2]) ^ XtimeD(state[3]);
	tmp[10] = XtimeD(state[0]) ^ Xtime9(state[1]) ^ XtimeE(state[2]) ^ XtimeB(state[3]);
	tmp[15] = XtimeB(state[0]) ^ XtimeD(state[1]) ^ Xtime9(state[2]) ^ XtimeE(state[3]);

	// restore column 1
	tmp[4] = XtimeE(state[4]) ^ XtimeB(state[5]) ^ XtimeD(state[6]) ^ Xtime9(state[7]);
	tmp[9] = Xtime9(state[4]) ^ XtimeE(state[5]) ^ XtimeB(state[6]) ^ XtimeD(state[7]);
	tmp[14] = XtimeD(state[4]) ^ Xtime9(state[5]) ^ XtimeE(state[6]) ^ XtimeB(state[7]);
	tmp[3] = XtimeB(state[4]) ^ XtimeD(state[5]) ^ Xtime9(state[6]) ^ XtimeE(state[7]);

	// restore column 2
	tmp[8] = XtimeE(state[8]) ^ XtimeB(state[9]) ^ XtimeD(state[10]) ^ Xtime9(state[11]);
	tmp[13] = Xtime9(state[8]) ^ XtimeE(state[9]) ^ XtimeB(state[10]) ^ XtimeD(state[11]);
	tmp[2]  = XtimeD(state[8]) ^ Xtime9(state[9]) ^ XtimeE(state[10]) ^ XtimeB(state[11]);
	tmp[7]  = XtimeB(state[8]) ^ XtimeD(state[9]) ^ Xtime9(state[10]) ^ XtimeE(state[11]);

	// restore column 3
	tmp[12] = XtimeE(state[12]) ^ XtimeB(state[13]) ^ XtimeD(state[14]) ^ Xtime9(state[15]);
	tmp[1] = Xtime9(state[12]) ^ XtimeE(state[13]) ^ XtimeB(state[14]) ^ XtimeD(state[15]);
	tmp[6] = XtimeD(state[12]) ^ Xtime9(state[13]) ^ XtimeE(state[14]) ^ XtimeB(state[15]);
	tmp[11] = XtimeB(state[12]) ^ XtimeD(state[13]) ^ Xtime9(state[14]) ^ XtimeE(state[15]);

	for( i=0; i < 4 * Nb; i++ )
		state[i] = InvSbox(tmp[i]);
}

// encrypt/decrypt columns of the key
// n.b. you can replace this with
//      byte-wise xor if you wish.

void AddRoundKey (unsigned *state, unsigned *key)
{
int idx;

	for( idx = 0; idx < 4; idx++ )
		state[idx] ^= key[idx];
}

unsigned char Rcon[11] = {
0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80, 0x1b, 0x36};

// produce Nb bytes for each round
void ExpandKey (unsigned char *key, unsigned char *expkey)
{
unsigned char tmp0, tmp1, tmp2, tmp3, tmp4;
unsigned idx;

	memcpy (expkey, key, Nk * 4);

	for( idx = Nk; idx < Nb * (Nr + 1); idx++ ) {
		tmp0 = expkey[4*idx - 4];
		tmp1 = expkey[4*idx - 3];
		tmp2 = expkey[4*idx - 2];
		tmp3 = expkey[4*idx - 1];
		if( !(idx % Nk) ) {
			tmp4 = tmp3;
			tmp3 = Sbox(tmp0);
			tmp0 = Sbox(tmp1) ^ Rcon[idx/Nk];
			tmp1 = Sbox(tmp2);
			tmp2 = Sbox(tmp4);
		} else if( Nk > 6 && idx % Nk == 4 ) {
			tmp0 = Sbox(tmp0);
			tmp1 = Sbox(tmp1);
			tmp2 = Sbox(tmp2);
			tmp3 = Sbox(tmp3);
		}

		expkey[4*idx+0] = expkey[4*idx - 4*Nk + 0] ^ tmp0;
		expkey[4*idx+1] = expkey[4*idx - 4*Nk + 1] ^ tmp1;
		expkey[4*idx+2] = expkey[4*idx - 4*Nk + 2] ^ tmp2;
		expkey[4*idx+3] = expkey[4*idx - 4*Nk + 3] ^ tmp3;
	}
}

// encrypt one 128 bit block
void Encrypt (unsigned char *in, unsigned char *expkey, unsigned char *out)
{
unsigned char state[Nb * 4];
unsigned round;

	memcpy (state, in, Nb * 4);
	AddRoundKey ((unsigned *)state, (unsigned *)expkey);

	for( round = 1; round < Nr + 1; round++ ) {
		if( round < Nr )
			MixSubColumns (state);
		else
			ShiftRows (state);

		AddRoundKey ((unsigned *)state, (unsigned *)expkey + round * Nb);
	}

	memcpy (out, state, sizeof(state));
}

void Decrypt (unsigned char *in, unsigned char *expkey, unsigned char *out)
{
unsigned char state[Nb * 4];
unsigned round;

	memcpy (state, in, sizeof(state));

	AddRoundKey ((unsigned *)state, (unsigned *)expkey + Nr * Nb);
	InvShiftRows(state);

	for( round = Nr; round--; )
	{
		AddRoundKey ((unsigned *)state, (unsigned *)expkey + round * Nb);
		if( round )
			InvMixSubColumns (state);
	} 

	memcpy (out, state, sizeof(state));
}


/*avr specific routines*/
#include "backward.h"
#include <avr/io.h>
#include <avr/pgmspace.h>
#include <avr/eeprom.h>
#include <avr/interrupt.h>
#include <avr/sleep.h>



#if defined(at90s2313) || defined(at90s8535)
#else
#define ATmega
#endif

#ifdef ATmega
#define USR UCSRA
#endif



void printP (PGM_P string){
        char c;
        c=pgm_read_byte(string);
                   while (c) {
                   loop_until_bit_is_set(USR, UDRE);
                   UDR = c;
                   c=pgm_read_byte(++string);
                   }
                   return;
                 }



void print (const char *string){
                   while (*string) {
                   loop_until_bit_is_set(USR, UDRE);
                   UDR = *string++;
                   }
                   return;
                 }

void scan(char *string){
char c;
        do      {
                do {
                        loop_until_bit_is_set(USR, RXC);
                        c =UDR;
                        } while bit_is_set(USR, FE);
                *string++ = c;
                //echo the character
                loop_until_bit_is_set(USR, UDRE);
                UDR = c;
                } while ( c != '\r' );
        loop_until_bit_is_set(USR, UDRE);
        UDR = '\n';
        string[-1]=0;
        }


//UART initialize
#ifdef ATmega
#define UCR UCSRB
#define UART_INIT(baud) { \
UBRRH=0; \
UBRRL= (XTAL/baud+15)/16-1; \
UCSRB=(1<<TXEN)|(1<<RXEN); \
UCSRC=(1<<URSEL)|(1<<UCSZ0)|(1<<UCSZ1)|(1<<USBS); }
#else
#define UART_INIT(baud) { \
UBRR = (XTAL/baud+15)/16-1; \
sbi(UCR, TXEN); \
sbi(UCR, RXEN); \
}
#endif

#define itoa10(N,S) itoa(N,S,10)
#define itoa16(N,S) itoa(N,S,16)


//DEMO

unsigned char sampleout[16];


unsigned char samplekey[] = {0x2b, 0x7e, 0x15, 0x16, 0x28, 0xae, 0xd2, 0xa6, 0xab,
0xf7, 0x15, 0x88, 0x09, 0xcf, 0x4f, 0x3c};

unsigned char samplein[] = {0x32, 0x43, 0xf6, 0xa8, 0x88, 0x5a, 0x30, 0x8d, 0x31,
0x31, 0x98, 0xa2, 0xe0, 0x37, 0x07, 0x34};

#define BAUD 115200

int main(void)
{
UART_INIT(BAUD);

unsigned char expkey[4 * Nb * (Nr + 1)];
unsigned char i;
char c[8];

	printP(PSTR("Original: "));
	for( i = 0; i < 16; i++ ) {itoa16(samplein[i],c);print(c); print(" ");}
	printP(PSTR("\n"));

	ExpandKey (samplekey, expkey);
	Encrypt (samplein, expkey, sampleout);

	printP(PSTR("Encrypted: "));
	for( i = 0; i < 16; i++ ) {itoa16(sampleout[i],c);print(c); print(" ");}
	printP(PSTR("\n"));

	Decrypt (sampleout, expkey, samplein);

	printP(PSTR("Decrypted: "));

	for( i = 0; i < 16; i++ ) {itoa16(samplein[i],c);print(c); print(" ");}
	printP(PSTR("\n"));
}