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AESCommon.cpp
1 /*
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22 
23 #include "AES.h"
24 #include "Crypto.h"
25 #include "utility/ProgMemUtil.h"
26 
48 // AES S-box (http://en.wikipedia.org/wiki/Rijndael_S-box)
49 static uint8_t const sbox[256] PROGMEM = {
50  0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, // 0x00
51  0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
52  0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, // 0x10
53  0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
54  0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, // 0x20
55  0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
56  0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, // 0x30
57  0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
58  0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, // 0x40
59  0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
60  0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, // 0x50
61  0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
62  0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, // 0x60
63  0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
64  0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, // 0x70
65  0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
66  0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, // 0x80
67  0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
68  0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, // 0x90
69  0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
70  0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, // 0xA0
71  0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
72  0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, // 0xB0
73  0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
74  0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, // 0xC0
75  0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
76  0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, // 0xD0
77  0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
78  0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, // 0xE0
79  0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
80  0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, // 0xF0
81  0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
82 };
83 
84 // AES inverse S-box (http://en.wikipedia.org/wiki/Rijndael_S-box)
85 static uint8_t const sbox_inverse[256] PROGMEM = {
86  0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, // 0x00
87  0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
88  0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, // 0x10
89  0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
90  0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, // 0x20
91  0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
92  0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, // 0x30
93  0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
94  0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, // 0x40
95  0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
96  0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, // 0x50
97  0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
98  0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, // 0x60
99  0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
100  0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, // 0x70
101  0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
102  0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, // 0x80
103  0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
104  0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, // 0x90
105  0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
106  0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, // 0xA0
107  0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
108  0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, // 0xB0
109  0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
110  0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, // 0xC0
111  0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
112  0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, // 0xD0
113  0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
114  0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, // 0xE0
115  0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
116  0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, // 0xF0
117  0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
118 };
119 
126  : rounds(0), schedule(0)
127 {
128 }
129 
135 {
136 }
137 
142 size_t AESCommon::blockSize() const
143 {
144  return 16;
145 }
146 
147 // Constants to correct Galois multiplication for the high bits
148 // that are shifted out when multiplying by powers of two.
149 static uint8_t const K[8] = {
150  0x00,
151  0x1B,
152  (0x1B << 1),
153  (0x1B << 1) ^ 0x1B,
154  (0x1B << 2),
155  (0x1B << 2) ^ 0x1B,
156  (0x1B << 2) ^ (0x1B << 1),
157  (0x1B << 2) ^ (0x1B << 1) ^ 0x1B
158 };
159 
160 // Multiply x by 2 in the Galois field, to achieve the effect of the following:
161 //
162 // if (x & 0x80)
163 // return (x << 1) ^ 0x1B;
164 // else
165 // return (x << 1);
166 //
167 // However, we don't want to use runtime conditionals if we can help it
168 // to avoid leaking timing information from the implementation.
169 // In this case, multiplication is slightly faster than table lookup on AVR.
170 #define gmul2(x) (t = ((uint16_t)(x)) << 1, \
171  ((uint8_t)t) ^ (uint8_t)(0x1B * ((uint8_t)(t >> 8))))
172 
173 // Multiply x by 4 in the Galois field.
174 #define gmul4(x) (t = ((uint16_t)(x)) << 2, ((uint8_t)t) ^ K[t >> 8])
175 
176 // Multiply x by 8 in the Galois field.
177 #define gmul8(x) (t = ((uint16_t)(x)) << 3, ((uint8_t)t) ^ K[t >> 8])
178 
179 #define OUT(col, row) output[(col) * 4 + (row)]
180 #define IN(col, row) input[(col) * 4 + (row)]
181 
182 static void subBytesAndShiftRows(uint8_t *output, const uint8_t *input)
183 {
184  OUT(0, 0) = pgm_read_byte(sbox + IN(0, 0));
185  OUT(0, 1) = pgm_read_byte(sbox + IN(1, 1));
186  OUT(0, 2) = pgm_read_byte(sbox + IN(2, 2));
187  OUT(0, 3) = pgm_read_byte(sbox + IN(3, 3));
188  OUT(1, 0) = pgm_read_byte(sbox + IN(1, 0));
189  OUT(1, 1) = pgm_read_byte(sbox + IN(2, 1));
190  OUT(1, 2) = pgm_read_byte(sbox + IN(3, 2));
191  OUT(1, 3) = pgm_read_byte(sbox + IN(0, 3));
192  OUT(2, 0) = pgm_read_byte(sbox + IN(2, 0));
193  OUT(2, 1) = pgm_read_byte(sbox + IN(3, 1));
194  OUT(2, 2) = pgm_read_byte(sbox + IN(0, 2));
195  OUT(2, 3) = pgm_read_byte(sbox + IN(1, 3));
196  OUT(3, 0) = pgm_read_byte(sbox + IN(3, 0));
197  OUT(3, 1) = pgm_read_byte(sbox + IN(0, 1));
198  OUT(3, 2) = pgm_read_byte(sbox + IN(1, 2));
199  OUT(3, 3) = pgm_read_byte(sbox + IN(2, 3));
200 }
201 
202 static void inverseShiftRowsAndSubBytes(uint8_t *output, const uint8_t *input)
203 {
204  OUT(0, 0) = pgm_read_byte(sbox_inverse + IN(0, 0));
205  OUT(0, 1) = pgm_read_byte(sbox_inverse + IN(3, 1));
206  OUT(0, 2) = pgm_read_byte(sbox_inverse + IN(2, 2));
207  OUT(0, 3) = pgm_read_byte(sbox_inverse + IN(1, 3));
208  OUT(1, 0) = pgm_read_byte(sbox_inverse + IN(1, 0));
209  OUT(1, 1) = pgm_read_byte(sbox_inverse + IN(0, 1));
210  OUT(1, 2) = pgm_read_byte(sbox_inverse + IN(3, 2));
211  OUT(1, 3) = pgm_read_byte(sbox_inverse + IN(2, 3));
212  OUT(2, 0) = pgm_read_byte(sbox_inverse + IN(2, 0));
213  OUT(2, 1) = pgm_read_byte(sbox_inverse + IN(1, 1));
214  OUT(2, 2) = pgm_read_byte(sbox_inverse + IN(0, 2));
215  OUT(2, 3) = pgm_read_byte(sbox_inverse + IN(3, 3));
216  OUT(3, 0) = pgm_read_byte(sbox_inverse + IN(3, 0));
217  OUT(3, 1) = pgm_read_byte(sbox_inverse + IN(2, 1));
218  OUT(3, 2) = pgm_read_byte(sbox_inverse + IN(1, 2));
219  OUT(3, 3) = pgm_read_byte(sbox_inverse + IN(0, 3));
220 }
221 
222 static void mixColumn(uint8_t *output, uint8_t *input)
223 {
224  uint16_t t; // Needed by the gmul2 macro.
225  uint8_t a = input[0];
226  uint8_t b = input[1];
227  uint8_t c = input[2];
228  uint8_t d = input[3];
229  uint8_t a2 = gmul2(a);
230  uint8_t b2 = gmul2(b);
231  uint8_t c2 = gmul2(c);
232  uint8_t d2 = gmul2(d);
233  output[0] = a2 ^ b2 ^ b ^ c ^ d;
234  output[1] = a ^ b2 ^ c2 ^ c ^ d;
235  output[2] = a ^ b ^ c2 ^ d2 ^ d;
236  output[3] = a2 ^ a ^ b ^ c ^ d2;
237 }
238 
239 static void inverseMixColumn(uint8_t *output, const uint8_t *input)
240 {
241  uint16_t t; // Needed by the gmul2, gmul4, and gmul8 macros.
242  uint8_t a = input[0];
243  uint8_t b = input[1];
244  uint8_t c = input[2];
245  uint8_t d = input[3];
246  uint8_t a2 = gmul2(a);
247  uint8_t b2 = gmul2(b);
248  uint8_t c2 = gmul2(c);
249  uint8_t d2 = gmul2(d);
250  uint8_t a4 = gmul4(a);
251  uint8_t b4 = gmul4(b);
252  uint8_t c4 = gmul4(c);
253  uint8_t d4 = gmul4(d);
254  uint8_t a8 = gmul8(a);
255  uint8_t b8 = gmul8(b);
256  uint8_t c8 = gmul8(c);
257  uint8_t d8 = gmul8(d);
258  output[0] = a8 ^ a4 ^ a2 ^ b8 ^ b2 ^ b ^ c8 ^ c4 ^ c ^ d8 ^ d;
259  output[1] = a8 ^ a ^ b8 ^ b4 ^ b2 ^ c8 ^ c2 ^ c ^ d8 ^ d4 ^ d;
260  output[2] = a8 ^ a4 ^ a ^ b8 ^ b ^ c8 ^ c4 ^ c2 ^ d8 ^ d2 ^ d;
261  output[3] = a8 ^ a2 ^ a ^ b8 ^ b4 ^ b ^ c8 ^ c ^ d8 ^ d4 ^ d2;
262 }
263 
264 void AESCommon::encryptBlock(uint8_t *output, const uint8_t *input)
265 {
266  const uint8_t *roundKey = schedule;
267  uint8_t posn;
268  uint8_t round;
269  uint8_t state1[16];
270  uint8_t state2[16];
271 
272  // Copy the input into the state and XOR with the first round key.
273  for (posn = 0; posn < 16; ++posn)
274  state1[posn] = input[posn] ^ roundKey[posn];
275  roundKey += 16;
276 
277  // Perform all rounds except the last.
278  for (round = rounds; round > 1; --round) {
279  subBytesAndShiftRows(state2, state1);
280  mixColumn(state1, state2);
281  mixColumn(state1 + 4, state2 + 4);
282  mixColumn(state1 + 8, state2 + 8);
283  mixColumn(state1 + 12, state2 + 12);
284  for (posn = 0; posn < 16; ++posn)
285  state1[posn] ^= roundKey[posn];
286  roundKey += 16;
287  }
288 
289  // Perform the final round.
290  subBytesAndShiftRows(state2, state1);
291  for (posn = 0; posn < 16; ++posn)
292  output[posn] = state2[posn] ^ roundKey[posn];
293 }
294 
295 void AESCommon::decryptBlock(uint8_t *output, const uint8_t *input)
296 {
297  const uint8_t *roundKey = schedule + rounds * 16;
298  uint8_t round;
299  uint8_t posn;
300  uint8_t state1[16];
301  uint8_t state2[16];
302 
303  // Copy the input into the state and reverse the final round.
304  for (posn = 0; posn < 16; ++posn)
305  state1[posn] = input[posn] ^ roundKey[posn];
306  inverseShiftRowsAndSubBytes(state2, state1);
307 
308  // Perform all other rounds in reverse.
309  for (round = rounds; round > 1; --round) {
310  roundKey -= 16;
311  for (posn = 0; posn < 16; ++posn)
312  state2[posn] ^= roundKey[posn];
313  inverseMixColumn(state1, state2);
314  inverseMixColumn(state1 + 4, state2 + 4);
315  inverseMixColumn(state1 + 8, state2 + 8);
316  inverseMixColumn(state1 + 12, state2 + 12);
317  inverseShiftRowsAndSubBytes(state2, state1);
318  }
319 
320  // Reverse the initial round and create the output words.
321  roundKey -= 16;
322  for (posn = 0; posn < 16; ++posn)
323  output[posn] = state2[posn] ^ roundKey[posn];
324 }
325 
327 {
328  clean(schedule, (rounds + 1) * 16);
329 }
330 
333 void AESCommon::keyScheduleCore(uint8_t *output, const uint8_t *input, uint8_t iteration)
334 {
335  // Rcon(i), 2^i in the Rijndael finite field, for i = 0..10.
336  // http://en.wikipedia.org/wiki/Rijndael_key_schedule
337  static uint8_t const rcon[11] PROGMEM = {
338  0x00, 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, // 0x00
339  0x80, 0x1B, 0x36
340  };
341  output[0] = pgm_read_byte(sbox + input[1]) ^ pgm_read_byte(rcon + iteration);
342  output[1] = pgm_read_byte(sbox + input[2]);
343  output[2] = pgm_read_byte(sbox + input[3]);
344  output[3] = pgm_read_byte(sbox + input[0]);
345 }
346 
347 void AESCommon::applySbox(uint8_t *output, const uint8_t *input)
348 {
349  output[0] = pgm_read_byte(sbox + input[0]);
350  output[1] = pgm_read_byte(sbox + input[1]);
351  output[2] = pgm_read_byte(sbox + input[2]);
352  output[3] = pgm_read_byte(sbox + input[3]);
353 }
354 
void decryptBlock(uint8_t *output, const uint8_t *input)
Decrypts a single block using this cipher.
Definition: AESCommon.cpp:295
AESCommon()
Constructs an AES block cipher object.
Definition: AESCommon.cpp:125
size_t blockSize() const
Size of an AES block in bytes.
Definition: AESCommon.cpp:142
virtual ~AESCommon()
Destroys this AES block cipher object after clearing sensitive information.
Definition: AESCommon.cpp:134
void clear()
Clears all security-sensitive state from this block cipher.
Definition: AESCommon.cpp:326
void encryptBlock(uint8_t *output, const uint8_t *input)
Encrypts a single block using this cipher.
Definition: AESCommon.cpp:264