150 lines
3.4 KiB
C
150 lines
3.4 KiB
C
#include "dev/types.h"
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#ifdef DEV_CRYPTO
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#include "dev_util.h"
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PAYLOAD_SECTION
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#endif
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void sub_bytes(unsigned char block[16], struct aes_constants *c)
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{
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int i;
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unsigned char val;
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for(i = 0; i < 16; i++)
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{
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val = block[i];
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block[i] = c->sbox[val >> 4u][val & 0xfu];
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}
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}
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#ifdef DEV_CRYPTO
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PAYLOAD_SECTION
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#endif
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void shift_rows(unsigned char block[16])
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{
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unsigned char temp1, temp2;
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temp1 = block[0x1];
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block[0x1] = block[0x5];
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block[0x5] = block[0x9];
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block[0x9] = block[0xd];
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block[0xd] = temp1;
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temp1 = block[0x2];
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temp2 = block[0xe];
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block[0x2] = block[0xa];
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block[0xe] = block[0x6];
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block[0xa] = temp1;
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block[0x6] = temp2;
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temp1 = block[0x3];
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block[0x3] = block[0xf];
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block[0xf] = block[0xb];
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block[0xb] = block[0x7];
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block[0x7] = temp1;
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}
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#ifdef DEV_CRYPTO
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PAYLOAD_SECTION
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#endif
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void mix_cols(unsigned char block[16], struct aes_constants *c)
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{
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unsigned char r0, r1, r2, r3;
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int i;
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for(i = 0; i < 4; i++)
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{
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r0 = block[4 * i];
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r1 = block[4 * i + 1];
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r2 = block[4 * i + 2];
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r3 = block[4 * i + 3];
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// no reason for the "+ 0" here but it makes the code look more lined up :)
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block[4 * i + 0] = c->mul2[r0] ^ c->mul3[r1] ^ r2 ^ r3;
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block[4 * i + 1] = r0 ^ c->mul2[r1] ^ c->mul3[r2] ^ r3;
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block[4 * i + 2] = r0 ^ r1 ^ c->mul2[r2] ^ c->mul3[r3];
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block[4 * i + 3] = c->mul3[r0] ^ r1 ^ r2 ^ c->mul2[r3];
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}
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}
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#ifdef DEV_CRYPTO
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PAYLOAD_SECTION
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#endif
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void add_key(unsigned char block[16], unsigned char key[16])
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{
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int i;
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for(i = 0; i < 16; i++)
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{
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block[i] = block[i] ^ key[i];
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}
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}
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#ifdef DEV_CRYPTO
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PAYLOAD_SECTION
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#endif
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void expand_key(unsigned char key[16], unsigned char key_sched[176], int n,
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struct aes_constants *c)
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{
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int i, j, prev_key_base, key_base = 0;
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unsigned char val;
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for(i = 0; i < 16; i++)
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{
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key_sched[i] = key[i];
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}
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for(i = 1; i < n; i++)
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{
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prev_key_base = key_base;
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key_base = 16 * i;
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for(j = 0; j < 3; j++)
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{
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val = key_sched[prev_key_base + 13 + j];
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key_sched[key_base + j] = c->sbox[val >> 4u][val & 0xfu];
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}
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val = key_sched[prev_key_base + 12];
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key_sched[key_base + 3] = c->sbox[val >> 4u][val & 0xfu];
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key_sched[key_base] ^= c->rc_lookup[i - 1];
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for(j = 0; j < 4; j++)
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{
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key_sched[key_base + j] = key_sched[key_base + j] ^ key_sched[prev_key_base + j];
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}
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for(j = 4; j < 16; j++)
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{
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key_sched[key_base + j] = key_sched[key_base + j - 4] ^ key_sched[prev_key_base + j];
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}
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}
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}
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#ifdef DEV_CRYPTO
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PAYLOAD_SECTION
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#endif
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void aes128_encrypt_ecb(unsigned char *msg, unsigned int msg_len,
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unsigned char key_sched[176], struct aes_constants *c)
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{
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unsigned int num_blocks = msg_len / 16;
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unsigned char *block;
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unsigned int i, j;
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for(i = 0; i < num_blocks; i++)
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{
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block = &msg[16 * i];
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add_key(block, key_sched);
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for(j = 0; j < 9; j++)
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{
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sub_bytes(block, c);
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shift_rows(block);
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mix_cols(block, c);
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add_key(block, &key_sched[16 * (j + 1)]);
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}
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sub_bytes(block, c);
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shift_rows(block);
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add_key(block, &key_sched[16 * (j + 1)]);
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}
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} |