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#include "types.h"
#include "aes.h"
void _gf_mul(unsigned char *pad)
{
unsigned int i;
unsigned cxor = (pad[0] & 0x80) ? 0x87 : 0;
for(i = 0; i < 15; i++)
pad[i] = (pad[i] << 1) | (pad[i + 1] >> 7);
pad[15] = (pad[15] << 1) ^ cxor;
}
void aes_omac1(u8 *digest, u8 *input, u32 length, u8 *key, u32 keybits)
{
u32 i, j;
u32 overflow;
aes_context ctxt;
unsigned char buffer1[16], buffer2[16], dbuf[16];
memset(buffer1, 0, 16);
aes_setkey_enc(&ctxt, key, keybits);
aes_crypt_ecb(&ctxt, AES_ENCRYPT, buffer1, buffer2);
_gf_mul(buffer2);
if(length > 16)
{
for(i = 0; i < length - 16; i += 16)
{
for(j = 0; j < 16; j++)
dbuf[j] = buffer1[j] ^ input[i + j];
aes_crypt_ecb(&ctxt, AES_ENCRYPT, dbuf, buffer1);
}
}
overflow = length & 0xf;
if(length % 16 == 0)
overflow = 16;
memset(dbuf, 0, 16);
memcpy(dbuf, &(input[i]), overflow);
if(overflow != 16)
{
dbuf[overflow] = 0x80;
_gf_mul(buffer2);
}
for(i = 0; i < 16; i++)
dbuf[i] ^= buffer1[i] ^ buffer2[i];
aes_crypt_ecb(&ctxt, AES_ENCRYPT, dbuf, digest);
}
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