static public int Diversification_AES128(byte[] base_key, byte[] diversification_input, int diversification_lenght, ref byte[] diversified_key)
{
int i = 0;
byte[] M = new byte[32];
bool padd = false;
// prepare the padding
init(base_key);
#if _DEBUG_DIVERSIFICATION
LogManager.DoLogOperation(string.Format("TEST K0={0}", BinConvert.ToHex(cmac_subkey_0)));
LogManager.DoLogOperation(string.Format("TEST K1={0}", BinConvert.ToHex(cmac_subkey_1)));
LogManager.DoLogOperation(string.Format("TEST K2={0}", BinConvert.ToHex(cmac_subkey_2)));
#endif
// add the div constant at the beginning of M
M[0] = 0x01;
for (i = 0; i < diversification_lenght; i++)
{
M[1 + i] = diversification_input[i];
}
i++;
// add the padding
if (((i % 32) != 0) && (i < 32))
{
M[i] = 0x80;
i++;
for (; i < 32; i++)
{
M[i] = 0x00;
}
padd = true;
}
#if _DEBUG_DIVERSIFICATION
LogManager.DoLogOperation(string.Format("CMAC Input D={0}", BinConvert.ToHex(M, 32)));
#endif
/* XOR the last 16 bytes with CMAC_SubKey */
for (i = 0; i < 16; i++)
{
if (padd)
{
M[16 + i] ^= cmac_subkey_2[i];
}
else
{
M[16 + i] ^= cmac_subkey_1[i];
}
}
#if _DEBUG_DIVERSIFICATION
LogManager.DoLogOperation(string.Format("XOR the last 16 bytes with CMAC_SubKey2={0}", BinConvert.ToHex(M, 32)));
int lsize = 32;
#endif
byte[] IV = new byte[] { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 };
/* Encryption using M */
byte[] result = AES_Encrypt(M, base_key, IV);
#if _DEBUG_DIVERSIFICATION
LogManager.DoLogOperation(string.Format("Encryption using M={0}", BinConvert.ToHex(M, lsize)));
#endif
for (i = 0; i < 16; i++)
{
diversified_key[i] = result[16 + i];
}
#if _DEBUG_DIVERSIFICATION
LogManager.DoLogOperation(string.Format("Diversification key={0}", BinConvert.ToHex(diversified_key, 16)));
#endif
return(0);
}