/**
* MAC1 as described in the IEEE P1363 standard. It computes a HMAC message authentication code
* tag from secret key KB and message M.
*/
public static int[] MAC1(int[] K, int[] M) {
int[] HH = new int[0];
try {
int i;
int[] KK;
MessageDigest sha = MessageDigest.getInstance("SHA");
// SHA1 Blocksize B = 512
if (K.length > (8 * 512)) {
sha.update(Utils.toByteArray(K));
// kkLen = 20 octets, 160 bits
KK = Utils.revIntArray(Utils.toIntArray(sha.digest()));
} else KK = K;
int[] P = new int[512 - KK.length];
for (i = 0; i < P.length; i++) {
P[i] = 0;
}
int[] K0 = Utils.concatenate(KK, P);
int[] iPad = new int[512];
for (i = 0; i < iPad.length; i++) {
iPad[i] = 0x36;
}
int[] oPad = new int[512];
for (i = 0; i < oPad.length; i++) {
oPad[i] = 0x54;
}
sha.reset();
sha.update(Utils.toByteArray(Utils.concatenate(Utils.xor(K0, iPad), M)));
int[] H = Utils.revIntArray(Utils.toIntArray(sha.digest()));
sha.reset();
sha.update(Utils.toByteArray(Utils.concatenate(Utils.xor(K0, oPad), H)));
HH = Utils.revIntArray(Utils.toIntArray(sha.digest()));
} catch (NoSuchAlgorithmException e) {
}
return HH;
}
