public const int TRAP = 200; // 200 for 4 digit PIN, 2000 for 6-digit PIN - approx 2*sqrt(MAXPIN)
/* Hash number (optional) and string to point on curve */
public static sbyte[] hashit(int n, sbyte[] ID)
{
HASH H = new HASH();
if (n != 0)
{
H.process_num(n);
}
H.process_array(ID);
sbyte[] h = H.hash();
return(h);
}
/* Key Derivation Functions */
/* Input octet Z */
/* Output key of length olen */
public static sbyte[] KDF1(sbyte[] Z, int olen)
{
/* NOTE: the parameter olen is the length of the output K in bytes */
HASH H = new HASH();
int hlen = HASH.len;
sbyte[] K = new sbyte[olen];
sbyte[] B;
int counter, cthreshold, k = 0;
for (int i = 0; i < K.Length; i++)
{
K[i] = 0;
}
cthreshold = olen / hlen;
if (olen % hlen != 0)
{
cthreshold++;
}
for (counter = 0; counter < cthreshold; counter++)
{
H.process_array(Z);
if (counter > 0)
{
H.process_num(counter);
}
B = H.hash();
if (k + hlen > olen)
{
for (int i = 0; i < olen % hlen; i++)
{
K[k++] = B[i];
}
}
else
{
for (int i = 0; i < hlen; i++)
{
K[k++] = B[i];
}
}
}
return(K);
}
/* Mask Generation Function */
public static void MGF1(sbyte[] Z, int olen, sbyte[] K)
{
HASH H = new HASH();
int hlen = HASH.len;
sbyte[] B = new sbyte[hlen];
int counter, cthreshold, k = 0;
for (int i = 0; i < K.Length; i++)
{
K[i] = 0;
}
cthreshold = olen / hlen;
if (olen % hlen != 0)
{
cthreshold++;
}
for (counter = 0; counter < cthreshold; counter++)
{
H.process_array(Z);
H.process_num(counter);
B = H.hash();
if (k + hlen > olen)
{
for (int i = 0; i < olen % hlen; i++)
{
K[k++] = B[i];
}
}
else
{
for (int i = 0; i < hlen; i++)
{
K[k++] = B[i];
}
}
}
}
