/*
** Name: encode
**
** Description:
** Applies the Driver semantics to convert the data and key
** into form acceptable to CI and encodes the data using the
** key provided. An optional key mask, CompatCI.CRYPT_SIZE
** in length, will be combined with the key if provided.
**
** Input:
** key Encryption key.
** mask Key mask, may be NULL.
** data Data to be encrypted.
**
** Output:
** None.
**
** Returns:
** byte [] Encrypted data.
**
** History:
** 6-May-99 (gordy)
** Created.
** 22-Sep-99 (gordy)
** Converted parameters to byte arrays for easier processing
** here and to support character set/encoding at a higher level.
** 21-Apr-00 (gordy)
** Extracted from class AdvanObject.
** 6-jul-04 (gordy; ported by thoda04)
** Added key mask.
*/
public static byte[] encode(byte[] key, byte[] mask, byte[] data)
{
byte[] buff = null;
int i, j, m, n, blocks;
lock (KS)
{
/*
** The key schedule is built from a single CRYPT_SIZE
** byte array. We use the input key to build the byte
** array, truncating or duplicating as necessary.
*/
for (m = n = 0; m < CI.CRYPT_SIZE; m++)
{
if (n >= key.Length)
{
n = 0;
}
kbuff[m] = (byte)(key[n++] ^
(mask != null ? mask[m] : (byte)0));
}
CI.set(kbuff, KS);
/*
** The data to be encoded must be padded to a multiple
** of CRYPT_SIZE bytes. Random data is used for the
** pad, so for strings the null terminator is included
** in the data. A random value is added to each block
** so that a given key/data pair does not encode the
** same way twice.
**
** The total number of blocks can be calculated from
** the string length plus the null terminator divided
** into CRYPT_SIZE blocks (with one random byte):
** ((len+1) + (CRYPT_SIZE-2)) / (CRYPT_SIZE-1)
** which can be simplified as:
** (len / (CRYPT_SIZE - 1) + 1
*/
blocks = (data.Length / (CI.CRYPT_SIZE - 1)) + 1;
buff = new byte[blocks * CI.CRYPT_SIZE];
for (i = m = n = 0; i < blocks; i++)
{
buff[m++] = (byte)(rand.Next(256));
for (j = 1; j < CI.CRYPT_SIZE; j++)
{
if (n < data.Length)
{
buff[m++] = data[n++];
}
else if (n > data.Length)
{
buff[m++] = (byte)(rand.Next(256));
}
else
{
buff[m++] = 0; // null terminator
n++;
}
}
}
// encode using obfuscated encode name method
// CI.encode (buff, 0, buff.Length, KS, buff, 0);
CI.toString(buff, 0, buff.Length, KS, buff, 0);
}
return(buff);
} // encode