/**
* Creates a DES encryption key from the given key material.
*
* @param bytes A byte array containing the DES key material.
* @param offset The offset in the given byte array at which the 7-byte key material starts.
* @return A DES encryption key created from the key material starting at the specified offset in
* the given byte array.
*/
private static Key createDESKey(byte[] bytes, int offset) {
byte[] keyBytes = new byte[7];
System.arraycopy(bytes, offset, keyBytes, 0, 7);
byte[] material = new byte[8];
material[0] = keyBytes[0];
material[1] = (byte) (keyBytes[0] << 7 | (keyBytes[1] & 0xff) >>> 1);
material[2] = (byte) (keyBytes[1] << 6 | (keyBytes[2] & 0xff) >>> 2);
material[3] = (byte) (keyBytes[2] << 5 | (keyBytes[3] & 0xff) >>> 3);
material[4] = (byte) (keyBytes[3] << 4 | (keyBytes[4] & 0xff) >>> 4);
material[5] = (byte) (keyBytes[4] << 3 | (keyBytes[5] & 0xff) >>> 5);
material[6] = (byte) (keyBytes[5] << 2 | (keyBytes[6] & 0xff) >>> 6);
material[7] = (byte) (keyBytes[6] << 1);
oddParity(material);
return new SecretKeySpec(material, "DES");
}
