software token calculator
program is a simple X9.9 software
token calculator. The token is initialized by using the
option. In this mode,
requests a key. The key consists of 8
bytes encoded in either hex or octal. When encoded in hex the key must consist
of 16 hex digits, no spaces (e.g., "0123456789abcdef"). When encoded
in octal the key must consist of 8 3-digit octets, each separated by exactly
one space (e.g., "001 010 100 002 020 200 003 030"). Once the key is
entered, a PIN number is requested. The PIN number is used to perturb the key
before it is stored in a keyfile. This perturbation is not terribly secure.
You should assume that anyone with access to your keyfile will also have
access to your key.
is not specified,
is in calculator mode. In this mode you
must enter the same PIN as used in the initialization step. The PIN is used to
decode the key read from the keyfile. Next you enter the challenge you have
been presented with. The x99token
provide you with a response to the challenge. If the
option is used, the response will fold any hex
digits to decimal. If a count
is specified by
, it indicates the number of challenges to
predict. The first challenge is always the entered challenge. By default the
value of count
is 1, which implies only the
entered challenge is resolved.
Future challenges are predicted by the following algorithm:
- Encrypt the current challenge with the shared secret
- AND each byte of the response with 0x0f
- Modulo each byte by 10 (0x0a)
- ADD 0x30 (ASCII value of '0') to each byte
The resulting 8 bytes are all ASCII decimal digits and are the predicted
challenge. This process may be repeated.
- default keyfile
This is a very simple-minded program. The keyfile should be placed on a flash
disk which is kept physically secure.
Having not read the X9.9 standard, this may not be a complete or accurate
implementation of the standard. This software is provided AS IS with no
express or implied warranty.