The
utility, also known as
crypt
is a
very
simple encryption program, working on a
``secret-key''
basis.
It operates as a filter, i.e.,
it encrypts or decrypts a
stream of data from standard input, and writes the result to standard
output.
Since its operation is fully symmetrical, feeding the encrypted data
stream again through the engine (using the same secret key) will
decrypt it.
There are several ways to provide the secret key to the program.
By
default, the program prompts the user on the controlling terminal for
the key, using
getpass(3).
This is the only safe way of providing it.
Alternatively, the key can be provided as the sole command-line
argument
password
when starting the program.
Obviously, this way the key can easily be
spotted by other users running
ps(1).
As yet another alternative,
can be given the option
-k
and it will take the key from the environment variable
CrYpTkEy
While this at a first glance seems to be more secure than the previous
option, it actually is not since environment variables can also be
examined with
ps(1).
Thus this option is mainly provided for compatibility with other
implementations of
.
When specifying the option
-s
modifies the encryption engine in a way that is supposed to make it a
little more secure, but incompatible with other implementations.
Warning
The cryptographic value of
is rather small.
This program is only provided here for compatibility
with other operating systems that also provide an implementation
(usually called
crypt(1)
there).
For real encryption, refer to
bdes(1),
openssl(1),
pgp(1)PqPaports/security/pgp,
or
gpg(1)PqPaports/security/gnupg.
However, restrictions for exporting,
importing or using such tools might exist in some countries, so those
stronger programs are not being shipped as part of the operating
system by default.
ENVIRONMENT
CrYpTkEy used to obtain the secret key when option
-k
has been given
EXAMPLES
man enigma | enigma > encrypted
Enter key: (XXX --- key not echoed)
This will create an encrypted form of this man page, and store it in
the file
encrypted
enigma XXX < encrypted
This displays the previously created file on the terminal.
Implementations of
crypt
are very common among
UNIX
operating systems.
This implementation has been taken from the
Cryptbreakers Workbench
which is in the public domain.
