133 lines
3.0 KiB
Groff
133 lines
3.0 KiB
Groff
.\"
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.\" enigma (aka. crypt) man page written by Joerg Wunsch.
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.\"
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.\" Since enigma itself is distributed in the Public Domain, this file
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.\" is also.
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.\"
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.\" $FreeBSD$
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.\" "
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.Dd May 14, 2004
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.Os
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.Dt ENIGMA 1
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.Sh NAME
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.Nm enigma ,
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.Nm crypt
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.Nd very simple file encryption
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.Sh SYNOPSIS
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.Nm
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.Op Fl s
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.Op Fl k
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.Op Ar password
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.Nm crypt
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.Op Fl s
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.Op Fl k
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.Op Ar password
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.Sh DESCRIPTION
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The
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.Nm
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utility, also known as
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.Nm crypt
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is a
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.Em very
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simple encryption program, working on a
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.Dq secret-key
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basis.
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It operates as a filter, i.e.,
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it encrypts or decrypts a
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stream of data from standard input, and writes the result to standard
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output.
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Since its operation is fully symmetrical, feeding the encrypted data
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stream again through the engine (using the same secret key) will
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decrypt it.
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.Pp
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There are several ways to provide the secret key to the program.
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By
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default, the program prompts the user on the controlling terminal for
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the key, using
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.Xr getpass 3 .
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This is the only safe way of providing it.
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.Pp
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Alternatively, the key can be provided as the sole command-line
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argument
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.Ar password
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when starting the program.
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Obviously, this way the key can easily be
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spotted by other users running
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.Xr ps 1 .
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As yet another alternative,
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.Nm
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can be given the option
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.Fl k ,
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and it will take the key from the environment variable
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.Ev CrYpTkEy .
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While this at a first glance seems to be more secure than the previous
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option, it actually is not since environment variables can also be
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examined with
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.Xr ps 1 .
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Thus this option is mainly provided for compatibility with other
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implementations of
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.Nm .
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.Pp
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When specifying the option
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.Fl s ,
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.Nm
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modifies the encryption engine in a way that is supposed to make it a
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little more secure, but incompatible with other implementations.
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.Pp
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.Ss Warning
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The cryptographic value of
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.Nm
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is rather small.
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This program is only provided here for compatibility
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with other operating systems that also provide an implementation
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(usually called
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.Xr crypt 1
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there).
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For real encryption, refer to
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.Xr bdes 1 ,
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.Xr openssl 1 ,
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.Xr pgp 1 Pq Pa ports/security/pgp ,
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or
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.Xr gpg 1 Pq Pa ports/security/gnupg .
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However, restrictions for exporting,
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importing or using such tools might exist in some countries, so those
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stronger programs are not being shipped as part of the operating
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system by default.
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.Sh ENVIRONMENT
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.Bl -tag -offset indent -width ".Ev CrYpTkEy"
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.It Ev CrYpTkEy
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used to obtain the secret key when option
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.Fl k
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has been given
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.El
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.Sh EXAMPLES
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.Bd -literal -offset indent
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man enigma | enigma > encrypted
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Enter key: (XXX \(em key not echoed)
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.Ed
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.Pp
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This will create an encrypted form of this man page, and store it in
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the file
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.Pa encrypted .
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.Bd -literal -offset indent
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enigma XXX < encrypted
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.Ed
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.Pp
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This displays the previously created file on the terminal.
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.Sh SEE ALSO
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.Xr bdes 1 ,
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.Xr gpg 1 ,
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.Xr openssl 1 ,
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.Xr pgp 1 ,
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.Xr ps 1 ,
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.Xr getpass 3
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.Sh HISTORY
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Implementations of
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.Nm crypt
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are very common among
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.Ux
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operating systems.
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This implementation has been taken from the
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.Em Cryptbreakers Workbench
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which is in the public domain.
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