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Annotation of 43BSDTahoe/man/man1/crypt.1, revision 1.1

1.1     ! root        1: .\"    @(#)crypt.1     6.2 (Berkeley) 7/14/87
        !             2: .\"
        !             3: .TH CRYPT 1 "July 14, 1987"
        !             4: .AT 3
        !             5: .SH NAME
        !             6: crypt \- encode/decode
        !             7: .SH SYNOPSIS
        !             8: .B crypt
        !             9: [ password ]
        !            10: .SH DESCRIPTION
        !            11: .I Crypt
        !            12: reads from the standard input and writes
        !            13: on the standard output.
        !            14: The
        !            15: .I password
        !            16: is a key that selects a particular transformation.
        !            17: If no
        !            18: .I password 
        !            19: is given,
        !            20: .I crypt
        !            21: demands a key from the terminal and turns
        !            22: off printing while the key is being typed in.
        !            23: .I Crypt
        !            24: encrypts and decrypts with the same key:
        !            25: .PP
        !            26:        crypt key <clear >cypher
        !            27: .br
        !            28:        crypt key <cypher | pr
        !            29: .PP
        !            30: will print the clear.
        !            31: .PP
        !            32: Files encrypted by
        !            33: .I crypt
        !            34: are compatible with those treated by the editor
        !            35: .I ed
        !            36: in encryption mode.
        !            37: .PP
        !            38: The security of encrypted files depends on three factors:
        !            39: the fundamental method must be hard to solve;
        !            40: direct search of the key space must be infeasible;
        !            41: `sneak paths' by which keys or cleartext can become
        !            42: visible must be minimized.
        !            43: .PP
        !            44: .I Crypt
        !            45: implements a one-rotor machine designed along the lines
        !            46: of the German Enigma, but with a 256-element rotor.
        !            47: Methods of attack on such machines are known, but not widely;
        !            48: moreover the amount of work required is likely to be large.
        !            49: .PP
        !            50: The transformation of a key into the internal
        !            51: settings of the machine is deliberately designed to
        !            52: be expensive, i.e. to take a substantial fraction of
        !            53: a second to compute.
        !            54: However,
        !            55: if keys are restricted to (say)
        !            56: three lower-case letters,
        !            57: then encrypted files can be read by expending only
        !            58: a substantial fraction of
        !            59: five minutes of machine time.
        !            60: .PP
        !            61: Since the key is an argument to the
        !            62: .I crypt
        !            63: command,
        !            64: it is potentially visible to users executing
        !            65: .IR ps (1)
        !            66: or a derivative.
        !            67: To minimize this possibility,
        !            68: .I crypt
        !            69: takes care to destroy any record of the key
        !            70: immediately upon entry.
        !            71: No doubt the choice of keys and key security
        !            72: are the most vulnerable aspect of
        !            73: .I crypt.
        !            74: .SH FILES
        !            75: /dev/tty for typed key
        !            76: .SH "SEE ALSO"
        !            77: ed(1),
        !            78: crypt(3),
        !            79: makekey(8)
        !            80: .SH BUGS
        !            81: There is no warranty of merchantability nor any warranty
        !            82: of fitness for a particular purpose nor any other warranty,
        !            83: either express or implied, as to the accuracy of the
        !            84: enclosed materials or as to their suitability for any
        !            85: particular purpose.  Accordingly, Bell Telephone
        !            86: Laboratories assumes no responsibility for their use by the
        !            87: recipient.   Further, Bell Laboratories assumes no obligation
        !            88: to furnish any assistance of any kind whatsoever, or to
        !            89: furnish any additional information or documentation.

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