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Annotation of 43BSDReno/old/crypt/crypt.1, revision 1.1

1.1     ! root        1: .\"    @(#)crypt.1     6.3 (Berkeley) 9/18/89
        !             2: .\"
        !             3: .TH CRYPT 1 "September 18, 1989"
        !             4: .AT 3
        !             5: .SH NAME
        !             6: crypt \- encode/decode
        !             7: .SH SYNOPSIS
        !             8: .B crypt
        !             9: [ password ]
        !            10: .SH DESCRIPTION
        !            11: .ft B
        !            12: This interface is obsoleted by des(1).
        !            13: .ft R
        !            14: .PP
        !            15: .I Crypt
        !            16: reads from the standard input and writes
        !            17: on the standard output.
        !            18: The
        !            19: .I password
        !            20: is a key that selects a particular transformation.
        !            21: If no
        !            22: .I password 
        !            23: is given,
        !            24: .I crypt
        !            25: demands a key from the terminal and turns
        !            26: off printing while the key is being typed in.
        !            27: .I Crypt
        !            28: encrypts and decrypts with the same key:
        !            29: .PP
        !            30:        crypt key <clear >cypher
        !            31: .br
        !            32:        crypt key <cypher | pr
        !            33: .PP
        !            34: will print the clear.
        !            35: .PP
        !            36: Files encrypted by
        !            37: .I crypt
        !            38: are compatible with those treated by the editor
        !            39: .I ed
        !            40: in encryption mode.
        !            41: .PP
        !            42: The security of encrypted files depends on three factors:
        !            43: the fundamental method must be hard to solve;
        !            44: direct search of the key space must be infeasible;
        !            45: `sneak paths' by which keys or cleartext can become
        !            46: visible must be minimized.
        !            47: .PP
        !            48: .I Crypt
        !            49: implements a one-rotor machine designed along the lines
        !            50: of the German Enigma, but with a 256-element rotor.
        !            51: Methods of attack on such machines are known, but not widely;
        !            52: moreover the amount of work required is likely to be large.
        !            53: .PP
        !            54: The transformation of a key into the internal
        !            55: settings of the machine is deliberately designed to
        !            56: be expensive, i.e. to take a substantial fraction of
        !            57: a second to compute.
        !            58: However,
        !            59: if keys are restricted to (say)
        !            60: three lower-case letters,
        !            61: then encrypted files can be read by expending only
        !            62: a substantial fraction of
        !            63: five minutes of machine time.
        !            64: .PP
        !            65: Since the key is an argument to the
        !            66: .I crypt
        !            67: command,
        !            68: it is potentially visible to users executing
        !            69: .IR ps (1)
        !            70: or a derivative.
        !            71: To minimize this possibility,
        !            72: .I crypt
        !            73: takes care to destroy any record of the key
        !            74: immediately upon entry.
        !            75: No doubt the choice of keys and key security
        !            76: are the most vulnerable aspect of
        !            77: .I crypt.
        !            78: .SH FILES
        !            79: /dev/tty for typed key
        !            80: .SH "SEE ALSO"
        !            81: ed(1),
        !            82: crypt(3),
        !            83: makekey(8)
        !            84: .SH BUGS
        !            85: There is no warranty of merchantability nor any warranty
        !            86: of fitness for a particular purpose nor any other warranty,
        !            87: either express or implied, as to the accuracy of the
        !            88: enclosed materials or as to their suitability for any
        !            89: particular purpose.  Accordingly, Bell Telephone
        !            90: Laboratories assumes no responsibility for their use by the
        !            91: recipient.   Further, Bell Laboratories assumes no obligation
        !            92: to furnish any assistance of any kind whatsoever, or to
        !            93: furnish any additional information or documentation.

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