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Annotation of 43BSDReno/domestic/src/crypt/crypt.1, revision 1.1.1.1

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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