mirror of https://github.com/GnoConsortium/gno.git
163 lines
4.3 KiB
Groff
163 lines
4.3 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)crypt.3 8.2 (Berkeley) 12/11/93
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.\"
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.TH CRYPT 3 "28 January 1997" GNO "Library Routines"
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.SH NAME
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.BR crypt ,
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.BR setkey ,
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.BR encrypt ,
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\- simple encryption
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.SH SYNOPSIS
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#include <unistd.h>
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.sp 1
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char
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*\fBcrypt\fR (const char *\fIkey\fR, const char *\fIsalt\fR);
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.br
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int
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\fBsetkey\fR (char *\fIkey\fR);
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.br
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int
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\fBencrypt\fR (char *\fIblock\fR, int \fIflag\fR);
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.SH DESCRIPTION
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The
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.BR crypt
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function
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performs password encryption.
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It is derived from an algorithm given in
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.I "Computer Networks"
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by Andy Tanenbaum.
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.LP
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The first argument to
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.BR crypt
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.RI ( key )
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is a
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.BR NULL -terminated
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string (normally a password typed by a user).
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The second,
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.IR salt ,
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is a two-character array that should be randomly generated by the caller
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in the case of encrypting a new password, or should be taken as the
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first two characters of the
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.BR /etc/passwd
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password entry in the case of validating a password.
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.LP
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The
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functions,
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.BR encrypt
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and
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.BR setkey
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allow limited access to the encryption
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algorithm itself.
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The
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.IR key
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argument to
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.BR setkey
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is a 64 character array of
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binary values (numeric 0 or 1).
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A 56-bit key is derived from this array by dividing the array
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into groups of 8 and ignoring the last bit in each group.
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.LP
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The
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.BR encrypt
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argument
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.I block
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is also a 64 character array of
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binary values.
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If the value of
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.I flag
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is 0,
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the argument
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.I block
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is encrypted, otherwise it
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is decrypted.
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The encryption or decryption is returned in the original
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array
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.I block
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after using the
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key specified
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by
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.BR setkey
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to process it.
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.LP
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The function
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.BR crypt
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returns a pointer to the encrypted value (which is formatted as
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printable ASCII characters) on success and NULL on failure.
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The functions
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.BR setkey
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and
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.BR encrypt
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return 0 on success and 1 on failure.
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.LP
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Use of these routines requires linking with the
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.BR libcrypt
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library.
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.SH SEE ALSO
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.BR login (1),
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.BR passwd (1),
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.BR getpass (3),
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.BR passwd (5)
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.sp
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.RS
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.I "Mathematical Cryptology for Computer Scientists and Mathematicians"
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by
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Wayne Patterson.
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1987.
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Volume ISBN 0-8476-7438-X.
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.RE
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.sp 1
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.RS
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.I "Password Security: A Case History"
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by
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R. Morris,
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Ken Thompson.
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.IR "Communications of the ACM" ,
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vol. 22, pp. 594-597. November 1979.
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.RE
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.sp 1
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.RS
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.I "DES will be Totally Insecure within Ten Years"
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by
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M.E. Hellman.
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.IR "IEEE Spectrum" ,
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vol. 16, pp. 32-39. July 1979.
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.RE
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.SH BUGS
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The
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.BR crypt
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function leaves its result in an internal static object and returns
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a pointer to that object.
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Subsequent calls to
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.BR crypt
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will modify the same object.
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