-.\" Copyright 2000 Nicolás Lichtmaier <nick@debian.org>
+.\" Copyright 2000 Nicolás Lichtmaier <nick@debian.org>
.\" Created 2000-07-22 00:52-0300
.\"
+.\" %%%LICENSE_START(GPLv2+_DOC_FULL)
.\" This is free documentation; you can redistribute it and/or
.\" modify it under the terms of the GNU General Public License as
.\" published by the Free Software Foundation; either version 2 of
.\" MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
.\" GNU General Public License for more details.
.\"
+.\" You should have received a copy of the GNU General Public
+.\" License along with this manual; if not, see
+.\" <http://www.gnu.org/licenses/>.
+.\" %%%LICENSE_END
+.\"
.\" Modified 2002-07-23 19:21:35 CEST 2002 Walter Harms
.\" <walter.harms@informatik.uni-oldenburg.de>
.\"
.\" Modified 2003-04-04, aeb
.\"
-.TH ENCRYPT 3 2003-04-04 "" "Cryptographic Functions"
+.TH ENCRYPT 3 2018-04-30 "" "Linux Programmer's Manual"
.SH NAME
encrypt, setkey, encrypt_r, setkey_r \- encrypt 64-bit messages
.SH SYNOPSIS
-.B #define _XOPEN_SOURCE
-.br
+.nf
+.BR "#define _XOPEN_SOURCE" " /* See feature_test_macros(7) */"
.B #include <unistd.h>
-.sp
+.PP
.BI "void encrypt(char " block "[64], int " edflag );
-.sp
-.B #define _XOPEN_SOURCE
-.br
+
+.BR "#define _XOPEN_SOURCE" " /* See feature_test_macros(7) */"
.B #include <stdlib.h>
-.sp
+.PP
.BI "void setkey(const char *" key );
-.sp
-.B #define _GNU_SOURCE
-.br
-.BI "#include <crypt.h>"
-.sp
+
+.BR "#define _GNU_SOURCE" " /* See feature_test_macros(7) */"
+.B "#include <crypt.h>"
+.PP
.BI "void setkey_r(const char *" key ", struct crypt_data *" data );
-.br
.BI "void encrypt_r(char *" block ", int " edflag \
", struct crypt_data *" data );
-.sp
-Each of these requires linking with
-.BR \-lcrypt .
+.fi
+.PP
+Each of these requires linking with \fI\-lcrypt\fP.
.SH DESCRIPTION
These functions encrypt and decrypt 64-bit messages.
The
.BR encrypt ().
The
.I key
-parameter used here is an array of 64 bytes, each of which has
+argument used here is an array of 64 bytes, each of which has
numerical value 1 or 0.
The bytes key[n] where n=8*i-1 are ignored,
so that the effective key length is 56 bits.
function modifies the passed buffer, encoding if
.I edflag
is 0, and decoding if 1 is being passed.
-Like the key parameter also
+Like the
+.I key
+argument, also
.I block
is a bit vector representation of the actual value that is encoded.
The result is returned in that same vector.
are the reentrant versions.
They use the following
structure to hold the key data:
-.RS
-.nf
+.PP
+.in +4n
+.EX
struct crypt_data {
char keysched[16 * 8];
char sb0[32768];
int direction;
int initialized;
};
-.fi
-.RE
+.EE
+.in
+.PP
Before calling
.BR setkey_r ()
set
-.I data->initialized
+.I data\->initialized
to zero.
-.SH "RETURN VALUE"
+.SH RETURN VALUE
These functions do not return any value.
.SH ERRORS
Set
to zero before calling the above functions.
On success, it is unchanged.
.TP
-.BR ENOSYS
+.B ENOSYS
The function is not provided.
(For example because of former USA export restrictions.)
+.SH VERSIONS
+Because they employ the DES block cipher,
+which is no longer considered secure,
+.BR crypt (),
+.BR crypt_r (),
+.BR setkey (),
+and
+.BR setkey_r ()
+were removed in glibc 2.28.
+Applications should switch to a modern cryptography library, such as
+.BR libgcrypt .
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbw23 lb lb
+l l l.
+Interface Attribute Value
+T{
+.BR encrypt (),
+.BR setkey ()
+T} Thread safety MT-Unsafe race:crypt
+T{
+.BR encrypt_r (),
+.BR setkey_r ()
+T} Thread safety MT-Safe
+.TE
+.SH CONFORMING TO
+.BR encrypt (),
+.BR setkey ():
+POSIX.1-2001, POSIX.1-2008, SUS, SVr4.
+.PP
+The functions
+.BR encrypt_r ()
+and
+.BR setkey_r ()
+are GNU extensions.
+.SH NOTES
+.SS Availability in glibc
+See
+.BR crypt (3).
+.SS Features in glibc
+In glibc 2.2, these functions use the DES algorithm.
.SH EXAMPLE
-You need to link with libcrypt to compile this example with glibc 2.2.
-To do useful work the key[] and txt[] arrays must be filled with a
-useful bit pattern.
-.sp
-.nf
+.EX
#define _XOPEN_SOURCE
-#include <unistd.h>
+#include <stdio.h>
#include <stdlib.h>
+#include <unistd.h>
+#include <crypt.h>
int
main(void)
{
- char key[64]; /* bit pattern for key */
- char txt[64]; /* bit pattern for messages */
+ char key[64];
+ char orig[9] = "eggplant";
+ char buf[64];
+ char txt[9];
+ int i, j;
+
+ for (i = 0; i < 64; i++) {
+ key[i] = rand() & 1;
+ }
+
+ for (i = 0; i < 8; i++) {
+ for (j = 0; j < 8; j++) {
+ buf[i * 8 + j] = orig[i] >> j & 1;
+ }
+ setkey(key);
+ }
+ printf("Before encrypting: %s\en", orig);
- setkey(key);
- encrypt(txt, 0); /* encode */
- encrypt(txt, 1); /* decode */
+ encrypt(buf, 0);
+ for (i = 0; i < 8; i++) {
+ for (j = 0, txt[i] = \(aq\e0\(aq; j < 8; j++) {
+ txt[i] |= buf[i * 8 + j] << j;
+ }
+ txt[8] = \(aq\e0\(aq;
+ }
+ printf("After encrypting: %s\en", txt);
+
+ encrypt(buf, 1);
+ for (i = 0; i < 8; i++) {
+ for (j = 0, txt[i] = \(aq\e0\(aq; j < 8; j++) {
+ txt[i] |= buf[i * 8 + j] << j;
+ }
+ txt[8] = \(aq\e0\(aq;
+ }
+ printf("After decrypting: %s\en", txt);
+ exit(EXIT_SUCCESS);
}
-.fi
-.SH NOTES
-In glibc 2.2 these functions use the DES algorithm.
-.SH "CONFORMING TO"
-The functions
-.BR encrypt ()
-and
-.BR setkey ()
-conform to SVr4, SUSv2, and POSIX.1-2001.
-The functions
-.BR encrypt_r ()
-and
-.BR setkey_r ()
-are GNU extensions.
-.SH "SEE ALSO"
+.EE
+.SH SEE ALSO
.BR cbc_crypt (3),
.BR crypt (3),
.BR ecb_crypt (3),
-.BR fcrypt (3),
-.BR feature_test_macros (7)
+.\" .BR fcrypt (3)
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