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diff --git a/usr.bin/bdes/bdes.1 b/usr.bin/bdes/bdes.1 new file mode 100644 index 0000000..eecd81b --- /dev/null +++ b/usr.bin/bdes/bdes.1 @@ -0,0 +1,304 @@ +.\" Copyright (c) 1991, 1993 +.\" The Regents of the University of California. All rights reserved. +.\" +.\" This code is derived from software contributed to Berkeley by +.\" Matt Bishop of Dartmouth College. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" 3. All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" This product includes software developed by the University of +.\" California, Berkeley and its contributors. +.\" 4. Neither the name of the University nor the names of its contributors +.\" may be used to endorse or promote products derived from this software +.\" without specific prior written permission. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +.\" SUCH DAMAGE. +.\" +.\" @(#)bdes.1 8.1 (Berkeley) 6/29/93 +.\" +.TH BDES 1 "June 29, 1993" +.UC 6 +.SH NAME +bdes \- encrypt/decrypt using the Data Encryption Standard +.SH SYNOPSIS +.nf +.ft B +bdes [ \-abdp ] [ \-F N ] [ \-f N ] [ \-k key ] +.ti +5 +[ \-m N ] [ \-o N ] [ \-v vector ] +.ft R +.fi +.SH DESCRIPTION +.I Bdes +implements all DES modes of operation described in FIPS PUB 81, +including alternative cipher feedback mode and both authentication +modes. +.I Bdes +reads from the standard input and writes to the standard output. +By default, the input is encrypted using cipher block chaining mode. +Using the same key for encryption and decryption preserves plain text. +.PP +All modes but the electronic code book mode require an initialization +vector; if none is supplied, the zero vector is used. +If no +.I key +is specified on the command line, the user is prompted for one (see +.IR getpass (3) +for more details). +.PP +The options are as follows: +.TP +\-a +The key and initialization vector strings are to be taken as ASCII, +suppressing the special interpretation given to leading ``0X'', ``0x'', +``0B'', and ``0b'' characters. +This flag applies to +.I both +the key and initialization vector. +.TP +\-b +Use electronic code book mode. +.TP +\-d +Decrypt the input. +.TP +\-F +Use +.IR N -bit +alternative cipher feedback mode. +Currently +.I N +must be a multiple of 7 between 7 and 56 inclusive (this does not conform +to the alternative CFB mode specification). +.TP +\-f +Use +.IR N -bit +cipher feedback mode. +Currently +.I N +must be a multiple of 8 between 8 and 64 inclusive (this does not conform +to the standard CFB mode specification). +.TP +\-k +Use +.I key +as the cryptographic key. +.TP +\-m +Compute a message authentication code (MAC) of +.I N +bits on the input. +The value of +.I N +must be between 1 and 64 inclusive; if +.I N +is not a multiple of 8, enough 0 bits will be added to pad the MAC length +to the nearest multiple of 8. +Only the MAC is output. +MACs are only available in cipher block chaining mode or in cipher feedback +mode. +.TP +\-o +Use +.IR N -bit +output feedback mode. +Currently +.I N +must be a multiple of 8 between 8 and 64 inclusive (this does not conform +to the OFB mode specification). +.TP +\-p +Disable the resetting of the parity bit. +This flag forces the parity bit of the key to be used as typed, rather than +making each character be of odd parity. +It is used only if the key is given in ASCII. +.TP +\-v +Set the initialization vector to +.IR vector ; +the vector is interpreted in the same way as the key. +The vector is ignored in electronic codebook mode. +.PP +The key and initialization vector are taken as sequences of ASCII +characters which are then mapped into their bit representations. +If either begins with ``0X'' or ``0x'', +that one is taken as a sequence of hexadecimal digits indicating the +bit pattern; +if either begins with ``0B'' or ``0b'', +that one is taken as a sequence of binary digits indicating the bit pattern. +In either case, +only the leading 64 bits of the key or initialization vector +are used, +and if fewer than 64 bits are provided, enough 0 bits are appended +to pad the key to 64 bits. +.PP +According to the DES standard, the low-order bit of each character in the +key string is deleted. +Since most ASCII representations set the high-order bit to 0, simply +deleting the low-order bit effectively reduces the size of the key space +from 2\u\s-356\s0\d to 2\u\s-348\s0\d keys. +To prevent this, the high-order bit must be a function depending in part +upon the low-order bit; so, the high-order bit is set to whatever value +gives odd parity. +This preserves the key space size. +Note this resetting of the parity bit is +.I not +done if the key is given in binary or hex, and can be disabled for ASCII +keys as well. +.PP +The DES is considered a very strong cryptosystem, and other than table lookup +attacks, key search attacks, and Hellman's time-memory tradeoff (all of which +are very expensive and time-consuming), no cryptanalytic methods for breaking +the DES are known in the open literature. +No doubt the choice of keys and key security are the most vulnerable aspect +of +.IR bdes . +.SH IMPLEMENTATION NOTES +For implementors wishing to write software compatible with this program, +the following notes are provided. +This software is believed to be compatible with the implementation of the +data encryption standard distributed by Sun Microsystems, Inc. +.PP +In the ECB and CBC modes, plaintext is encrypted in units of 64 bits (8 bytes, +also called a block). +To ensure that the plaintext file is encrypted correctly, +.I bdes +will (internally) append from 1 to 8 bytes, the last byte containing an +integer stating how many bytes of that final block are from the plaintext +file, and encrypt the resulting block. +Hence, when decrypting, the last block may contain from 0 to 7 characters +present in the plaintext file, and the last byte tells how many. +Note that if during decryption the last byte of the file does not contain an +integer between 0 and 7, either the file has been corrupted or an incorrect +key has been given. +A similar mechanism is used for the OFB and CFB modes, except that those +simply require the length of the input to be a multiple of the mode size, +and the final byte contains an integer between 0 and one less than the number +of bytes being used as the mode. +(This was another reason that the mode size must be a multiple of 8 for those +modes.) +.PP +Unlike Sun's implementation, unused bytes of that last block are not filled +with random data, but instead contain what was in those byte positions in +the preceding block. +This is quicker and more portable, and does not weaken the encryption +significantly. +.PP +If the key is entered in ASCII, the parity bits of the key characters are set +so that each key character is of odd parity. +Unlike Sun's implementation, it is possible to enter binary or hexadecimal +keys on the command line, and if this is done, the parity bits are +.I not +reset. +This allows testing using arbitrary bit patterns as keys. +.PP +The Sun implementation always uses an initialization vector of 0 +(that is, all zeroes). +By default, +.I bdes +does too, but this may be changed from the command line. +.SH SEE ALSO +crypt(1), crypt(3), getpass(3) +.sp +.IR "Data Encryption Standard" , +Federal Information Processing Standard #46, +National Bureau of Standards, +U.S. Department of Commerce, +Washington DC +(Jan. 1977) +.sp +.IR "DES Modes of Operation" , +Federal Information Processing Standard #81, +National Bureau of Standards, +U.S. Department of Commerce +Washington DC +(Dec. 1980) +.sp +Dorothy Denning, +.IR "Cryptography and Data Security" , +Addison-Wesley Publishing Co., +Reading, MA +\(co1982. +.sp +Matt Bishop, +.IR "Implementation Notes on bdes(1)" , +Technical Report PCS-TR-91-158, +Department of Mathematics and Computer Science, +Dartmouth College, +Hanover, NH 03755 +(Apr. 1991). +.SH DISCLAIMER +.nf +THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND +ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE +ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE +FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS +OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) +HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT +LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY +OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF +SUCH DAMAGE. +.fi +.SH BUGS +There is a controversy raging over whether the DES will still be secure +in a few years. +The advent of special-purpose hardware could reduce the cost of any of the +methods of attack named above so that they are no longer computationally +infeasible. +.PP +As the key or key schedule is stored in memory, the encryption can be +compromised if memory is readable. +Additionally, programs which display programs' arguments may compromise the +key and initialization vector, if they are specified on the command line. +To avoid this +.I bdes +overwrites its arguments, however, the obvious race cannot currently be +avoided. +.PP +Certain specific keys should be avoided because they introduce potential +weaknesses; these keys, called the +.I weak +and +.I semiweak +keys, are (in hex notation, where p is either 0 or 1, and P is either +e or f): +.sp +.nf +.in +10n +.ta \w'0x0p0p0p0p0p0p0p0p\0\0\0'u+5n +0x0p0p0p0p0p0p0p0p 0x0p1P0p1P0p0P0p0P +0x0pep0pep0pfp0pfp 0x0pfP0pfP0pfP0pfP +0x1P0p1P0p0P0p0P0p 0x1P1P1P1P0P0P0P0P +0x1Pep1Pep0Pfp0Pfp 0x1PfP1PfP0PfP0PfP +0xep0pep0pfp0pfp0p 0xep1Pep1pfp0Pfp0P +0xepepepepepepepep 0xepfPepfPfpfPfpfP +0xfP0pfP0pfP0pfP0p 0xfP1PfP1PfP0PfP0P +0xfPepfPepfPepfPep 0xfPfPfPfPfPfPfPfP +.fi +.in -10n +.sp +This is inherent in the DES algorithm (see Moore and Simmons, +\*(LqCycle structure of the DES with weak and semi-weak keys,\*(Rq +.I "Advances in Cryptology \- Crypto '86 Proceedings" , +Springer-Verlag New York, \(co1987, pp. 9-32.) |
