--- /dev/null
+=pod
+
+=head1 NAME
+
+des - encrypt or decrypt data using Data Encryption Standard
+
+=head1 SYNOPSIS
+
+B<des>
+(
+B<-e>
+|
+B<-E>
+) | (
+B<-d>
+|
+B<-D>
+) | (
+B<->[B<cC>][B<ckname>]
+) |
+[
+B<-b3hfs>
+] [
+B<-k>
+I<key>
+]
+] [
+B<-u>[I<uuname>]
+[
+I<input-file>
+[
+I<output-file>
+] ]
+
+=head1 NOTE
+
+This page describes the B<des> stand-alone program, not the B<openssl des>
+command.
+
+=head1 DESCRIPTION
+
+B<des>
+encrypts and decrypts data using the
+Data Encryption Standard algorithm.
+One of
+B<-e>, B<-E>
+(for encrypt) or
+B<-d>, B<-D>
+(for decrypt) must be specified.
+It is also possible to use
+B<-c>
+or
+B<-C>
+in conjunction or instead of the a encrypt/decrypt option to generate
+a 16 character hexadecimal checksum, generated via the
+I<des_cbc_cksum>.
+
+Two standard encryption modes are supported by the
+B<des>
+program, Cipher Block Chaining (the default) and Electronic Code Book
+(specified with
+B<-b>).
+
+The key used for the DES
+algorithm is obtained by prompting the user unless the
+B<-k>
+I<key>
+option is given.
+If the key is an argument to the
+B<des>
+command, it is potentially visible to users executing
+ps(1)
+or a derivative. To minimise this possibility,
+B<des>
+takes care to destroy the key argument immediately upon entry.
+If your shell keeps a history file be careful to make sure it is not
+world readable.
+
+Since this program attempts to maintain compatibility with sunOS's
+des(1) command, there are 2 different methods used to convert the user
+supplied key to a des key.
+Whenever and one or more of
+B<-E>, B<-D>, B<-C>
+or
+B<-3>
+options are used, the key conversion procedure will not be compatible
+with the sunOS des(1) version but will use all the user supplied
+character to generate the des key.
+B<des>
+command reads from standard input unless
+I<input-file>
+is specified and writes to standard output unless
+I<output-file>
+is given.
+
+=head1 OPTIONS
+
+=over 4
+
+=item B<-b>
+
+Select ECB
+(eight bytes at a time) encryption mode.
+
+=item B<-3>
+
+Encrypt using triple encryption.
+By default triple cbc encryption is used but if the
+B<-b>
+option is used then triple ECB encryption is performed.
+If the key is less than 8 characters long, the flag has no effect.
+
+=item B<-e>
+
+Encrypt data using an 8 byte key in a manner compatible with sunOS
+des(1).
+
+=item B<-E>
+
+Encrypt data using a key of nearly unlimited length (1024 bytes).
+This will product a more secure encryption.
+
+=item B<-d>
+
+Decrypt data that was encrypted with the B<-e> option.
+
+=item B<-D>
+
+Decrypt data that was encrypted with the B<-E> option.
+
+=item B<-c>
+
+Generate a 16 character hexadecimal cbc checksum and output this to
+stderr.
+If a filename was specified after the
+B<-c>
+option, the checksum is output to that file.
+The checksum is generated using a key generated in a sunOS compatible
+manner.
+
+=item B<-C>
+
+A cbc checksum is generated in the same manner as described for the
+B<-c>
+option but the DES key is generated in the same manner as used for the
+B<-E>
+and
+B<-D>
+options
+
+=item B<-f>
+
+Does nothing - allowed for compatibility with sunOS des(1) command.
+
+=item B<-s>
+
+Does nothing - allowed for compatibility with sunOS des(1) command.
+
+=item B<-k> I<key>
+
+Use the encryption
+I<key>
+specified.
+
+=item B<-h>
+
+The
+I<key>
+is assumed to be a 16 character hexadecimal number.
+If the
+B<-3>
+option is used the key is assumed to be a 32 character hexadecimal
+number.
+
+=item B<-u>
+
+This flag is used to read and write uuencoded files. If decrypting,
+the input file is assumed to contain uuencoded, DES encrypted data.
+If encrypting, the characters following the B<-u> are used as the name of
+the uuencoded file to embed in the begin line of the uuencoded
+output. If there is no name specified after the B<-u>, the name text.des
+will be embedded in the header.
+
+=head1 SEE ALSO
+
+ps(1),
+L<des_crypt(3)|des_crypt(3)>
+
+=head1 BUGS
+
+The problem with using the
+B<-e>
+option is the short key length.
+It would be better to use a real 56-bit key rather than an
+ASCII-based 56-bit pattern. Knowing that the key was derived from ASCII
+radically reduces the time necessary for a brute-force cryptographic attack.
+My attempt to remove this problem is to add an alternative text-key to
+DES-key function. This alternative function (accessed via
+B<-E>, B<-D>, B<-S>
+and
+B<-3>)
+uses DES to help generate the key.
+
+Be carefully when using the B<-u> option. Doing B<des -ud> I<filename> will
+not decrypt filename (the B<-u> option will gobble the B<-d> option).
+
+The VMS operating system operates in a world where files are always a
+multiple of 512 bytes. This causes problems when encrypted data is
+send from Unix to VMS since a 88 byte file will suddenly be padded
+with 424 null bytes. To get around this problem, use the B<-u> option
+to uuencode the data before it is send to the VMS system.
+
+=head1 AUTHOR
+
+Eric Young (eay@cryptsoft.com)
+
+=cut
projects / openssl.git / blobdiff