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.TH DES 1
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.SH NAME
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=pod
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=head1 NAME
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des - encrypt or decrypt data using Data Encryption Standard
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.SH SYNOPSIS
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.B des
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=head1 SYNOPSIS
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B<des>
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(
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.B \-e
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B<-e>
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|
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.B \-E
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B<-E>
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) | (
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.B \-d
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B<-d>
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|
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.B \-D
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B<-D>
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) | (
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.B \-\fR[\fPcC\fR][\fPckname\fR]\fP
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B<->[B<cC>][B<ckname>]
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) |
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[
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.B \-b3hfs
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B<-b3hfs>
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] [
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.B \-k
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.I key
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B<-k>
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I<key>
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]
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] [
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.B \-u\fR[\fIuuname\fR]
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B<-u>[I<uuname>]
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[
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.I input-file
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I<input-file>
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[
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.I output-file
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I<output-file>
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] ]
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.SH DESCRIPTION
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.B des
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=head1 NOTE
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This page describes the B<des> stand-alone program, not the B<openssl des>
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command.
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=head1 DESCRIPTION
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B<des>
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encrypts and decrypts data using the
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Data Encryption Standard algorithm.
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One of
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.B \-e, \-E
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B<-e>, B<-E>
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(for encrypt) or
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.B \-d, \-D
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B<-d>, B<-D>
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(for decrypt) must be specified.
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It is also possible to use
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.B \-c
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B<-c>
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or
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.B \-C
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B<-C>
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in conjunction or instead of the a encrypt/decrypt option to generate
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a 16 character hexadecimal checksum, generated via the
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.I des_cbc_cksum.
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.LP
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I<des_cbc_cksum>.
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Two standard encryption modes are supported by the
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.B des
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B<des>
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program, Cipher Block Chaining (the default) and Electronic Code Book
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(specified with
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.B \-b
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).
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.LP
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B<-b>).
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The key used for the DES
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algorithm is obtained by prompting the user unless the
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.B `\-k
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.I key'
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B<-k>
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I<key>
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option is given.
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If the key is an argument to the
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.B des
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B<des>
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command, it is potentially visible to users executing
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.BR ps (1)
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ps(1)
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or a derivative. To minimise this possibility,
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.B des
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B<des>
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takes care to destroy the key argument immediately upon entry.
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If your shell keeps a history file be careful to make sure it is not
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world readable.
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.LP
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Since this program attempts to maintain compatability with sunOS's
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Since this program attempts to maintain compatibility with sunOS's
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des(1) command, there are 2 different methods used to convert the user
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supplied key to a des key.
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Whenever and one or more of
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.B \-E, \-D, \-C
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B<-E>, B<-D>, B<-C>
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or
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.B \-3
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B<-3>
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options are used, the key conversion procedure will not be compatible
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with the sunOS des(1) version but will use all the user supplied
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character to generate the des key.
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.B des
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B<des>
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command reads from standard input unless
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.I input-file
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I<input-file>
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is specified and writes to standard output unless
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.I output-file
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I<output-file>
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is given.
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.SH OPTIONS
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.TP
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.B \-b
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=head1 OPTIONS
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=over 4
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=item B<-b>
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Select ECB
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(eight bytes at a time) encryption mode.
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.TP
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.B \-3
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=item B<-3>
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Encrypt using triple encryption.
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By default triple cbc encryption is used but if the
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.B \-b
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option is used then triple ecb encryption is performed.
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B<-b>
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option is used then triple ECB encryption is performed.
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If the key is less than 8 characters long, the flag has no effect.
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.TP
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.B \-e
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=item B<-e>
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Encrypt data using an 8 byte key in a manner compatible with sunOS
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des(1).
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.TP
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.B \-E
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=item B<-E>
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Encrypt data using a key of nearly unlimited length (1024 bytes).
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This will product a more secure encryption.
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.TP
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.B \-d
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Decrypt data that was encrypted with the \-e option.
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.TP
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.B \-D
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Decrypt data that was encrypted with the \-E option.
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.TP
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.B \-c
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=item B<-d>
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Decrypt data that was encrypted with the B<-e> option.
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=item B<-D>
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Decrypt data that was encrypted with the B<-E> option.
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=item B<-c>
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Generate a 16 character hexadecimal cbc checksum and output this to
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stderr.
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If a filename was specified after the
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.B \-c
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B<-c>
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option, the checksum is output to that file.
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The checksum is generated using a key generated in a sunOS compatible
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manner.
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.TP
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.B \-C
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=item B<-C>
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A cbc checksum is generated in the same manner as described for the
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.B \-c
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B<-c>
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option but the DES key is generated in the same manner as used for the
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.B \-E
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B<-E>
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and
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.B \-D
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B<-D>
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options
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.TP
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.B \-f
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=item B<-f>
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Does nothing - allowed for compatibility with sunOS des(1) command.
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.TP
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.B \-s
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=item B<-s>
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Does nothing - allowed for compatibility with sunOS des(1) command.
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.TP
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.B "\-k \fIkey\fP"
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=item B<-k> I<key>
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Use the encryption
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.I key
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I<key>
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specified.
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.TP
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.B "\-h"
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=item B<-h>
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The
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.I key
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I<key>
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is assumed to be a 16 character hexadecimal number.
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If the
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.B "\-3"
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B<-3>
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option is used the key is assumed to be a 32 character hexadecimal
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number.
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.TP
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.B \-u
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=item B<-u>
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This flag is used to read and write uuencoded files. If decrypting,
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the input file is assumed to contain uuencoded, DES encrypted data.
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If encrypting, the characters following the -u are used as the name of
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If encrypting, the characters following the B<-u> are used as the name of
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the uuencoded file to embed in the begin line of the uuencoded
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output. If there is no name specified after the -u, the name text.des
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output. If there is no name specified after the B<-u>, the name text.des
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will be embedded in the header.
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.SH SEE ALSO
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.B ps (1)
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.B des_crypt(3)
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.SH BUGS
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.LP
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=head1 SEE ALSO
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ps(1),
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L<des_crypt(3)|des_crypt(3)>
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=head1 BUGS
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The problem with using the
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.B -e
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B<-e>
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option is the short key length.
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It would be better to use a real 56-bit key rather than an
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ASCII-based 56-bit pattern. Knowing that the key was derived from ASCII
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radically reduces the time necessary for a brute-force cryptographic attack.
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My attempt to remove this problem is to add an alternative text-key to
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DES-key function. This alternative function (accessed via
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.B -E, -D, -S
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B<-E>, B<-D>, B<-S>
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and
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.B -3
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)
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B<-3>)
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uses DES to help generate the key.
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.LP
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Be carefully when using the -u option. Doing des -ud <filename> will
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not decrypt filename (the -u option will gobble the d option).
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.LP
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Be carefully when using the B<-u> option. Doing B<des -ud> I<filename> will
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not decrypt filename (the B<-u> option will gobble the B<-d> option).
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The VMS operating system operates in a world where files are always a
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multiple of 512 bytes. This causes problems when encrypted data is
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send from unix to VMS since a 88 byte file will suddenly be padded
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with 424 null bytes. To get around this problem, use the -u option
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send from Unix to VMS since a 88 byte file will suddenly be padded
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with 424 null bytes. To get around this problem, use the B<-u> option
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to uuencode the data before it is send to the VMS system.
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.SH AUTHOR
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.LP
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=head1 AUTHOR
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Eric Young (eay@cryptsoft.com)
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=cut
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@ -1,508 +0,0 @@
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.TH DES_CRYPT 3
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.SH NAME
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des_read_password, des_read_2password,
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des_string_to_key, des_string_to_2key, des_read_pw_string,
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des_random_key, des_set_key,
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des_key_sched, des_ecb_encrypt, des_ecb3_encrypt, des_cbc_encrypt,
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des_3cbc_encrypt,
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des_pcbc_encrypt, des_cfb_encrypt, des_ofb_encrypt,
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des_cbc_cksum, des_quad_cksum,
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des_enc_read, des_enc_write, des_set_odd_parity,
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des_is_weak_key, crypt \- (non USA) DES encryption
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.SH SYNOPSIS
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.nf
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.nj
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.ft B
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#include <des.h>
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.PP
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.B int des_read_password(key,prompt,verify)
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des_cblock *key;
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char *prompt;
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int verify;
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.PP
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.B int des_read_2password(key1,key2,prompt,verify)
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des_cblock *key1,*key2;
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char *prompt;
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int verify;
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.PP
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.B int des_string_to_key(str,key)
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char *str;
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des_cblock *key;
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.PP
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.B int des_string_to_2keys(str,key1,key2)
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char *str;
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des_cblock *key1,*key2;
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.PP
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.B int des_read_pw_string(buf,length,prompt,verify)
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char *buf;
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int length;
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char *prompt;
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int verify;
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.PP
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.B int des_random_key(key)
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des_cblock *key;
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.PP
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.B int des_set_key(key,schedule)
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des_cblock *key;
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des_key_schedule schedule;
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.PP
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.B int des_key_sched(key,schedule)
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des_cblock *key;
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des_key_schedule schedule;
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.PP
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.B int des_ecb_encrypt(input,output,schedule,encrypt)
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des_cblock *input;
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des_cblock *output;
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des_key_schedule schedule;
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int encrypt;
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.PP
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.B int des_ecb3_encrypt(input,output,ks1,ks2,encrypt)
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des_cblock *input;
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des_cblock *output;
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des_key_schedule ks1,ks2;
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int encrypt;
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.PP
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.B int des_cbc_encrypt(input,output,length,schedule,ivec,encrypt)
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des_cblock *input;
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des_cblock *output;
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long length;
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des_key_schedule schedule;
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des_cblock *ivec;
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int encrypt;
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.PP
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.B int des_3cbc_encrypt(input,output,length,sk1,sk2,ivec1,ivec2,encrypt)
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des_cblock *input;
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des_cblock *output;
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long length;
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des_key_schedule sk1;
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des_key_schedule sk2;
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des_cblock *ivec1;
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des_cblock *ivec2;
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int encrypt;
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.PP
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.B int des_pcbc_encrypt(input,output,length,schedule,ivec,encrypt)
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des_cblock *input;
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des_cblock *output;
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long length;
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des_key_schedule schedule;
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des_cblock *ivec;
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int encrypt;
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.PP
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.B int des_cfb_encrypt(input,output,numbits,length,schedule,ivec,encrypt)
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unsigned char *input;
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unsigned char *output;
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int numbits;
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long length;
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des_key_schedule schedule;
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des_cblock *ivec;
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int encrypt;
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.PP
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.B int des_ofb_encrypt(input,output,numbits,length,schedule,ivec)
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unsigned char *input,*output;
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int numbits;
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long length;
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des_key_schedule schedule;
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des_cblock *ivec;
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.PP
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.B unsigned long des_cbc_cksum(input,output,length,schedule,ivec)
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des_cblock *input;
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des_cblock *output;
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long length;
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des_key_schedule schedule;
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des_cblock *ivec;
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.PP
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.B unsigned long des_quad_cksum(input,output,length,out_count,seed)
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des_cblock *input;
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des_cblock *output;
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long length;
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int out_count;
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des_cblock *seed;
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.PP
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.B int des_check_key;
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.PP
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.B int des_enc_read(fd,buf,len,sched,iv)
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int fd;
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char *buf;
|
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int len;
|
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des_key_schedule sched;
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des_cblock *iv;
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.PP
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.B int des_enc_write(fd,buf,len,sched,iv)
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int fd;
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char *buf;
|
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int len;
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des_key_schedule sched;
|
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des_cblock *iv;
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.PP
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.B extern int des_rw_mode;
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.PP
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.B void des_set_odd_parity(key)
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des_cblock *key;
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.PP
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.B int des_is_weak_key(key)
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des_cblock *key;
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.PP
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||||
.B char *crypt(passwd,salt)
|
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char *passwd;
|
||||
char *salt;
|
||||
.PP
|
||||
.fi
|
||||
.SH DESCRIPTION
|
||||
This library contains a fast implementation of the DES encryption
|
||||
algorithm.
|
||||
.PP
|
||||
There are two phases to the use of DES encryption.
|
||||
The first is the generation of a
|
||||
.I des_key_schedule
|
||||
from a key,
|
||||
the second is the actual encryption.
|
||||
A des key is of type
|
||||
.I des_cblock.
|
||||
This type is made from 8 characters with odd parity.
|
||||
The least significant bit in the character is the parity bit.
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The key schedule is an expanded form of the key; it is used to speed the
|
||||
encryption process.
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.PP
|
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.I des_read_password
|
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writes the string specified by prompt to the standard output,
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turns off echo and reads an input string from standard input
|
||||
until terminated with a newline.
|
||||
If verify is non-zero, it prompts and reads the input again and verifies
|
||||
that both entered passwords are the same.
|
||||
The entered string is converted into a des key by using the
|
||||
.I des_string_to_key
|
||||
routine.
|
||||
The new key is placed in the
|
||||
.I des_cblock
|
||||
that was passed (by reference) to the routine.
|
||||
If there were no errors,
|
||||
.I des_read_password
|
||||
returns 0,
|
||||
-1 is returned if there was a terminal error and 1 is returned for
|
||||
any other error.
|
||||
.PP
|
||||
.I des_read_2password
|
||||
operates in the same way as
|
||||
.I des_read_password
|
||||
except that it generates 2 keys by using the
|
||||
.I des_string_to_2key
|
||||
function.
|
||||
.PP
|
||||
.I des_read_pw_string
|
||||
is called by
|
||||
.I des_read_password
|
||||
to read and verify a string from a terminal device.
|
||||
The string is returned in
|
||||
.I buf.
|
||||
The size of
|
||||
.I buf
|
||||
is passed to the routine via the
|
||||
.I length
|
||||
parameter.
|
||||
.PP
|
||||
.I des_string_to_key
|
||||
converts a string into a valid des key.
|
||||
.PP
|
||||
.I des_string_to_2key
|
||||
converts a string into 2 valid des keys.
|
||||
This routine is best suited for used to generate keys for use with
|
||||
.I des_ecb3_encrypt.
|
||||
.PP
|
||||
.I des_random_key
|
||||
returns a random key that is made of a combination of process id,
|
||||
time and an increasing counter.
|
||||
.PP
|
||||
Before a des key can be used it is converted into a
|
||||
.I des_key_schedule
|
||||
via the
|
||||
.I des_set_key
|
||||
routine.
|
||||
If the
|
||||
.I des_check_key
|
||||
flag is non-zero,
|
||||
.I des_set_key
|
||||
will check that the key passed is of odd parity and is not a week or
|
||||
semi-weak key.
|
||||
If the parity is wrong,
|
||||
then -1 is returned.
|
||||
If the key is a weak key,
|
||||
then -2 is returned.
|
||||
If an error is returned,
|
||||
the key schedule is not generated.
|
||||
.PP
|
||||
.I des_key_sched
|
||||
is another name for the
|
||||
.I des_set_key
|
||||
function.
|
||||
.PP
|
||||
The following routines mostly operate on an input and output stream of
|
||||
.I des_cblock's.
|
||||
.PP
|
||||
.I des_ecb_encrypt
|
||||
is the basic DES encryption routine that encrypts or decrypts a single 8-byte
|
||||
.I des_cblock
|
||||
in
|
||||
.I electronic code book
|
||||
mode.
|
||||
It always transforms the input data, pointed to by
|
||||
.I input,
|
||||
into the output data,
|
||||
pointed to by the
|
||||
.I output
|
||||
argument.
|
||||
If the
|
||||
.I encrypt
|
||||
argument is non-zero (DES_ENCRYPT),
|
||||
the
|
||||
.I input
|
||||
(cleartext) is encrypted in to the
|
||||
.I output
|
||||
(ciphertext) using the key_schedule specified by the
|
||||
.I schedule
|
||||
argument,
|
||||
previously set via
|
||||
.I des_set_key.
|
||||
If
|
||||
.I encrypt
|
||||
is zero (DES_DECRYPT),
|
||||
the
|
||||
.I input
|
||||
(now ciphertext)
|
||||
is decrypted into the
|
||||
.I output
|
||||
(now cleartext).
|
||||
Input and output may overlap.
|
||||
No meaningful value is returned.
|
||||
.PP
|
||||
.I des_ecb3_encrypt
|
||||
encrypts/decrypts the
|
||||
.I input
|
||||
block by using triple ecb DES encryption.
|
||||
This involves encrypting the input with
|
||||
.I ks1,
|
||||
decryption with the key schedule
|
||||
.I ks2,
|
||||
and then encryption with the first again.
|
||||
This routine greatly reduces the chances of brute force breaking of
|
||||
DES and has the advantage of if
|
||||
.I ks1
|
||||
and
|
||||
.I ks2
|
||||
are the same, it is equivalent to just encryption using ecb mode and
|
||||
.I ks1
|
||||
as the key.
|
||||
.PP
|
||||
.I des_cbc_encrypt
|
||||
encrypts/decrypts using the
|
||||
.I cipher-block-chaining
|
||||
mode of DES.
|
||||
If the
|
||||
.I encrypt
|
||||
argument is non-zero,
|
||||
the routine cipher-block-chain encrypts the cleartext data pointed to by the
|
||||
.I input
|
||||
argument into the ciphertext pointed to by the
|
||||
.I output
|
||||
argument,
|
||||
using the key schedule provided by the
|
||||
.I schedule
|
||||
argument,
|
||||
and initialisation vector provided by the
|
||||
.I ivec
|
||||
argument.
|
||||
If the
|
||||
.I length
|
||||
argument is not an integral multiple of eight bytes,
|
||||
the last block is copied to a temporary area and zero filled.
|
||||
The output is always
|
||||
an integral multiple of eight bytes.
|
||||
To make multiple cbc encrypt calls on a large amount of data appear to
|
||||
be one
|
||||
.I des_cbc_encrypt
|
||||
call, the
|
||||
.I ivec
|
||||
of subsequent calls should be the last 8 bytes of the output.
|
||||
.PP
|
||||
.I des_3cbc_encrypt
|
||||
encrypts/decrypts the
|
||||
.I input
|
||||
block by using triple cbc DES encryption.
|
||||
This involves encrypting the input with key schedule
|
||||
.I ks1,
|
||||
decryption with the key schedule
|
||||
.I ks2,
|
||||
and then encryption with the first again.
|
||||
2 initialisation vectors are required,
|
||||
.I ivec1
|
||||
and
|
||||
.I ivec2.
|
||||
Unlike
|
||||
.I des_cbc_encrypt,
|
||||
these initialisation vectors are modified by the subroutine.
|
||||
This routine greatly reduces the chances of brute force breaking of
|
||||
DES and has the advantage of if
|
||||
.I ks1
|
||||
and
|
||||
.I ks2
|
||||
are the same, it is equivalent to just encryption using cbc mode and
|
||||
.I ks1
|
||||
as the key.
|
||||
.PP
|
||||
.I des_pcbc_encrypt
|
||||
encrypt/decrypts using a modified block chaining mode.
|
||||
It provides better error propagation characteristics than cbc
|
||||
encryption.
|
||||
.PP
|
||||
.I des_cfb_encrypt
|
||||
encrypt/decrypts using cipher feedback mode. This method takes an
|
||||
array of characters as input and outputs and array of characters. It
|
||||
does not require any padding to 8 character groups. Note: the ivec
|
||||
variable is changed and the new changed value needs to be passed to
|
||||
the next call to this function. Since this function runs a complete
|
||||
DES ecb encryption per numbits, this function is only suggested for
|
||||
use when sending small numbers of characters.
|
||||
.PP
|
||||
.I des_ofb_encrypt
|
||||
encrypt using output feedback mode. This method takes an
|
||||
array of characters as input and outputs and array of characters. It
|
||||
does not require any padding to 8 character groups. Note: the ivec
|
||||
variable is changed and the new changed value needs to be passed to
|
||||
the next call to this function. Since this function runs a complete
|
||||
DES ecb encryption per numbits, this function is only suggested for
|
||||
use when sending small numbers of characters.
|
||||
.PP
|
||||
.I des_cbc_cksum
|
||||
produces an 8 byte checksum based on the input stream (via cbc encryption).
|
||||
The last 4 bytes of the checksum is returned and the complete 8 bytes is
|
||||
placed in
|
||||
.I output.
|
||||
.PP
|
||||
.I des_quad_cksum
|
||||
returns a 4 byte checksum from the input bytes.
|
||||
The algorithm can be iterated over the input,
|
||||
depending on
|
||||
.I out_count,
|
||||
1, 2, 3 or 4 times.
|
||||
If
|
||||
.I output
|
||||
is non-NULL,
|
||||
the 8 bytes generated by each pass are written into
|
||||
.I output.
|
||||
.PP
|
||||
.I des_enc_write
|
||||
is used to write
|
||||
.I len
|
||||
bytes
|
||||
to file descriptor
|
||||
.I fd
|
||||
from buffer
|
||||
.I buf.
|
||||
The data is encrypted via
|
||||
.I pcbc_encrypt
|
||||
(default) using
|
||||
.I sched
|
||||
for the key and
|
||||
.I iv
|
||||
as a starting vector.
|
||||
The actual data send down
|
||||
.I fd
|
||||
consists of 4 bytes (in network byte order) containing the length of the
|
||||
following encrypted data. The encrypted data then follows, padded with random
|
||||
data out to a multiple of 8 bytes.
|
||||
.PP
|
||||
.I des_enc_read
|
||||
is used to read
|
||||
.I len
|
||||
bytes
|
||||
from file descriptor
|
||||
.I fd
|
||||
into buffer
|
||||
.I buf.
|
||||
The data being read from
|
||||
.I fd
|
||||
is assumed to have come from
|
||||
.I des_enc_write
|
||||
and is decrypted using
|
||||
.I sched
|
||||
for the key schedule and
|
||||
.I iv
|
||||
for the initial vector.
|
||||
The
|
||||
.I des_enc_read/des_enc_write
|
||||
pair can be used to read/write to files, pipes and sockets.
|
||||
I have used them in implementing a version of rlogin in which all
|
||||
data is encrypted.
|
||||
.PP
|
||||
.I des_rw_mode
|
||||
is used to specify the encryption mode to use with
|
||||
.I des_enc_read
|
||||
and
|
||||
.I des_end_write.
|
||||
If set to
|
||||
.I DES_PCBC_MODE
|
||||
(the default), des_pcbc_encrypt is used.
|
||||
If set to
|
||||
.I DES_CBC_MODE
|
||||
des_cbc_encrypt is used.
|
||||
These two routines and the variable are not part of the normal MIT library.
|
||||
.PP
|
||||
.I des_set_odd_parity
|
||||
sets the parity of the passed
|
||||
.I key
|
||||
to odd. This routine is not part of the standard MIT library.
|
||||
.PP
|
||||
.I des_is_weak_key
|
||||
returns 1 is the passed key is a weak key (pick again :-),
|
||||
0 if it is ok.
|
||||
This routine is not part of the standard MIT library.
|
||||
.PP
|
||||
.I crypt
|
||||
is a replacement for the normal system crypt.
|
||||
It is much faster than the system crypt.
|
||||
.PP
|
||||
.SH FILES
|
||||
/usr/include/des.h
|
||||
.br
|
||||
/usr/lib/libdes.a
|
||||
.PP
|
||||
The encryption routines have been tested on 16bit, 32bit and 64bit
|
||||
machines of various endian and even works under VMS.
|
||||
.PP
|
||||
.SH BUGS
|
||||
.PP
|
||||
If you think this manual is sparse,
|
||||
read the des_crypt(3) manual from the MIT kerberos (or bones outside
|
||||
of the USA) distribution.
|
||||
.PP
|
||||
.I des_cfb_encrypt
|
||||
and
|
||||
.I des_ofb_encrypt
|
||||
operates on input of 8 bits. What this means is that if you set
|
||||
numbits to 12, and length to 2, the first 12 bits will come from the 1st
|
||||
input byte and the low half of the second input byte. The second 12
|
||||
bits will have the low 8 bits taken from the 3rd input byte and the
|
||||
top 4 bits taken from the 4th input byte. The same holds for output.
|
||||
This function has been implemented this way because most people will
|
||||
be using a multiple of 8 and because once you get into pulling bytes input
|
||||
bytes apart things get ugly!
|
||||
.PP
|
||||
.I des_read_pw_string
|
||||
is the most machine/OS dependent function and normally generates the
|
||||
most problems when porting this code.
|
||||
.PP
|
||||
.I des_string_to_key
|
||||
is probably different from the MIT version since there are lots
|
||||
of fun ways to implement one-way encryption of a text string.
|
||||
.PP
|
||||
The routines are optimised for 32 bit machines and so are not efficient
|
||||
on IBM PCs.
|
||||
.PP
|
||||
NOTE: extensive work has been done on this library since this document
|
||||
was origionally written. Please try to read des.doc from the libdes
|
||||
distribution since it is far more upto date and documents more of the
|
||||
functions. Libdes is now also being shipped as part of SSLeay, a
|
||||
general cryptographic library that amonst other things implements
|
||||
netscapes SSL protocoll. The most recent version can be found in
|
||||
SSLeay distributions.
|
||||
.SH AUTHOR
|
||||
Eric Young (eay@cryptsoft.com)
|
||||
261
crypto/des/des_crypt.pod
Normal file
261
crypto/des/des_crypt.pod
Normal file
@ -0,0 +1,261 @@
|
||||
=pod
|
||||
|
||||
=head1 NAME
|
||||
|
||||
des_read_password, des_read_2password, des_string_to_key,
|
||||
des_string_to_2key, des_read_pw_string, des_random_key, des_set_key,
|
||||
des_key_sched, des_ecb_encrypt, des_ecb3_encrypt, des_cbc_encrypt,
|
||||
des_3cbc_encrypt, des_pcbc_encrypt, des_cfb_encrypt, des_ofb_encrypt,
|
||||
des_cbc_cksum, des_quad_cksum, des_enc_read, des_enc_write,
|
||||
des_set_odd_parity, des_is_weak_key, crypt - (non USA) DES encryption
|
||||
|
||||
=head1 SYNOPSIS
|
||||
|
||||
#include <des.h>
|
||||
|
||||
int des_read_password(des_cblock *key, char *prompt, int verify);
|
||||
|
||||
int des_read_2password(des_cblock *key1, des_cblock *key2, char *prompt,
|
||||
int verify);
|
||||
|
||||
int des_string_to_key(char *str, des_cblock *key);
|
||||
|
||||
int des_string_to_2keys(char *str, des_cblock *key1, des_cblock *key2);
|
||||
|
||||
int des_read_pw_string(char *buf, int length, char *prompt, int verify);
|
||||
|
||||
int des_random_key(des_cblock *key);
|
||||
|
||||
int des_set_key(des_cblock *key, des_key_schedule schedule);
|
||||
|
||||
int des_key_sched(des_cblock *key, des_key_schedule schedule);
|
||||
|
||||
int des_ecb_encrypt(des_cblock *input, des_cblock *output,
|
||||
des_key_schedule schedule, int encrypt);
|
||||
|
||||
int des_ecb3_encrypt(des_cblock *input, des_cblock *output,
|
||||
des_key_schedule ks1, des_key_schedule ks2, int encrypt);
|
||||
|
||||
int des_cbc_encrypt(des_cblock *input, des_cblock *output,
|
||||
long length, des_key_schedule schedule, des_cblock *ivec,
|
||||
int encrypt);
|
||||
|
||||
int des_3cbc_encrypt(des_cblock *input, des_cblock *output,
|
||||
long length, des_key_schedule sk1, des_key_schedule sk2,
|
||||
des_cblock *ivec1, des_cblock *ivec2, int encrypt);
|
||||
|
||||
int des_pcbc_encrypt(des_cblock *input, des_cblock *output,
|
||||
long length, des_key_schedule schedule, des_cblock *ivec,
|
||||
int encrypt);
|
||||
|
||||
int des_cfb_encrypt(unsigned char *input, unsigned char *output,
|
||||
int numbits, long length, des_key_schedule schedule,
|
||||
des_cblock *ivec, int encrypt);
|
||||
|
||||
int des_ofb_encrypt(unsigned char *input, unsigned char *output,
|
||||
int numbits, long length, des_key_schedule schedule,
|
||||
des_cblock *ivec);
|
||||
|
||||
unsigned long des_cbc_cksum(des_cblock *input, des_cblock *output,
|
||||
long length, des_key_schedule schedule, des_cblock *ivec);
|
||||
|
||||
unsigned long des_quad_cksum(des_cblock *input, des_cblock *output,
|
||||
long length, int out_count, des_cblock *seed);
|
||||
|
||||
int des_check_key;
|
||||
|
||||
int des_enc_read(int fd, char *buf, int len, des_key_schedule sched,
|
||||
des_cblock *iv);
|
||||
|
||||
int des_enc_write(int fd, char *buf, int len, des_key_schedule sched,
|
||||
des_cblock *iv);
|
||||
|
||||
extern int des_rw_mode;
|
||||
|
||||
void des_set_odd_parity(des_cblock *key);
|
||||
|
||||
int des_is_weak_key(des_cblock *key);
|
||||
|
||||
char *crypt(char *passwd, char *salt);
|
||||
|
||||
=head1 DESCRIPTION
|
||||
|
||||
This library contains a fast implementation of the DES encryption
|
||||
algorithm.
|
||||
|
||||
There are two phases to the use of DES encryption. The first is the
|
||||
generation of a I<des_key_schedule> from a key, the second is the
|
||||
actual encryption. A des key is of type I<des_cblock>. This type is
|
||||
made from 8 characters with odd parity. The least significant bit in
|
||||
the character is the parity bit. The key schedule is an expanded form
|
||||
of the key; it is used to speed the encryption process.
|
||||
|
||||
I<des_read_password> writes the string specified by prompt to the
|
||||
standard output, turns off echo and reads an input string from
|
||||
standard input until terminated with a newline. If verify is
|
||||
non-zero, it prompts and reads the input again and verifies that both
|
||||
entered passwords are the same. The entered string is converted into
|
||||
a des key by using the I<des_string_to_key> routine. The new key is
|
||||
placed in the I<des_cblock> that was passed (by reference) to the
|
||||
routine. If there were no errors, I<des_read_password> returns 0, -1
|
||||
is returned if there was a terminal error and 1 is returned for any
|
||||
other error.
|
||||
|
||||
I<des_read_2password> operates in the same way as I<des_read_password>
|
||||
except that it generates two keys by using the I<des_string_to_2key>
|
||||
function.
|
||||
|
||||
I<des_read_pw_string> is called by I<des_read_password> to read and
|
||||
verify a string from a terminal device. The string is returned in
|
||||
I<buf>. The size of I<buf> is passed to the routine via the I<length>
|
||||
parameter.
|
||||
|
||||
I<des_string_to_key> converts a string into a valid des key.
|
||||
|
||||
I<des_string_to_2key> converts a string into two valid des keys. This
|
||||
routine is best suited for used to generate keys for use with
|
||||
I<des_ecb3_encrypt>.
|
||||
|
||||
I<des_random_key> returns a random key that is made of a combination
|
||||
of process id, time and an increasing counter.
|
||||
|
||||
Before a des key can be used, it is converted into a
|
||||
I<des_key_schedule> via the I<des_set_key> routine. If the
|
||||
I<des_check_key> flag is non-zero, I<des_set_key> will check that the
|
||||
key passed is of odd parity and is not a week or semi-weak key. If
|
||||
the parity is wrong, then -1 is returned. If the key is a weak key,
|
||||
then -2 is returned. If an error is returned, the key schedule is not
|
||||
generated.
|
||||
|
||||
I<des_key_sched> is another name for the I<des_set_key> function.
|
||||
|
||||
The following routines mostly operate on an input and output stream of
|
||||
I<des_cblock>'s.
|
||||
|
||||
I<des_ecb_encrypt> is the basic DES encryption routine that encrypts
|
||||
or decrypts a single 8-byte I<des_cblock> in I<electronic code book>
|
||||
mode. It always transforms the input data, pointed to by I<input>,
|
||||
into the output data, pointed to by the I<output> argument. If the
|
||||
I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input>
|
||||
(cleartext) is encrypted in to the I<output> (ciphertext) using the
|
||||
key_schedule specified by the I<schedule> argument, previously set via
|
||||
I<des_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now
|
||||
ciphertext) is decrypted into the I<output> (now cleartext). Input
|
||||
and output may overlap. No meaningful value is returned.
|
||||
|
||||
I<des_ecb3_encrypt> encrypts/decrypts the I<input> block by using
|
||||
triple ecb DES encryption. This involves encrypting the input with
|
||||
I<ks1>, decryption with the key schedule I<ks2>, and then encryption
|
||||
with the first again. This routine greatly reduces the chances of
|
||||
brute force breaking of DES and has the advantage of if I<ks1> and
|
||||
I<ks2> are the same, it is equivalent to just encryption using ecb
|
||||
mode and I<ks1> as the key.
|
||||
|
||||
I<des_cbc_encrypt> encrypts/decrypts using the
|
||||
I<cipher-block-chaining> mode of DES. If the I<encrypt> argument is
|
||||
non-zero, the routine cipher-block-chain encrypts the cleartext data
|
||||
pointed to by the I<input> argument into the ciphertext pointed to by
|
||||
the I<output> argument, using the key schedule provided by the
|
||||
I<schedule> argument, and initialization vector provided by the
|
||||
I<ivec> argument. If the I<length> argument is not an integral
|
||||
multiple of eight bytes, the last block is copied to a temporary area
|
||||
and zero filled. The output is always an integral multiple of eight
|
||||
bytes. To make multiple cbc encrypt calls on a large amount of data
|
||||
appear to be one I<des_cbc_encrypt> call, the I<ivec> of subsequent
|
||||
calls should be the last 8 bytes of the output.
|
||||
|
||||
I<des_3cbc_encrypt> encrypts/decrypts the I<input> block by using
|
||||
triple cbc DES encryption. This involves encrypting the input with
|
||||
key schedule I<ks1>, decryption with the key schedule I<ks2>, and then
|
||||
encryption with the first again. Two initialization vectors are
|
||||
required, I<ivec1> and I<ivec2>. Unlike I<des_cbc_encrypt>, these
|
||||
initialization vectors are modified by the subroutine. This routine
|
||||
greatly reduces the chances of brute force breaking of DES and has the
|
||||
advantage of if I<ks1> and I<ks2> are the same, it is equivalent to
|
||||
just encryption using cbc mode and I<ks1> as the key.
|
||||
|
||||
I<des_pcbc_encrypt> encrypt/decrypts using a modified block chaining
|
||||
mode. It provides better error propagation characteristics than cbc
|
||||
encryption.
|
||||
|
||||
I<des_cfb_encrypt> encrypt/decrypts using cipher feedback mode. This
|
||||
method takes an array of characters as input and outputs and array of
|
||||
characters. It does not require any padding to 8 character groups.
|
||||
Note: the ivec variable is changed and the new changed value needs to
|
||||
be passed to the next call to this function. Since this function runs
|
||||
a complete DES ecb encryption per numbits, this function is only
|
||||
suggested for use when sending small numbers of characters.
|
||||
|
||||
I<des_ofb_encrypt> encrypt using output feedback mode. This method
|
||||
takes an array of characters as input and outputs and array of
|
||||
characters. It does not require any padding to 8 character groups.
|
||||
Note: the ivec variable is changed and the new changed value needs to
|
||||
be passed to the next call to this function. Since this function runs
|
||||
a complete DES ecb encryption per numbits, this function is only
|
||||
suggested for use when sending small numbers of characters.
|
||||
|
||||
I<des_cbc_cksum> produces an 8 byte checksum based on the input stream
|
||||
(via cbc encryption). The last 4 bytes of the checksum is returned
|
||||
and the complete 8 bytes is placed in I<output>.
|
||||
|
||||
I<des_quad_cksum> returns a 4 byte checksum from the input bytes. The
|
||||
algorithm can be iterated over the input, depending on I<out_count>,
|
||||
1, 2, 3 or 4 times. If I<output> is non-NULL, the 8 bytes generated
|
||||
by each pass are written into I<output>.
|
||||
|
||||
I<des_enc_write> is used to write I<len> bytes to file descriptor
|
||||
I<fd> from buffer I<buf>. The data is encrypted via I<pcbc_encrypt>
|
||||
(default) using I<sched> for the key and I<iv> as a starting vector.
|
||||
The actual data send down I<fd> consists of 4 bytes (in network byte
|
||||
order) containing the length of the following encrypted data. The
|
||||
encrypted data then follows, padded with random data out to a multiple
|
||||
of 8 bytes.
|
||||
|
||||
I<des_enc_read> is used to read I<len> bytes from file descriptor
|
||||
I<fd> into buffer I<buf>. The data being read from I<fd> is assumed to
|
||||
have come from I<des_enc_write> and is decrypted using I<sched> for
|
||||
the key schedule and I<iv> for the initial vector. The
|
||||
I<des_enc_read/des_enc_write> pair can be used to read/write to files,
|
||||
pipes and sockets. I have used them in implementing a version of
|
||||
rlogin in which all data is encrypted.
|
||||
|
||||
I<des_rw_mode> is used to specify the encryption mode to use with
|
||||
I<des_enc_read> and I<des_end_write>. If set to I<DES_PCBC_MODE> (the
|
||||
default), des_pcbc_encrypt is used. If set to I<DES_CBC_MODE>
|
||||
des_cbc_encrypt is used. These two routines and the variable are not
|
||||
part of the normal MIT library.
|
||||
|
||||
I<des_set_odd_parity> sets the parity of the passed I<key> to odd.
|
||||
This routine is not part of the standard MIT library.
|
||||
|
||||
I<des_is_weak_key> returns 1 is the passed key is a weak key (pick
|
||||
again :-), 0 if it is ok. This routine is not part of the standard
|
||||
MIT library.
|
||||
|
||||
I<crypt> is a replacement for the normal system crypt. It is much
|
||||
faster than the system crypt.
|
||||
|
||||
=head1 BUGS
|
||||
|
||||
I<des_cfb_encrypt> and I<des_ofb_encrypt> operates on input of 8 bits.
|
||||
What this means is that if you set numbits to 12, and length to 2, the
|
||||
first 12 bits will come from the 1st input byte and the low half of
|
||||
the second input byte. The second 12 bits will have the low 8 bits
|
||||
taken from the 3rd input byte and the top 4 bits taken from the 4th
|
||||
input byte. The same holds for output. This function has been
|
||||
implemented this way because most people will be using a multiple of 8
|
||||
and because once you get into pulling bytes input bytes apart things
|
||||
get ugly!
|
||||
|
||||
I<des_read_pw_string> is the most machine/OS dependent function and
|
||||
normally generates the most problems when porting this code.
|
||||
|
||||
I<des_string_to_key> is probably different from the MIT version since
|
||||
there are lots of fun ways to implement one-way encryption of a text
|
||||
string.
|
||||
|
||||
=head1 AUTHOR
|
||||
|
||||
Eric Young (eay@cryptsoft.com)
|
||||
|
||||
=cut
|
||||
Loading…
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Reference in New Issue
Block a user