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Diffstat (limited to 'bitmask_android/openssl/crypto/des/des.pod')
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diff --git a/bitmask_android/openssl/crypto/des/des.pod b/bitmask_android/openssl/crypto/des/des.pod new file mode 100644 index 00000000..bf479e83 --- /dev/null +++ b/bitmask_android/openssl/crypto/des/des.pod @@ -0,0 +1,217 @@ +=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 |