diff --git a/crypto/des/des.man b/crypto/des/des.pod similarity index 68% rename from crypto/des/des.man rename to crypto/des/des.pod index 7e06a1851a0d0d1acf795c195f64d1e7f53c2042..bf479e83d26b7d98d7a3fabf93efb5313a8d4374 100644 --- a/crypto/des/des.man +++ b/crypto/des/des.pod @@ -1,186 +1,217 @@ -.TH DES 1 -.SH NAME +=pod + +=head1 NAME + des - encrypt or decrypt data using Data Encryption Standard -.SH SYNOPSIS -.B des + +=head1 SYNOPSIS + +B ( -.B \-e +B<-e> | -.B \-E +B<-E> ) | ( -.B \-d +B<-d> | -.B \-D +B<-D> ) | ( -.B \-\fR[\fPcC\fR][\fPckname\fR]\fP +B<->[B][B] ) | [ -.B \-b3hfs +B<-b3hfs> ] [ -.B \-k -.I key +B<-k> +I ] ] [ -.B \-u\fR[\fIuuname\fR] +B<-u>[I] [ -.I input-file +I [ -.I output-file +I ] ] -.SH DESCRIPTION -.B des + +=head1 NOTE + +This page describes the B stand-alone program, not the B +command. + +=head1 DESCRIPTION + +B encrypts and decrypts data using the Data Encryption Standard algorithm. One of -.B \-e, \-E +B<-e>, B<-E> (for encrypt) or -.B \-d, \-D +B<-d>, B<-D> (for decrypt) must be specified. It is also possible to use -.B \-c +B<-c> or -.B \-C +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. -.LP +I. + Two standard encryption modes are supported by the -.B des +B program, Cipher Block Chaining (the default) and Electronic Code Book (specified with -.B \-b -). -.LP +B<-b>). + The key used for the DES algorithm is obtained by prompting the user unless the -.B `\-k -.I key' +B<-k> +I option is given. If the key is an argument to the -.B des +B command, it is potentially visible to users executing -.BR ps (1) +ps(1) or a derivative. To minimise this possibility, -.B des +B 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. -.LP -Since this program attempts to maintain compatability with sunOS's + +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, \-D, \-C +B<-E>, B<-D>, B<-C> or -.B \-3 +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 +B command reads from standard input unless -.I input-file +I is specified and writes to standard output unless -.I output-file +I is given. -.SH OPTIONS -.TP -.B \-b + +=head1 OPTIONS + +=over 4 + +=item B<-b> + Select ECB (eight bytes at a time) encryption mode. -.TP -.B \-3 + +=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. +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. -.TP -.B \-e + +=item B<-e> + Encrypt data using an 8 byte key in a manner compatible with sunOS des(1). -.TP -.B \-E + +=item B<-E> + Encrypt data using a key of nearly unlimited length (1024 bytes). This will product a more secure encryption. -.TP -.B \-d -Decrypt data that was encrypted with the \-e option. -.TP -.B \-D -Decrypt data that was encrypted with the \-E option. -.TP -.B \-c + +=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 +B<-c> option, the checksum is output to that file. The checksum is generated using a key generated in a sunOS compatible manner. -.TP -.B \-C + +=item B<-C> + A cbc checksum is generated in the same manner as described for the -.B \-c +B<-c> option but the DES key is generated in the same manner as used for the -.B \-E +B<-E> and -.B \-D +B<-D> options -.TP -.B \-f + +=item B<-f> + Does nothing - allowed for compatibility with sunOS des(1) command. -.TP -.B \-s + +=item B<-s> + Does nothing - allowed for compatibility with sunOS des(1) command. -.TP -.B "\-k \fIkey\fP" + +=item B<-k> I + Use the encryption -.I key +I specified. -.TP -.B "\-h" + +=item B<-h> + The -.I key +I is assumed to be a 16 character hexadecimal number. If the -.B "\-3" +B<-3> option is used the key is assumed to be a 32 character hexadecimal number. -.TP -.B \-u + +=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 -u are used as the name of +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 -u, the name text.des +output. If there is no name specified after the B<-u>, the name text.des will be embedded in the header. -.SH SEE ALSO -.B ps (1) -.B des_crypt(3) -.SH BUGS -.LP + +=head1 SEE ALSO + +ps(1), +L + +=head1 BUGS + The problem with using the -.B -e +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, -D, -S +B<-E>, B<-D>, B<-S> and -.B -3 -) +B<-3>) uses DES to help generate the key. -.LP -Be carefully when using the -u option. Doing des -ud will -not decrypt filename (the -u option will gobble the d option). -.LP + +Be carefully when using the B<-u> option. Doing B I 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 -u option +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. -.SH AUTHOR -.LP + +=head1 AUTHOR + Eric Young (eay@cryptsoft.com) + +=cut diff --git a/crypto/des/des_crypt.man b/crypto/des/des_crypt.man deleted file mode 100644 index 0ecc416877fe6d7c8b2416dd546b615d665b325e..0000000000000000000000000000000000000000 --- a/crypto/des/des_crypt.man +++ /dev/null @@ -1,508 +0,0 @@ -.TH DES_CRYPT 3 -.SH 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 -.SH SYNOPSIS -.nf -.nj -.ft B -#include -.PP -.B int des_read_password(key,prompt,verify) -des_cblock *key; -char *prompt; -int verify; -.PP -.B int des_read_2password(key1,key2,prompt,verify) -des_cblock *key1,*key2; -char *prompt; -int verify; -.PP -.B int des_string_to_key(str,key) -char *str; -des_cblock *key; -.PP -.B int des_string_to_2keys(str,key1,key2) -char *str; -des_cblock *key1,*key2; -.PP -.B int des_read_pw_string(buf,length,prompt,verify) -char *buf; -int length; -char *prompt; -int verify; -.PP -.B int des_random_key(key) -des_cblock *key; -.PP -.B int des_set_key(key,schedule) -des_cblock *key; -des_key_schedule schedule; -.PP -.B int des_key_sched(key,schedule) -des_cblock *key; -des_key_schedule schedule; -.PP -.B int des_ecb_encrypt(input,output,schedule,encrypt) -des_cblock *input; -des_cblock *output; -des_key_schedule schedule; -int encrypt; -.PP -.B int des_ecb3_encrypt(input,output,ks1,ks2,encrypt) -des_cblock *input; -des_cblock *output; -des_key_schedule ks1,ks2; -int encrypt; -.PP -.B int des_cbc_encrypt(input,output,length,schedule,ivec,encrypt) -des_cblock *input; -des_cblock *output; -long length; -des_key_schedule schedule; -des_cblock *ivec; -int encrypt; -.PP -.B int des_3cbc_encrypt(input,output,length,sk1,sk2,ivec1,ivec2,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; -.PP -.B int des_pcbc_encrypt(input,output,length,schedule,ivec,encrypt) -des_cblock *input; -des_cblock *output; -long length; -des_key_schedule schedule; -des_cblock *ivec; -int encrypt; -.PP -.B int des_cfb_encrypt(input,output,numbits,length,schedule,ivec,encrypt) -unsigned char *input; -unsigned char *output; -int numbits; -long length; -des_key_schedule schedule; -des_cblock *ivec; -int encrypt; -.PP -.B int des_ofb_encrypt(input,output,numbits,length,schedule,ivec) -unsigned char *input,*output; -int numbits; -long length; -des_key_schedule schedule; -des_cblock *ivec; -.PP -.B unsigned long des_cbc_cksum(input,output,length,schedule,ivec) -des_cblock *input; -des_cblock *output; -long length; -des_key_schedule schedule; -des_cblock *ivec; -.PP -.B unsigned long des_quad_cksum(input,output,length,out_count,seed) -des_cblock *input; -des_cblock *output; -long length; -int out_count; -des_cblock *seed; -.PP -.B int des_check_key; -.PP -.B int des_enc_read(fd,buf,len,sched,iv) -int fd; -char *buf; -int len; -des_key_schedule sched; -des_cblock *iv; -.PP -.B int des_enc_write(fd,buf,len,sched,iv) -int fd; -char *buf; -int len; -des_key_schedule sched; -des_cblock *iv; -.PP -.B extern int des_rw_mode; -.PP -.B void des_set_odd_parity(key) -des_cblock *key; -.PP -.B int des_is_weak_key(key) -des_cblock *key; -.PP -.B char *crypt(passwd,salt) -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. -The key schedule is an expanded form of the key; it is used to speed the -encryption process. -.PP -.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. -.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) diff --git a/crypto/des/des_crypt.pod b/crypto/des/des_crypt.pod new file mode 100644 index 0000000000000000000000000000000000000000..673215f75883188ed206ba4b6957e18a5d50328c --- /dev/null +++ b/crypto/des/des_crypt.pod @@ -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 + + 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 from a key, the second is the +actual encryption. A des key is of type I. 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 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 routine. The new key is +placed in the I that was passed (by reference) to the +routine. If there were no errors, I returns 0, -1 +is returned if there was a terminal error and 1 is returned for any +other error. + +I operates in the same way as I +except that it generates two keys by using the I +function. + +I is called by I to read and +verify a string from a terminal device. The string is returned in +I. The size of I is passed to the routine via the I +parameter. + +I converts a string into a valid des key. + +I converts a string into two valid des keys. This +routine is best suited for used to generate keys for use with +I. + +I 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 via the I routine. If the +I flag is non-zero, I 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 is another name for the I function. + +The following routines mostly operate on an input and output stream of +I's. + +I is the basic DES encryption routine that encrypts +or decrypts a single 8-byte I in I +mode. It always transforms the input data, pointed to by I, +into the output data, pointed to by the I argument. If the +I argument is non-zero (DES_ENCRYPT), the I +(cleartext) is encrypted in to the I (ciphertext) using the +key_schedule specified by the I argument, previously set via +I. If I is zero (DES_DECRYPT), the I (now +ciphertext) is decrypted into the I (now cleartext). Input +and output may overlap. No meaningful value is returned. + +I encrypts/decrypts the I block by using +triple ecb DES encryption. This involves encrypting the input with +I, decryption with the key schedule I, 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 and +I are the same, it is equivalent to just encryption using ecb +mode and I as the key. + +I encrypts/decrypts using the +I mode of DES. If the I argument is +non-zero, the routine cipher-block-chain encrypts the cleartext data +pointed to by the I argument into the ciphertext pointed to by +the I argument, using the key schedule provided by the +I argument, and initialization vector provided by the +I argument. If the I 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 call, the I of subsequent +calls should be the last 8 bytes of the output. + +I encrypts/decrypts the I block by using +triple cbc DES encryption. This involves encrypting the input with +key schedule I, decryption with the key schedule I, and then +encryption with the first again. Two initialization vectors are +required, I and I. Unlike I, 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 and I are the same, it is equivalent to +just encryption using cbc mode and I as the key. + +I encrypt/decrypts using a modified block chaining +mode. It provides better error propagation characteristics than cbc +encryption. + +I 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 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 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. + +I returns a 4 byte checksum from the input bytes. The +algorithm can be iterated over the input, depending on I, +1, 2, 3 or 4 times. If I is non-NULL, the 8 bytes generated +by each pass are written into I. + +I is used to write I bytes to file descriptor +I from buffer I. The data is encrypted via I +(default) using I for the key and I as a starting vector. +The actual data send down I 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 is used to read I bytes from file descriptor +I into buffer I. The data being read from I is assumed to +have come from I and is decrypted using I for +the key schedule and I for the initial vector. The +I 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 is used to specify the encryption mode to use with +I and I. If set to I (the +default), des_pcbc_encrypt is used. If set to I +des_cbc_encrypt is used. These two routines and the variable are not +part of the normal MIT library. + +I sets the parity of the passed I to odd. +This routine is not part of the standard MIT library. + +I 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 is a replacement for the normal system crypt. It is much +faster than the system crypt. + +=head1 BUGS + +I and I 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 is the most machine/OS dependent function and +normally generates the most problems when porting this code. + +I 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