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des(3) OpenSSL des(3)
NAME
DES_random_key, DES_set_key, DES_key_sched,
DES_set_key_checked, DES_set_key_unchecked,
DES_set_odd_parity, DES_is_weak_key, DES_ecb_encrypt,
DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt,
DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt,
DES_cfb64_encrypt, DES_ofb64_encrypt, DES_xcbc_encrypt,
DES_ede2_cbc_encrypt, DES_ede2_cfb64_encrypt,
DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt,
DES_ede3_cbcm_encrypt, DES_ede3_cfb64_encrypt,
DES_ede3_ofb64_encrypt, DES_cbc_cksum, DES_quad_cksum,
DES_string_to_key, DES_string_to_2keys, DES_fcrypt,
DES_crypt, DES_enc_read, DES_enc_write - DES encryption
SYNOPSIS
#include
void DES_random_key(DES_cblock *ret);
int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule);
int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule);
int DES_set_key_checked(const_DES_cblock *key,
DES_key_schedule *schedule);
void DES_set_key_unchecked(const_DES_cblock *key,
DES_key_schedule *schedule);
void DES_set_odd_parity(DES_cblock *key);
int DES_is_weak_key(const_DES_cblock *key);
void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output,
DES_key_schedule *ks, int enc);
void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output,
DES_key_schedule *ks1, DES_key_schedule *ks2, int enc);
void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output,
DES_key_schedule *ks1, DES_key_schedule *ks2,
DES_key_schedule *ks3, int enc);
void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output,
long length, DES_key_schedule *schedule, DES_cblock *ivec,
int enc);
void DES_cfb_encrypt(const unsigned char *in, unsigned char *out,
int numbits, long length, DES_key_schedule *schedule,
DES_cblock *ivec, int enc);
void DES_ofb_encrypt(const unsigned char *in, unsigned char *out,
int numbits, long length, DES_key_schedule *schedule,
DES_cblock *ivec);
void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output,
long length, DES_key_schedule *schedule, DES_cblock *ivec,
int enc);
void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
long length, DES_key_schedule *schedule, DES_cblock *ivec,
int *num, int enc);
void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out,
long length, DES_key_schedule *schedule, DES_cblock *ivec,
int *num);
void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output,
long length, DES_key_schedule *schedule, DES_cblock *ivec,
const_DES_cblock *inw, const_DES_cblock *outw, int enc);
void DES_ede2_cbc_encrypt(const unsigned char *input,
unsigned char *output, long length, DES_key_schedule *ks1,
DES_key_schedule *ks2, DES_cblock *ivec, int enc);
void DES_ede2_cfb64_encrypt(const unsigned char *in,
unsigned char *out, long length, DES_key_schedule *ks1,
DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc);
void DES_ede2_ofb64_encrypt(const unsigned char *in,
unsigned char *out, long length, DES_key_schedule *ks1,
DES_key_schedule *ks2, DES_cblock *ivec, int *num);
void DES_ede3_cbc_encrypt(const unsigned char *input,
unsigned char *output, long length, DES_key_schedule *ks1,
DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec,
int enc);
void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out,
long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2,
int enc);
void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out,
long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc);
void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out,
long length, DES_key_schedule *ks1,
DES_key_schedule *ks2, DES_key_schedule *ks3,
DES_cblock *ivec, int *num);
DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output,
long length, DES_key_schedule *schedule,
const_DES_cblock *ivec);
DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[],
long length, int out_count, DES_cblock *seed);
void DES_string_to_key(const char *str, DES_cblock *key);
void DES_string_to_2keys(const char *str, DES_cblock *key1,
DES_cblock *key2);
char *DES_fcrypt(const char *buf, const char *salt, char *ret);
char *DES_crypt(const char *buf, const char *salt);
int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched,
DES_cblock *iv);
int DES_enc_write(int fd, const void *buf, int len,
DES_key_schedule *sched, DES_cblock *iv);
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 DES_key_schedule from a key,
the second is the actual encryption. A DES key is of type
DES_cblock. This type is consists of 8 bytes with odd par-
ity. The least significant bit in each byte is the parity
bit. The key schedule is an expanded form of the key; it
is used to speed the encryption process.
DES_random_key() generates a random key. The PRNG must be
seeded prior to using this function (see rand(3)). If the
PRNG could not generate a secure key, 0 is returned.
Before a DES key can be used, it must be converted into
the architecture dependent DES_key_schedule via the
DES_set_key_checked() or DES_set_key_unchecked() function.
DES_set_key_checked() 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.
DES_set_key() works like DES_set_key_checked() if the
DES_check_key flag is non-zero, otherwise like
DES_set_key_unchecked(). These functions are available
for compatibility; it is recommended to use a function
that does not depend on a global variable.
DES_set_odd_parity() sets the parity of the passed key to
odd.
DES_is_weak_key() returns 1 is the passed key is a weak
key, 0 if it is ok. The probability that a randomly gen-
erated key is weak is 1/2^52, so it is not really worth
checking for them.
The following routines mostly operate on an input and out-
put stream of DES_cblocks.
DES_ecb_encrypt() is the basic DES encryption routine that
encrypts or decrypts a single 8-byte DES_cblock in elec-
tronic code book (ECB) mode. It always transforms the
input data, pointed to by input, into the output data,
pointed to by the output argument. If the encrypt argu-
ment is non-zero (DES_ENCRYPT), the input (cleartext) is
encrypted in to the output (ciphertext) using the
key_schedule specified by the schedule argument, previ-
ously set via DES_set_key. If encrypt is zero
(DES_DECRYPT), the input (now ciphertext) is decrypted
into the output (now cleartext). Input and output may
overlap. DES_ecb_encrypt() does not return a value.
DES_ecb3_encrypt() encrypts/decrypts the input block by
using three-key Triple-DES encryption in ECB mode. This
involves encrypting the input with ks1, decrypting with
the key schedule ks2, and then encrypting with ks3. This
routine greatly reduces the chances of brute force break-
ing of DES and has the advantage of if ks1, ks2 and ks3
are the same, it is equivalent to just encryption using
ECB mode and ks1 as the key.
The macro DES_ecb2_encrypt() is provided to perform two-
key Triple-DES encryption by using ks1 for the final
encryption.
DES_ncbc_encrypt() encrypts/decrypts using the cipher-
block-chaining (CBC) mode of DES. If the encrypt argument
is non-zero, the routine cipher-block-chain encrypts the
cleartext data pointed to by the input argument into the
ciphertext pointed to by the output argument, using the
key schedule provided by the schedule argument, and ini-
tialization vector provided by the ivec argument. If the
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.
DES_xcbc_encrypt() is RSA's DESX mode of DES. It uses inw
and outw to 'whiten' the encryption. inw and outw are
secret (unlike the iv) and are as such, part of the key.
So the key is sort of 24 bytes. This is much better than
CBC DES.
DES_ede3_cbc_encrypt() implements outer triple CBC DES
encryption with three keys. This means that each DES oper-
ation inside the CBC mode is really an
"C=E(ks3,D(ks2,E(ks1,M)))". This mode is used by SSL.
The DES_ede2_cbc_encrypt() macro implements two-key
Triple-DES by reusing ks1 for the final encryption.
"C=E(ks1,D(ks2,E(ks1,M)))". This form of Triple-DES is
used by the RSAREF library.
DES_pcbc_encrypt() encrypt/decrypts using the propagating
cipher block chaining mode used by Kerberos v4. Its param-
eters are the same as DES_ncbc_encrypt().
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 vari-
able 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.
DES_cfb64_encrypt() implements CFB mode of DES with 64bit
feedback. Why is this useful you ask? Because this rou-
tine will allow you to encrypt an arbitrary number of
bytes, no 8 byte padding. Each call to this routine will
encrypt the input bytes to output and then update ivec and
num. num contains 'how far' we are though ivec. If this
does not make much sense, read more about cfb mode of DES
:-).
DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is
the same as DES_cfb64_encrypt() except that Triple-DES is
used.
DES_ofb_encrypt() encrypts using output feedback mode.
This method takes an array of characters as input and out-
puts 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.
DES_ofb64_encrypt() is the same as DES_cfb64_encrypt()
using Output Feed Back mode.
DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is
the same as DES_ofb64_encrypt(), using Triple-DES.
The following functions are included in the DES library
for compatibility with the MIT Kerberos library.
DES_cbc_cksum() produces an 8 byte checksum based on the
input stream (via CBC encryption). The last 4 bytes of
the checksum are returned and the complete 8 bytes are
placed in output. This function is used by Kerberos v4.
Other applications should use EVP_DigestInit(3) etc.
instead.
DES_quad_cksum() is a Kerberos v4 function. It returns a
4 byte checksum from the input bytes. The algorithm can
be iterated over the input, depending on out_count, 1, 2,
3 or 4 times. If output is non-NULL, the 8 bytes
generated by each pass are written into output.
The following are DES-based transformations:
DES_fcrypt() is a fast version of the Unix crypt(3) func-
tion. This version takes only a small amount of space
relative to other fast crypt() implementations. This is
different to the normal crypt in that the third parameter
is the buffer that the return value is written into. It
needs to be at least 14 bytes long. This function is
thread safe, unlike the normal crypt.
DES_crypt() is a faster replacement for the normal system
crypt(). This function calls DES_fcrypt() with a static
array passed as the third parameter. This emulates the
normal non-thread safe semantics of crypt(3).
DES_enc_write() writes len bytes to file descriptor fd
from buffer buf. The data is encrypted via pcbc_encrypt
(default) using sched for the key and iv as a starting
vector. The actual data send down fd consists of 4 bytes
(in network byte order) containing the length of the fol-
lowing encrypted data. The encrypted data then follows,
padded with random data out to a multiple of 8 bytes.
DES_enc_read() is used to read len bytes from file
descriptor fd into buffer buf. The data being read from fd
is assumed to have come from DES_enc_write() and is
decrypted using sched for the key schedule and iv for the
initial vector.
Warning: The data format used by DES_enc_write() and
DES_enc_read() has a cryptographic weakness: When asked to
write more than MAXWRITE bytes, DES_enc_write() will split
the data into several chunks that are all encrypted using
the same IV. So don't use these functions unless you are
sure you know what you do (in which case you might not
want to use them anyway). They cannot handle non-blocking
sockets. DES_enc_read() uses an internal state and thus
cannot be used on multiple files.
DES_rw_mode is used to specify the encryption mode to use
with DES_enc_read() and DES_end_write(). If set to
DES_PCBC_MODE (the default), DES_pcbc_encrypt is used. If
set to DES_CBC_MODE DES_cbc_encrypt is used.
NOTES
Single-key DES is insecure due to its short key size. ECB
mode is not suitable for most applications; see
DES_modes(7).
The evp(3) library provides higher-level encryption func-
tions.
BUGS
DES_3cbc_encrypt() is flawed and must not be used in
applications.
DES_cbc_encrypt() does not modify ivec; use
DES_ncbc_encrypt() instead.
DES_cfb_encrypt() and 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!
DES_string_to_key() is available for backward compatibil-
ity with the MIT library. New applications should use a
cryptographic hash function. The same applies for
DES_string_to_2key().
CONFORMING TO
ANSI X3.106
The des library was written to be source code compatible
with the MIT Kerberos library.
SEE ALSO
crypt(3), des_modes(7), evp(3), rand(3)
HISTORY
In OpenSSL 0.9.7, all des_ functions were renamed to DES_
to avoid clashes with older versions of libdes. Compati-
bility des_ functions are provided for a short while, as
well as crypt(). Declarations for these are in
. There is no DES_ variant for des_ran-
dom_seed(). This will happen to other functions as well
if they are deemed redundant (des_random_seed() just calls
RAND_seed() and is present for backward compatibility
only), buggy or already scheduled for removal.
des_cbc_cksum(), des_cbc_encrypt(), des_ecb_encrypt(),
des_is_weak_key(), des_key_sched(), des_pcbc_encrypt(),
des_quad_cksum(), des_random_key() and des_string_to_key()
are available in the MIT Kerberos library;
des_check_key_parity(), des_fixup_key_parity() and
des_is_weak_key() are available in newer versions of that
library.
des_set_key_checked() and des_set_key_unchecked() were
added in OpenSSL 0.9.5.
des_generate_random_block(), des_init_random_number_gener-
ator(), des_new_random_key(), des_set_random_genera-
tor_seed() and des_set_sequence_number() and
des_rand_data() are used in newer versions of Kerberos but
are not implemented here.
des_random_key() generated cryptographically weak random
data in SSLeay and in OpenSSL prior version 0.9.5, as well
as in the original MIT library.
AUTHOR
Eric Young (). Modified for the OpenSSL
project (http://www.openssl.org).
0.9.7c 2001-10-25 des(3)
Time taken: 1.04715 seconds
Created with the man page lookup class by Andrew Collington,
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