mirror of
https://github.com/openssl/openssl.git
synced 2024-12-16 13:33:49 +08:00
359 lines
16 KiB
Plaintext
359 lines
16 KiB
Plaintext
=pod
|
|
|
|
=head1 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
|
|
|
|
=head1 SYNOPSIS
|
|
|
|
#include <openssl/des.h>
|
|
|
|
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);
|
|
|
|
=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
|
|
consists of 8 bytes with odd parity. 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 L<rand(3)|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 I<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 I<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 I<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 generated 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 output stream of
|
|
I<DES_cblock>s.
|
|
|
|
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>
|
|
(ECB) 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. DES_ecb_encrypt() does not return a value.
|
|
|
|
DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using
|
|
three-key Triple-DES encryption in ECB mode. This involves encrypting
|
|
the input with I<ks1>, decrypting with the key schedule I<ks2>, and
|
|
then encrypting with I<ks3>. This routine greatly reduces the chances
|
|
of brute force breaking of DES and has the advantage of if I<ks1>,
|
|
I<ks2> and I<ks3> are the same, it is equivalent to just encryption
|
|
using ECB mode and I<ks1> as the key.
|
|
|
|
The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES
|
|
encryption by using I<ks1> for the final encryption.
|
|
|
|
DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining>
|
|
(CBC) 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.
|
|
|
|
DES_xcbc_encrypt() is RSA's DESX mode of DES. It uses I<inw> and
|
|
I<outw> to 'whiten' the encryption. I<inw> and I<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 operation inside the CBC mode is
|
|
really an C<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 I<ks1> for the final encryption. C<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 parameters 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 I<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 I<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 routine 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 outputs and array of
|
|
characters. It does not require any padding to 8 character groups.
|
|
Note: the I<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 I<output>. This function is
|
|
used by Kerberos v4. Other applications should use
|
|
L<EVP_DigestInit(3)|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 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>.
|
|
|
|
The following are DES-based transformations:
|
|
|
|
DES_fcrypt() is a fast version of the Unix crypt(3) function. 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 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.
|
|
|
|
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 DES_enc_write() and is decrypted using I<sched> for
|
|
the key schedule and I<iv> for the initial vector.
|
|
|
|
B<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.
|
|
|
|
I<DES_rw_mode> is used to specify the encryption mode to use with
|
|
DES_enc_read() and 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.
|
|
|
|
=head1 NOTES
|
|
|
|
Single-key DES is insecure due to its short key size. ECB mode is
|
|
not suitable for most applications; see L<des_modes(7)|des_modes(7)>.
|
|
|
|
The L<evp(3)|evp(3)> library provides higher-level encryption functions.
|
|
|
|
=head1 BUGS
|
|
|
|
DES_3cbc_encrypt() is flawed and must not be used in applications.
|
|
|
|
DES_cbc_encrypt() does not modify B<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 compatibility with the
|
|
MIT library. New applications should use a cryptographic hash function.
|
|
The same applies for DES_string_to_2key().
|
|
|
|
=head1 CONFORMING TO
|
|
|
|
ANSI X3.106
|
|
|
|
The B<des> library was written to be source code compatible with
|
|
the MIT Kerberos library.
|
|
|
|
=head1 SEE ALSO
|
|
|
|
crypt(3), L<des_modes(7)|des_modes(7)>, L<evp(3)|evp(3)>, L<rand(3)|rand(3)>
|
|
|
|
=head1 HISTORY
|
|
|
|
In OpenSSL 0.9.7, all des_ functions were renamed to DES_ to avoid
|
|
clashes with older versions of libdes. Compatibility des_ functions
|
|
are provided for a short while, as well as crypt().
|
|
Declarations for these are in <openssl/des_old.h>. There is no DES_
|
|
variant for des_random_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_generator(),
|
|
des_new_random_key(), des_set_random_generator_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.
|
|
|
|
=head1 AUTHOR
|
|
|
|
Eric Young (eay@cryptsoft.com). Modified for the OpenSSL project
|
|
(http://www.openssl.org).
|
|
|
|
=cut
|