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 encryption
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);
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, and the second is the actual encryption. A DES key is of type DES_cblock. This type 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 in odd parity.
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 weak 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.
The following routines mostly operate on an input and output stream of DES_cblocks.
DES_ecb_encrypt()
is the basic DES encryption routine that encrypts or decrypts a single
8-byte DES_cblock in electronic 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 enc
argument is non-zero (DES_ENCRYPT), the
input (cleartext) is encrypted into the
output (ciphertext) using the key_schedule specified
by the schedule argument, previously set via
DES_set_key(). If enc 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 breaking 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
enc 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 initialization 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 operation inside the CBC mode is
"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()
encrypts/decrypts using the propagating cipher block chaining mode used by
Kerberos v4. Its parameters are the same as
DES_ncbc_encrypt().
DES_cfb_encrypt()
encrypts/decrypts using cipher feedback mode. This method takes an array of
characters as input and outputs an 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 a small number of characters.
DES_cfb64_encrypt()
implements CFB mode of DES with 64-bit feedback. Why is this useful you ask?
Because this routine will allow you to encrypt an arbitrary number of bytes,
without 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.
The
DES_ede3_cfb64_encrypt()
function and the
DES_ede2_cfb64_encrypt()
macro are 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 an 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 a small number of characters.
DES_ofb64_encrypt()
is the same as DES_cfb64_encrypt() using Output Feed
Back mode.
The
DES_ede3_ofb64_encrypt()
function and the
DES_ede2_ofb64_encrypt()
macro are 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)
function. The salt must be two ASCII characters. This
version is different from 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. The fourteenth byte is set to NUL. This version takes only a
small amount of space relative to other fast crypt implementations. It is
thread safe, unlike the normal crypt.
DES_crypt()
is a faster replacement for the normal system
crypt(3).
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).
RETURN VALUES
DES_set_key(),
DES_key_sched(), and
DES_set_key_checked() return 0 on success or a
negative value on error.
DES_is_weak_key() returns 1 if the passed
key is a weak key or 0 if it is ok.
DES_cbc_cksum() and
DES_quad_cksum() return a 4-byte integer
representing the last 4 bytes of the checksum of the input.
DES_fcrypt() returns a pointer to the
caller-provided buffer ret, and
DES_crypt() returns a pointer to a static buffer.
Both are allowed to return NULL to indicate failure,
but currently, they cannot fail.
SEE ALSO
STANDARDS
ANSI X3.106
The DES library was initially written to be source code compatible with the MIT Kerberos library.
HISTORY
DES_random_key(),
DES_set_key(),
DES_key_sched(),
DES_set_odd_parity(),
DES_is_weak_key(),
DES_ecb_encrypt(),
DES_cfb_encrypt(),
DES_ofb_encrypt(),
DES_pcbc_encrypt(),
DES_cfb64_encrypt(),
DES_ofb64_encrypt(),
DES_ede3_cbc_encrypt(),
DES_cbc_cksum(),
DES_quad_cksum(),
DES_string_to_key(),
DES_string_to_2keys(), and
DES_crypt() appeared in SSLeay 0.4 or earlier.
DES_ncbc_encrypt() first appeared in SSLeay 0.4.2.
DES_ede2_cbc_encrypt() first appeared in SSLeay
0.4.4. DES_ecb2_encrypt(),
DES_ecb3_encrypt(),
DES_ede2_cfb64_encrypt(),
DES_ede2_ofb64_encrypt(),
DES_ede3_cfb64_encrypt(), and
DES_ede3_ofb64_encrypt() first appeared in SSLeay
0.5.1. DES_xcbc_encrypt() first appeared in SSLeay
0.6.2. DES_fcrypt() first appeared in SSLeay 0.6.5.
These functions have been available since OpenBSD
2.4.
DES_set_key_checked() and
DES_set_key_unchecked() first appeared in OpenSSL
0.9.5 and have been available since OpenBSD 2.7.
In OpenSSL 0.9.7 and OpenBSD 3.2, all des_ functions were renamed to DES_ to avoid clashes with older versions of libdes.
AUTHORS
Eric Young <[email protected]>
CAVEATS
Single-key DES is insecure due to its short key size. ECB mode is not suitable for most applications.
BUGS
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 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().