1=pod
2
3=head1 NAME
4
5DES_random_key, DES_set_key, DES_key_sched, DES_set_key_checked,
6DES_set_key_unchecked, DES_set_odd_parity, DES_is_weak_key,
7DES_ecb_encrypt, DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt,
8DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt, DES_cfb64_encrypt,
9DES_ofb64_encrypt, DES_xcbc_encrypt, DES_ede2_cbc_encrypt,
10DES_ede2_cfb64_encrypt, DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt,
11DES_ede3_cfb64_encrypt, DES_ede3_ofb64_encrypt,
12DES_cbc_cksum, DES_quad_cksum, DES_string_to_key, DES_string_to_2keys,
13DES_fcrypt, DES_crypt - DES encryption
14
15=head1 SYNOPSIS
16
17 #include <openssl/des.h>
18
19 void DES_random_key(DES_cblock *ret);
20
21 int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule);
22 int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule);
23 int DES_set_key_checked(const_DES_cblock *key, DES_key_schedule *schedule);
24 void DES_set_key_unchecked(const_DES_cblock *key, DES_key_schedule *schedule);
25
26 void DES_set_odd_parity(DES_cblock *key);
27 int DES_is_weak_key(const_DES_cblock *key);
28
29 void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output,
30                      DES_key_schedule *ks, int enc);
31 void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output,
32                       DES_key_schedule *ks1, DES_key_schedule *ks2, int enc);
33 void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output,
34                       DES_key_schedule *ks1, DES_key_schedule *ks2,
35                       DES_key_schedule *ks3, int enc);
36
37 void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output,
38                       long length, DES_key_schedule *schedule, DES_cblock *ivec,
39                       int enc);
40 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out,
41                      int numbits, long length, DES_key_schedule *schedule,
42                      DES_cblock *ivec, int enc);
43 void DES_ofb_encrypt(const unsigned char *in, unsigned char *out,
44                      int numbits, long length, DES_key_schedule *schedule,
45                      DES_cblock *ivec);
46 void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output,
47                       long length, DES_key_schedule *schedule, DES_cblock *ivec,
48                       int enc);
49 void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
50                        long length, DES_key_schedule *schedule, DES_cblock *ivec,
51                        int *num, int enc);
52 void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out,
53                        long length, DES_key_schedule *schedule, DES_cblock *ivec,
54                        int *num);
55
56 void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output,
57                       long length, DES_key_schedule *schedule, DES_cblock *ivec,
58                       const_DES_cblock *inw, const_DES_cblock *outw, int enc);
59
60 void DES_ede2_cbc_encrypt(const unsigned char *input, unsigned char *output,
61                           long length, DES_key_schedule *ks1,
62                           DES_key_schedule *ks2, DES_cblock *ivec, int enc);
63 void DES_ede2_cfb64_encrypt(const unsigned char *in, unsigned char *out,
64                             long length, DES_key_schedule *ks1,
65                             DES_key_schedule *ks2, DES_cblock *ivec,
66                             int *num, int enc);
67 void DES_ede2_ofb64_encrypt(const unsigned char *in, unsigned char *out,
68                             long length, DES_key_schedule *ks1,
69                             DES_key_schedule *ks2, DES_cblock *ivec, int *num);
70
71 void DES_ede3_cbc_encrypt(const unsigned char *input, unsigned char *output,
72                           long length, DES_key_schedule *ks1,
73                           DES_key_schedule *ks2, DES_key_schedule *ks3,
74                           DES_cblock *ivec, int enc);
75 void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out,
76                             long length, DES_key_schedule *ks1,
77                             DES_key_schedule *ks2, DES_key_schedule *ks3,
78                             DES_cblock *ivec, int *num, int enc);
79 void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out,
80                             long length, DES_key_schedule *ks1,
81                             DES_key_schedule *ks2, DES_key_schedule *ks3,
82                             DES_cblock *ivec, int *num);
83
84 DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output,
85                        long length, DES_key_schedule *schedule,
86                        const_DES_cblock *ivec);
87 DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[],
88                         long length, int out_count, DES_cblock *seed);
89 void DES_string_to_key(const char *str, DES_cblock *key);
90 void DES_string_to_2keys(const char *str, DES_cblock *key1, DES_cblock *key2);
91
92 char *DES_fcrypt(const char *buf, const char *salt, char *ret);
93 char *DES_crypt(const char *buf, const char *salt);
94
95=head1 DESCRIPTION
96
97This library contains a fast implementation of the DES encryption
98algorithm.
99
100There are two phases to the use of DES encryption.  The first is the
101generation of a I<DES_key_schedule> from a key, the second is the
102actual encryption.  A DES key is of type I<DES_cblock>. This type
103consists of 8 bytes with odd parity.  The least significant bit in
104each byte is the parity bit.  The key schedule is an expanded form of
105the key; it is used to speed the encryption process.
106
107DES_random_key() generates a random key.  The PRNG must be seeded
108prior to using this function (see L<RAND_bytes(3)>).  If the PRNG
109could not generate a secure key, 0 is returned.
110
111Before a DES key can be used, it must be converted into the
112architecture dependent I<DES_key_schedule> via the
113DES_set_key_checked() or DES_set_key_unchecked() function.
114
115DES_set_key_checked() will check that the key passed is of odd parity
116and is not a weak or semi-weak key.  If the parity is wrong, then -1
117is returned.  If the key is a weak key, then -2 is returned.  If an
118error is returned, the key schedule is not generated.
119
120DES_set_key() works like
121DES_set_key_checked() if the I<DES_check_key> flag is non-zero,
122otherwise like DES_set_key_unchecked().  These functions are available
123for compatibility; it is recommended to use a function that does not
124depend on a global variable.
125
126DES_set_odd_parity() sets the parity of the passed I<key> to odd.
127
128DES_is_weak_key() returns 1 if the passed key is a weak key, 0 if it
129is ok.
130
131The following routines mostly operate on an input and output stream of
132I<DES_cblock>s.
133
134DES_ecb_encrypt() is the basic DES encryption routine that encrypts or
135decrypts a single 8-byte I<DES_cblock> in I<electronic code book>
136(ECB) mode.  It always transforms the input data, pointed to by
137I<input>, into the output data, pointed to by the I<output> argument.
138If the I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input>
139(cleartext) is encrypted in to the I<output> (ciphertext) using the
140key_schedule specified by the I<schedule> argument, previously set via
141I<DES_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now
142ciphertext) is decrypted into the I<output> (now cleartext).  Input
143and output may overlap.  DES_ecb_encrypt() does not return a value.
144
145DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using
146three-key Triple-DES encryption in ECB mode.  This involves encrypting
147the input with I<ks1>, decrypting with the key schedule I<ks2>, and
148then encrypting with I<ks3>.  This routine greatly reduces the chances
149of brute force breaking of DES and has the advantage of if I<ks1>,
150I<ks2> and I<ks3> are the same, it is equivalent to just encryption
151using ECB mode and I<ks1> as the key.
152
153The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES
154encryption by using I<ks1> for the final encryption.
155
156DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining>
157(CBC) mode of DES.  If the I<encrypt> argument is non-zero, the
158routine cipher-block-chain encrypts the cleartext data pointed to by
159the I<input> argument into the ciphertext pointed to by the I<output>
160argument, using the key schedule provided by the I<schedule> argument,
161and initialization vector provided by the I<ivec> argument.  If the
162I<length> argument is not an integral multiple of eight bytes, the
163last block is copied to a temporary area and zero filled.  The output
164is always an integral multiple of eight bytes.
165
166DES_xcbc_encrypt() is RSA's DESX mode of DES.  It uses I<inw> and
167I<outw> to 'whiten' the encryption.  I<inw> and I<outw> are secret
168(unlike the iv) and are as such, part of the key.  So the key is sort
169of 24 bytes.  This is much better than CBC DES.
170
171DES_ede3_cbc_encrypt() implements outer triple CBC DES encryption with
172three keys. This means that each DES operation inside the CBC mode is
173C<C=E(ks3,D(ks2,E(ks1,M)))>.  This mode is used by SSL.
174
175The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by
176reusing I<ks1> for the final encryption.  C<C=E(ks1,D(ks2,E(ks1,M)))>.
177This form of Triple-DES is used by the RSAREF library.
178
179DES_pcbc_encrypt() encrypts/decrypts using the propagating cipher block
180chaining mode used by Kerberos v4. Its parameters are the same as
181DES_ncbc_encrypt().
182
183DES_cfb_encrypt() encrypts/decrypts using cipher feedback mode.  This
184method takes an array of characters as input and outputs an array of
185characters.  It does not require any padding to 8 character groups.
186Note: the I<ivec> variable is changed and the new changed value needs to
187be passed to the next call to this function.  Since this function runs
188a complete DES ECB encryption per I<numbits>, this function is only
189suggested for use when sending a small number of characters.
190
191DES_cfb64_encrypt()
192implements CFB mode of DES with 64-bit feedback.  Why is this
193useful you ask?  Because this routine will allow you to encrypt an
194arbitrary number of bytes, without 8 byte padding.  Each call to this
195routine will encrypt the input bytes to output and then update ivec
196and num.  num contains 'how far' we are though ivec.  If this does
197not make much sense, read more about CFB mode of DES.
198
199DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as
200DES_cfb64_encrypt() except that Triple-DES is used.
201
202DES_ofb_encrypt() encrypts using output feedback mode.  This method
203takes an array of characters as input and outputs an array of
204characters.  It does not require any padding to 8 character groups.
205Note: the I<ivec> variable is changed and the new changed value needs to
206be passed to the next call to this function.  Since this function runs
207a complete DES ECB encryption per I<numbits>, this function is only
208suggested for use when sending a small number of characters.
209
210DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output
211Feed Back mode.
212
213DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as
214DES_ofb64_encrypt(), using Triple-DES.
215
216The following functions are included in the DES library for
217compatibility with the MIT Kerberos library.
218
219DES_cbc_cksum() produces an 8 byte checksum based on the input stream
220(via CBC encryption).  The last 4 bytes of the checksum are returned
221and the complete 8 bytes are placed in I<output>. This function is
222used by Kerberos v4.  Other applications should use
223L<EVP_DigestInit(3)> etc. instead.
224
225DES_quad_cksum() is a Kerberos v4 function.  It returns a 4 byte
226checksum from the input bytes.  The algorithm can be iterated over the
227input, depending on I<out_count>, 1, 2, 3 or 4 times.  If I<output> is
228non-NULL, the 8 bytes generated by each pass are written into
229I<output>.
230
231The following are DES-based transformations:
232
233DES_fcrypt() is a fast version of the Unix crypt(3) function.  This
234version takes only a small amount of space relative to other fast
235crypt() implementations.  This is different to the normal crypt() in
236that the third parameter is the buffer that the return value is
237written into.  It needs to be at least 14 bytes long.  This function
238is thread safe, unlike the normal crypt().
239
240DES_crypt() is a faster replacement for the normal system crypt().
241This function calls DES_fcrypt() with a static array passed as the
242third parameter.  This mostly emulates the normal non-thread-safe semantics
243of crypt(3).
244The B<salt> must be two ASCII characters.
245
246The values returned by DES_fcrypt() and DES_crypt() are terminated by NUL
247character.
248
249DES_enc_write() writes I<len> bytes to file descriptor I<fd> from
250buffer I<buf>. The data is encrypted via I<pcbc_encrypt> (default)
251using I<sched> for the key and I<iv> as a starting vector.  The actual
252data send down I<fd> consists of 4 bytes (in network byte order)
253containing the length of the following encrypted data.  The encrypted
254data then follows, padded with random data out to a multiple of 8
255bytes.
256
257=head1 BUGS
258
259DES_cbc_encrypt() does not modify B<ivec>; use DES_ncbc_encrypt()
260instead.
261
262DES_cfb_encrypt() and DES_ofb_encrypt() operates on input of 8 bits.
263What this means is that if you set numbits to 12, and length to 2, the
264first 12 bits will come from the 1st input byte and the low half of
265the second input byte.  The second 12 bits will have the low 8 bits
266taken from the 3rd input byte and the top 4 bits taken from the 4th
267input byte.  The same holds for output.  This function has been
268implemented this way because most people will be using a multiple of 8
269and because once you get into pulling bytes input bytes apart things
270get ugly!
271
272DES_string_to_key() is available for backward compatibility with the
273MIT library.  New applications should use a cryptographic hash function.
274The same applies for DES_string_to_2key().
275
276=head1 NOTES
277
278The B<des> library was written to be source code compatible with
279the MIT Kerberos library.
280
281Applications should use the higher level functions
282L<EVP_EncryptInit(3)> etc. instead of calling these
283functions directly.
284
285Single-key DES is insecure due to its short key size.  ECB mode is
286not suitable for most applications; see L<des_modes(7)>.
287
288=head1 RETURN VALUES
289
290DES_set_key(), DES_key_sched(), DES_set_key_checked() and DES_is_weak_key()
291return 0 on success or negative values on error.
292
293DES_cbc_cksum() and DES_quad_cksum() return 4-byte integer representing the
294last 4 bytes of the checksum of the input.
295
296DES_fcrypt() returns a pointer to the caller-provided buffer and DES_crypt() -
297to a static buffer on success; otherwise they return NULL.
298
299=head1 HISTORY
300
301The requirement that the B<salt> parameter to DES_crypt() and DES_fcrypt()
302be two ASCII characters was first enforced in
303OpenSSL 1.1.0.  Previous versions tried to use the letter uppercase B<A>
304if both character were not present, and could crash when given non-ASCII
305on some platforms.
306
307=head1 SEE ALSO
308
309L<des_modes(7)>,
310L<EVP_EncryptInit(3)>
311
312=head1 COPYRIGHT
313
314Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
315
316Licensed under the OpenSSL license (the "License").  You may not use
317this file except in compliance with the License.  You can obtain a copy
318in the file LICENSE in the source distribution or at
319L<https://www.openssl.org/source/license.html>.
320
321=cut
322