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 random generator must be
108seeded when calling this function.
109If the automatic seeding or reseeding of the OpenSSL CSPRNG fails due to
110external circumstances (see L<RAND(7)>), the operation will fail.
111If the function fails, 0 is returned.
112
113Before a DES key can be used, it must be converted into the
114architecture dependent I<DES_key_schedule> via the
115DES_set_key_checked() or DES_set_key_unchecked() function.
116
117DES_set_key_checked() will check that the key passed is of odd parity
118and is not a weak or semi-weak key.  If the parity is wrong, then -1
119is returned.  If the key is a weak key, then -2 is returned.  If an
120error is returned, the key schedule is not generated.
121
122DES_set_key() works like
123DES_set_key_checked() if the I<DES_check_key> flag is non-zero,
124otherwise like DES_set_key_unchecked().  These functions are available
125for compatibility; it is recommended to use a function that does not
126depend on a global variable.
127
128DES_set_odd_parity() sets the parity of the passed I<key> to odd.
129
130DES_is_weak_key() returns 1 if the passed key is a weak key, 0 if it
131is ok.
132
133The following routines mostly operate on an input and output stream of
134I<DES_cblock>s.
135
136DES_ecb_encrypt() is the basic DES encryption routine that encrypts or
137decrypts a single 8-byte I<DES_cblock> in I<electronic code book>
138(ECB) mode.  It always transforms the input data, pointed to by
139I<input>, into the output data, pointed to by the I<output> argument.
140If the I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input>
141(cleartext) is encrypted in to the I<output> (ciphertext) using the
142key_schedule specified by the I<schedule> argument, previously set via
143I<DES_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now
144ciphertext) is decrypted into the I<output> (now cleartext).  Input
145and output may overlap.  DES_ecb_encrypt() does not return a value.
146
147DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using
148three-key Triple-DES encryption in ECB mode.  This involves encrypting
149the input with I<ks1>, decrypting with the key schedule I<ks2>, and
150then encrypting with I<ks3>.  This routine greatly reduces the chances
151of brute force breaking of DES and has the advantage of if I<ks1>,
152I<ks2> and I<ks3> are the same, it is equivalent to just encryption
153using ECB mode and I<ks1> as the key.
154
155The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES
156encryption by using I<ks1> for the final encryption.
157
158DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining>
159(CBC) mode of DES.  If the I<encrypt> argument is non-zero, the
160routine cipher-block-chain encrypts the cleartext data pointed to by
161the I<input> argument into the ciphertext pointed to by the I<output>
162argument, using the key schedule provided by the I<schedule> argument,
163and initialization vector provided by the I<ivec> argument.  If the
164I<length> argument is not an integral multiple of eight bytes, the
165last block is copied to a temporary area and zero filled.  The output
166is always an integral multiple of eight bytes.
167
168DES_xcbc_encrypt() is RSA's DESX mode of DES.  It uses I<inw> and
169I<outw> to 'whiten' the encryption.  I<inw> and I<outw> are secret
170(unlike the iv) and are as such, part of the key.  So the key is sort
171of 24 bytes.  This is much better than CBC DES.
172
173DES_ede3_cbc_encrypt() implements outer triple CBC DES encryption with
174three keys. This means that each DES operation inside the CBC mode is
175C<C=E(ks3,D(ks2,E(ks1,M)))>.  This mode is used by SSL.
176
177The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by
178reusing I<ks1> for the final encryption.  C<C=E(ks1,D(ks2,E(ks1,M)))>.
179This form of Triple-DES is used by the RSAREF library.
180
181DES_pcbc_encrypt() encrypts/decrypts using the propagating cipher block
182chaining mode used by Kerberos v4. Its parameters are the same as
183DES_ncbc_encrypt().
184
185DES_cfb_encrypt() encrypts/decrypts using cipher feedback mode.  This
186method takes an array of characters as input and outputs an array of
187characters.  It does not require any padding to 8 character groups.
188Note: the I<ivec> variable is changed and the new changed value needs to
189be passed to the next call to this function.  Since this function runs
190a complete DES ECB encryption per I<numbits>, this function is only
191suggested for use when sending a small number of characters.
192
193DES_cfb64_encrypt()
194implements CFB mode of DES with 64-bit feedback.  Why is this
195useful you ask?  Because this routine will allow you to encrypt an
196arbitrary number of bytes, without 8 byte padding.  Each call to this
197routine will encrypt the input bytes to output and then update ivec
198and num.  num contains 'how far' we are though ivec.  If this does
199not make much sense, read more about CFB mode of DES.
200
201DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as
202DES_cfb64_encrypt() except that Triple-DES is used.
203
204DES_ofb_encrypt() encrypts using output feedback mode.  This method
205takes an array of characters as input and outputs an array of
206characters.  It does not require any padding to 8 character groups.
207Note: the I<ivec> variable is changed and the new changed value needs to
208be passed to the next call to this function.  Since this function runs
209a complete DES ECB encryption per I<numbits>, this function is only
210suggested for use when sending a small number of characters.
211
212DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output
213Feed Back mode.
214
215DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as
216DES_ofb64_encrypt(), using Triple-DES.
217
218The following functions are included in the DES library for
219compatibility with the MIT Kerberos library.
220
221DES_cbc_cksum() produces an 8 byte checksum based on the input stream
222(via CBC encryption).  The last 4 bytes of the checksum are returned
223and the complete 8 bytes are placed in I<output>. This function is
224used by Kerberos v4.  Other applications should use
225L<EVP_DigestInit(3)> etc. instead.
226
227DES_quad_cksum() is a Kerberos v4 function.  It returns a 4 byte
228checksum from the input bytes.  The algorithm can be iterated over the
229input, depending on I<out_count>, 1, 2, 3 or 4 times.  If I<output> is
230non-NULL, the 8 bytes generated by each pass are written into
231I<output>.
232
233The following are DES-based transformations:
234
235DES_fcrypt() is a fast version of the Unix crypt(3) function.  This
236version takes only a small amount of space relative to other fast
237crypt() implementations.  This is different to the normal crypt() in
238that the third parameter is the buffer that the return value is
239written into.  It needs to be at least 14 bytes long.  This function
240is thread safe, unlike the normal crypt().
241
242DES_crypt() is a faster replacement for the normal system crypt().
243This function calls DES_fcrypt() with a static array passed as the
244third parameter.  This mostly emulates the normal non-thread-safe semantics
245of crypt(3).
246The B<salt> must be two ASCII characters.
247
248The values returned by DES_fcrypt() and DES_crypt() are terminated by NUL
249character.
250
251DES_enc_write() writes I<len> bytes to file descriptor I<fd> from
252buffer I<buf>. The data is encrypted via I<pcbc_encrypt> (default)
253using I<sched> for the key and I<iv> as a starting vector.  The actual
254data send down I<fd> consists of 4 bytes (in network byte order)
255containing the length of the following encrypted data.  The encrypted
256data then follows, padded with random data out to a multiple of 8
257bytes.
258
259=head1 BUGS
260
261DES_cbc_encrypt() does not modify B<ivec>; use DES_ncbc_encrypt()
262instead.
263
264DES_cfb_encrypt() and DES_ofb_encrypt() operates on input of 8 bits.
265What this means is that if you set numbits to 12, and length to 2, the
266first 12 bits will come from the 1st input byte and the low half of
267the second input byte.  The second 12 bits will have the low 8 bits
268taken from the 3rd input byte and the top 4 bits taken from the 4th
269input byte.  The same holds for output.  This function has been
270implemented this way because most people will be using a multiple of 8
271and because once you get into pulling bytes input bytes apart things
272get ugly!
273
274DES_string_to_key() is available for backward compatibility with the
275MIT library.  New applications should use a cryptographic hash function.
276The same applies for DES_string_to_2key().
277
278=head1 NOTES
279
280The B<des> library was written to be source code compatible with
281the MIT Kerberos library.
282
283Applications should use the higher level functions
284L<EVP_EncryptInit(3)> etc. instead of calling these
285functions directly.
286
287Single-key DES is insecure due to its short key size.  ECB mode is
288not suitable for most applications; see L<des_modes(7)>.
289
290=head1 RETURN VALUES
291
292DES_set_key(), DES_key_sched(), DES_set_key_checked() and DES_is_weak_key()
293return 0 on success or negative values on error.
294
295DES_cbc_cksum() and DES_quad_cksum() return 4-byte integer representing the
296last 4 bytes of the checksum of the input.
297
298DES_fcrypt() returns a pointer to the caller-provided buffer and DES_crypt() -
299to a static buffer on success; otherwise they return NULL.
300
301=head1 SEE ALSO
302
303L<des_modes(7)>,
304L<EVP_EncryptInit(3)>
305
306=head1 HISTORY
307
308The requirement that the B<salt> parameter to DES_crypt() and DES_fcrypt()
309be two ASCII characters was first enforced in
310OpenSSL 1.1.0.  Previous versions tried to use the letter uppercase B<A>
311if both character were not present, and could crash when given non-ASCII
312on some platforms.
313
314=head1 COPYRIGHT
315
316Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
317
318Licensed under the OpenSSL license (the "License").  You may not use
319this file except in compliance with the License.  You can obtain a copy
320in the file LICENSE in the source distribution or at
321L<https://www.openssl.org/source/license.html>.
322
323=cut
324