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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_cbcm_encrypt, DES_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_enc_read, DES_enc_write - 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,
24 DES_key_schedule *schedule);
25 void DES_set_key_unchecked(const_DES_cblock *key,
26 DES_key_schedule *schedule);
27
28 void DES_set_odd_parity(DES_cblock *key);
29 int DES_is_weak_key(const_DES_cblock *key);
30
31 void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output,
32 DES_key_schedule *ks, int enc);
33 void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output,
34 DES_key_schedule *ks1, DES_key_schedule *ks2, int enc);
35 void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output,
36 DES_key_schedule *ks1, DES_key_schedule *ks2,
37 DES_key_schedule *ks3, int enc);
38
39 void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output,
40 long length, DES_key_schedule *schedule, DES_cblock *ivec,
41 int enc);
42 void DES_cfb_encrypt(const unsigned char *in, unsigned char *out,
43 int numbits, long length, DES_key_schedule *schedule,
44 DES_cblock *ivec, int enc);
45 void DES_ofb_encrypt(const unsigned char *in, unsigned char *out,
46 int numbits, long length, DES_key_schedule *schedule,
47 DES_cblock *ivec);
48 void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output,
49 long length, DES_key_schedule *schedule, DES_cblock *ivec,
50 int enc);
51 void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
52 long length, DES_key_schedule *schedule, DES_cblock *ivec,
53 int *num, int enc);
54 void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out,
55 long length, DES_key_schedule *schedule, DES_cblock *ivec,
56 int *num);
57
58 void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output,
59 long length, DES_key_schedule *schedule, DES_cblock *ivec,
60 const_DES_cblock *inw, const_DES_cblock *outw, int enc);
61
62 void DES_ede2_cbc_encrypt(const unsigned char *input,
63 unsigned char *output, long length, DES_key_schedule *ks1,
64 DES_key_schedule *ks2, DES_cblock *ivec, int enc);
65 void DES_ede2_cfb64_encrypt(const unsigned char *in,
66 unsigned char *out, long length, DES_key_schedule *ks1,
67 DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc);
68 void DES_ede2_ofb64_encrypt(const unsigned char *in,
69 unsigned char *out, long length, DES_key_schedule *ks1,
70 DES_key_schedule *ks2, DES_cblock *ivec, int *num);
71
72 void DES_ede3_cbc_encrypt(const unsigned char *input,
73 unsigned char *output, long length, DES_key_schedule *ks1,
74 DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec,
75 int enc);
76 void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out,
77 long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
78 DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2,
79 int enc);
80 void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out,
81 long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
82 DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc);
83 void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out,
84 long length, DES_key_schedule *ks1,
85 DES_key_schedule *ks2, DES_key_schedule *ks3,
86 DES_cblock *ivec, int *num);
87
88 DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output,
89 long length, DES_key_schedule *schedule,
90 const_DES_cblock *ivec);
91 DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[],
92 long length, int out_count, DES_cblock *seed);
93 void DES_string_to_key(const char *str, DES_cblock *key);
94 void DES_string_to_2keys(const char *str, DES_cblock *key1,
95 DES_cblock *key2);
96
97 char *DES_fcrypt(const char *buf, const char *salt, char *ret);
98 char *DES_crypt(const char *buf, const char *salt);
99
100 int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched,
101 DES_cblock *iv);
102 int DES_enc_write(int fd, const void *buf, int len,
103 DES_key_schedule *sched, DES_cblock *iv);
104
105=head1 DESCRIPTION
106
107This library contains a fast implementation of the DES encryption
108algorithm.
109
110There are two phases to the use of DES encryption. The first is the
111generation of a I<DES_key_schedule> from a key, the second is the
112actual encryption. A DES key is of type I<DES_cblock>. This type is
113consists of 8 bytes with odd parity. The least significant bit in
114each byte is the parity bit. The key schedule is an expanded form of
115the key; it is used to speed the encryption process.
116
117DES_random_key() generates a random key in odd parity.
118
119Before a DES key can be used, it must be converted into the
120architecture dependent I<DES_key_schedule> via the
121DES_set_key_checked() or DES_set_key_unchecked() function.
122
123DES_set_key_checked() will check that the key passed is of odd parity
124and is not a week or semi-weak key. If the parity is wrong, then -1
125is returned. If the key is a weak key, then -2 is returned. If an
126error is returned, the key schedule is not generated.
127
128DES_set_key() works like
129DES_set_key_checked() if the I<DES_check_key> flag is non-zero,
130otherwise like DES_set_key_unchecked(). These functions are available
131for compatibility; it is recommended to use a function that does not
132depend on a global variable.
133
134DES_set_odd_parity() sets the parity of the passed I<key> to odd.
135
136DES_is_weak_key() returns 1 is the passed key is a weak key, 0 if it
137is ok.
138
139The following routines mostly operate on an input and output stream of
140I<DES_cblock>s.
141
142DES_ecb_encrypt() is the basic DES encryption routine that encrypts or
143decrypts a single 8-byte I<DES_cblock> in I<electronic code book>
144(ECB) mode. It always transforms the input data, pointed to by
145I<input>, into the output data, pointed to by the I<output> argument.
146If the I<encrypt> argument is non-zero (DES_ENCRYPT), the I<input>
147(cleartext) is encrypted in to the I<output> (ciphertext) using the
148key_schedule specified by the I<schedule> argument, previously set via
149I<DES_set_key>. If I<encrypt> is zero (DES_DECRYPT), the I<input> (now
150ciphertext) is decrypted into the I<output> (now cleartext). Input
151and output may overlap. DES_ecb_encrypt() does not return a value.
152
153DES_ecb3_encrypt() encrypts/decrypts the I<input> block by using
154three-key Triple-DES encryption in ECB mode. This involves encrypting
155the input with I<ks1>, decrypting with the key schedule I<ks2>, and
156then encrypting with I<ks3>. This routine greatly reduces the chances
157of brute force breaking of DES and has the advantage of if I<ks1>,
158I<ks2> and I<ks3> are the same, it is equivalent to just encryption
159using ECB mode and I<ks1> as the key.
160
161The macro DES_ecb2_encrypt() is provided to perform two-key Triple-DES
162encryption by using I<ks1> for the final encryption.
163
164DES_ncbc_encrypt() encrypts/decrypts using the I<cipher-block-chaining>
165(CBC) mode of DES. If the I<encrypt> argument is non-zero, the
166routine cipher-block-chain encrypts the cleartext data pointed to by
167the I<input> argument into the ciphertext pointed to by the I<output>
168argument, using the key schedule provided by the I<schedule> argument,
169and initialization vector provided by the I<ivec> argument. If the
170I<length> argument is not an integral multiple of eight bytes, the
171last block is copied to a temporary area and zero filled. The output
172is always an integral multiple of eight bytes.
173
174DES_xcbc_encrypt() is RSA's DESX mode of DES. It uses I<inw> and
175I<outw> to 'whiten' the encryption. I<inw> and I<outw> are secret
176(unlike the iv) and are as such, part of the key. So the key is sort
177of 24 bytes. This is much better than CBC DES.
178
179DES_ede3_cbc_encrypt() implements outer triple CBC DES encryption with
180three keys. This means that each DES operation inside the CBC mode is
181really an C<C=E(ks3,D(ks2,E(ks1,M)))>. This mode is used by SSL.
182
183The DES_ede2_cbc_encrypt() macro implements two-key Triple-DES by
184reusing I<ks1> for the final encryption. C<C=E(ks1,D(ks2,E(ks1,M)))>.
185This form of Triple-DES is used by the RSAREF library.
186
187DES_pcbc_encrypt() encrypt/decrypts using the propagating cipher block
188chaining mode used by Kerberos v4. Its parameters are the same as
189DES_ncbc_encrypt().
190
191DES_cfb_encrypt() encrypt/decrypts using cipher feedback mode. This
192method takes an array of characters as input and outputs and array of
193characters. It does not require any padding to 8 character groups.
194Note: the I<ivec> variable is changed and the new changed value needs to
195be passed to the next call to this function. Since this function runs
196a complete DES ECB encryption per I<numbits>, this function is only
197suggested for use when sending small numbers of characters.
198
199DES_cfb64_encrypt()
200implements CFB mode of DES with 64bit feedback. Why is this
201useful you ask? Because this routine will allow you to encrypt an
202arbitrary number of bytes, no 8 byte padding. Each call to this
203routine will encrypt the input bytes to output and then update ivec
204and num. num contains 'how far' we are though ivec. If this does
205not make much sense, read more about cfb mode of DES :-).
206
207DES_ede3_cfb64_encrypt() and DES_ede2_cfb64_encrypt() is the same as
208DES_cfb64_encrypt() except that Triple-DES is used.
209
210DES_ofb_encrypt() encrypts using output feedback mode. This method
211takes an array of characters as input and outputs and array of
212characters. It does not require any padding to 8 character groups.
213Note: the I<ivec> variable is changed and the new changed value needs to
214be passed to the next call to this function. Since this function runs
215a complete DES ECB encryption per numbits, this function is only
216suggested for use when sending small numbers of characters.
217
218DES_ofb64_encrypt() is the same as DES_cfb64_encrypt() using Output
219Feed Back mode.
220
221DES_ede3_ofb64_encrypt() and DES_ede2_ofb64_encrypt() is the same as
222DES_ofb64_encrypt(), using Triple-DES.
223
224The following functions are included in the DES library for
225compatibility with the MIT Kerberos library.
226
227DES_cbc_cksum() produces an 8 byte checksum based on the input stream
228(via CBC encryption). The last 4 bytes of the checksum are returned
229and the complete 8 bytes are placed in I<output>. This function is
230used by Kerberos v4. Other applications should use
231L<EVP_DigestInit(3)|EVP_DigestInit(3)> etc. instead.
232
233DES_quad_cksum() is a Kerberos v4 function. It returns a 4 byte
234checksum from the input bytes. The algorithm can be iterated over the
235input, depending on I<out_count>, 1, 2, 3 or 4 times. If I<output> is
236non-NULL, the 8 bytes generated by each pass are written into
237I<output>.
238
239The following are DES-based transformations:
240
241DES_fcrypt() is a fast version of the Unix crypt(3) function. This
242version takes only a small amount of space relative to other fast
243crypt() implementations. This is different to the normal crypt in
244that the third parameter is the buffer that the return value is
245written into. It needs to be at least 14 bytes long. This function
246is thread safe, unlike the normal crypt.
247
248DES_crypt() is a faster replacement for the normal system crypt().
249This function calls DES_fcrypt() with a static array passed as the
250third parameter. This emulates the normal non-thread safe semantics
251of crypt(3).
252
253DES_enc_write() writes I<len> bytes to file descriptor I<fd> from
254buffer I<buf>. The data is encrypted via I<pcbc_encrypt> (default)
255using I<sched> for the key and I<iv> as a starting vector. The actual
256data send down I<fd> consists of 4 bytes (in network byte order)
257containing the length of the following encrypted data. The encrypted
258data then follows, padded with random data out to a multiple of 8
259bytes.
260
261DES_enc_read() is used to read I<len> bytes from file descriptor
262I<fd> into buffer I<buf>. The data being read from I<fd> is assumed to
263have come from DES_enc_write() and is decrypted using I<sched> for
264the key schedule and I<iv> for the initial vector.
265
266B<Warning:> The data format used by DES_enc_write() and DES_enc_read()
267has a cryptographic weakness: When asked to write more than MAXWRITE
268bytes, DES_enc_write() will split the data into several chunks that
269are all encrypted using the same IV. So don't use these functions
270unless you are sure you know what you do (in which case you might not
271want to use them anyway). They cannot handle non-blocking sockets.
272DES_enc_read() uses an internal state and thus cannot be used on
273multiple files.
274
275I<DES_rw_mode> is used to specify the encryption mode to use with
276DES_enc_read() and DES_end_write(). If set to I<DES_PCBC_MODE> (the
277default), DES_pcbc_encrypt is used. If set to I<DES_CBC_MODE>
278DES_cbc_encrypt is used.
279
280=head1 NOTES
281
282Single-key DES is insecure due to its short key size. ECB mode is
283not suitable for most applications.
284
285The L<evp(3)|evp(3)> library provides higher-level encryption functions.
286
287=head1 BUGS
288
289DES_cbc_encrypt() does not modify B<ivec>; use DES_ncbc_encrypt()
290instead.
291
292DES_cfb_encrypt() and DES_ofb_encrypt() operates on input of 8 bits.
293What this means is that if you set numbits to 12, and length to 2, the
294first 12 bits will come from the 1st input byte and the low half of
295the second input byte. The second 12 bits will have the low 8 bits
296taken from the 3rd input byte and the top 4 bits taken from the 4th
297input byte. The same holds for output. This function has been
298implemented this way because most people will be using a multiple of 8
299and because once you get into pulling bytes input bytes apart things
300get ugly!
301
302DES_string_to_key() is available for backward compatibility with the
303MIT library. New applications should use a cryptographic hash function.
304The same applies for DES_string_to_2key().
305
306=head1 CONFORMING TO
307
308ANSI X3.106
309
310The B<des> library was initially written to be source code compatible with
311the MIT Kerberos library.
312
313=head1 SEE ALSO
314
315crypt(3), L<evp(3)|evp(3)>, L<rand(3)|rand(3)>
316
317=head1 HISTORY
318
319In OpenSSL 0.9.7, all des_ functions were renamed to DES_ to avoid
320clashes with older versions of libdes.
321
322DES_set_key_checked() and DES_set_key_unchecked() were added in
323OpenSSL 0.9.5.
324
325des_generate_random_block(), des_init_random_number_generator(),
326des_new_random_key(), des_set_random_generator_seed() and
327des_set_sequence_number() and des_rand_data() are used in newer
328versions of Kerberos but are not implemented here.
329
330DES_random_key() generated cryptographically weak random data in
331SSLeay and in OpenSSL prior version 0.9.5, as well as in the original
332MIT library.
333
334=head1 AUTHOR
335
336Eric Young (eay@cryptsoft.com). Modified for the OpenSSL project
337(http://www.openssl.org).
338
339=cut