des.3 21 KB

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  129. .\" ========================================================================
  130. .\"
  131. .IX Title "des 3"
  132. .TH des 3 "2019-09-12" "1.0.2g" "OpenSSL"
  133. .\" For nroff, turn off justification. Always turn off hyphenation; it makes
  134. .\" way too many mistakes in technical documents.
  135. .if n .ad l
  136. .nh
  137. .SH "NAME"
  138. DES_random_key, DES_set_key, DES_key_sched, DES_set_key_checked,
  139. DES_set_key_unchecked, DES_set_odd_parity, DES_is_weak_key,
  140. DES_ecb_encrypt, DES_ecb2_encrypt, DES_ecb3_encrypt, DES_ncbc_encrypt,
  141. DES_cfb_encrypt, DES_ofb_encrypt, DES_pcbc_encrypt, DES_cfb64_encrypt,
  142. DES_ofb64_encrypt, DES_xcbc_encrypt, DES_ede2_cbc_encrypt,
  143. DES_ede2_cfb64_encrypt, DES_ede2_ofb64_encrypt, DES_ede3_cbc_encrypt,
  144. DES_ede3_cbcm_encrypt, DES_ede3_cfb64_encrypt, DES_ede3_ofb64_encrypt,
  145. DES_cbc_cksum, DES_quad_cksum, DES_string_to_key, DES_string_to_2keys,
  146. DES_fcrypt, DES_crypt, DES_enc_read, DES_enc_write \- DES encryption
  147. .SH "SYNOPSIS"
  148. .IX Header "SYNOPSIS"
  149. .Vb 1
  150. \& #include <openssl/des.h>
  151. \&
  152. \& void DES_random_key(DES_cblock *ret);
  153. \&
  154. \& int DES_set_key(const_DES_cblock *key, DES_key_schedule *schedule);
  155. \& int DES_key_sched(const_DES_cblock *key, DES_key_schedule *schedule);
  156. \& int DES_set_key_checked(const_DES_cblock *key,
  157. \& DES_key_schedule *schedule);
  158. \& void DES_set_key_unchecked(const_DES_cblock *key,
  159. \& DES_key_schedule *schedule);
  160. \&
  161. \& void DES_set_odd_parity(DES_cblock *key);
  162. \& int DES_is_weak_key(const_DES_cblock *key);
  163. \&
  164. \& void DES_ecb_encrypt(const_DES_cblock *input, DES_cblock *output,
  165. \& DES_key_schedule *ks, int enc);
  166. \& void DES_ecb2_encrypt(const_DES_cblock *input, DES_cblock *output,
  167. \& DES_key_schedule *ks1, DES_key_schedule *ks2, int enc);
  168. \& void DES_ecb3_encrypt(const_DES_cblock *input, DES_cblock *output,
  169. \& DES_key_schedule *ks1, DES_key_schedule *ks2,
  170. \& DES_key_schedule *ks3, int enc);
  171. \&
  172. \& void DES_ncbc_encrypt(const unsigned char *input, unsigned char *output,
  173. \& long length, DES_key_schedule *schedule, DES_cblock *ivec,
  174. \& int enc);
  175. \& void DES_cfb_encrypt(const unsigned char *in, unsigned char *out,
  176. \& int numbits, long length, DES_key_schedule *schedule,
  177. \& DES_cblock *ivec, int enc);
  178. \& void DES_ofb_encrypt(const unsigned char *in, unsigned char *out,
  179. \& int numbits, long length, DES_key_schedule *schedule,
  180. \& DES_cblock *ivec);
  181. \& void DES_pcbc_encrypt(const unsigned char *input, unsigned char *output,
  182. \& long length, DES_key_schedule *schedule, DES_cblock *ivec,
  183. \& int enc);
  184. \& void DES_cfb64_encrypt(const unsigned char *in, unsigned char *out,
  185. \& long length, DES_key_schedule *schedule, DES_cblock *ivec,
  186. \& int *num, int enc);
  187. \& void DES_ofb64_encrypt(const unsigned char *in, unsigned char *out,
  188. \& long length, DES_key_schedule *schedule, DES_cblock *ivec,
  189. \& int *num);
  190. \&
  191. \& void DES_xcbc_encrypt(const unsigned char *input, unsigned char *output,
  192. \& long length, DES_key_schedule *schedule, DES_cblock *ivec,
  193. \& const_DES_cblock *inw, const_DES_cblock *outw, int enc);
  194. \&
  195. \& void DES_ede2_cbc_encrypt(const unsigned char *input,
  196. \& unsigned char *output, long length, DES_key_schedule *ks1,
  197. \& DES_key_schedule *ks2, DES_cblock *ivec, int enc);
  198. \& void DES_ede2_cfb64_encrypt(const unsigned char *in,
  199. \& unsigned char *out, long length, DES_key_schedule *ks1,
  200. \& DES_key_schedule *ks2, DES_cblock *ivec, int *num, int enc);
  201. \& void DES_ede2_ofb64_encrypt(const unsigned char *in,
  202. \& unsigned char *out, long length, DES_key_schedule *ks1,
  203. \& DES_key_schedule *ks2, DES_cblock *ivec, int *num);
  204. \&
  205. \& void DES_ede3_cbc_encrypt(const unsigned char *input,
  206. \& unsigned char *output, long length, DES_key_schedule *ks1,
  207. \& DES_key_schedule *ks2, DES_key_schedule *ks3, DES_cblock *ivec,
  208. \& int enc);
  209. \& void DES_ede3_cbcm_encrypt(const unsigned char *in, unsigned char *out,
  210. \& long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
  211. \& DES_key_schedule *ks3, DES_cblock *ivec1, DES_cblock *ivec2,
  212. \& int enc);
  213. \& void DES_ede3_cfb64_encrypt(const unsigned char *in, unsigned char *out,
  214. \& long length, DES_key_schedule *ks1, DES_key_schedule *ks2,
  215. \& DES_key_schedule *ks3, DES_cblock *ivec, int *num, int enc);
  216. \& void DES_ede3_ofb64_encrypt(const unsigned char *in, unsigned char *out,
  217. \& long length, DES_key_schedule *ks1,
  218. \& DES_key_schedule *ks2, DES_key_schedule *ks3,
  219. \& DES_cblock *ivec, int *num);
  220. \&
  221. \& DES_LONG DES_cbc_cksum(const unsigned char *input, DES_cblock *output,
  222. \& long length, DES_key_schedule *schedule,
  223. \& const_DES_cblock *ivec);
  224. \& DES_LONG DES_quad_cksum(const unsigned char *input, DES_cblock output[],
  225. \& long length, int out_count, DES_cblock *seed);
  226. \& void DES_string_to_key(const char *str, DES_cblock *key);
  227. \& void DES_string_to_2keys(const char *str, DES_cblock *key1,
  228. \& DES_cblock *key2);
  229. \&
  230. \& char *DES_fcrypt(const char *buf, const char *salt, char *ret);
  231. \& char *DES_crypt(const char *buf, const char *salt);
  232. \&
  233. \& int DES_enc_read(int fd, void *buf, int len, DES_key_schedule *sched,
  234. \& DES_cblock *iv);
  235. \& int DES_enc_write(int fd, const void *buf, int len,
  236. \& DES_key_schedule *sched, DES_cblock *iv);
  237. .Ve
  238. .SH "DESCRIPTION"
  239. .IX Header "DESCRIPTION"
  240. This library contains a fast implementation of the \s-1DES\s0 encryption
  241. algorithm.
  242. .PP
  243. There are two phases to the use of \s-1DES\s0 encryption. The first is the
  244. generation of a \fIDES_key_schedule\fR from a key, the second is the
  245. actual encryption. A \s-1DES\s0 key is of type \fIDES_cblock\fR. This type is
  246. consists of 8 bytes with odd parity. The least significant bit in
  247. each byte is the parity bit. The key schedule is an expanded form of
  248. the key; it is used to speed the encryption process.
  249. .PP
  250. \&\fIDES_random_key()\fR generates a random key. The \s-1PRNG\s0 must be seeded
  251. prior to using this function (see \fIrand\fR\|(3)). If the \s-1PRNG\s0
  252. could not generate a secure key, 0 is returned.
  253. .PP
  254. Before a \s-1DES\s0 key can be used, it must be converted into the
  255. architecture dependent \fIDES_key_schedule\fR via the
  256. \&\fIDES_set_key_checked()\fR or \fIDES_set_key_unchecked()\fR function.
  257. .PP
  258. \&\fIDES_set_key_checked()\fR will check that the key passed is of odd parity
  259. and is not a week or semi-weak key. If the parity is wrong, then \-1
  260. is returned. If the key is a weak key, then \-2 is returned. If an
  261. error is returned, the key schedule is not generated.
  262. .PP
  263. \&\fIDES_set_key()\fR works like
  264. \&\fIDES_set_key_checked()\fR if the \fIDES_check_key\fR flag is non-zero,
  265. otherwise like \fIDES_set_key_unchecked()\fR. These functions are available
  266. for compatibility; it is recommended to use a function that does not
  267. depend on a global variable.
  268. .PP
  269. \&\fIDES_set_odd_parity()\fR sets the parity of the passed \fIkey\fR to odd.
  270. .PP
  271. \&\fIDES_is_weak_key()\fR returns 1 if the passed key is a weak key, 0 if it
  272. is ok.
  273. .PP
  274. The following routines mostly operate on an input and output stream of
  275. \&\fIDES_cblock\fRs.
  276. .PP
  277. \&\fIDES_ecb_encrypt()\fR is the basic \s-1DES\s0 encryption routine that encrypts or
  278. decrypts a single 8\-byte \fIDES_cblock\fR in \fIelectronic code book\fR
  279. (\s-1ECB\s0) mode. It always transforms the input data, pointed to by
  280. \&\fIinput\fR, into the output data, pointed to by the \fIoutput\fR argument.
  281. If the \fIencrypt\fR argument is non-zero (\s-1DES_ENCRYPT\s0), the \fIinput\fR
  282. (cleartext) is encrypted in to the \fIoutput\fR (ciphertext) using the
  283. key_schedule specified by the \fIschedule\fR argument, previously set via
  284. \&\fIDES_set_key\fR. If \fIencrypt\fR is zero (\s-1DES_DECRYPT\s0), the \fIinput\fR (now
  285. ciphertext) is decrypted into the \fIoutput\fR (now cleartext). Input
  286. and output may overlap. \fIDES_ecb_encrypt()\fR does not return a value.
  287. .PP
  288. \&\fIDES_ecb3_encrypt()\fR encrypts/decrypts the \fIinput\fR block by using
  289. three-key Triple-DES encryption in \s-1ECB\s0 mode. This involves encrypting
  290. the input with \fIks1\fR, decrypting with the key schedule \fIks2\fR, and
  291. then encrypting with \fIks3\fR. This routine greatly reduces the chances
  292. of brute force breaking of \s-1DES\s0 and has the advantage of if \fIks1\fR,
  293. \&\fIks2\fR and \fIks3\fR are the same, it is equivalent to just encryption
  294. using \s-1ECB\s0 mode and \fIks1\fR as the key.
  295. .PP
  296. The macro \fIDES_ecb2_encrypt()\fR is provided to perform two-key Triple-DES
  297. encryption by using \fIks1\fR for the final encryption.
  298. .PP
  299. \&\fIDES_ncbc_encrypt()\fR encrypts/decrypts using the \fIcipher-block-chaining\fR
  300. (\s-1CBC\s0) mode of \s-1DES.\s0 If the \fIencrypt\fR argument is non-zero, the
  301. routine cipher-block-chain encrypts the cleartext data pointed to by
  302. the \fIinput\fR argument into the ciphertext pointed to by the \fIoutput\fR
  303. argument, using the key schedule provided by the \fIschedule\fR argument,
  304. and initialization vector provided by the \fIivec\fR argument. If the
  305. \&\fIlength\fR argument is not an integral multiple of eight bytes, the
  306. last block is copied to a temporary area and zero filled. The output
  307. is always an integral multiple of eight bytes.
  308. .PP
  309. \&\fIDES_xcbc_encrypt()\fR is \s-1RSA\s0's \s-1DESX\s0 mode of \s-1DES.\s0 It uses \fIinw\fR and
  310. \&\fIoutw\fR to 'whiten' the encryption. \fIinw\fR and \fIoutw\fR are secret
  311. (unlike the iv) and are as such, part of the key. So the key is sort
  312. of 24 bytes. This is much better than \s-1CBC DES.\s0
  313. .PP
  314. \&\fIDES_ede3_cbc_encrypt()\fR implements outer triple \s-1CBC DES\s0 encryption with
  315. three keys. This means that each \s-1DES\s0 operation inside the \s-1CBC\s0 mode is
  316. an \f(CW\*(C`C=E(ks3,D(ks2,E(ks1,M)))\*(C'\fR. This mode is used by \s-1SSL.\s0
  317. .PP
  318. The \fIDES_ede2_cbc_encrypt()\fR macro implements two-key Triple-DES by
  319. reusing \fIks1\fR for the final encryption. \f(CW\*(C`C=E(ks1,D(ks2,E(ks1,M)))\*(C'\fR.
  320. This form of Triple-DES is used by the \s-1RSAREF\s0 library.
  321. .PP
  322. \&\fIDES_pcbc_encrypt()\fR encrypt/decrypts using the propagating cipher block
  323. chaining mode used by Kerberos v4. Its parameters are the same as
  324. \&\fIDES_ncbc_encrypt()\fR.
  325. .PP
  326. \&\fIDES_cfb_encrypt()\fR encrypt/decrypts using cipher feedback mode. This
  327. method takes an array of characters as input and outputs and array of
  328. characters. It does not require any padding to 8 character groups.
  329. Note: the \fIivec\fR variable is changed and the new changed value needs to
  330. be passed to the next call to this function. Since this function runs
  331. a complete \s-1DES ECB\s0 encryption per \fInumbits\fR, this function is only
  332. suggested for use when sending small numbers of characters.
  333. .PP
  334. \&\fIDES_cfb64_encrypt()\fR
  335. implements \s-1CFB\s0 mode of \s-1DES\s0 with 64bit feedback. Why is this
  336. useful you ask? Because this routine will allow you to encrypt an
  337. arbitrary number of bytes, no 8 byte padding. Each call to this
  338. routine will encrypt the input bytes to output and then update ivec
  339. and num. num contains 'how far' we are though ivec. If this does
  340. not make much sense, read more about cfb mode of \s-1DES :\-\s0).
  341. .PP
  342. \&\fIDES_ede3_cfb64_encrypt()\fR and \fIDES_ede2_cfb64_encrypt()\fR is the same as
  343. \&\fIDES_cfb64_encrypt()\fR except that Triple-DES is used.
  344. .PP
  345. \&\fIDES_ofb_encrypt()\fR encrypts using output feedback mode. This method
  346. takes an array of characters as input and outputs and array of
  347. characters. It does not require any padding to 8 character groups.
  348. Note: the \fIivec\fR variable is changed and the new changed value needs to
  349. be passed to the next call to this function. Since this function runs
  350. a complete \s-1DES ECB\s0 encryption per numbits, this function is only
  351. suggested for use when sending small numbers of characters.
  352. .PP
  353. \&\fIDES_ofb64_encrypt()\fR is the same as \fIDES_cfb64_encrypt()\fR using Output
  354. Feed Back mode.
  355. .PP
  356. \&\fIDES_ede3_ofb64_encrypt()\fR and \fIDES_ede2_ofb64_encrypt()\fR is the same as
  357. \&\fIDES_ofb64_encrypt()\fR, using Triple-DES.
  358. .PP
  359. The following functions are included in the \s-1DES\s0 library for
  360. compatibility with the \s-1MIT\s0 Kerberos library.
  361. .PP
  362. \&\fIDES_cbc_cksum()\fR produces an 8 byte checksum based on the input stream
  363. (via \s-1CBC\s0 encryption). The last 4 bytes of the checksum are returned
  364. and the complete 8 bytes are placed in \fIoutput\fR. This function is
  365. used by Kerberos v4. Other applications should use
  366. \&\fIEVP_DigestInit\fR\|(3) etc. instead.
  367. .PP
  368. \&\fIDES_quad_cksum()\fR is a Kerberos v4 function. It returns a 4 byte
  369. checksum from the input bytes. The algorithm can be iterated over the
  370. input, depending on \fIout_count\fR, 1, 2, 3 or 4 times. If \fIoutput\fR is
  371. non-NULL, the 8 bytes generated by each pass are written into
  372. \&\fIoutput\fR.
  373. .PP
  374. The following are DES-based transformations:
  375. .PP
  376. \&\fIDES_fcrypt()\fR is a fast version of the Unix \fIcrypt\fR\|(3) function. This
  377. version takes only a small amount of space relative to other fast
  378. \&\fIcrypt()\fR implementations. This is different to the normal crypt in
  379. that the third parameter is the buffer that the return value is
  380. written into. It needs to be at least 14 bytes long. This function
  381. is thread safe, unlike the normal crypt.
  382. .PP
  383. \&\fIDES_crypt()\fR is a faster replacement for the normal system \fIcrypt()\fR.
  384. This function calls \fIDES_fcrypt()\fR with a static array passed as the
  385. third parameter. This emulates the normal non-thread safe semantics
  386. of \fIcrypt\fR\|(3).
  387. .PP
  388. \&\fIDES_enc_write()\fR writes \fIlen\fR bytes to file descriptor \fIfd\fR from
  389. buffer \fIbuf\fR. The data is encrypted via \fIpcbc_encrypt\fR (default)
  390. using \fIsched\fR for the key and \fIiv\fR as a starting vector. The actual
  391. data send down \fIfd\fR consists of 4 bytes (in network byte order)
  392. containing the length of the following encrypted data. The encrypted
  393. data then follows, padded with random data out to a multiple of 8
  394. bytes.
  395. .PP
  396. \&\fIDES_enc_read()\fR is used to read \fIlen\fR bytes from file descriptor
  397. \&\fIfd\fR into buffer \fIbuf\fR. The data being read from \fIfd\fR is assumed to
  398. have come from \fIDES_enc_write()\fR and is decrypted using \fIsched\fR for
  399. the key schedule and \fIiv\fR for the initial vector.
  400. .PP
  401. \&\fBWarning:\fR The data format used by \fIDES_enc_write()\fR and \fIDES_enc_read()\fR
  402. has a cryptographic weakness: When asked to write more than \s-1MAXWRITE\s0
  403. bytes, \fIDES_enc_write()\fR will split the data into several chunks that
  404. are all encrypted using the same \s-1IV.\s0 So don't use these functions
  405. unless you are sure you know what you do (in which case you might not
  406. want to use them anyway). They cannot handle non-blocking sockets.
  407. \&\fIDES_enc_read()\fR uses an internal state and thus cannot be used on
  408. multiple files.
  409. .PP
  410. \&\fIDES_rw_mode\fR is used to specify the encryption mode to use with
  411. \&\fIDES_enc_read()\fR and \fIDES_end_write()\fR. If set to \fI\s-1DES_PCBC_MODE\s0\fR (the
  412. default), DES_pcbc_encrypt is used. If set to \fI\s-1DES_CBC_MODE\s0\fR
  413. DES_cbc_encrypt is used.
  414. .SH "NOTES"
  415. .IX Header "NOTES"
  416. Single-key \s-1DES\s0 is insecure due to its short key size. \s-1ECB\s0 mode is
  417. not suitable for most applications; see \fIdes_modes\fR\|(7).
  418. .PP
  419. The \fIevp\fR\|(3) library provides higher-level encryption functions.
  420. .SH "BUGS"
  421. .IX Header "BUGS"
  422. \&\fIDES_3cbc_encrypt()\fR is flawed and must not be used in applications.
  423. .PP
  424. \&\fIDES_cbc_encrypt()\fR does not modify \fBivec\fR; use \fIDES_ncbc_encrypt()\fR
  425. instead.
  426. .PP
  427. \&\fIDES_cfb_encrypt()\fR and \fIDES_ofb_encrypt()\fR operates on input of 8 bits.
  428. What this means is that if you set numbits to 12, and length to 2, the
  429. first 12 bits will come from the 1st input byte and the low half of
  430. the second input byte. The second 12 bits will have the low 8 bits
  431. taken from the 3rd input byte and the top 4 bits taken from the 4th
  432. input byte. The same holds for output. This function has been
  433. implemented this way because most people will be using a multiple of 8
  434. and because once you get into pulling bytes input bytes apart things
  435. get ugly!
  436. .PP
  437. \&\fIDES_string_to_key()\fR is available for backward compatibility with the
  438. \&\s-1MIT\s0 library. New applications should use a cryptographic hash function.
  439. The same applies for \fIDES_string_to_2key()\fR.
  440. .SH "CONFORMING TO"
  441. .IX Header "CONFORMING TO"
  442. \&\s-1ANSI X3.106\s0
  443. .PP
  444. The \fBdes\fR library was written to be source code compatible with
  445. the \s-1MIT\s0 Kerberos library.
  446. .SH "SEE ALSO"
  447. .IX Header "SEE ALSO"
  448. \&\fIcrypt\fR\|(3), \fIdes_modes\fR\|(7), \fIevp\fR\|(3), \fIrand\fR\|(3)
  449. .SH "HISTORY"
  450. .IX Header "HISTORY"
  451. In OpenSSL 0.9.7, all des_ functions were renamed to \s-1DES_\s0 to avoid
  452. clashes with older versions of libdes. Compatibility des_ functions
  453. are provided for a short while, as well as \fIcrypt()\fR.
  454. Declarations for these are in <openssl/des_old.h>. There is no \s-1DES_\s0
  455. variant for \fIdes_random_seed()\fR.
  456. This will happen to other functions
  457. as well if they are deemed redundant (\fIdes_random_seed()\fR just calls
  458. \&\fIRAND_seed()\fR and is present for backward compatibility only), buggy or
  459. already scheduled for removal.
  460. .PP
  461. \&\fIdes_cbc_cksum()\fR, \fIdes_cbc_encrypt()\fR, \fIdes_ecb_encrypt()\fR,
  462. \&\fIdes_is_weak_key()\fR, \fIdes_key_sched()\fR, \fIdes_pcbc_encrypt()\fR,
  463. \&\fIdes_quad_cksum()\fR, \fIdes_random_key()\fR and \fIdes_string_to_key()\fR
  464. are available in the \s-1MIT\s0 Kerberos library;
  465. \&\fIdes_check_key_parity()\fR, \fIdes_fixup_key_parity()\fR and \fIdes_is_weak_key()\fR
  466. are available in newer versions of that library.
  467. .PP
  468. \&\fIdes_set_key_checked()\fR and \fIdes_set_key_unchecked()\fR were added in
  469. OpenSSL 0.9.5.
  470. .PP
  471. \&\fIdes_generate_random_block()\fR, \fIdes_init_random_number_generator()\fR,
  472. \&\fIdes_new_random_key()\fR, \fIdes_set_random_generator_seed()\fR and
  473. \&\fIdes_set_sequence_number()\fR and \fIdes_rand_data()\fR are used in newer
  474. versions of Kerberos but are not implemented here.
  475. .PP
  476. \&\fIdes_random_key()\fR generated cryptographically weak random data in
  477. SSLeay and in OpenSSL prior version 0.9.5, as well as in the original
  478. \&\s-1MIT\s0 library.
  479. .SH "AUTHOR"
  480. .IX Header "AUTHOR"
  481. Eric Young (eay@cryptsoft.com). Modified for the OpenSSL project
  482. (http://www.openssl.org).