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129 .\" ========================================================================
130 .\"
131 .IX Title "EVP_EncryptInit 3"
132 .TH EVP_EncryptInit 3 "2009-07-23" "0.9.8k" "OpenSSL"
133 .SH "NAME"
134 EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate,
135 EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate,
136 EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate,
137 EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length,
138 EVP_CIPHER_CTX_ctrl, EVP_CIPHER_CTX_cleanup, EVP_EncryptInit,
139 EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal,
140 EVP_CipherInit, EVP_CipherFinal, EVP_get_cipherbyname,
141 EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_nid,
142 EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length,
143 EVP_CIPHER_flags, EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher,
144 EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length,
145 EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data,
146 EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags,
147 EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param,
148 EVP_CIPHER_CTX_set_padding \- EVP cipher routines
149 .SH "SYNOPSIS"
150 .IX Header "SYNOPSIS"
151 .Vb 1
152 \& #include <openssl/evp.h>
153 .Ve
154 .PP
155 .Vb 1
156 \& void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
157 .Ve
158 .PP
159 .Vb 6
160 \& int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
161 \& ENGINE *impl, unsigned char *key, unsigned char *iv);
162 \& int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
163 \& int *outl, unsigned char *in, int inl);
164 \& int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
165 \& int *outl);
166 .Ve
167 .PP
168 .Vb 6
169 \& int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
170 \& ENGINE *impl, unsigned char *key, unsigned char *iv);
171 \& int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
172 \& int *outl, unsigned char *in, int inl);
173 \& int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
174 \& int *outl);
175 .Ve
176 .PP
177 .Vb 6
178 \& int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
179 \& ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
180 \& int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
181 \& int *outl, unsigned char *in, int inl);
182 \& int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
183 \& int *outl);
184 .Ve
185 .PP
186 .Vb 4
187 \& int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
188 \& unsigned char *key, unsigned char *iv);
189 \& int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
190 \& int *outl);
191 .Ve
192 .PP
193 .Vb 4
194 \& int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
195 \& unsigned char *key, unsigned char *iv);
196 \& int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
197 \& int *outl);
198 .Ve
199 .PP
200 .Vb 4
201 \& int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
202 \& unsigned char *key, unsigned char *iv, int enc);
203 \& int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
204 \& int *outl);
205 .Ve
206 .PP
207 .Vb 4
208 \& int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
209 \& int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
210 \& int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
211 \& int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
212 .Ve
213 .PP
214 .Vb 3
215 \& const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
216 \& #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
217 \& #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
218 .Ve
219 .PP
220 .Vb 7
221 \& #define EVP_CIPHER_nid(e) ((e)->nid)
222 \& #define EVP_CIPHER_block_size(e) ((e)->block_size)
223 \& #define EVP_CIPHER_key_length(e) ((e)->key_len)
224 \& #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
225 \& #define EVP_CIPHER_flags(e) ((e)->flags)
226 \& #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
227 \& int EVP_CIPHER_type(const EVP_CIPHER *ctx);
228 .Ve
229 .PP
230 .Vb 10
231 \& #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
232 \& #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
233 \& #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
234 \& #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
235 \& #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
236 \& #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
237 \& #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
238 \& #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
239 \& #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
240 \& #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
241 .Ve
242 .PP
243 .Vb 2
244 \& int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
245 \& int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
246 .Ve
247 .SH "DESCRIPTION"
248 .IX Header "DESCRIPTION"
249 The \s-1EVP\s0 cipher routines are a high level interface to certain
250 symmetric ciphers.
251 .PP
252 \&\fIEVP_CIPHER_CTX_init()\fR initializes cipher contex \fBctx\fR.
253 .PP
254 \&\fIEVP_EncryptInit_ex()\fR sets up cipher context \fBctx\fR for encryption
255 with cipher \fBtype\fR from \s-1ENGINE\s0 \fBimpl\fR. \fBctx\fR must be initialized
256 before calling this function. \fBtype\fR is normally supplied
257 by a function such as \fIEVP_des_cbc()\fR. If \fBimpl\fR is \s-1NULL\s0 then the
258 default implementation is used. \fBkey\fR is the symmetric key to use
259 and \fBiv\fR is the \s-1IV\s0 to use (if necessary), the actual number of bytes
260 used for the key and \s-1IV\s0 depends on the cipher. It is possible to set
261 all parameters to \s-1NULL\s0 except \fBtype\fR in an initial call and supply
262 the remaining parameters in subsequent calls, all of which have \fBtype\fR
263 set to \s-1NULL\s0. This is done when the default cipher parameters are not
264 appropriate.
265 .PP
266 \&\fIEVP_EncryptUpdate()\fR encrypts \fBinl\fR bytes from the buffer \fBin\fR and
267 writes the encrypted version to \fBout\fR. This function can be called
268 multiple times to encrypt successive blocks of data. The amount
269 of data written depends on the block alignment of the encrypted data:
270 as a result the amount of data written may be anything from zero bytes
271 to (inl + cipher_block_size \- 1) so \fBoutl\fR should contain sufficient
272 room. The actual number of bytes written is placed in \fBoutl\fR.
273 .PP
274 If padding is enabled (the default) then \fIEVP_EncryptFinal_ex()\fR encrypts
275 the \*(L"final\*(R" data, that is any data that remains in a partial block.
276 It uses standard block padding (aka \s-1PKCS\s0 padding). The encrypted
277 final data is written to \fBout\fR which should have sufficient space for
278 one cipher block. The number of bytes written is placed in \fBoutl\fR. After
279 this function is called the encryption operation is finished and no further
280 calls to \fIEVP_EncryptUpdate()\fR should be made.
281 .PP
282 If padding is disabled then \fIEVP_EncryptFinal_ex()\fR will not encrypt any more
283 data and it will return an error if any data remains in a partial block:
284 that is if the total data length is not a multiple of the block size.
285 .PP
286 \&\fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptUpdate()\fR and \fIEVP_DecryptFinal_ex()\fR are the
287 corresponding decryption operations. \fIEVP_DecryptFinal()\fR will return an
288 error code if padding is enabled and the final block is not correctly
289 formatted. The parameters and restrictions are identical to the encryption
290 operations except that if padding is enabled the decrypted data buffer \fBout\fR
291 passed to \fIEVP_DecryptUpdate()\fR should have sufficient room for
292 (\fBinl\fR + cipher_block_size) bytes unless the cipher block size is 1 in
293 which case \fBinl\fR bytes is sufficient.
294 .PP
295 \&\fIEVP_CipherInit_ex()\fR, \fIEVP_CipherUpdate()\fR and \fIEVP_CipherFinal_ex()\fR are
296 functions that can be used for decryption or encryption. The operation
297 performed depends on the value of the \fBenc\fR parameter. It should be set
298 to 1 for encryption, 0 for decryption and \-1 to leave the value unchanged
299 (the actual value of 'enc' being supplied in a previous call).
300 .PP
301 \&\fIEVP_CIPHER_CTX_cleanup()\fR clears all information from a cipher context
302 and free up any allocated memory associate with it. It should be called
303 after all operations using a cipher are complete so sensitive information
304 does not remain in memory.
305 .PP
306 \&\fIEVP_EncryptInit()\fR, \fIEVP_DecryptInit()\fR and \fIEVP_CipherInit()\fR behave in a
307 similar way to \fIEVP_EncryptInit_ex()\fR, EVP_DecryptInit_ex and
308 \&\fIEVP_CipherInit_ex()\fR except the \fBctx\fR paramter does not need to be
309 initialized and they always use the default cipher implementation.
310 .PP
311 \&\fIEVP_EncryptFinal()\fR, \fIEVP_DecryptFinal()\fR and \fIEVP_CipherFinal()\fR behave in a
312 similar way to \fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptFinal_ex()\fR and
313 \&\fIEVP_CipherFinal_ex()\fR except \fBctx\fR is automatically cleaned up
314 after the call.
315 .PP
316 \&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
317 return an \s-1EVP_CIPHER\s0 structure when passed a cipher name, a \s-1NID\s0 or an
318 \&\s-1ASN1_OBJECT\s0 structure.
319 .PP
320 \&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return the \s-1NID\s0 of a cipher when
321 passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR structure. The actual \s-1NID\s0
322 value is an internal value which may not have a corresponding \s-1OBJECT\s0
323 \&\s-1IDENTIFIER\s0.
324 .PP
325 \&\fIEVP_CIPHER_CTX_set_padding()\fR enables or disables padding. By default
326 encryption operations are padded using standard block padding and the
327 padding is checked and removed when decrypting. If the \fBpad\fR parameter
328 is zero then no padding is performed, the total amount of data encrypted
329 or decrypted must then be a multiple of the block size or an error will
330 occur.
331 .PP
332 \&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
333 length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
334 structure. The constant \fB\s-1EVP_MAX_KEY_LENGTH\s0\fR is the maximum key length
335 for all ciphers. Note: although \fIEVP_CIPHER_key_length()\fR is fixed for a
336 given cipher, the value of \fIEVP_CIPHER_CTX_key_length()\fR may be different
337 for variable key length ciphers.
338 .PP
339 \&\fIEVP_CIPHER_CTX_set_key_length()\fR sets the key length of the cipher ctx.
340 If the cipher is a fixed length cipher then attempting to set the key
341 length to any value other than the fixed value is an error.
342 .PP
343 \&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
344 length of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR.
345 It will return zero if the cipher does not use an \s-1IV\s0. The constant
346 \&\fB\s-1EVP_MAX_IV_LENGTH\s0\fR is the maximum \s-1IV\s0 length for all ciphers.
347 .PP
348 \&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
349 size of a cipher when passed an \fB\s-1EVP_CIPHER\s0\fR or \fB\s-1EVP_CIPHER_CTX\s0\fR
350 structure. The constant \fB\s-1EVP_MAX_IV_LENGTH\s0\fR is also the maximum block
351 length for all ciphers.
352 .PP
353 \&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the type of the passed
354 cipher or context. This \*(L"type\*(R" is the actual \s-1NID\s0 of the cipher \s-1OBJECT\s0
355 \&\s-1IDENTIFIER\s0 as such it ignores the cipher parameters and 40 bit \s-1RC2\s0 and
356 128 bit \s-1RC2\s0 have the same \s-1NID\s0. If the cipher does not have an object
357 identifier or does not have \s-1ASN1\s0 support this function will return
358 \&\fBNID_undef\fR.
359 .PP
360 \&\fIEVP_CIPHER_CTX_cipher()\fR returns the \fB\s-1EVP_CIPHER\s0\fR structure when passed
361 an \fB\s-1EVP_CIPHER_CTX\s0\fR structure.
362 .PP
363 \&\fIEVP_CIPHER_mode()\fR and \fIEVP_CIPHER_CTX_mode()\fR return the block cipher mode:
364 \&\s-1EVP_CIPH_ECB_MODE\s0, \s-1EVP_CIPH_CBC_MODE\s0, \s-1EVP_CIPH_CFB_MODE\s0 or
365 \&\s-1EVP_CIPH_OFB_MODE\s0. If the cipher is a stream cipher then
366 \&\s-1EVP_CIPH_STREAM_CIPHER\s0 is returned.
367 .PP
368 \&\fIEVP_CIPHER_param_to_asn1()\fR sets the AlgorithmIdentifier \*(L"parameter\*(R" based
369 on the passed cipher. This will typically include any parameters and an
370 \&\s-1IV\s0. The cipher \s-1IV\s0 (if any) must be set when this call is made. This call
371 should be made before the cipher is actually \*(L"used\*(R" (before any
372 \&\fIEVP_EncryptUpdate()\fR, \fIEVP_DecryptUpdate()\fR calls for example). This function
373 may fail if the cipher does not have any \s-1ASN1\s0 support.
374 .PP
375 \&\fIEVP_CIPHER_asn1_to_param()\fR sets the cipher parameters based on an \s-1ASN1\s0
376 AlgorithmIdentifier \*(L"parameter\*(R". The precise effect depends on the cipher
377 In the case of \s-1RC2\s0, for example, it will set the \s-1IV\s0 and effective key length.
378 This function should be called after the base cipher type is set but before
379 the key is set. For example \fIEVP_CipherInit()\fR will be called with the \s-1IV\s0 and
380 key set to \s-1NULL\s0, \fIEVP_CIPHER_asn1_to_param()\fR will be called and finally
381 \&\fIEVP_CipherInit()\fR again with all parameters except the key set to \s-1NULL\s0. It is
382 possible for this function to fail if the cipher does not have any \s-1ASN1\s0 support
383 or the parameters cannot be set (for example the \s-1RC2\s0 effective key length
384 is not supported.
385 .PP
386 \&\fIEVP_CIPHER_CTX_ctrl()\fR allows various cipher specific parameters to be determined
387 and set. Currently only the \s-1RC2\s0 effective key length and the number of rounds of
388 \&\s-1RC5\s0 can be set.
389 .SH "RETURN VALUES"
390 .IX Header "RETURN VALUES"
391 \&\fIEVP_EncryptInit_ex()\fR, \fIEVP_EncryptUpdate()\fR and \fIEVP_EncryptFinal_ex()\fR
392 return 1 for success and 0 for failure.
393 .PP
394 \&\fIEVP_DecryptInit_ex()\fR and \fIEVP_DecryptUpdate()\fR return 1 for success and 0 for failure.
395 \&\fIEVP_DecryptFinal_ex()\fR returns 0 if the decrypt failed or 1 for success.
396 .PP
397 \&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherUpdate()\fR return 1 for success and 0 for failure.
398 \&\fIEVP_CipherFinal_ex()\fR returns 0 for a decryption failure or 1 for success.
399 .PP
400 \&\fIEVP_CIPHER_CTX_cleanup()\fR returns 1 for success and 0 for failure.
401 .PP
402 \&\fIEVP_get_cipherbyname()\fR, \fIEVP_get_cipherbynid()\fR and \fIEVP_get_cipherbyobj()\fR
403 return an \fB\s-1EVP_CIPHER\s0\fR structure or \s-1NULL\s0 on error.
404 .PP
405 \&\fIEVP_CIPHER_nid()\fR and \fIEVP_CIPHER_CTX_nid()\fR return a \s-1NID\s0.
406 .PP
407 \&\fIEVP_CIPHER_block_size()\fR and \fIEVP_CIPHER_CTX_block_size()\fR return the block
408 size.
409 .PP
410 \&\fIEVP_CIPHER_key_length()\fR and \fIEVP_CIPHER_CTX_key_length()\fR return the key
411 length.
412 .PP
413 \&\fIEVP_CIPHER_CTX_set_padding()\fR always returns 1.
414 .PP
415 \&\fIEVP_CIPHER_iv_length()\fR and \fIEVP_CIPHER_CTX_iv_length()\fR return the \s-1IV\s0
416 length or zero if the cipher does not use an \s-1IV\s0.
417 .PP
418 \&\fIEVP_CIPHER_type()\fR and \fIEVP_CIPHER_CTX_type()\fR return the \s-1NID\s0 of the cipher's
419 \&\s-1OBJECT\s0 \s-1IDENTIFIER\s0 or NID_undef if it has no defined \s-1OBJECT\s0 \s-1IDENTIFIER\s0.
420 .PP
421 \&\fIEVP_CIPHER_CTX_cipher()\fR returns an \fB\s-1EVP_CIPHER\s0\fR structure.
422 .PP
423 \&\fIEVP_CIPHER_param_to_asn1()\fR and \fIEVP_CIPHER_asn1_to_param()\fR return 1 for
424 success or zero for failure.
425 .SH "CIPHER LISTING"
426 .IX Header "CIPHER LISTING"
427 All algorithms have a fixed key length unless otherwise stated.
428 .IP "\fIEVP_enc_null()\fR" 4
429 .IX Item "EVP_enc_null()"
430 Null cipher: does nothing.
431 .IP "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)" 4
432 .IX Item "EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)"
433 \&\s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
434 .IP "EVP_des_ede_cbc(void), \fIEVP_des_ede()\fR, EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)" 4
435 .IX Item "EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)"
436 Two key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
437 .IP "EVP_des_ede3_cbc(void), \fIEVP_des_ede3()\fR, EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)" 4
438 .IX Item "EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)"
439 Three key triple \s-1DES\s0 in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
440 .IP "EVP_desx_cbc(void)" 4
441 .IX Item "EVP_desx_cbc(void)"
442 \&\s-1DESX\s0 algorithm in \s-1CBC\s0 mode.
443 .IP "EVP_rc4(void)" 4
444 .IX Item "EVP_rc4(void)"
445 \&\s-1RC4\s0 stream cipher. This is a variable key length cipher with default key length 128 bits.
446 .IP "EVP_rc4_40(void)" 4
447 .IX Item "EVP_rc4_40(void)"
448 \&\s-1RC4\s0 stream cipher with 40 bit key length. This is obsolete and new code should use \fIEVP_rc4()\fR
449 and the \fIEVP_CIPHER_CTX_set_key_length()\fR function.
450 .IP "\fIEVP_idea_cbc()\fR EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)" 4
451 .IX Item "EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)"
452 \&\s-1IDEA\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively.
453 .IP "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)" 4
454 .IX Item "EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)"
455 \&\s-1RC2\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
456 length cipher with an additional parameter called \*(L"effective key bits\*(R" or \*(L"effective key length\*(R".
457 By default both are set to 128 bits.
458 .IP "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)" 4
459 .IX Item "EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)"
460 \&\s-1RC2\s0 algorithm in \s-1CBC\s0 mode with a default key length and effective key length of 40 and 64 bits.
461 These are obsolete and new code should use \fIEVP_rc2_cbc()\fR, \fIEVP_CIPHER_CTX_set_key_length()\fR and
462 \&\fIEVP_CIPHER_CTX_ctrl()\fR to set the key length and effective key length.
463 .IP "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);" 4
464 .IX Item "EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);"
465 Blowfish encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
466 length cipher.
467 .IP "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)" 4
468 .IX Item "EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)"
469 \&\s-1CAST\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key
470 length cipher.
471 .IP "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)" 4
472 .IX Item "EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)"
473 \&\s-1RC5\s0 encryption algorithm in \s-1CBC\s0, \s-1ECB\s0, \s-1CFB\s0 and \s-1OFB\s0 modes respectively. This is a variable key length
474 cipher with an additional \*(L"number of rounds\*(R" parameter. By default the key length is set to 128
475 bits and 12 rounds.
476 .SH "NOTES"
477 .IX Header "NOTES"
478 Where possible the \fB\s-1EVP\s0\fR interface to symmetric ciphers should be used in
479 preference to the low level interfaces. This is because the code then becomes
480 transparent to the cipher used and much more flexible.
481 .PP
482 \&\s-1PKCS\s0 padding works by adding \fBn\fR padding bytes of value \fBn\fR to make the total
483 length of the encrypted data a multiple of the block size. Padding is always
484 added so if the data is already a multiple of the block size \fBn\fR will equal
485 the block size. For example if the block size is 8 and 11 bytes are to be
486 encrypted then 5 padding bytes of value 5 will be added.
487 .PP
488 When decrypting the final block is checked to see if it has the correct form.
489 .PP
490 Although the decryption operation can produce an error if padding is enabled,
491 it is not a strong test that the input data or key is correct. A random block
492 has better than 1 in 256 chance of being of the correct format and problems with
493 the input data earlier on will not produce a final decrypt error.
494 .PP
495 If padding is disabled then the decryption operation will always succeed if
496 the total amount of data decrypted is a multiple of the block size.
497 .PP
498 The functions \fIEVP_EncryptInit()\fR, \fIEVP_EncryptFinal()\fR, \fIEVP_DecryptInit()\fR,
499 \&\fIEVP_CipherInit()\fR and \fIEVP_CipherFinal()\fR are obsolete but are retained for
500 compatibility with existing code. New code should use \fIEVP_EncryptInit_ex()\fR,
501 \&\fIEVP_EncryptFinal_ex()\fR, \fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptFinal_ex()\fR,
502 \&\fIEVP_CipherInit_ex()\fR and \fIEVP_CipherFinal_ex()\fR because they can reuse an
503 existing context without allocating and freeing it up on each call.
504 .SH "BUGS"
505 .IX Header "BUGS"
506 For \s-1RC5\s0 the number of rounds can currently only be set to 8, 12 or 16. This is
507 a limitation of the current \s-1RC5\s0 code rather than the \s-1EVP\s0 interface.
508 .PP
509 \&\s-1EVP_MAX_KEY_LENGTH\s0 and \s-1EVP_MAX_IV_LENGTH\s0 only refer to the internal ciphers with
510 default key lengths. If custom ciphers exceed these values the results are
511 unpredictable. This is because it has become standard practice to define a
512 generic key as a fixed unsigned char array containing \s-1EVP_MAX_KEY_LENGTH\s0 bytes.
513 .PP
514 The \s-1ASN1\s0 code is incomplete (and sometimes inaccurate) it has only been tested
515 for certain common S/MIME ciphers (\s-1RC2\s0, \s-1DES\s0, triple \s-1DES\s0) in \s-1CBC\s0 mode.
516 .SH "EXAMPLES"
517 .IX Header "EXAMPLES"
518 Get the number of rounds used in \s-1RC5:\s0
519 .PP
520 .Vb 2
521 \& int nrounds;
522 \& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &nrounds);
523 .Ve
524 .PP
525 Get the \s-1RC2\s0 effective key length:
526 .PP
527 .Vb 2
528 \& int key_bits;
529 \& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &key_bits);
530 .Ve
531 .PP
532 Set the number of rounds used in \s-1RC5:\s0
533 .PP
534 .Vb 2
535 \& int nrounds;
536 \& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, nrounds, NULL);
537 .Ve
538 .PP
539 Set the effective key length used in \s-1RC2:\s0
540 .PP
541 .Vb 2
542 \& int key_bits;
543 \& EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, key_bits, NULL);
544 .Ve
545 .PP
546 Encrypt a string using blowfish:
547 .PP
548 .Vb 14
549 \& int do_crypt(char *outfile)
550 \& {
551 \& unsigned char outbuf[1024];
552 \& int outlen, tmplen;
553 \& /* Bogus key and IV: we'd normally set these from
554 \& * another source.
555 \& */
556 \& unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
557 \& unsigned char iv[] = {1,2,3,4,5,6,7,8};
558 \& char intext[] = "Some Crypto Text";
559 \& EVP_CIPHER_CTX ctx;
560 \& FILE *out;
561 \& EVP_CIPHER_CTX_init(&ctx);
562 \& EVP_EncryptInit_ex(&ctx, EVP_bf_cbc(), NULL, key, iv);
563 .Ve
564 .PP
565 .Vb 25
566 \& if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
567 \& {
568 \& /* Error */
569 \& return 0;
570 \& }
571 \& /* Buffer passed to EVP_EncryptFinal() must be after data just
572 \& * encrypted to avoid overwriting it.
573 \& */
574 \& if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen))
575 \& {
576 \& /* Error */
577 \& return 0;
578 \& }
579 \& outlen += tmplen;
580 \& EVP_CIPHER_CTX_cleanup(&ctx);
581 \& /* Need binary mode for fopen because encrypted data is
582 \& * binary data. Also cannot use strlen() on it because
583 \& * it wont be null terminated and may contain embedded
584 \& * nulls.
585 \& */
586 \& out = fopen(outfile, "wb");
587 \& fwrite(outbuf, 1, outlen, out);
588 \& fclose(out);
589 \& return 1;
590 \& }
591 .Ve
592 .PP
593 The ciphertext from the above example can be decrypted using the \fBopenssl\fR
594 utility with the command line:
595 .PP
596 .Vb 1
597 \& S<openssl bf -in cipher.bin -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 -d>
598 .Ve
599 .PP
600 General encryption, decryption function example using \s-1FILE\s0 I/O and \s-1RC2\s0 with an
601 80 bit key:
602 .PP
603 .Vb 16
604 \& int do_crypt(FILE *in, FILE *out, int do_encrypt)
605 \& {
606 \& /* Allow enough space in output buffer for additional block */
607 \& inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
608 \& int inlen, outlen;
609 \& /* Bogus key and IV: we'd normally set these from
610 \& * another source.
611 \& */
612 \& unsigned char key[] = "0123456789";
613 \& unsigned char iv[] = "12345678";
614 \& /* Don't set key or IV because we will modify the parameters */
615 \& EVP_CIPHER_CTX_init(&ctx);
616 \& EVP_CipherInit_ex(&ctx, EVP_rc2(), NULL, NULL, NULL, do_encrypt);
617 \& EVP_CIPHER_CTX_set_key_length(&ctx, 10);
618 \& /* We finished modifying parameters so now we can set key and IV */
619 \& EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
620 .Ve
621 .PP
622 .Vb 19
623 \& for(;;)
624 \& {
625 \& inlen = fread(inbuf, 1, 1024, in);
626 \& if(inlen <= 0) break;
627 \& if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
628 \& {
629 \& /* Error */
630 \& EVP_CIPHER_CTX_cleanup(&ctx);
631 \& return 0;
632 \& }
633 \& fwrite(outbuf, 1, outlen, out);
634 \& }
635 \& if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
636 \& {
637 \& /* Error */
638 \& EVP_CIPHER_CTX_cleanup(&ctx);
639 \& return 0;
640 \& }
641 \& fwrite(outbuf, 1, outlen, out);
642 .Ve
643 .PP
644 .Vb 3
645 \& EVP_CIPHER_CTX_cleanup(&ctx);
646 \& return 1;
647 \& }
648 .Ve
649 .SH "SEE ALSO"
650 .IX Header "SEE ALSO"
651 \&\fIevp\fR\|(3)
652 .SH "HISTORY"
653 .IX Header "HISTORY"
654 \&\fIEVP_CIPHER_CTX_init()\fR, \fIEVP_EncryptInit_ex()\fR, \fIEVP_EncryptFinal_ex()\fR,
655 \&\fIEVP_DecryptInit_ex()\fR, \fIEVP_DecryptFinal_ex()\fR, \fIEVP_CipherInit_ex()\fR,
656 \&\fIEVP_CipherFinal_ex()\fR and \fIEVP_CIPHER_CTX_set_padding()\fR appeared in
657 OpenSSL 0.9.7.