20 EVP_CIPHER_CTX_set_key_length,
35 EVP_CIPHER_get_params,
36 EVP_CIPHER_gettable_params,
37 EVP_CIPHER_block_size,
38 EVP_CIPHER_key_length,
43 EVP_CIPHER_CTX_cipher,
46 EVP_CIPHER_CTX_get_params,
47 EVP_CIPHER_gettable_ctx_params,
48 EVP_CIPHER_CTX_set_params,
49 EVP_CIPHER_settable_ctx_params,
50 EVP_CIPHER_CTX_block_size,
51 EVP_CIPHER_CTX_key_length,
52 EVP_CIPHER_CTX_iv_length,
53 EVP_CIPHER_CTX_tag_length,
54 EVP_CIPHER_CTX_get_app_data,
55 EVP_CIPHER_CTX_set_app_data,
59 EVP_CIPHER_param_to_asn1,
60 EVP_CIPHER_asn1_to_param,
61 EVP_CIPHER_CTX_set_padding,
70 #include <openssl/evp.h>
72 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
73 const char *properties);
74 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
75 void EVP_CIPHER_free(EVP_CIPHER *cipher);
76 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
77 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
78 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
80 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
81 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
82 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
83 int *outl, const unsigned char *in, int inl);
84 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
86 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
87 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
88 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
89 int *outl, const unsigned char *in, int inl);
90 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
92 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
93 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
94 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
95 int *outl, const unsigned char *in, int inl);
96 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
98 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
99 const unsigned char *key, const unsigned char *iv);
100 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
102 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
103 const unsigned char *key, const unsigned char *iv);
104 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
106 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
107 const unsigned char *key, const unsigned char *iv, int enc);
108 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
110 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
111 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
112 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
113 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
115 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
116 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
117 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
119 int EVP_CIPHER_nid(const EVP_CIPHER *e);
120 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
121 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
122 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
123 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
124 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
125 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
126 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
127 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
128 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
130 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
131 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
132 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
134 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
135 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
136 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
137 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
138 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
139 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
140 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
141 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
142 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
143 int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
144 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
145 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
146 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
147 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
149 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
150 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
152 void EVP_CIPHER_do_all_ex(OPENSSL_CTX *libctx,
153 void (*fn)(EVP_CIPHER *cipher, void *arg),
158 The EVP cipher routines are a high level interface to certain
161 The B<EVP_CIPHER> type is a structure for cipher method implementation.
163 EVP_CIPHER_fetch() fetches the cipher implementation for the given
164 B<algorithm> from any provider offering it, within the criteria given
165 by the B<properties>.
166 See L<provider(7)/Fetching algorithms> for further information.
168 The returned value must eventually be freed with EVP_CIPHER_free().
170 EVP_CIPHER_up_ref() increments the reference count for an B<EVP_CIPHER>
173 EVP_CIPHER_free() decrements the reference count for the B<EVP_CIPHER>
175 If the reference count drops to 0 then the structure is freed.
177 EVP_CIPHER_CTX_new() creates a cipher context.
179 EVP_CIPHER_CTX_free() clears all information from a cipher context
180 and free up any allocated memory associate with it, including B<ctx>
181 itself. This function should be called after all operations using a
182 cipher are complete so sensitive information does not remain in
185 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
186 with cipher B<type>. B<type> is typically supplied by a function such
187 as EVP_aes_256_cbc(), or a value explicitly fetched with
188 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
189 cipher B<type> is used if there is one, and if not, the default
190 implementation is used. B<key> is the symmetric key to use
191 and B<iv> is the IV to use (if necessary), the actual number of bytes
192 used for the key and IV depends on the cipher. It is possible to set
193 all parameters to NULL except B<type> in an initial call and supply
194 the remaining parameters in subsequent calls, all of which have B<type>
195 set to NULL. This is done when the default cipher parameters are not
197 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
200 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
201 writes the encrypted version to B<out>. This function can be called
202 multiple times to encrypt successive blocks of data. The amount
203 of data written depends on the block alignment of the encrypted data:
204 as a result the amount of data written may be anything from zero bytes
205 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
206 room. The actual number of bytes written is placed in B<outl>. It also
207 checks if B<in> and B<out> are partially overlapping, and if they are
208 0 is returned to indicate failure.
210 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
211 the "final" data, that is any data that remains in a partial block.
212 It uses standard block padding (aka PKCS padding) as described in
213 the NOTES section, below. The encrypted
214 final data is written to B<out> which should have sufficient space for
215 one cipher block. The number of bytes written is placed in B<outl>. After
216 this function is called the encryption operation is finished and no further
217 calls to EVP_EncryptUpdate() should be made.
219 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
220 data and it will return an error if any data remains in a partial block:
221 that is if the total data length is not a multiple of the block size.
223 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
224 corresponding decryption operations. EVP_DecryptFinal() will return an
225 error code if padding is enabled and the final block is not correctly
226 formatted. The parameters and restrictions are identical to the encryption
227 operations except that if padding is enabled the decrypted data buffer B<out>
228 passed to EVP_DecryptUpdate() should have sufficient room for
229 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
230 which case B<inl> bytes is sufficient.
232 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
233 functions that can be used for decryption or encryption. The operation
234 performed depends on the value of the B<enc> parameter. It should be set
235 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
236 (the actual value of 'enc' being supplied in a previous call).
238 EVP_CIPHER_CTX_reset() clears all information from a cipher context
239 and free up any allocated memory associate with it, except the B<ctx>
240 itself. This function should be called anytime B<ctx> is to be reused
241 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
244 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
245 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
246 EVP_CipherInit_ex() except they always use the default cipher implementation.
248 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
249 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
250 EVP_CipherFinal_ex(). In previous releases they also cleaned up
251 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
252 must be called to free any context resources.
254 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
255 return an EVP_CIPHER structure when passed a cipher name, a NID or an
256 ASN1_OBJECT structure.
258 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
259 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
260 value is an internal value which may not have a corresponding OBJECT
263 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
264 function should be called after the context is set up for encryption
265 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
266 EVP_CipherInit_ex(). By default encryption operations are padded using
267 standard block padding and the padding is checked and removed when
268 decrypting. If the B<pad> parameter is zero then no padding is
269 performed, the total amount of data encrypted or decrypted must then
270 be a multiple of the block size or an error will occur.
272 EVP_CIPHER_get_params() retrieves the requested list of algorithm
273 B<params> from a B<cipher>.
275 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
278 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
279 B<params> from CIPHER context B<ctx>.
281 EVP_CIPHER_gettable_params(), EVP_CIPHER_gettable_ctx_params(), and
282 EVP_CIPHER_settable_ctx_params() get a constant B<OSSL_PARAM> array
283 that decribes the retrievable and settable parameters, i.e. parameters
284 that can be used with EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params()
285 and EVP_CIPHER_CTX_set_params(), respectively.
286 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
288 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
289 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
290 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
291 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
292 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
293 for variable key length ciphers.
295 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
296 If the cipher is a fixed length cipher then attempting to set the key
297 length to any value other than the fixed value is an error.
299 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
300 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
301 It will return zero if the cipher does not use an IV. The constant
302 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
304 EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed
305 a B<EVP_CIPHER_CTX>. It will return zero if the cipher does not support a tag.
306 It returns a default value if the tag length has not been set.
308 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
309 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
310 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
311 length for all ciphers.
313 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
314 cipher or context. This "type" is the actual NID of the cipher OBJECT
315 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
316 128 bit RC2 have the same NID. If the cipher does not have an object
317 identifier or does not have ASN1 support this function will return
320 EVP_CIPHER_is_a() returns 1 if the given I<cipher> is an implementation of an
321 algorithm that's identifiable with I<name>, otherwise 0.
323 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
326 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
327 that implements the given B<EVP_CIPHER>.
329 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
330 an B<EVP_CIPHER_CTX> structure.
332 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
333 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
334 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
335 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
336 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
338 EVP_CIPHER_flags() returns any flags associated with the cipher. See
339 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
341 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
342 on the passed cipher. This will typically include any parameters and an
343 IV. The cipher IV (if any) must be set when this call is made. This call
344 should be made before the cipher is actually "used" (before any
345 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
346 may fail if the cipher does not have any ASN1 support.
348 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
349 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
350 In the case of RC2, for example, it will set the IV and effective key length.
351 This function should be called after the base cipher type is set but before
352 the key is set. For example EVP_CipherInit() will be called with the IV and
353 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
354 EVP_CipherInit() again with all parameters except the key set to NULL. It is
355 possible for this function to fail if the cipher does not have any ASN1 support
356 or the parameters cannot be set (for example the RC2 effective key length
359 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
362 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
363 based on the cipher context. The EVP_CIPHER can provide its own random key
364 generation routine to support keys of a specific form. B<Key> must point to a
365 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
367 EVP_CIPHER_do_all_ex() traverses all ciphers implemented by all activated
368 providers in the given library context I<libctx>, and for each of the
369 implementations, calls the given function I<fn> with the implementation method
370 and the given I<arg> as argument.
374 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
375 and B<NULL> for failure.
377 EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
379 EVP_CIPHER_CTX_new() returns a pointer to a newly created
380 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
382 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
383 return 1 for success and 0 for failure.
385 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
386 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
388 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
389 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
391 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
393 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
394 return an B<EVP_CIPHER> structure or NULL on error.
396 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
398 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
401 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
404 EVP_CIPHER_CTX_set_padding() always returns 1.
406 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
407 length or zero if the cipher does not use an IV.
409 EVP_CIPHER_CTX_tag_length() return the tag length or zero if the cipher does not
412 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
413 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
415 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
417 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
418 than zero for success and zero or a negative number on failure.
420 EVP_CIPHER_CTX_rand_key() returns 1 for success.
422 =head1 CIPHER LISTING
424 All algorithms have a fixed key length unless otherwise stated.
426 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
433 Null cipher: does nothing.
437 =head1 AEAD INTERFACE
439 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
440 modes are subtly altered and several additional I<ctrl> operations are supported
441 depending on the mode specified.
443 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
444 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
445 parameter B<out> set to B<NULL>.
447 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
448 indicates whether the operation was successful. If it does not indicate success,
449 the authentication operation has failed and any output data B<MUST NOT> be used
452 =head2 GCM and OCB Modes
454 The following I<ctrl>s are supported in GCM and OCB modes.
458 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
460 Sets the IV length. This call can only be made before specifying an IV. If
461 not called a default IV length is used.
463 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
466 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
468 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
469 This call can only be made when encrypting data and B<after> all data has been
470 processed (e.g. after an EVP_EncryptFinal() call).
472 For OCB, C<taglen> must either be 16 or the value previously set via
473 B<EVP_CTRL_AEAD_SET_TAG>.
475 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
477 Sets the expected tag to C<taglen> bytes from C<tag>.
478 The tag length can only be set before specifying an IV.
479 C<taglen> must be between 1 and 16 inclusive.
481 For GCM, this call is only valid when decrypting data.
483 For OCB, this call is valid when decrypting data to set the expected tag,
484 and before encryption to set the desired tag length.
486 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
487 tag length. If this is not called prior to encryption, a default tag length is
490 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
491 maximum tag length for OCB.
497 The EVP interface for CCM mode is similar to that of the GCM mode but with a
498 few additional requirements and different I<ctrl> values.
500 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
501 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
502 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
503 the B<inl> parameter.
505 The following I<ctrl>s are supported in CCM mode.
509 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
511 This call is made to set the expected B<CCM> tag value when decrypting or
512 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
513 The tag length is often referred to as B<M>. If not set a default value is
514 used (12 for AES). When decrypting, the tag needs to be set before passing
515 in data to be decrypted, but as in GCM and OCB mode, it can be set after
516 passing additional authenticated data (see L</AEAD INTERFACE>).
518 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
520 Sets the CCM B<L> value. If not set a default is used (8 for AES).
522 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
524 Sets the CCM nonce (IV) length. This call can only be made before specifying an
525 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
532 For SIV mode ciphers the behaviour of the EVP interface is subtly
533 altered and several additional ctrl operations are supported.
535 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
536 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
537 with the output parameter B<out> set to B<NULL>.
539 RFC5297 states that the Nonce is the last piece of AAD before the actual
540 encrypt/decrypt takes place. The API does not differentiate the Nonce from
543 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
544 indicates if the operation was successful. If it does not indicate success
545 the authentication operation has failed and any output data B<MUST NOT>
546 be used as it is corrupted.
548 The following ctrls are supported in both SIV modes.
552 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
554 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
555 This call can only be made when encrypting data and B<after> all data has been
556 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
559 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
561 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
562 when decrypting data and must be made B<before> any data is processed (e.g.
563 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
567 SIV mode makes two passes over the input data, thus, only one call to
568 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
569 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
570 EVP_CipherFinal() is not required, but will indicate if the update
573 =head2 ChaCha20-Poly1305
575 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
579 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
581 Sets the nonce length. This call can only be made before specifying the nonce.
582 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
583 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
584 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
587 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
589 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
590 This call can only be made when encrypting data and B<after> all data has been
591 processed (e.g. after an EVP_EncryptFinal() call).
593 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
596 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
598 Sets the expected tag to C<taglen> bytes from C<tag>.
599 The tag length can only be set before specifying an IV.
600 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
601 This call is only valid when decrypting data.
607 Where possible the B<EVP> interface to symmetric ciphers should be used in
608 preference to the low level interfaces. This is because the code then becomes
609 transparent to the cipher used and much more flexible. Additionally, the
610 B<EVP> interface will ensure the use of platform specific cryptographic
611 acceleration such as AES-NI (the low level interfaces do not provide the
614 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
615 length of the encrypted data a multiple of the block size. Padding is always
616 added so if the data is already a multiple of the block size B<n> will equal
617 the block size. For example if the block size is 8 and 11 bytes are to be
618 encrypted then 5 padding bytes of value 5 will be added.
620 When decrypting the final block is checked to see if it has the correct form.
622 Although the decryption operation can produce an error if padding is enabled,
623 it is not a strong test that the input data or key is correct. A random block
624 has better than 1 in 256 chance of being of the correct format and problems with
625 the input data earlier on will not produce a final decrypt error.
627 If padding is disabled then the decryption operation will always succeed if
628 the total amount of data decrypted is a multiple of the block size.
630 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
631 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
632 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
633 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
634 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
635 existing context without allocating and freeing it up on each call.
637 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
641 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
642 ciphers with default key lengths. If custom ciphers exceed these values the
643 results are unpredictable. This is because it has become standard practice to
644 define a generic key as a fixed unsigned char array containing
645 B<EVP_MAX_KEY_LENGTH> bytes.
647 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
648 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
652 Encrypt a string using IDEA:
654 int do_crypt(char *outfile)
656 unsigned char outbuf[1024];
659 * Bogus key and IV: we'd normally set these from
662 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
663 unsigned char iv[] = {1,2,3,4,5,6,7,8};
664 char intext[] = "Some Crypto Text";
668 ctx = EVP_CIPHER_CTX_new();
669 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
671 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
673 EVP_CIPHER_CTX_free(ctx);
677 * Buffer passed to EVP_EncryptFinal() must be after data just
678 * encrypted to avoid overwriting it.
680 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
682 EVP_CIPHER_CTX_free(ctx);
686 EVP_CIPHER_CTX_free(ctx);
688 * Need binary mode for fopen because encrypted data is
689 * binary data. Also cannot use strlen() on it because
690 * it won't be NUL terminated and may contain embedded
693 out = fopen(outfile, "wb");
698 fwrite(outbuf, 1, outlen, out);
703 The ciphertext from the above example can be decrypted using the B<openssl>
704 utility with the command line (shown on two lines for clarity):
707 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
709 General encryption and decryption function example using FILE I/O and AES128
712 int do_crypt(FILE *in, FILE *out, int do_encrypt)
714 /* Allow enough space in output buffer for additional block */
715 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
719 * Bogus key and IV: we'd normally set these from
722 unsigned char key[] = "0123456789abcdeF";
723 unsigned char iv[] = "1234567887654321";
725 /* Don't set key or IV right away; we want to check lengths */
726 ctx = EVP_CIPHER_CTX_new();
727 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
729 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
730 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
732 /* Now we can set key and IV */
733 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
736 inlen = fread(inbuf, 1, 1024, in);
739 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
741 EVP_CIPHER_CTX_free(ctx);
744 fwrite(outbuf, 1, outlen, out);
746 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
748 EVP_CIPHER_CTX_free(ctx);
751 fwrite(outbuf, 1, outlen, out);
753 EVP_CIPHER_CTX_free(ctx);
762 Supported ciphers are listed in:
781 Support for OCB mode was added in OpenSSL 1.1.0.
783 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
784 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
785 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
786 EVP_CIPHER_CTX_reset().
788 The EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
789 EVP_CIPHER_CTX_set_params() and EVP_CIPHER_CTX_get_params() functions
794 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
796 Licensed under the Apache License 2.0 (the "License"). You may not use
797 this file except in compliance with the License. You can obtain a copy
798 in the file LICENSE in the source distribution or at
799 L<https://www.openssl.org/source/license.html>.