18 EVP_CIPHER_CTX_set_key_length,
32 EVP_CIPHER_get_params,
33 EVP_CIPHER_gettable_params,
34 EVP_CIPHER_block_size,
35 EVP_CIPHER_key_length,
40 EVP_CIPHER_CTX_cipher,
43 EVP_CIPHER_CTX_get_params,
44 EVP_CIPHER_CTX_gettable_params,
45 EVP_CIPHER_CTX_set_params,
46 EVP_CIPHER_CTX_settable_params,
47 EVP_CIPHER_CTX_block_size,
48 EVP_CIPHER_CTX_key_length,
49 EVP_CIPHER_CTX_iv_length,
50 EVP_CIPHER_CTX_get_app_data,
51 EVP_CIPHER_CTX_set_app_data,
55 EVP_CIPHER_param_to_asn1,
56 EVP_CIPHER_asn1_to_param,
57 EVP_CIPHER_CTX_set_padding,
66 #include <openssl/evp.h>
68 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
69 const char *properties);
70 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
71 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
72 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
74 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
75 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
76 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
77 int *outl, const unsigned char *in, int inl);
78 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
80 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
81 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
82 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
83 int *outl, const unsigned char *in, int inl);
84 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
86 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
87 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
88 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
89 int *outl, const unsigned char *in, int inl);
90 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
92 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
93 const unsigned char *key, const unsigned char *iv);
94 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
96 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
97 const unsigned char *key, const unsigned char *iv);
98 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
100 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
101 const unsigned char *key, const unsigned char *iv, int enc);
102 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
104 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
105 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
106 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
107 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
109 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
110 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
111 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
113 int EVP_CIPHER_nid(const EVP_CIPHER *e);
114 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
115 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
116 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
117 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
118 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
119 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
120 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
121 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
123 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
124 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
125 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
127 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
128 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
129 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
130 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
131 const OSSL_PARAM *EVP_CIPHER_CTX_settable_params(const EVP_CIPHER *cipher);
132 const OSSL_PARAM *EVP_CIPHER_CTX_gettable_params(const EVP_CIPHER *cipher);
133 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
134 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
135 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
136 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
137 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
138 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
139 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
141 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
142 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
144 void EVP_CIPHER_do_all_ex(OPENSSL_CTX *libctx,
145 void (*fn)(EVP_CIPHER *cipher, void *arg),
150 The EVP cipher routines are a high level interface to certain
153 EVP_CIPHER_fetch() fetches the cipher implementation for the given
154 B<algorithm> from any provider offering it, within the criteria given
155 by the B<properties>.
156 See L<provider(7)/Fetching algorithms> for further information.
158 The returned value must eventually be freed with
159 L<EVP_CIPHER_meth_free(3)>.
161 EVP_CIPHER_CTX_new() creates a cipher context.
163 EVP_CIPHER_CTX_free() clears all information from a cipher context
164 and free up any allocated memory associate with it, including B<ctx>
165 itself. This function should be called after all operations using a
166 cipher are complete so sensitive information does not remain in
169 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
170 with cipher B<type>. B<type> is typically supplied by a function such
171 as EVP_aes_256_cbc(), or a value explicitly fetched with
172 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
173 cipher B<type> is used if there is one, and if not, the default
174 implementation is used. B<key> is the symmetric key to use
175 and B<iv> is the IV to use (if necessary), the actual number of bytes
176 used for the key and IV depends on the cipher. It is possible to set
177 all parameters to NULL except B<type> in an initial call and supply
178 the remaining parameters in subsequent calls, all of which have B<type>
179 set to NULL. This is done when the default cipher parameters are not
181 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
184 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
185 writes the encrypted version to B<out>. This function can be called
186 multiple times to encrypt successive blocks of data. The amount
187 of data written depends on the block alignment of the encrypted data:
188 as a result the amount of data written may be anything from zero bytes
189 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
190 room. The actual number of bytes written is placed in B<outl>. It also
191 checks if B<in> and B<out> are partially overlapping, and if they are
192 0 is returned to indicate failure.
194 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
195 the "final" data, that is any data that remains in a partial block.
196 It uses standard block padding (aka PKCS padding) as described in
197 the NOTES section, below. The encrypted
198 final data is written to B<out> which should have sufficient space for
199 one cipher block. The number of bytes written is placed in B<outl>. After
200 this function is called the encryption operation is finished and no further
201 calls to EVP_EncryptUpdate() should be made.
203 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
204 data and it will return an error if any data remains in a partial block:
205 that is if the total data length is not a multiple of the block size.
207 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
208 corresponding decryption operations. EVP_DecryptFinal() will return an
209 error code if padding is enabled and the final block is not correctly
210 formatted. The parameters and restrictions are identical to the encryption
211 operations except that if padding is enabled the decrypted data buffer B<out>
212 passed to EVP_DecryptUpdate() should have sufficient room for
213 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
214 which case B<inl> bytes is sufficient.
216 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
217 functions that can be used for decryption or encryption. The operation
218 performed depends on the value of the B<enc> parameter. It should be set
219 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
220 (the actual value of 'enc' being supplied in a previous call).
222 EVP_CIPHER_CTX_reset() clears all information from a cipher context
223 and free up any allocated memory associate with it, except the B<ctx>
224 itself. This function should be called anytime B<ctx> is to be reused
225 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
228 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
229 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
230 EVP_CipherInit_ex() except they always use the default cipher implementation.
232 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
233 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
234 EVP_CipherFinal_ex(). In previous releases they also cleaned up
235 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
236 must be called to free any context resources.
238 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
239 return an EVP_CIPHER structure when passed a cipher name, a NID or an
240 ASN1_OBJECT structure.
242 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
243 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
244 value is an internal value which may not have a corresponding OBJECT
247 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
248 function should be called after the context is set up for encryption
249 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
250 EVP_CipherInit_ex(). By default encryption operations are padded using
251 standard block padding and the padding is checked and removed when
252 decrypting. If the B<pad> parameter is zero then no padding is
253 performed, the total amount of data encrypted or decrypted must then
254 be a multiple of the block size or an error will occur.
256 EVP_CIPHER_get_params() retrieves the requested list of algorithm
257 B<params> from a B<cipher>.
259 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
262 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
263 B<params> from CIPHER context B<ctx>.
265 EVP_CIPHER_gettable_params(), EVP_CIPHER_CTX_gettable_params(), and
266 EVP_CIPHER_CTX_settable_params() get a constant B<OSSL_PARAM> array
267 that decribes the retrievable and settable parameters, i.e. parameters
268 that can be used with EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params()
269 and EVP_CIPHER_CTX_set_params(), respectively.
270 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
272 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
273 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
274 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
275 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
276 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
277 for variable key length ciphers.
279 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
280 If the cipher is a fixed length cipher then attempting to set the key
281 length to any value other than the fixed value is an error.
283 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
284 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
285 It will return zero if the cipher does not use an IV. The constant
286 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
288 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
289 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
290 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
291 length for all ciphers.
293 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
294 cipher or context. This "type" is the actual NID of the cipher OBJECT
295 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
296 128 bit RC2 have the same NID. If the cipher does not have an object
297 identifier or does not have ASN1 support this function will return
300 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
303 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
304 that implements the given B<EVP_CIPHER>.
306 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
307 an B<EVP_CIPHER_CTX> structure.
309 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
310 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
311 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
312 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
313 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
315 EVP_CIPHER_flags() returns any flags associated with the cipher. See
316 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
318 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
319 on the passed cipher. This will typically include any parameters and an
320 IV. The cipher IV (if any) must be set when this call is made. This call
321 should be made before the cipher is actually "used" (before any
322 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
323 may fail if the cipher does not have any ASN1 support.
325 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
326 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
327 In the case of RC2, for example, it will set the IV and effective key length.
328 This function should be called after the base cipher type is set but before
329 the key is set. For example EVP_CipherInit() will be called with the IV and
330 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
331 EVP_CipherInit() again with all parameters except the key set to NULL. It is
332 possible for this function to fail if the cipher does not have any ASN1 support
333 or the parameters cannot be set (for example the RC2 effective key length
336 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
339 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
340 based on the cipher context. The EVP_CIPHER can provide its own random key
341 generation routine to support keys of a specific form. B<Key> must point to a
342 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
344 EVP_CIPHER_do_all_ex() traverses all ciphers implemented by all activated
345 providers in the given library context I<libctx>, and for each of the
346 implementations, calls the given function I<fn> with the implementation method
347 and the given I<arg> as argument.
351 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
352 and B<NULL> for failure.
354 EVP_CIPHER_CTX_new() returns a pointer to a newly created
355 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
357 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
358 return 1 for success and 0 for failure.
360 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
361 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
363 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
364 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
366 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
368 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
369 return an B<EVP_CIPHER> structure or NULL on error.
371 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
373 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
376 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
379 EVP_CIPHER_CTX_set_padding() always returns 1.
381 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
382 length or zero if the cipher does not use an IV.
384 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
385 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
387 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
389 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
390 than zero for success and zero or a negative number on failure.
392 EVP_CIPHER_CTX_rand_key() returns 1 for success.
394 =head1 CIPHER LISTING
396 All algorithms have a fixed key length unless otherwise stated.
398 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
405 Null cipher: does nothing.
409 =head1 AEAD INTERFACE
411 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
412 modes are subtly altered and several additional I<ctrl> operations are supported
413 depending on the mode specified.
415 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
416 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
417 parameter B<out> set to B<NULL>.
419 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
420 indicates whether the operation was successful. If it does not indicate success,
421 the authentication operation has failed and any output data B<MUST NOT> be used
424 =head2 GCM and OCB Modes
426 The following I<ctrl>s are supported in GCM and OCB modes.
430 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
432 Sets the IV length. This call can only be made before specifying an IV. If
433 not called a default IV length is used.
435 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
438 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
440 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
441 This call can only be made when encrypting data and B<after> all data has been
442 processed (e.g. after an EVP_EncryptFinal() call).
444 For OCB, C<taglen> must either be 16 or the value previously set via
445 B<EVP_CTRL_AEAD_SET_TAG>.
447 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
449 Sets the expected tag to C<taglen> bytes from C<tag>.
450 The tag length can only be set before specifying an IV.
451 C<taglen> must be between 1 and 16 inclusive.
453 For GCM, this call is only valid when decrypting data.
455 For OCB, this call is valid when decrypting data to set the expected tag,
456 and before encryption to set the desired tag length.
458 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
459 tag length. If this is not called prior to encryption, a default tag length is
462 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
463 maximum tag length for OCB.
469 The EVP interface for CCM mode is similar to that of the GCM mode but with a
470 few additional requirements and different I<ctrl> values.
472 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
473 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
474 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
475 the B<inl> parameter.
477 The following I<ctrl>s are supported in CCM mode.
481 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
483 This call is made to set the expected B<CCM> tag value when decrypting or
484 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
485 The tag length is often referred to as B<M>. If not set a default value is
486 used (12 for AES). When decrypting, the tag needs to be set before passing
487 in data to be decrypted, but as in GCM and OCB mode, it can be set after
488 passing additional authenticated data (see L</AEAD INTERFACE>).
490 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
492 Sets the CCM B<L> value. If not set a default is used (8 for AES).
494 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
496 Sets the CCM nonce (IV) length. This call can only be made before specifying an
497 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
504 For SIV mode ciphers the behaviour of the EVP interface is subtly
505 altered and several additional ctrl operations are supported.
507 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
508 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
509 with the output parameter B<out> set to B<NULL>.
511 RFC5297 states that the Nonce is the last piece of AAD before the actual
512 encrypt/decrypt takes place. The API does not differentiate the Nonce from
515 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
516 indicates if the operation was successful. If it does not indicate success
517 the authentication operation has failed and any output data B<MUST NOT>
518 be used as it is corrupted.
520 The following ctrls are supported in both SIV modes.
524 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
526 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
527 This call can only be made when encrypting data and B<after> all data has been
528 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
531 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
533 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
534 when decrypting data and must be made B<before> any data is processed (e.g.
535 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
539 SIV mode makes two passes over the input data, thus, only one call to
540 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
541 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
542 EVP_CipherFinal() is not required, but will indicate if the update
545 =head2 ChaCha20-Poly1305
547 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
551 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
553 Sets the nonce length. This call can only be made before specifying the nonce.
554 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
555 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
556 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
559 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
561 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
562 This call can only be made when encrypting data and B<after> all data has been
563 processed (e.g. after an EVP_EncryptFinal() call).
565 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
568 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
570 Sets the expected tag to C<taglen> bytes from C<tag>.
571 The tag length can only be set before specifying an IV.
572 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
573 This call is only valid when decrypting data.
579 Where possible the B<EVP> interface to symmetric ciphers should be used in
580 preference to the low level interfaces. This is because the code then becomes
581 transparent to the cipher used and much more flexible. Additionally, the
582 B<EVP> interface will ensure the use of platform specific cryptographic
583 acceleration such as AES-NI (the low level interfaces do not provide the
586 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
587 length of the encrypted data a multiple of the block size. Padding is always
588 added so if the data is already a multiple of the block size B<n> will equal
589 the block size. For example if the block size is 8 and 11 bytes are to be
590 encrypted then 5 padding bytes of value 5 will be added.
592 When decrypting the final block is checked to see if it has the correct form.
594 Although the decryption operation can produce an error if padding is enabled,
595 it is not a strong test that the input data or key is correct. A random block
596 has better than 1 in 256 chance of being of the correct format and problems with
597 the input data earlier on will not produce a final decrypt error.
599 If padding is disabled then the decryption operation will always succeed if
600 the total amount of data decrypted is a multiple of the block size.
602 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
603 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
604 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
605 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
606 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
607 existing context without allocating and freeing it up on each call.
609 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
613 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
614 ciphers with default key lengths. If custom ciphers exceed these values the
615 results are unpredictable. This is because it has become standard practice to
616 define a generic key as a fixed unsigned char array containing
617 B<EVP_MAX_KEY_LENGTH> bytes.
619 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
620 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
624 Encrypt a string using IDEA:
626 int do_crypt(char *outfile)
628 unsigned char outbuf[1024];
631 * Bogus key and IV: we'd normally set these from
634 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
635 unsigned char iv[] = {1,2,3,4,5,6,7,8};
636 char intext[] = "Some Crypto Text";
640 ctx = EVP_CIPHER_CTX_new();
641 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
643 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
645 EVP_CIPHER_CTX_free(ctx);
649 * Buffer passed to EVP_EncryptFinal() must be after data just
650 * encrypted to avoid overwriting it.
652 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
654 EVP_CIPHER_CTX_free(ctx);
658 EVP_CIPHER_CTX_free(ctx);
660 * Need binary mode for fopen because encrypted data is
661 * binary data. Also cannot use strlen() on it because
662 * it won't be NUL terminated and may contain embedded
665 out = fopen(outfile, "wb");
670 fwrite(outbuf, 1, outlen, out);
675 The ciphertext from the above example can be decrypted using the B<openssl>
676 utility with the command line (shown on two lines for clarity):
679 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
681 General encryption and decryption function example using FILE I/O and AES128
684 int do_crypt(FILE *in, FILE *out, int do_encrypt)
686 /* Allow enough space in output buffer for additional block */
687 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
691 * Bogus key and IV: we'd normally set these from
694 unsigned char key[] = "0123456789abcdeF";
695 unsigned char iv[] = "1234567887654321";
697 /* Don't set key or IV right away; we want to check lengths */
698 ctx = EVP_CIPHER_CTX_new();
699 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
701 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
702 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
704 /* Now we can set key and IV */
705 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
708 inlen = fread(inbuf, 1, 1024, in);
711 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
713 EVP_CIPHER_CTX_free(ctx);
716 fwrite(outbuf, 1, outlen, out);
718 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
720 EVP_CIPHER_CTX_free(ctx);
723 fwrite(outbuf, 1, outlen, out);
725 EVP_CIPHER_CTX_free(ctx);
734 Supported ciphers are listed in:
753 Support for OCB mode was added in OpenSSL 1.1.0.
755 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
756 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
757 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
758 EVP_CIPHER_CTX_reset().
762 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
764 Licensed under the Apache License 2.0 (the "License"). You may not use
765 this file except in compliance with the License. You can obtain a copy
766 in the file LICENSE in the source distribution or at
767 L<https://www.openssl.org/source/license.html>.