20 EVP_CIPHER_CTX_set_key_length,
36 EVP_CIPHER_get_params,
37 EVP_CIPHER_gettable_params,
38 EVP_CIPHER_block_size,
39 EVP_CIPHER_key_length,
44 EVP_CIPHER_CTX_cipher,
47 EVP_CIPHER_CTX_get_params,
48 EVP_CIPHER_gettable_ctx_params,
49 EVP_CIPHER_CTX_set_params,
50 EVP_CIPHER_settable_ctx_params,
51 EVP_CIPHER_CTX_block_size,
52 EVP_CIPHER_CTX_key_length,
53 EVP_CIPHER_CTX_iv_length,
54 EVP_CIPHER_CTX_tag_length,
55 EVP_CIPHER_CTX_get_app_data,
56 EVP_CIPHER_CTX_set_app_data,
60 EVP_CIPHER_param_to_asn1,
61 EVP_CIPHER_asn1_to_param,
62 EVP_CIPHER_CTX_set_padding,
64 EVP_CIPHER_do_all_provided
71 #include <openssl/evp.h>
73 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
74 const char *properties);
75 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
76 void EVP_CIPHER_free(EVP_CIPHER *cipher);
77 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
78 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
79 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
81 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
82 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
83 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
84 int *outl, const unsigned char *in, int inl);
85 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
87 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
88 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
89 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
90 int *outl, const unsigned char *in, int inl);
91 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
93 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
94 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
95 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
96 int *outl, const unsigned char *in, int inl);
97 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
99 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
100 const unsigned char *key, const unsigned char *iv);
101 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
103 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
104 const unsigned char *key, const unsigned char *iv);
105 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
107 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
108 const unsigned char *key, const unsigned char *iv, int enc);
109 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
111 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
112 const unsigned char *in, unsigned int inl);
114 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
115 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
116 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
117 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
119 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
120 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
121 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
123 int EVP_CIPHER_nid(const EVP_CIPHER *e);
124 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
125 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
126 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
127 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
128 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
129 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
130 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
131 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
132 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
134 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
135 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
136 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
138 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
139 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
140 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
141 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
142 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
143 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
144 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
145 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
146 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
147 int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
148 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
149 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
150 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
151 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
153 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
154 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
156 void EVP_CIPHER_do_all_provided(OPENSSL_CTX *libctx,
157 void (*fn)(EVP_CIPHER *cipher, void *arg),
162 The EVP cipher routines are a high level interface to certain
165 The B<EVP_CIPHER> type is a structure for cipher method implementation.
167 EVP_CIPHER_fetch() fetches the cipher implementation for the given
168 B<algorithm> from any provider offering it, within the criteria given
169 by the B<properties>.
170 See L<provider(7)/Fetching algorithms> for further information.
172 The returned value must eventually be freed with EVP_CIPHER_free().
174 EVP_CIPHER_up_ref() increments the reference count for an B<EVP_CIPHER>
177 EVP_CIPHER_free() decrements the reference count for the B<EVP_CIPHER>
179 If the reference count drops to 0 then the structure is freed.
181 EVP_CIPHER_CTX_new() creates a cipher context.
183 EVP_CIPHER_CTX_free() clears all information from a cipher context
184 and free up any allocated memory associate with it, including B<ctx>
185 itself. This function should be called after all operations using a
186 cipher are complete so sensitive information does not remain in
189 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
190 with cipher B<type>. B<type> is typically supplied by a function such
191 as EVP_aes_256_cbc(), or a value explicitly fetched with
192 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
193 cipher B<type> is used if there is one, and if not, the default
194 implementation is used. B<key> is the symmetric key to use
195 and B<iv> is the IV to use (if necessary), the actual number of bytes
196 used for the key and IV depends on the cipher. It is possible to set
197 all parameters to NULL except B<type> in an initial call and supply
198 the remaining parameters in subsequent calls, all of which have B<type>
199 set to NULL. This is done when the default cipher parameters are not
201 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
204 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
205 writes the encrypted version to B<out>. This function can be called
206 multiple times to encrypt successive blocks of data. The amount
207 of data written depends on the block alignment of the encrypted data:
208 as a result the amount of data written may be anything from zero bytes
209 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
210 room. The actual number of bytes written is placed in B<outl>. It also
211 checks if B<in> and B<out> are partially overlapping, and if they are
212 0 is returned to indicate failure.
214 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
215 the "final" data, that is any data that remains in a partial block.
216 It uses standard block padding (aka PKCS padding) as described in
217 the NOTES section, below. The encrypted
218 final data is written to B<out> which should have sufficient space for
219 one cipher block. The number of bytes written is placed in B<outl>. After
220 this function is called the encryption operation is finished and no further
221 calls to EVP_EncryptUpdate() should be made.
223 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
224 data and it will return an error if any data remains in a partial block:
225 that is if the total data length is not a multiple of the block size.
227 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
228 corresponding decryption operations. EVP_DecryptFinal() will return an
229 error code if padding is enabled and the final block is not correctly
230 formatted. The parameters and restrictions are identical to the encryption
231 operations except that if padding is enabled the decrypted data buffer B<out>
232 passed to EVP_DecryptUpdate() should have sufficient room for
233 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
234 which case B<inl> bytes is sufficient.
236 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
237 functions that can be used for decryption or encryption. The operation
238 performed depends on the value of the B<enc> parameter. It should be set
239 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
240 (the actual value of 'enc' being supplied in a previous call).
242 EVP_CIPHER_CTX_reset() clears all information from a cipher context
243 and free up any allocated memory associate with it, except the B<ctx>
244 itself. This function should be called anytime B<ctx> is to be reused
245 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
248 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
249 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
250 EVP_CipherInit_ex() except they always use the default cipher implementation.
252 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
253 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
254 EVP_CipherFinal_ex(). In previous releases they also cleaned up
255 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
256 must be called to free any context resources.
258 EVP_Cipher() encrypts or decrypts a maximum I<inl> amount of bytes from
259 I<in> and leaves the result in I<out>.
260 If the cipher doesn't have the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set,
261 then I<inl> must be a multiple of EVP_CIPHER_block_size(). If it isn't,
262 the result is undefined. If the cipher has that flag set, then I<inl>
264 This function is historic and shouldn't be used in an application, please
265 consider using EVP_CipherUpdate() and EVP_CipherFinal_ex instead.
267 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
268 return an EVP_CIPHER structure when passed a cipher name, a NID or an
269 ASN1_OBJECT structure.
271 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
272 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
273 value is an internal value which may not have a corresponding OBJECT
276 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
277 function should be called after the context is set up for encryption
278 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
279 EVP_CipherInit_ex(). By default encryption operations are padded using
280 standard block padding and the padding is checked and removed when
281 decrypting. If the B<pad> parameter is zero then no padding is
282 performed, the total amount of data encrypted or decrypted must then
283 be a multiple of the block size or an error will occur.
285 EVP_CIPHER_get_params() retrieves the requested list of algorithm
286 B<params> from a B<cipher>.
288 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
291 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
292 B<params> from CIPHER context B<ctx>.
294 EVP_CIPHER_gettable_params(), EVP_CIPHER_gettable_ctx_params(), and
295 EVP_CIPHER_settable_ctx_params() get a constant B<OSSL_PARAM> array
296 that decribes the retrievable and settable parameters, i.e. parameters
297 that can be used with EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params()
298 and EVP_CIPHER_CTX_set_params(), respectively.
299 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
301 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
302 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
303 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
304 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
305 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
306 for variable key length ciphers.
308 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
309 If the cipher is a fixed length cipher then attempting to set the key
310 length to any value other than the fixed value is an error.
312 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
313 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
314 It will return zero if the cipher does not use an IV. The constant
315 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
317 EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed
318 a B<EVP_CIPHER_CTX>. It will return zero if the cipher does not support a tag.
319 It returns a default value if the tag length has not been set.
321 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
322 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
323 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
324 length for all ciphers.
326 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
327 cipher or context. This "type" is the actual NID of the cipher OBJECT
328 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
329 128 bit RC2 have the same NID. If the cipher does not have an object
330 identifier or does not have ASN1 support this function will return
333 EVP_CIPHER_is_a() returns 1 if I<cipher> is an implementation of an
334 algorithm that's identifiable with I<name>, otherwise 0.
336 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
337 cipher or context. For fetched ciphers with multiple names, only one
340 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
341 that implements the given B<EVP_CIPHER>.
343 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
344 an B<EVP_CIPHER_CTX> structure.
346 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
347 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
348 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
349 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
350 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
352 EVP_CIPHER_flags() returns any flags associated with the cipher. See
353 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
355 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
356 on the passed cipher. This will typically include any parameters and an
357 IV. The cipher IV (if any) must be set when this call is made. This call
358 should be made before the cipher is actually "used" (before any
359 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
360 may fail if the cipher does not have any ASN1 support.
362 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
363 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
364 In the case of RC2, for example, it will set the IV and effective key length.
365 This function should be called after the base cipher type is set but before
366 the key is set. For example EVP_CipherInit() will be called with the IV and
367 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
368 EVP_CipherInit() again with all parameters except the key set to NULL. It is
369 possible for this function to fail if the cipher does not have any ASN1 support
370 or the parameters cannot be set (for example the RC2 effective key length
373 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
376 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
377 based on the cipher context. The EVP_CIPHER can provide its own random key
378 generation routine to support keys of a specific form. B<Key> must point to a
379 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
381 EVP_CIPHER_do_all_provided() traverses all ciphers implemented by all activated
382 providers in the given library context I<libctx>, and for each of the
383 implementations, calls the given function I<fn> with the implementation method
384 and the given I<arg> as argument.
388 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
389 and B<NULL> for failure.
391 EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
393 EVP_CIPHER_CTX_new() returns a pointer to a newly created
394 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
396 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
397 return 1 for success and 0 for failure.
399 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
400 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
402 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
403 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
405 EVP_Cipher() returns the amount of encrypted / decrypted bytes, or -1
406 on failure, if the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the
407 cipher. EVP_Cipher() returns 1 on success or 0 on failure, if the flag
408 B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher.
410 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
412 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
413 return an B<EVP_CIPHER> structure or NULL on error.
415 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
417 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
420 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
423 EVP_CIPHER_CTX_set_padding() always returns 1.
425 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
426 length or zero if the cipher does not use an IV.
428 EVP_CIPHER_CTX_tag_length() return the tag length or zero if the cipher does not
431 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
432 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
434 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
436 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
437 than zero for success and zero or a negative number on failure.
439 EVP_CIPHER_CTX_rand_key() returns 1 for success.
441 =head1 CIPHER LISTING
443 All algorithms have a fixed key length unless otherwise stated.
445 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
452 Null cipher: does nothing.
456 =head1 AEAD INTERFACE
458 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
459 modes are subtly altered and several additional I<ctrl> operations are supported
460 depending on the mode specified.
462 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
463 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
464 parameter B<out> set to B<NULL>.
466 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
467 indicates whether the operation was successful. If it does not indicate success,
468 the authentication operation has failed and any output data B<MUST NOT> be used
471 =head2 GCM and OCB Modes
473 The following I<ctrl>s are supported in GCM and OCB modes.
477 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
479 Sets the IV length. This call can only be made before specifying an IV. If
480 not called a default IV length is used.
482 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
485 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
487 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
488 This call can only be made when encrypting data and B<after> all data has been
489 processed (e.g. after an EVP_EncryptFinal() call).
491 For OCB, C<taglen> must either be 16 or the value previously set via
492 B<EVP_CTRL_AEAD_SET_TAG>.
494 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
496 Sets the expected tag to C<taglen> bytes from C<tag>.
497 The tag length can only be set before specifying an IV.
498 C<taglen> must be between 1 and 16 inclusive.
500 For GCM, this call is only valid when decrypting data.
502 For OCB, this call is valid when decrypting data to set the expected tag,
503 and before encryption to set the desired tag length.
505 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
506 tag length. If this is not called prior to encryption, a default tag length is
509 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
510 maximum tag length for OCB.
516 The EVP interface for CCM mode is similar to that of the GCM mode but with a
517 few additional requirements and different I<ctrl> values.
519 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
520 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
521 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
522 the B<inl> parameter.
524 The following I<ctrl>s are supported in CCM mode.
528 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
530 This call is made to set the expected B<CCM> tag value when decrypting or
531 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
532 The tag length is often referred to as B<M>. If not set a default value is
533 used (12 for AES). When decrypting, the tag needs to be set before passing
534 in data to be decrypted, but as in GCM and OCB mode, it can be set after
535 passing additional authenticated data (see L</AEAD INTERFACE>).
537 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
539 Sets the CCM B<L> value. If not set a default is used (8 for AES).
541 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
543 Sets the CCM nonce (IV) length. This call can only be made before specifying an
544 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
551 For SIV mode ciphers the behaviour of the EVP interface is subtly
552 altered and several additional ctrl operations are supported.
554 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
555 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
556 with the output parameter B<out> set to B<NULL>.
558 RFC5297 states that the Nonce is the last piece of AAD before the actual
559 encrypt/decrypt takes place. The API does not differentiate the Nonce from
562 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
563 indicates if the operation was successful. If it does not indicate success
564 the authentication operation has failed and any output data B<MUST NOT>
565 be used as it is corrupted.
567 The following ctrls are supported in both SIV modes.
571 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
573 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
574 This call can only be made when encrypting data and B<after> all data has been
575 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
578 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
580 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
581 when decrypting data and must be made B<before> any data is processed (e.g.
582 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
586 SIV mode makes two passes over the input data, thus, only one call to
587 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
588 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
589 EVP_CipherFinal() is not required, but will indicate if the update
592 =head2 ChaCha20-Poly1305
594 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
598 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
600 Sets the nonce length. This call can only be made before specifying the nonce.
601 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
602 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
603 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
606 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
608 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
609 This call can only be made when encrypting data and B<after> all data has been
610 processed (e.g. after an EVP_EncryptFinal() call).
612 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
615 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
617 Sets the expected tag to C<taglen> bytes from C<tag>.
618 The tag length can only be set before specifying an IV.
619 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
620 This call is only valid when decrypting data.
626 Where possible the B<EVP> interface to symmetric ciphers should be used in
627 preference to the low level interfaces. This is because the code then becomes
628 transparent to the cipher used and much more flexible. Additionally, the
629 B<EVP> interface will ensure the use of platform specific cryptographic
630 acceleration such as AES-NI (the low level interfaces do not provide the
633 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
634 length of the encrypted data a multiple of the block size. Padding is always
635 added so if the data is already a multiple of the block size B<n> will equal
636 the block size. For example if the block size is 8 and 11 bytes are to be
637 encrypted then 5 padding bytes of value 5 will be added.
639 When decrypting the final block is checked to see if it has the correct form.
641 Although the decryption operation can produce an error if padding is enabled,
642 it is not a strong test that the input data or key is correct. A random block
643 has better than 1 in 256 chance of being of the correct format and problems with
644 the input data earlier on will not produce a final decrypt error.
646 If padding is disabled then the decryption operation will always succeed if
647 the total amount of data decrypted is a multiple of the block size.
649 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
650 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
651 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
652 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
653 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
654 existing context without allocating and freeing it up on each call.
656 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
660 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
661 ciphers with default key lengths. If custom ciphers exceed these values the
662 results are unpredictable. This is because it has become standard practice to
663 define a generic key as a fixed unsigned char array containing
664 B<EVP_MAX_KEY_LENGTH> bytes.
666 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
667 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
671 Encrypt a string using IDEA:
673 int do_crypt(char *outfile)
675 unsigned char outbuf[1024];
678 * Bogus key and IV: we'd normally set these from
681 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
682 unsigned char iv[] = {1,2,3,4,5,6,7,8};
683 char intext[] = "Some Crypto Text";
687 ctx = EVP_CIPHER_CTX_new();
688 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
690 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
692 EVP_CIPHER_CTX_free(ctx);
696 * Buffer passed to EVP_EncryptFinal() must be after data just
697 * encrypted to avoid overwriting it.
699 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
701 EVP_CIPHER_CTX_free(ctx);
705 EVP_CIPHER_CTX_free(ctx);
707 * Need binary mode for fopen because encrypted data is
708 * binary data. Also cannot use strlen() on it because
709 * it won't be NUL terminated and may contain embedded
712 out = fopen(outfile, "wb");
717 fwrite(outbuf, 1, outlen, out);
722 The ciphertext from the above example can be decrypted using the B<openssl>
723 utility with the command line (shown on two lines for clarity):
726 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
728 General encryption and decryption function example using FILE I/O and AES128
731 int do_crypt(FILE *in, FILE *out, int do_encrypt)
733 /* Allow enough space in output buffer for additional block */
734 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
738 * Bogus key and IV: we'd normally set these from
741 unsigned char key[] = "0123456789abcdeF";
742 unsigned char iv[] = "1234567887654321";
744 /* Don't set key or IV right away; we want to check lengths */
745 ctx = EVP_CIPHER_CTX_new();
746 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
748 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
749 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
751 /* Now we can set key and IV */
752 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
755 inlen = fread(inbuf, 1, 1024, in);
758 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
760 EVP_CIPHER_CTX_free(ctx);
763 fwrite(outbuf, 1, outlen, out);
765 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
767 EVP_CIPHER_CTX_free(ctx);
770 fwrite(outbuf, 1, outlen, out);
772 EVP_CIPHER_CTX_free(ctx);
781 Supported ciphers are listed in:
800 Support for OCB mode was added in OpenSSL 1.1.0.
802 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
803 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
804 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
805 EVP_CIPHER_CTX_reset().
807 The EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
808 EVP_CIPHER_CTX_set_params() and EVP_CIPHER_CTX_get_params() functions
813 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
815 Licensed under the Apache License 2.0 (the "License"). You may not use
816 this file except in compliance with the License. You can obtain a copy
817 in the file LICENSE in the source distribution or at
818 L<https://www.openssl.org/source/license.html>.