20 EVP_CIPHER_CTX_set_key_length,
35 EVP_CIPHER_names_do_all,
38 EVP_CIPHER_get_params,
39 EVP_CIPHER_gettable_params,
40 EVP_CIPHER_block_size,
41 EVP_CIPHER_key_length,
46 EVP_CIPHER_CTX_cipher,
49 EVP_CIPHER_CTX_get_params,
50 EVP_CIPHER_gettable_ctx_params,
51 EVP_CIPHER_CTX_set_params,
52 EVP_CIPHER_settable_ctx_params,
53 EVP_CIPHER_CTX_block_size,
54 EVP_CIPHER_CTX_key_length,
55 EVP_CIPHER_CTX_iv_length,
56 EVP_CIPHER_CTX_tag_length,
57 EVP_CIPHER_CTX_get_app_data,
58 EVP_CIPHER_CTX_set_app_data,
62 EVP_CIPHER_param_to_asn1,
63 EVP_CIPHER_asn1_to_param,
64 EVP_CIPHER_CTX_set_padding,
66 EVP_CIPHER_do_all_provided
73 #include <openssl/evp.h>
75 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
76 const char *properties);
77 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
78 void EVP_CIPHER_free(EVP_CIPHER *cipher);
79 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
80 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
81 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
83 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
84 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
85 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
86 int *outl, const unsigned char *in, int inl);
87 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
89 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
90 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
91 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
92 int *outl, const unsigned char *in, int inl);
93 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
95 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
96 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
97 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
98 int *outl, const unsigned char *in, int inl);
99 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
101 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
102 const unsigned char *key, const unsigned char *iv);
103 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
105 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
106 const unsigned char *key, const unsigned char *iv);
107 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
109 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
110 const unsigned char *key, const unsigned char *iv, int enc);
111 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
113 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
114 const unsigned char *in, unsigned int inl);
116 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
117 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
118 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
119 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
121 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
122 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
123 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
125 int EVP_CIPHER_nid(const EVP_CIPHER *e);
126 int EVP_CIPHER_number(const EVP_CIPHER *e);
127 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
128 void EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
129 void (*fn)(const char *name, void *data),
131 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
132 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
133 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
134 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
135 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
136 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
137 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
138 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
140 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
141 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
142 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
144 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
145 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
146 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
147 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
148 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
149 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
150 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
151 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
152 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
153 int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
154 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
155 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
156 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
157 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
159 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
160 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
162 void EVP_CIPHER_do_all_provided(OPENSSL_CTX *libctx,
163 void (*fn)(EVP_CIPHER *cipher, void *arg),
168 The EVP cipher routines are a high level interface to certain
171 The B<EVP_CIPHER> type is a structure for cipher method implementation.
173 EVP_CIPHER_fetch() fetches the cipher implementation for the given
174 B<algorithm> from any provider offering it, within the criteria given
175 by the B<properties>.
176 See L<provider(7)/Fetching algorithms> for further information.
178 The returned value must eventually be freed with EVP_CIPHER_free().
180 EVP_CIPHER_up_ref() increments the reference count for an B<EVP_CIPHER>
183 EVP_CIPHER_free() decrements the reference count for the B<EVP_CIPHER>
185 If the reference count drops to 0 then the structure is freed.
187 EVP_CIPHER_CTX_new() creates a cipher context.
189 EVP_CIPHER_CTX_free() clears all information from a cipher context
190 and free up any allocated memory associate with it, including B<ctx>
191 itself. This function should be called after all operations using a
192 cipher are complete so sensitive information does not remain in
195 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
196 with cipher B<type>. B<type> is typically supplied by a function such
197 as EVP_aes_256_cbc(), or a value explicitly fetched with
198 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
199 cipher B<type> is used if there is one, and if not, the default
200 implementation is used. B<key> is the symmetric key to use
201 and B<iv> is the IV to use (if necessary), the actual number of bytes
202 used for the key and IV depends on the cipher. It is possible to set
203 all parameters to NULL except B<type> in an initial call and supply
204 the remaining parameters in subsequent calls, all of which have B<type>
205 set to NULL. This is done when the default cipher parameters are not
207 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
210 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
211 writes the encrypted version to B<out>. This function can be called
212 multiple times to encrypt successive blocks of data. The amount
213 of data written depends on the block alignment of the encrypted data:
214 as a result the amount of data written may be anything from zero bytes
215 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
216 room. The actual number of bytes written is placed in B<outl>. It also
217 checks if B<in> and B<out> are partially overlapping, and if they are
218 0 is returned to indicate failure.
220 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
221 the "final" data, that is any data that remains in a partial block.
222 It uses standard block padding (aka PKCS padding) as described in
223 the NOTES section, below. The encrypted
224 final data is written to B<out> which should have sufficient space for
225 one cipher block. The number of bytes written is placed in B<outl>. After
226 this function is called the encryption operation is finished and no further
227 calls to EVP_EncryptUpdate() should be made.
229 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
230 data and it will return an error if any data remains in a partial block:
231 that is if the total data length is not a multiple of the block size.
233 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
234 corresponding decryption operations. EVP_DecryptFinal() will return an
235 error code if padding is enabled and the final block is not correctly
236 formatted. The parameters and restrictions are identical to the encryption
237 operations except that if padding is enabled the decrypted data buffer B<out>
238 passed to EVP_DecryptUpdate() should have sufficient room for
239 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
240 which case B<inl> bytes is sufficient.
242 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
243 functions that can be used for decryption or encryption. The operation
244 performed depends on the value of the B<enc> parameter. It should be set
245 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
246 (the actual value of 'enc' being supplied in a previous call).
248 EVP_CIPHER_CTX_reset() clears all information from a cipher context
249 and free up any allocated memory associate with it, except the B<ctx>
250 itself. This function should be called anytime B<ctx> is to be reused
251 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
254 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
255 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
256 EVP_CipherInit_ex() except they always use the default cipher implementation.
258 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
259 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
260 EVP_CipherFinal_ex(). In previous releases they also cleaned up
261 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
262 must be called to free any context resources.
264 EVP_Cipher() encrypts or decrypts a maximum I<inl> amount of bytes from
265 I<in> and leaves the result in I<out>.
266 If the cipher doesn't have the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set,
267 then I<inl> must be a multiple of EVP_CIPHER_block_size(). If it isn't,
268 the result is undefined. If the cipher has that flag set, then I<inl>
270 This function is historic and shouldn't be used in an application, please
271 consider using EVP_CipherUpdate() and EVP_CipherFinal_ex instead.
273 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
274 return an EVP_CIPHER structure when passed a cipher name, a NID or an
275 ASN1_OBJECT structure.
277 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
278 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
279 value is an internal value which may not have a corresponding OBJECT
282 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
283 function should be called after the context is set up for encryption
284 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
285 EVP_CipherInit_ex(). By default encryption operations are padded using
286 standard block padding and the padding is checked and removed when
287 decrypting. If the B<pad> parameter is zero then no padding is
288 performed, the total amount of data encrypted or decrypted must then
289 be a multiple of the block size or an error will occur.
291 EVP_CIPHER_get_params() retrieves the requested list of algorithm
292 B<params> from a B<cipher>.
294 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
297 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
298 B<params> from CIPHER context B<ctx>.
300 EVP_CIPHER_gettable_params(), EVP_CIPHER_gettable_ctx_params(), and
301 EVP_CIPHER_settable_ctx_params() get a constant B<OSSL_PARAM> array
302 that describes the retrievable and settable parameters, i.e. parameters
303 that can be used with EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params()
304 and EVP_CIPHER_CTX_set_params(), respectively.
305 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
307 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
308 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
309 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
310 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
311 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
312 for variable key length ciphers.
314 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
315 If the cipher is a fixed length cipher then attempting to set the key
316 length to any value other than the fixed value is an error.
318 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
319 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
320 It will return zero if the cipher does not use an IV. The constant
321 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
323 EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed
324 a B<EVP_CIPHER_CTX>. It will return zero if the cipher does not support a tag.
325 It returns a default value if the tag length has not been set.
327 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
328 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
329 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
330 length for all ciphers.
332 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
333 cipher or context. This "type" is the actual NID of the cipher OBJECT
334 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
335 128 bit RC2 have the same NID. If the cipher does not have an object
336 identifier or does not have ASN1 support this function will return
339 EVP_CIPHER_is_a() returns 1 if I<cipher> is an implementation of an
340 algorithm that's identifiable with I<name>, otherwise 0.
342 EVP_CIPHER_number() returns the internal dynamic number assigned to
343 the I<cipher>. This is only useful with fetched B<EVP_CIPHER>s.
345 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
346 cipher or context. For fetched ciphers with multiple names, only one
347 of them is returned; it's recommended to use EVP_CIPHER_names_do_all()
350 EVP_CIPHER_names_do_all() traverses all names for the I<cipher>, and
351 calls I<fn> with each name and I<data>. This is only useful with
352 fetched B<EVP_CIPHER>s.
354 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
355 that implements the given B<EVP_CIPHER>.
357 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
358 an B<EVP_CIPHER_CTX> structure.
360 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
361 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
362 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
363 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
364 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
366 EVP_CIPHER_flags() returns any flags associated with the cipher. See
367 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
369 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
370 on the passed cipher. This will typically include any parameters and an
371 IV. The cipher IV (if any) must be set when this call is made. This call
372 should be made before the cipher is actually "used" (before any
373 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
374 may fail if the cipher does not have any ASN1 support.
376 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
377 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
378 In the case of RC2, for example, it will set the IV and effective key length.
379 This function should be called after the base cipher type is set but before
380 the key is set. For example EVP_CipherInit() will be called with the IV and
381 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
382 EVP_CipherInit() again with all parameters except the key set to NULL. It is
383 possible for this function to fail if the cipher does not have any ASN1 support
384 or the parameters cannot be set (for example the RC2 effective key length
387 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
390 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
391 based on the cipher context. The EVP_CIPHER can provide its own random key
392 generation routine to support keys of a specific form. B<Key> must point to a
393 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
395 EVP_CIPHER_do_all_provided() traverses all ciphers implemented by all activated
396 providers in the given library context I<libctx>, and for each of the
397 implementations, calls the given function I<fn> with the implementation method
398 and the given I<arg> as argument.
402 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
403 and B<NULL> for failure.
405 EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
407 EVP_CIPHER_CTX_new() returns a pointer to a newly created
408 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
410 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
411 return 1 for success and 0 for failure.
413 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
414 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
416 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
417 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
419 EVP_Cipher() returns the amount of encrypted / decrypted bytes, or -1
420 on failure, if the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the
421 cipher. EVP_Cipher() returns 1 on success or 0 on failure, if the flag
422 B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher.
424 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
426 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
427 return an B<EVP_CIPHER> structure or NULL on error.
429 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
431 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
434 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
437 EVP_CIPHER_CTX_set_padding() always returns 1.
439 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
440 length or zero if the cipher does not use an IV.
442 EVP_CIPHER_CTX_tag_length() return the tag length or zero if the cipher does not
445 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
446 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
448 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
450 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
451 than zero for success and zero or a negative number on failure.
453 EVP_CIPHER_CTX_rand_key() returns 1 for success.
455 =head1 CIPHER LISTING
457 All algorithms have a fixed key length unless otherwise stated.
459 Refer to L</SEE ALSO> for the full list of ciphers available through the EVP
466 Null cipher: does nothing.
470 =head1 AEAD INTERFACE
472 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
473 modes are subtly altered and several additional I<ctrl> operations are supported
474 depending on the mode specified.
476 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
477 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
478 parameter B<out> set to B<NULL>.
480 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
481 indicates whether the operation was successful. If it does not indicate success,
482 the authentication operation has failed and any output data B<MUST NOT> be used
485 =head2 GCM and OCB Modes
487 The following I<ctrl>s are supported in GCM and OCB modes.
491 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
493 Sets the IV length. This call can only be made before specifying an IV. If
494 not called a default IV length is used.
496 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
499 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
501 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
502 This call can only be made when encrypting data and B<after> all data has been
503 processed (e.g. after an EVP_EncryptFinal() call).
505 For OCB, C<taglen> must either be 16 or the value previously set via
506 B<EVP_CTRL_AEAD_SET_TAG>.
508 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
510 Sets the expected tag to C<taglen> bytes from C<tag>.
511 The tag length can only be set before specifying an IV.
512 C<taglen> must be between 1 and 16 inclusive.
514 For GCM, this call is only valid when decrypting data.
516 For OCB, this call is valid when decrypting data to set the expected tag,
517 and before encryption to set the desired tag length.
519 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
520 tag length. If this is not called prior to encryption, a default tag length is
523 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
524 maximum tag length for OCB.
530 The EVP interface for CCM mode is similar to that of the GCM mode but with a
531 few additional requirements and different I<ctrl> values.
533 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
534 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
535 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
536 the B<inl> parameter.
538 The following I<ctrl>s are supported in CCM mode.
542 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
544 This call is made to set the expected B<CCM> tag value when decrypting or
545 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
546 The tag length is often referred to as B<M>. If not set a default value is
547 used (12 for AES). When decrypting, the tag needs to be set before passing
548 in data to be decrypted, but as in GCM and OCB mode, it can be set after
549 passing additional authenticated data (see L</AEAD INTERFACE>).
551 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
553 Sets the CCM B<L> value. If not set a default is used (8 for AES).
555 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
557 Sets the CCM nonce (IV) length. This call can only be made before specifying an
558 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
565 For SIV mode ciphers the behaviour of the EVP interface is subtly
566 altered and several additional ctrl operations are supported.
568 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
569 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
570 with the output parameter B<out> set to B<NULL>.
572 RFC5297 states that the Nonce is the last piece of AAD before the actual
573 encrypt/decrypt takes place. The API does not differentiate the Nonce from
576 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
577 indicates if the operation was successful. If it does not indicate success
578 the authentication operation has failed and any output data B<MUST NOT>
579 be used as it is corrupted.
581 The following ctrls are supported in both SIV modes.
585 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
587 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
588 This call can only be made when encrypting data and B<after> all data has been
589 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
592 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
594 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
595 when decrypting data and must be made B<before> any data is processed (e.g.
596 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
600 SIV mode makes two passes over the input data, thus, only one call to
601 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
602 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
603 EVP_CipherFinal() is not required, but will indicate if the update
606 =head2 ChaCha20-Poly1305
608 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
612 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
614 Sets the nonce length. This call can only be made before specifying the nonce.
615 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
616 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
617 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
620 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
622 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
623 This call can only be made when encrypting data and B<after> all data has been
624 processed (e.g. after an EVP_EncryptFinal() call).
626 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
629 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
631 Sets the expected tag to C<taglen> bytes from C<tag>.
632 The tag length can only be set before specifying an IV.
633 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
634 This call is only valid when decrypting data.
640 Where possible the B<EVP> interface to symmetric ciphers should be used in
641 preference to the low level interfaces. This is because the code then becomes
642 transparent to the cipher used and much more flexible. Additionally, the
643 B<EVP> interface will ensure the use of platform specific cryptographic
644 acceleration such as AES-NI (the low level interfaces do not provide the
647 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
648 length of the encrypted data a multiple of the block size. Padding is always
649 added so if the data is already a multiple of the block size B<n> will equal
650 the block size. For example if the block size is 8 and 11 bytes are to be
651 encrypted then 5 padding bytes of value 5 will be added.
653 When decrypting the final block is checked to see if it has the correct form.
655 Although the decryption operation can produce an error if padding is enabled,
656 it is not a strong test that the input data or key is correct. A random block
657 has better than 1 in 256 chance of being of the correct format and problems with
658 the input data earlier on will not produce a final decrypt error.
660 If padding is disabled then the decryption operation will always succeed if
661 the total amount of data decrypted is a multiple of the block size.
663 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
664 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
665 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
666 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
667 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
668 existing context without allocating and freeing it up on each call.
670 There are some differences between functions EVP_CipherInit() and
671 EVP_CipherInit_ex(), significant in some circumstances. EVP_CipherInit() fills
672 the passed context object with zeros. As a consequence, EVP_CipherInit() does
673 not allow step-by-step initialization of the ctx when the I<key> and I<iv> are
674 passed in separate calls. It also means that the flags set for the CTX are
675 removed, and it is especially important for the
676 B<EVP_CIPHER_CTX_FLAG_WRAP_ALLOW> flag treated specially in
679 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
683 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
684 ciphers with default key lengths. If custom ciphers exceed these values the
685 results are unpredictable. This is because it has become standard practice to
686 define a generic key as a fixed unsigned char array containing
687 B<EVP_MAX_KEY_LENGTH> bytes.
689 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
690 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
694 Encrypt a string using IDEA:
696 int do_crypt(char *outfile)
698 unsigned char outbuf[1024];
701 * Bogus key and IV: we'd normally set these from
704 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
705 unsigned char iv[] = {1,2,3,4,5,6,7,8};
706 char intext[] = "Some Crypto Text";
710 ctx = EVP_CIPHER_CTX_new();
711 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
713 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
715 EVP_CIPHER_CTX_free(ctx);
719 * Buffer passed to EVP_EncryptFinal() must be after data just
720 * encrypted to avoid overwriting it.
722 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
724 EVP_CIPHER_CTX_free(ctx);
728 EVP_CIPHER_CTX_free(ctx);
730 * Need binary mode for fopen because encrypted data is
731 * binary data. Also cannot use strlen() on it because
732 * it won't be NUL terminated and may contain embedded
735 out = fopen(outfile, "wb");
740 fwrite(outbuf, 1, outlen, out);
745 The ciphertext from the above example can be decrypted using the B<openssl>
746 utility with the command line (shown on two lines for clarity):
749 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
751 General encryption and decryption function example using FILE I/O and AES128
754 int do_crypt(FILE *in, FILE *out, int do_encrypt)
756 /* Allow enough space in output buffer for additional block */
757 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
761 * Bogus key and IV: we'd normally set these from
764 unsigned char key[] = "0123456789abcdeF";
765 unsigned char iv[] = "1234567887654321";
767 /* Don't set key or IV right away; we want to check lengths */
768 ctx = EVP_CIPHER_CTX_new();
769 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
771 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
772 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
774 /* Now we can set key and IV */
775 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
778 inlen = fread(inbuf, 1, 1024, in);
781 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
783 EVP_CIPHER_CTX_free(ctx);
786 fwrite(outbuf, 1, outlen, out);
788 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
790 EVP_CIPHER_CTX_free(ctx);
793 fwrite(outbuf, 1, outlen, out);
795 EVP_CIPHER_CTX_free(ctx);
804 Supported ciphers are listed in:
806 L<EVP_aes_128_gcm(3)>,
807 L<EVP_aria_128_gcm(3)>,
809 L<EVP_camellia_128_ecb(3)>,
817 L<EVP_rc5_32_12_16_cbc(3)>,
823 Support for OCB mode was added in OpenSSL 1.1.0.
825 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
826 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
827 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
828 EVP_CIPHER_CTX_reset().
830 The EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
831 EVP_CIPHER_CTX_set_params() and EVP_CIPHER_CTX_get_params() functions
836 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
838 Licensed under the Apache License 2.0 (the "License"). You may not use
839 this file except in compliance with the License. You can obtain a copy
840 in the file LICENSE in the source distribution or at
841 L<https://www.openssl.org/source/license.html>.