23 EVP_CIPHER_CTX_set_key_length,
37 EVP_CIPHER_description,
39 EVP_CIPHER_names_do_all,
42 EVP_CIPHER_get_params,
43 EVP_CIPHER_gettable_params,
44 EVP_CIPHER_block_size,
45 EVP_CIPHER_key_length,
50 EVP_CIPHER_CTX_cipher,
51 EVP_CIPHER_CTX_get0_cipher,
52 EVP_CIPHER_CTX_get1_cipher,
55 EVP_CIPHER_CTX_get_params,
56 EVP_CIPHER_gettable_ctx_params,
57 EVP_CIPHER_CTX_gettable_params,
58 EVP_CIPHER_CTX_set_params,
59 EVP_CIPHER_settable_ctx_params,
60 EVP_CIPHER_CTX_settable_params,
61 EVP_CIPHER_CTX_block_size,
62 EVP_CIPHER_CTX_key_length,
63 EVP_CIPHER_CTX_iv_length,
64 EVP_CIPHER_CTX_tag_length,
65 EVP_CIPHER_CTX_get_app_data,
66 EVP_CIPHER_CTX_set_app_data,
70 EVP_CIPHER_param_to_asn1,
71 EVP_CIPHER_asn1_to_param,
72 EVP_CIPHER_CTX_set_padding,
74 EVP_CIPHER_do_all_provided
81 #include <openssl/evp.h>
83 EVP_CIPHER *EVP_CIPHER_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
84 const char *properties);
85 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
86 void EVP_CIPHER_free(EVP_CIPHER *cipher);
87 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
88 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
89 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
91 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
92 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
93 int EVP_EncryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
94 const unsigned char *key, const unsigned char *iv,
95 const OSSL_PARAM params[]);
96 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
97 int *outl, const unsigned char *in, int inl);
98 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
100 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
101 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
102 int EVP_DecryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
103 const unsigned char *key, const unsigned char *iv,
104 const OSSL_PARAM params[]);
105 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
106 int *outl, const unsigned char *in, int inl);
107 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
109 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
110 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
111 int EVP_CipherInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
112 const unsigned char *key, const unsigned char *iv,
113 int enc, const OSSL_PARAM params[]);
114 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
115 int *outl, const unsigned char *in, int inl);
116 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
118 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
119 const unsigned char *key, const unsigned char *iv);
120 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
122 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
123 const unsigned char *key, const unsigned char *iv);
124 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
126 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
127 const unsigned char *key, const unsigned char *iv, int enc);
128 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
130 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
131 const unsigned char *in, unsigned int inl);
133 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
134 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
135 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
136 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
138 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
139 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
140 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
142 int EVP_CIPHER_nid(const EVP_CIPHER *e);
143 int EVP_CIPHER_number(const EVP_CIPHER *e);
144 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
145 int EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
146 void (*fn)(const char *name, void *data),
148 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
149 const char *EVP_CIPHER_description(const EVP_CIPHER *cipher);
150 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
151 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
152 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
153 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
154 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
155 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
156 int EVP_CIPHER_type(const EVP_CIPHER *cipher);
158 const EVP_CIPHER *EVP_CIPHER_CTX_get0_cipher(const EVP_CIPHER_CTX *ctx);
159 EVP_CIPHER *EVP_CIPHER_CTX_get1_cipher(const EVP_CIPHER_CTX *ctx);
160 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
161 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
163 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
164 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
165 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
166 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
167 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
168 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
169 const OSSL_PARAM *EVP_CIPHER_CTX_settable_params(EVP_CIPHER_CTX *ctx);
170 const OSSL_PARAM *EVP_CIPHER_CTX_gettable_params(EVP_CIPHER_CTX *ctx);
171 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
172 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
173 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
174 int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
175 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
176 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
177 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
178 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
180 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
181 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
183 void EVP_CIPHER_do_all_provided(OSSL_LIB_CTX *libctx,
184 void (*fn)(EVP_CIPHER *cipher, void *arg),
187 Deprecated since OpenSSL 3.0, can be hidden entirely by defining
188 B<OPENSSL_API_COMPAT> with a suitable version value, see
189 L<openssl_user_macros(7)>:
191 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
195 The EVP cipher routines are a high-level interface to certain
198 The B<EVP_CIPHER> type is a structure for cipher method implementation.
200 EVP_CIPHER_fetch() fetches the cipher implementation for the given
201 B<algorithm> from any provider offering it, within the criteria given
202 by the B<properties>.
203 See L<crypto(7)/ALGORITHM FETCHING> for further information.
205 The returned value must eventually be freed with EVP_CIPHER_free().
207 EVP_CIPHER_up_ref() increments the reference count for an B<EVP_CIPHER>
210 EVP_CIPHER_free() decrements the reference count for the B<EVP_CIPHER>
212 If the reference count drops to 0 then the structure is freed.
214 EVP_CIPHER_CTX_new() creates a cipher context.
216 EVP_CIPHER_CTX_free() clears all information from a cipher context
217 and free up any allocated memory associate with it, including B<ctx>
218 itself. This function should be called after all operations using a
219 cipher are complete so sensitive information does not remain in
222 EVP_EncryptInit_ex2() sets up cipher context B<ctx> for encryption
223 with cipher B<type>. B<type> is typically supplied by a function such
224 as EVP_aes_256_cbc(), or a value explicitly fetched with
225 EVP_CIPHER_fetch(). B<key> is the symmetric key to use
226 and B<iv> is the IV to use (if necessary), the actual number of bytes
227 used for the key and IV depends on the cipher. The parameters B<params> will
228 be set on the context after initialisation. It is possible to set
229 all parameters to NULL except B<type> in an initial call and supply
230 the remaining parameters in subsequent calls, all of which have B<type>
231 set to NULL. This is done when the default cipher parameters are not
233 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
236 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
237 with cipher B<type>. B<type> is typically supplied by a function such
238 as EVP_aes_256_cbc(), or a value explicitly fetched with
239 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
240 cipher B<type> is used if there is one, and if not, the default
241 implementation is used. B<key> is the symmetric key to use
242 and B<iv> is the IV to use (if necessary), the actual number of bytes
243 used for the key and IV depends on the cipher. It is possible to set
244 all parameters to NULL except B<type> in an initial call and supply
245 the remaining parameters in subsequent calls, all of which have B<type>
246 set to NULL. This is done when the default cipher parameters are not
248 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
251 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
252 writes the encrypted version to B<out>. This function can be called
253 multiple times to encrypt successive blocks of data. The amount
254 of data written depends on the block alignment of the encrypted data.
255 For most ciphers and modes, the amount of data written can be anything
256 from zero bytes to (inl + cipher_block_size - 1) bytes.
257 For wrap cipher modes, the amount of data written can be anything
258 from zero bytes to (inl + cipher_block_size) bytes.
259 For stream ciphers, the amount of data written can be anything from zero
261 Thus, B<out> should contain sufficient room for the operation being performed.
262 The actual number of bytes written is placed in B<outl>. It also
263 checks if B<in> and B<out> are partially overlapping, and if they are
264 0 is returned to indicate failure.
266 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
267 the "final" data, that is any data that remains in a partial block.
268 It uses standard block padding (aka PKCS padding) as described in
269 the NOTES section, below. The encrypted
270 final data is written to B<out> which should have sufficient space for
271 one cipher block. The number of bytes written is placed in B<outl>. After
272 this function is called the encryption operation is finished and no further
273 calls to EVP_EncryptUpdate() should be made.
275 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
276 data and it will return an error if any data remains in a partial block:
277 that is if the total data length is not a multiple of the block size.
279 EVP_DecryptInit_ex2(), EVP_DecryptInit_ex(), EVP_DecryptUpdate()
280 and EVP_DecryptFinal_ex() are the corresponding decryption
281 operations. EVP_DecryptFinal() will return an error code if padding is
282 enabled and the final block is not correctly formatted. The parameters
283 and restrictions are identical to the encryption operations except
284 that if padding is enabled the decrypted data buffer B<out> passed
285 to EVP_DecryptUpdate() should have sufficient room for (B<inl> +
286 cipher_block_size) bytes unless the cipher block size is 1 in which case
287 B<inl> bytes is sufficient.
289 EVP_CipherInit_ex2(), EVP_CipherInit_ex(), EVP_CipherUpdate() and
290 EVP_CipherFinal_ex() are functions that can be used for decryption or
291 encryption. The operation performed depends on the value of the B<enc>
292 parameter. It should be set to 1 for encryption, 0 for decryption and -1
293 to leave the value unchanged (the actual value of 'enc' being supplied
296 EVP_CIPHER_CTX_reset() clears all information from a cipher context
297 and free up any allocated memory associate with it, except the B<ctx>
298 itself. This function should be called anytime B<ctx> is to be reused
299 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
302 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
303 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
304 EVP_CipherInit_ex() except they always use the default cipher implementation.
306 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
307 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
308 EVP_CipherFinal_ex(). In previous releases they also cleaned up
309 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
310 must be called to free any context resources.
312 EVP_Cipher() encrypts or decrypts a maximum I<inl> amount of bytes from
313 I<in> and leaves the result in I<out>.
314 If the cipher doesn't have the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set,
315 then I<inl> must be a multiple of EVP_CIPHER_block_size(). If it isn't,
316 the result is undefined. If the cipher has that flag set, then I<inl>
318 This function is historic and shouldn't be used in an application, please
319 consider using EVP_CipherUpdate() and EVP_CipherFinal_ex instead.
321 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
322 return an EVP_CIPHER structure when passed a cipher name, a NID or an
323 ASN1_OBJECT structure.
325 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
326 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
327 value is an internal value which may not have a corresponding OBJECT
330 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
331 function should be called after the context is set up for encryption
332 or decryption with EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2() or
333 EVP_CipherInit_ex2(). By default encryption operations are padded using
334 standard block padding and the padding is checked and removed when
335 decrypting. If the B<pad> parameter is zero then no padding is
336 performed, the total amount of data encrypted or decrypted must then
337 be a multiple of the block size or an error will occur.
339 EVP_CIPHER_get_params() retrieves the requested list of algorithm
340 B<params> from a B<cipher>.
342 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
345 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
346 B<params> from CIPHER context B<ctx>.
348 EVP_CIPHER_gettable_params() returns an B<OSSL_PARAM> array that describes
349 the retrievable and settable parameters. EVP_CIPHER_gettable_params()
350 returns parameters that can be used with EVP_CIPHER_get_params(). See
351 L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as a parameter descriptor.
353 EVP_CIPHER_gettable_ctx_params() and EVP_CIPHER_CTX_gettable_params()
354 return constant B<OSSL_PARAM> arrays that describe the retrievable
355 parameters that can be used with EVP_CIPHER_CTX_get_params().
356 EVP_CIPHER_gettable_ctx_params() returns the parameters that can be
357 retrieved from the algorithm, whereas EVP_CIPHER_CTX_gettable_params()
358 returns the parameters that can be retrieved in the context's current
359 state. See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as a parameter
362 EVP_CIPHER_settable_ctx_params() and EVP_CIPHER_CTX_settable_params()
363 return constant B<OSSL_PARAM> arrays that describe the settable
364 parameters that can be used with EVP_CIPHER_CTX_set_params().
365 EVP_CIPHER_settable_ctx_params() returns the parameters that can be
366 retrieved from the algorithm, whereas EVP_CIPHER_CTX_settable_params()
367 returns the parameters that can be retrieved in the context's current
368 state. See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as a parameter
371 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
372 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
373 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
374 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
375 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
376 for variable key length ciphers.
378 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
379 If the cipher is a fixed length cipher then attempting to set the key
380 length to any value other than the fixed value is an error.
382 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
383 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
384 It will return zero if the cipher does not use an IV. The constant
385 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
387 EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed
388 a B<EVP_CIPHER_CTX>. It will return zero if the cipher does not support a tag.
389 It returns a default value if the tag length has not been set.
391 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
392 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
393 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
394 length for all ciphers.
396 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
397 cipher or context. This "type" is the actual NID of the cipher OBJECT
398 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
399 128 bit RC2 have the same NID. If the cipher does not have an object
400 identifier or does not have ASN1 support this function will return
403 EVP_CIPHER_is_a() returns 1 if I<cipher> is an implementation of an
404 algorithm that's identifiable with I<name>, otherwise 0.
405 If I<cipher> is a legacy cipher (it's the return value from the likes
406 of EVP_aes128() rather than the result of an EVP_CIPHER_fetch()), only
407 cipher names registered with the default library context (see
408 L<OSSL_LIB_CTX(3)>) will be considered.
410 EVP_CIPHER_number() returns the internal dynamic number assigned to
411 the I<cipher>. This is only useful with fetched B<EVP_CIPHER>s.
413 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
414 cipher or context. For fetched ciphers with multiple names, only one
415 of them is returned; it's recommended to use EVP_CIPHER_names_do_all()
418 EVP_CIPHER_names_do_all() traverses all names for the I<cipher>, and
419 calls I<fn> with each name and I<data>. This is only useful with
420 fetched B<EVP_CIPHER>s.
422 EVP_CIPHER_description() returns a description of the cipher, meant for
423 display and human consumption. The description is at the discretion of the
424 cipher implementation.
426 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
427 that implements the given B<EVP_CIPHER>.
429 EVP_CIPHER_CTX_get0_cipher() returns the B<EVP_CIPHER> structure when passed
430 an B<EVP_CIPHER_CTX> structure.
431 EVP_CIPHER_CTX_get1_cipher() is the same except the ownership is passed to
434 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
435 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
436 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
437 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
438 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
440 EVP_CIPHER_flags() returns any flags associated with the cipher. See
441 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
443 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
444 on the passed cipher. This will typically include any parameters and an
445 IV. The cipher IV (if any) must be set when this call is made. This call
446 should be made before the cipher is actually "used" (before any
447 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
448 may fail if the cipher does not have any ASN1 support.
450 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
451 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
452 In the case of RC2, for example, it will set the IV and effective key length.
453 This function should be called after the base cipher type is set but before
454 the key is set. For example EVP_CipherInit() will be called with the IV and
455 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
456 EVP_CipherInit() again with all parameters except the key set to NULL. It is
457 possible for this function to fail if the cipher does not have any ASN1 support
458 or the parameters cannot be set (for example the RC2 effective key length
461 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
464 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
465 based on the cipher context. The EVP_CIPHER can provide its own random key
466 generation routine to support keys of a specific form. B<Key> must point to a
467 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
469 EVP_CIPHER_do_all_provided() traverses all ciphers implemented by all activated
470 providers in the given library context I<libctx>, and for each of the
471 implementations, calls the given function I<fn> with the implementation method
472 and the given I<arg> as argument.
476 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
477 and B<NULL> for failure.
479 EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
481 EVP_CIPHER_CTX_new() returns a pointer to a newly created
482 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
484 EVP_EncryptInit_ex2(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
485 return 1 for success and 0 for failure.
487 EVP_DecryptInit_ex2() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
488 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
490 EVP_CipherInit_ex2() and EVP_CipherUpdate() return 1 for success and 0 for failure.
491 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
493 EVP_Cipher() returns the amount of encrypted / decrypted bytes, or -1
494 on failure, if the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the
495 cipher. EVP_Cipher() returns 1 on success or 0 on failure, if the flag
496 B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher.
498 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
500 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
501 return an B<EVP_CIPHER> structure or NULL on error.
503 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
505 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
508 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
511 EVP_CIPHER_CTX_set_padding() always returns 1.
513 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
514 length or zero if the cipher does not use an IV.
516 EVP_CIPHER_CTX_tag_length() return the tag length or zero if the cipher does not
519 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
520 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
522 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
524 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
525 than zero for success and zero or a negative number on failure.
527 EVP_CIPHER_CTX_rand_key() returns 1 for success.
529 EVP_CIPHER_names_do_all() returns 1 if the callback was called for all names.
530 A return value of 0 means that the callback was not called for any names.
532 =head1 CIPHER LISTING
534 All algorithms have a fixed key length unless otherwise stated.
536 Refer to L</SEE ALSO> for the full list of ciphers available through the EVP
543 Null cipher: does nothing.
547 =head1 AEAD INTERFACE
549 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
550 modes are subtly altered and several additional I<ctrl> operations are supported
551 depending on the mode specified.
553 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
554 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
555 parameter B<out> set to B<NULL>.
557 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
558 indicates whether the operation was successful. If it does not indicate success,
559 the authentication operation has failed and any output data B<MUST NOT> be used
562 =head2 GCM and OCB Modes
564 The following I<ctrl>s are supported in GCM and OCB modes.
568 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
570 Sets the IV length. This call can only be made before specifying an IV. If
571 not called a default IV length is used.
573 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
576 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
578 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
579 This call can only be made when encrypting data and B<after> all data has been
580 processed (e.g. after an EVP_EncryptFinal() call).
582 For OCB, C<taglen> must either be 16 or the value previously set via
583 B<EVP_CTRL_AEAD_SET_TAG>.
585 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
587 Sets the expected tag to C<taglen> bytes from C<tag>.
588 The tag length can only be set before specifying an IV.
589 C<taglen> must be between 1 and 16 inclusive.
591 For GCM, this call is only valid when decrypting data.
593 For OCB, this call is valid when decrypting data to set the expected tag,
594 and before encryption to set the desired tag length.
596 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
597 tag length. If this is not called prior to encryption, a default tag length is
600 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
601 maximum tag length for OCB.
607 The EVP interface for CCM mode is similar to that of the GCM mode but with a
608 few additional requirements and different I<ctrl> values.
610 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
611 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
612 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
613 the B<inl> parameter.
615 The following I<ctrl>s are supported in CCM mode.
619 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
621 This call is made to set the expected B<CCM> tag value when decrypting or
622 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
623 The tag length is often referred to as B<M>. If not set a default value is
624 used (12 for AES). When decrypting, the tag needs to be set before passing
625 in data to be decrypted, but as in GCM and OCB mode, it can be set after
626 passing additional authenticated data (see L</AEAD INTERFACE>).
628 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
630 Sets the CCM B<L> value. If not set a default is used (8 for AES).
632 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
634 Sets the CCM nonce (IV) length. This call can only be made before specifying a
635 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
642 For SIV mode ciphers the behaviour of the EVP interface is subtly
643 altered and several additional ctrl operations are supported.
645 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
646 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
647 with the output parameter B<out> set to B<NULL>.
649 RFC5297 states that the Nonce is the last piece of AAD before the actual
650 encrypt/decrypt takes place. The API does not differentiate the Nonce from
653 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
654 indicates if the operation was successful. If it does not indicate success
655 the authentication operation has failed and any output data B<MUST NOT>
656 be used as it is corrupted.
658 The following ctrls are supported in both SIV modes.
662 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
664 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
665 This call can only be made when encrypting data and B<after> all data has been
666 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
669 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
671 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
672 when decrypting data and must be made B<before> any data is processed (e.g.
673 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
677 SIV mode makes two passes over the input data, thus, only one call to
678 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
679 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
680 EVP_CipherFinal() is not required, but will indicate if the update
683 =head2 ChaCha20-Poly1305
685 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
689 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
691 Sets the nonce length. This call can only be made before specifying the nonce.
692 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
693 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
694 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
697 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
699 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
700 This call can only be made when encrypting data and B<after> all data has been
701 processed (e.g. after an EVP_EncryptFinal() call).
703 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
706 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
708 Sets the expected tag to C<taglen> bytes from C<tag>.
709 The tag length can only be set before specifying an IV.
710 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
711 This call is only valid when decrypting data.
717 Where possible the B<EVP> interface to symmetric ciphers should be used in
718 preference to the low-level interfaces. This is because the code then becomes
719 transparent to the cipher used and much more flexible. Additionally, the
720 B<EVP> interface will ensure the use of platform specific cryptographic
721 acceleration such as AES-NI (the low-level interfaces do not provide the
724 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
725 length of the encrypted data a multiple of the block size. Padding is always
726 added so if the data is already a multiple of the block size B<n> will equal
727 the block size. For example if the block size is 8 and 11 bytes are to be
728 encrypted then 5 padding bytes of value 5 will be added.
730 When decrypting the final block is checked to see if it has the correct form.
732 Although the decryption operation can produce an error if padding is enabled,
733 it is not a strong test that the input data or key is correct. A random block
734 has better than 1 in 256 chance of being of the correct format and problems with
735 the input data earlier on will not produce a final decrypt error.
737 If padding is disabled then the decryption operation will always succeed if
738 the total amount of data decrypted is a multiple of the block size.
740 The functions EVP_EncryptInit(), EVP_EncryptInit_ex1(),
741 EVP_EncryptFinal(), EVP_DecryptInit(), EVP_DecryptInit_ex1(),
742 EVP_CipherInit(), EVP_CipherInit_ex1() and EVP_CipherFinal() are obsolete
743 but are retained for compatibility with existing code. New code should
744 use EVP_EncryptInit_ex2(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex2(),
745 EVP_DecryptFinal_ex(), EVP_CipherInit_ex2() and EVP_CipherFinal_ex()
746 because they can reuse an existing context without allocating and freeing
749 There are some differences between functions EVP_CipherInit() and
750 EVP_CipherInit_ex(), significant in some circumstances. EVP_CipherInit() fills
751 the passed context object with zeros. As a consequence, EVP_CipherInit() does
752 not allow step-by-step initialization of the ctx when the I<key> and I<iv> are
753 passed in separate calls. It also means that the flags set for the CTX are
754 removed, and it is especially important for the
755 B<EVP_CIPHER_CTX_FLAG_WRAP_ALLOW> flag treated specially in
758 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
762 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
763 ciphers with default key lengths. If custom ciphers exceed these values the
764 results are unpredictable. This is because it has become standard practice to
765 define a generic key as a fixed unsigned char array containing
766 B<EVP_MAX_KEY_LENGTH> bytes.
768 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
769 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
773 Encrypt a string using IDEA:
775 int do_crypt(char *outfile)
777 unsigned char outbuf[1024];
780 * Bogus key and IV: we'd normally set these from
783 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
784 unsigned char iv[] = {1,2,3,4,5,6,7,8};
785 char intext[] = "Some Crypto Text";
789 ctx = EVP_CIPHER_CTX_new();
790 EVP_EncryptInit_ex2(ctx, EVP_idea_cbc(), key, iv, NULL);
792 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
794 EVP_CIPHER_CTX_free(ctx);
798 * Buffer passed to EVP_EncryptFinal() must be after data just
799 * encrypted to avoid overwriting it.
801 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
803 EVP_CIPHER_CTX_free(ctx);
807 EVP_CIPHER_CTX_free(ctx);
809 * Need binary mode for fopen because encrypted data is
810 * binary data. Also cannot use strlen() on it because
811 * it won't be NUL terminated and may contain embedded
814 out = fopen(outfile, "wb");
819 fwrite(outbuf, 1, outlen, out);
824 The ciphertext from the above example can be decrypted using the B<openssl>
825 utility with the command line (shown on two lines for clarity):
828 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
830 General encryption and decryption function example using FILE I/O and AES128
833 int do_crypt(FILE *in, FILE *out, int do_encrypt)
835 /* Allow enough space in output buffer for additional block */
836 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
840 * Bogus key and IV: we'd normally set these from
843 unsigned char key[] = "0123456789abcdeF";
844 unsigned char iv[] = "1234567887654321";
846 /* Don't set key or IV right away; we want to check lengths */
847 ctx = EVP_CIPHER_CTX_new();
848 EVP_CipherInit_ex2(ctx, EVP_aes_128_cbc(), NULL, NULL,
850 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
851 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
853 /* Now we can set key and IV */
854 EVP_CipherInit_ex2(ctx, NULL, key, iv, do_encrypt, NULL);
857 inlen = fread(inbuf, 1, 1024, in);
860 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
862 EVP_CIPHER_CTX_free(ctx);
865 fwrite(outbuf, 1, outlen, out);
867 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
869 EVP_CIPHER_CTX_free(ctx);
872 fwrite(outbuf, 1, outlen, out);
874 EVP_CIPHER_CTX_free(ctx);
878 Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext stealing.
880 int encrypt(const unsigned char *key, const unsigned char *iv,
881 const unsigned char *msg, size_t msg_len, unsigned char *out)
884 * This assumes that key size is 32 bytes and the iv is 16 bytes.
885 * For ciphertext stealing mode the length of the ciphertext "out" will be
886 * the same size as the plaintext size "msg_len".
887 * The "msg_len" can be any size >= 16.
889 int ret = 0, encrypt = 1, outlen, len;
890 EVP_CIPHER_CTX *ctx = NULL;
891 EVP_CIPHER *cipher = NULL;
892 OSSL_PARAM params[2];
894 ctx = EVP_CIPHER_CTX_new();
895 cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL);
896 if (ctx == NULL || cipher == NULL)
900 * The default is "CS1" so this is not really needed,
901 * but would be needed to set either "CS2" or "CS3".
903 params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE,
905 params[1] = OSSL_PARAM_construct_end();
907 if (!EVP_CipherInit_ex2(ctx, cipher, key, iv, encrypt, params))
910 /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */
911 if (!EVP_CipherUpdate(ctx, encrypted, &outlen, msg, msglen))
913 if (!EVP_CipherFinal_ex(ctx, encrypted + outlen, &len))
917 EVP_CIPHER_free(cipher);
918 EVP_CIPHER_CTX_free(ctx);
926 Supported ciphers are listed in:
928 L<EVP_aes_128_gcm(3)>,
929 L<EVP_aria_128_gcm(3)>,
931 L<EVP_camellia_128_ecb(3)>,
939 L<EVP_rc5_32_12_16_cbc(3)>,
945 Support for OCB mode was added in OpenSSL 1.1.0.
947 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
948 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
949 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
950 EVP_CIPHER_CTX_reset().
952 The EVP_CIPHER_CTX_cipher() function was deprecated in OpenSSL 3.0; use
953 EVP_CIPHER_CTX_get0_cipher() instead.
955 The EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2(), EVP_CipherInit_ex2(),
956 EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
957 EVP_CIPHER_CTX_get0_cipher(), EVP_CIPHER_CTX_get1_cipher(),
958 EVP_CIPHER_get_params(), EVP_CIPHER_CTX_set_params(),
959 EVP_CIPHER_CTX_get_params(), EVP_CIPHER_gettable_params(),
960 EVP_CIPHER_settable_ctx_params(), EVP_CIPHER_gettable_ctx_params(),
961 EVP_CIPHER_CTX_settable_params() and EVP_CIPHER_CTX_gettable_params()
962 functions were added in 3.0.
966 Copyright 2000-2021 The OpenSSL Project Authors. All Rights Reserved.
968 Licensed under the Apache License 2.0 (the "License"). You may not use
969 this file except in compliance with the License. You can obtain a copy
970 in the file LICENSE in the source distribution or at
971 L<https://www.openssl.org/source/license.html>.