20 EVP_CIPHER_CTX_set_key_length,
34 EVP_CIPHER_names_do_all,
37 EVP_CIPHER_get_params,
38 EVP_CIPHER_gettable_params,
39 EVP_CIPHER_block_size,
40 EVP_CIPHER_key_length,
45 EVP_CIPHER_CTX_cipher,
48 EVP_CIPHER_CTX_get_params,
49 EVP_CIPHER_gettable_ctx_params,
50 EVP_CIPHER_CTX_set_params,
51 EVP_CIPHER_settable_ctx_params,
52 EVP_CIPHER_CTX_block_size,
53 EVP_CIPHER_CTX_key_length,
54 EVP_CIPHER_CTX_iv_length,
55 EVP_CIPHER_CTX_tag_length,
56 EVP_CIPHER_CTX_get_app_data,
57 EVP_CIPHER_CTX_set_app_data,
61 EVP_CIPHER_param_to_asn1,
62 EVP_CIPHER_asn1_to_param,
63 EVP_CIPHER_CTX_set_padding,
65 EVP_CIPHER_do_all_provided
72 #include <openssl/evp.h>
74 EVP_CIPHER *EVP_CIPHER_fetch(OPENSSL_CTX *ctx, const char *algorithm,
75 const char *properties);
76 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
77 void EVP_CIPHER_free(EVP_CIPHER *cipher);
78 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
79 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
80 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
82 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
83 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
84 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
85 int *outl, const unsigned char *in, int inl);
86 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
88 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
89 ENGINE *impl, const unsigned char *key, const unsigned char *iv);
90 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
91 int *outl, const unsigned char *in, int inl);
92 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
94 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
95 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
96 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
97 int *outl, const unsigned char *in, int inl);
98 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
100 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
101 const unsigned char *key, const unsigned char *iv);
102 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
104 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
105 const unsigned char *key, const unsigned char *iv);
106 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
108 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
109 const unsigned char *key, const unsigned char *iv, int enc);
110 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
112 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
113 const unsigned char *in, unsigned int inl);
115 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
116 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
117 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
118 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
120 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
121 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
122 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
124 int EVP_CIPHER_nid(const EVP_CIPHER *e);
125 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
126 void EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
127 void (*fn)(const char *name, void *data),
129 const char *EVP_CIPHER_name(const EVP_CIPHER *cipher);
130 const OSSL_PROVIDER *EVP_CIPHER_provider(const EVP_CIPHER *cipher);
131 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
132 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
133 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
134 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
135 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
136 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
138 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
139 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
140 const char *EVP_CIPHER_CTX_name(const EVP_CIPHER_CTX *ctx);
142 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
143 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
144 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
145 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
146 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
147 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
148 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
149 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
150 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
151 int EVP_CIPHER_CTX_tag_length(const EVP_CIPHER_CTX *ctx);
152 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
153 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
154 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
155 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
157 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
158 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
160 void EVP_CIPHER_do_all_provided(OPENSSL_CTX *libctx,
161 void (*fn)(EVP_CIPHER *cipher, void *arg),
166 The EVP cipher routines are a high level interface to certain
169 The B<EVP_CIPHER> type is a structure for cipher method implementation.
171 EVP_CIPHER_fetch() fetches the cipher implementation for the given
172 B<algorithm> from any provider offering it, within the criteria given
173 by the B<properties>.
174 See L<provider(7)/Fetching algorithms> for further information.
176 The returned value must eventually be freed with EVP_CIPHER_free().
178 EVP_CIPHER_up_ref() increments the reference count for an B<EVP_CIPHER>
181 EVP_CIPHER_free() decrements the reference count for the B<EVP_CIPHER>
183 If the reference count drops to 0 then the structure is freed.
185 EVP_CIPHER_CTX_new() creates a cipher context.
187 EVP_CIPHER_CTX_free() clears all information from a cipher context
188 and free up any allocated memory associate with it, including B<ctx>
189 itself. This function should be called after all operations using a
190 cipher are complete so sensitive information does not remain in
193 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
194 with cipher B<type>. B<type> is typically supplied by a function such
195 as EVP_aes_256_cbc(), or a value explicitly fetched with
196 EVP_CIPHER_fetch(). If B<impl> is non-NULL, its implementation of the
197 cipher B<type> is used if there is one, and if not, the default
198 implementation is used. B<key> is the symmetric key to use
199 and B<iv> is the IV to use (if necessary), the actual number of bytes
200 used for the key and IV depends on the cipher. It is possible to set
201 all parameters to NULL except B<type> in an initial call and supply
202 the remaining parameters in subsequent calls, all of which have B<type>
203 set to NULL. This is done when the default cipher parameters are not
205 For EVP_CIPH_GCM_MODE the IV will be generated internally if it is not
208 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
209 writes the encrypted version to B<out>. This function can be called
210 multiple times to encrypt successive blocks of data. The amount
211 of data written depends on the block alignment of the encrypted data:
212 as a result the amount of data written may be anything from zero bytes
213 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
214 room. The actual number of bytes written is placed in B<outl>. It also
215 checks if B<in> and B<out> are partially overlapping, and if they are
216 0 is returned to indicate failure.
218 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
219 the "final" data, that is any data that remains in a partial block.
220 It uses standard block padding (aka PKCS padding) as described in
221 the NOTES section, below. The encrypted
222 final data is written to B<out> which should have sufficient space for
223 one cipher block. The number of bytes written is placed in B<outl>. After
224 this function is called the encryption operation is finished and no further
225 calls to EVP_EncryptUpdate() should be made.
227 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
228 data and it will return an error if any data remains in a partial block:
229 that is if the total data length is not a multiple of the block size.
231 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
232 corresponding decryption operations. EVP_DecryptFinal() will return an
233 error code if padding is enabled and the final block is not correctly
234 formatted. The parameters and restrictions are identical to the encryption
235 operations except that if padding is enabled the decrypted data buffer B<out>
236 passed to EVP_DecryptUpdate() should have sufficient room for
237 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
238 which case B<inl> bytes is sufficient.
240 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
241 functions that can be used for decryption or encryption. The operation
242 performed depends on the value of the B<enc> parameter. It should be set
243 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
244 (the actual value of 'enc' being supplied in a previous call).
246 EVP_CIPHER_CTX_reset() clears all information from a cipher context
247 and free up any allocated memory associate with it, except the B<ctx>
248 itself. This function should be called anytime B<ctx> is to be reused
249 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
252 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
253 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
254 EVP_CipherInit_ex() except they always use the default cipher implementation.
256 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
257 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
258 EVP_CipherFinal_ex(). In previous releases they also cleaned up
259 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
260 must be called to free any context resources.
262 EVP_Cipher() encrypts or decrypts a maximum I<inl> amount of bytes from
263 I<in> and leaves the result in I<out>.
264 If the cipher doesn't have the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set,
265 then I<inl> must be a multiple of EVP_CIPHER_block_size(). If it isn't,
266 the result is undefined. If the cipher has that flag set, then I<inl>
268 This function is historic and shouldn't be used in an application, please
269 consider using EVP_CipherUpdate() and EVP_CipherFinal_ex instead.
271 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
272 return an EVP_CIPHER structure when passed a cipher name, a NID or an
273 ASN1_OBJECT structure.
275 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
276 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
277 value is an internal value which may not have a corresponding OBJECT
280 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
281 function should be called after the context is set up for encryption
282 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
283 EVP_CipherInit_ex(). By default encryption operations are padded using
284 standard block padding and the padding is checked and removed when
285 decrypting. If the B<pad> parameter is zero then no padding is
286 performed, the total amount of data encrypted or decrypted must then
287 be a multiple of the block size or an error will occur.
289 EVP_CIPHER_get_params() retrieves the requested list of algorithm
290 B<params> from a B<cipher>.
292 EVP_CIPHER_CTX_set_params() Sets the list of operation B<params> into a CIPHER
295 EVP_CIPHER_CTX_get_params() retrieves the requested list of operation
296 B<params> from CIPHER context B<ctx>.
298 EVP_CIPHER_gettable_params(), EVP_CIPHER_gettable_ctx_params(), and
299 EVP_CIPHER_settable_ctx_params() get a constant B<OSSL_PARAM> array
300 that decribes the retrievable and settable parameters, i.e. parameters
301 that can be used with EVP_CIPHER_get_params(), EVP_CIPHER_CTX_get_params()
302 and EVP_CIPHER_CTX_set_params(), respectively.
303 See L<OSSL_PARAM(3)> for the use of B<OSSL_PARAM> as parameter descriptor.
305 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
306 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
307 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
308 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
309 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
310 for variable key length ciphers.
312 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
313 If the cipher is a fixed length cipher then attempting to set the key
314 length to any value other than the fixed value is an error.
316 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
317 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
318 It will return zero if the cipher does not use an IV. The constant
319 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
321 EVP_CIPHER_CTX_tag_length() returns the tag length of a AEAD cipher when passed
322 a B<EVP_CIPHER_CTX>. It will return zero if the cipher does not support a tag.
323 It returns a default value if the tag length has not been set.
325 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
326 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
327 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
328 length for all ciphers.
330 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
331 cipher or context. This "type" is the actual NID of the cipher OBJECT
332 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
333 128 bit RC2 have the same NID. If the cipher does not have an object
334 identifier or does not have ASN1 support this function will return
337 EVP_CIPHER_is_a() returns 1 if I<cipher> is an implementation of an
338 algorithm that's identifiable with I<name>, otherwise 0.
340 EVP_CIPHER_name() and EVP_CIPHER_CTX_name() return the name of the passed
341 cipher or context. For fetched ciphers with multiple names, only one
342 of them is returned; it's recommended to use EVP_CIPHER_names_do_all()
345 EVP_CIPHER_names_do_all() traverses all names for the I<cipher>, and
346 calls I<fn> with each name and I<data>. This is only useful with
347 fetched B<EVP_CIPHER>s.
349 EVP_CIPHER_provider() returns an B<OSSL_PROVIDER> pointer to the provider
350 that implements the given B<EVP_CIPHER>.
352 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
353 an B<EVP_CIPHER_CTX> structure.
355 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
356 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
357 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
358 EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. If the cipher is a
359 stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
361 EVP_CIPHER_flags() returns any flags associated with the cipher. See
362 EVP_CIPHER_meth_set_flags() for a list of currently defined flags.
364 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
365 on the passed cipher. This will typically include any parameters and an
366 IV. The cipher IV (if any) must be set when this call is made. This call
367 should be made before the cipher is actually "used" (before any
368 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
369 may fail if the cipher does not have any ASN1 support.
371 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
372 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
373 In the case of RC2, for example, it will set the IV and effective key length.
374 This function should be called after the base cipher type is set but before
375 the key is set. For example EVP_CipherInit() will be called with the IV and
376 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
377 EVP_CipherInit() again with all parameters except the key set to NULL. It is
378 possible for this function to fail if the cipher does not have any ASN1 support
379 or the parameters cannot be set (for example the RC2 effective key length
382 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
385 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
386 based on the cipher context. The EVP_CIPHER can provide its own random key
387 generation routine to support keys of a specific form. B<Key> must point to a
388 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
390 EVP_CIPHER_do_all_provided() traverses all ciphers implemented by all activated
391 providers in the given library context I<libctx>, and for each of the
392 implementations, calls the given function I<fn> with the implementation method
393 and the given I<arg> as argument.
397 EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success
398 and B<NULL> for failure.
400 EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
402 EVP_CIPHER_CTX_new() returns a pointer to a newly created
403 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
405 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
406 return 1 for success and 0 for failure.
408 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
409 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
411 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
412 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
414 EVP_Cipher() returns the amount of encrypted / decrypted bytes, or -1
415 on failure, if the flag B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the
416 cipher. EVP_Cipher() returns 1 on success or 0 on failure, if the flag
417 B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher.
419 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
421 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
422 return an B<EVP_CIPHER> structure or NULL on error.
424 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
426 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
429 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
432 EVP_CIPHER_CTX_set_padding() always returns 1.
434 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
435 length or zero if the cipher does not use an IV.
437 EVP_CIPHER_CTX_tag_length() return the tag length or zero if the cipher does not
440 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
441 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
443 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
445 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
446 than zero for success and zero or a negative number on failure.
448 EVP_CIPHER_CTX_rand_key() returns 1 for success.
450 =head1 CIPHER LISTING
452 All algorithms have a fixed key length unless otherwise stated.
454 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
461 Null cipher: does nothing.
465 =head1 AEAD INTERFACE
467 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
468 modes are subtly altered and several additional I<ctrl> operations are supported
469 depending on the mode specified.
471 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
472 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
473 parameter B<out> set to B<NULL>.
475 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
476 indicates whether the operation was successful. If it does not indicate success,
477 the authentication operation has failed and any output data B<MUST NOT> be used
480 =head2 GCM and OCB Modes
482 The following I<ctrl>s are supported in GCM and OCB modes.
486 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
488 Sets the IV length. This call can only be made before specifying an IV. If
489 not called a default IV length is used.
491 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
494 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
496 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
497 This call can only be made when encrypting data and B<after> all data has been
498 processed (e.g. after an EVP_EncryptFinal() call).
500 For OCB, C<taglen> must either be 16 or the value previously set via
501 B<EVP_CTRL_AEAD_SET_TAG>.
503 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
505 Sets the expected tag to C<taglen> bytes from C<tag>.
506 The tag length can only be set before specifying an IV.
507 C<taglen> must be between 1 and 16 inclusive.
509 For GCM, this call is only valid when decrypting data.
511 For OCB, this call is valid when decrypting data to set the expected tag,
512 and before encryption to set the desired tag length.
514 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
515 tag length. If this is not called prior to encryption, a default tag length is
518 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
519 maximum tag length for OCB.
525 The EVP interface for CCM mode is similar to that of the GCM mode but with a
526 few additional requirements and different I<ctrl> values.
528 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
529 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
530 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
531 the B<inl> parameter.
533 The following I<ctrl>s are supported in CCM mode.
537 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
539 This call is made to set the expected B<CCM> tag value when decrypting or
540 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
541 The tag length is often referred to as B<M>. If not set a default value is
542 used (12 for AES). When decrypting, the tag needs to be set before passing
543 in data to be decrypted, but as in GCM and OCB mode, it can be set after
544 passing additional authenticated data (see L</AEAD INTERFACE>).
546 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
548 Sets the CCM B<L> value. If not set a default is used (8 for AES).
550 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
552 Sets the CCM nonce (IV) length. This call can only be made before specifying an
553 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
560 For SIV mode ciphers the behaviour of the EVP interface is subtly
561 altered and several additional ctrl operations are supported.
563 To specify any additional authenticated data (AAD) and/or a Nonce, a call to
564 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
565 with the output parameter B<out> set to B<NULL>.
567 RFC5297 states that the Nonce is the last piece of AAD before the actual
568 encrypt/decrypt takes place. The API does not differentiate the Nonce from
571 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
572 indicates if the operation was successful. If it does not indicate success
573 the authentication operation has failed and any output data B<MUST NOT>
574 be used as it is corrupted.
576 The following ctrls are supported in both SIV modes.
580 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
582 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
583 This call can only be made when encrypting data and B<after> all data has been
584 processed (e.g. after an EVP_EncryptFinal() call). For SIV mode the taglen must
587 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
589 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
590 when decrypting data and must be made B<before> any data is processed (e.g.
591 before any EVP_DecryptUpdate() call). For SIV mode the taglen must be 16.
595 SIV mode makes two passes over the input data, thus, only one call to
596 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made
597 with B<out> set to a non-B<NULL> value. A call to EVP_Decrypt_Final() or
598 EVP_CipherFinal() is not required, but will indicate if the update
601 =head2 ChaCha20-Poly1305
603 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
607 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
609 Sets the nonce length. This call can only be made before specifying the nonce.
610 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
611 nonce length is 12 bytes (i.e. 96-bits). If a nonce of less than 12 bytes is set
612 then the nonce is automatically padded with leading 0 bytes to make it 12 bytes
615 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
617 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
618 This call can only be made when encrypting data and B<after> all data has been
619 processed (e.g. after an EVP_EncryptFinal() call).
621 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
624 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
626 Sets the expected tag to C<taglen> bytes from C<tag>.
627 The tag length can only be set before specifying an IV.
628 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
629 This call is only valid when decrypting data.
635 Where possible the B<EVP> interface to symmetric ciphers should be used in
636 preference to the low level interfaces. This is because the code then becomes
637 transparent to the cipher used and much more flexible. Additionally, the
638 B<EVP> interface will ensure the use of platform specific cryptographic
639 acceleration such as AES-NI (the low level interfaces do not provide the
642 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
643 length of the encrypted data a multiple of the block size. Padding is always
644 added so if the data is already a multiple of the block size B<n> will equal
645 the block size. For example if the block size is 8 and 11 bytes are to be
646 encrypted then 5 padding bytes of value 5 will be added.
648 When decrypting the final block is checked to see if it has the correct form.
650 Although the decryption operation can produce an error if padding is enabled,
651 it is not a strong test that the input data or key is correct. A random block
652 has better than 1 in 256 chance of being of the correct format and problems with
653 the input data earlier on will not produce a final decrypt error.
655 If padding is disabled then the decryption operation will always succeed if
656 the total amount of data decrypted is a multiple of the block size.
658 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
659 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
660 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
661 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
662 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
663 existing context without allocating and freeing it up on each call.
665 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
669 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
670 ciphers with default key lengths. If custom ciphers exceed these values the
671 results are unpredictable. This is because it has become standard practice to
672 define a generic key as a fixed unsigned char array containing
673 B<EVP_MAX_KEY_LENGTH> bytes.
675 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
676 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
680 Encrypt a string using IDEA:
682 int do_crypt(char *outfile)
684 unsigned char outbuf[1024];
687 * Bogus key and IV: we'd normally set these from
690 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
691 unsigned char iv[] = {1,2,3,4,5,6,7,8};
692 char intext[] = "Some Crypto Text";
696 ctx = EVP_CIPHER_CTX_new();
697 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
699 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
701 EVP_CIPHER_CTX_free(ctx);
705 * Buffer passed to EVP_EncryptFinal() must be after data just
706 * encrypted to avoid overwriting it.
708 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
710 EVP_CIPHER_CTX_free(ctx);
714 EVP_CIPHER_CTX_free(ctx);
716 * Need binary mode for fopen because encrypted data is
717 * binary data. Also cannot use strlen() on it because
718 * it won't be NUL terminated and may contain embedded
721 out = fopen(outfile, "wb");
726 fwrite(outbuf, 1, outlen, out);
731 The ciphertext from the above example can be decrypted using the B<openssl>
732 utility with the command line (shown on two lines for clarity):
735 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
737 General encryption and decryption function example using FILE I/O and AES128
740 int do_crypt(FILE *in, FILE *out, int do_encrypt)
742 /* Allow enough space in output buffer for additional block */
743 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
747 * Bogus key and IV: we'd normally set these from
750 unsigned char key[] = "0123456789abcdeF";
751 unsigned char iv[] = "1234567887654321";
753 /* Don't set key or IV right away; we want to check lengths */
754 ctx = EVP_CIPHER_CTX_new();
755 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
757 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
758 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
760 /* Now we can set key and IV */
761 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
764 inlen = fread(inbuf, 1, 1024, in);
767 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
769 EVP_CIPHER_CTX_free(ctx);
772 fwrite(outbuf, 1, outlen, out);
774 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
776 EVP_CIPHER_CTX_free(ctx);
779 fwrite(outbuf, 1, outlen, out);
781 EVP_CIPHER_CTX_free(ctx);
790 Supported ciphers are listed in:
809 Support for OCB mode was added in OpenSSL 1.1.0.
811 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
812 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
813 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
814 EVP_CIPHER_CTX_reset().
816 The EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
817 EVP_CIPHER_CTX_set_params() and EVP_CIPHER_CTX_get_params() functions
822 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
824 Licensed under the Apache License 2.0 (the "License"). You may not use
825 this file except in compliance with the License. You can obtain a copy
826 in the file LICENSE in the source distribution or at
827 L<https://www.openssl.org/source/license.html>.