1EVP_ENCRYPTINIT(3ossl)              OpenSSL             EVP_ENCRYPTINIT(3ossl)
2
3
4

NAME

6       EVP_CIPHER_fetch, EVP_CIPHER_up_ref, EVP_CIPHER_free,
7       EVP_CIPHER_CTX_new, EVP_CIPHER_CTX_reset, EVP_CIPHER_CTX_free,
8       EVP_EncryptInit_ex, EVP_EncryptInit_ex2, EVP_EncryptUpdate,
9       EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptInit_ex2,
10       EVP_DecryptUpdate, EVP_DecryptFinal_ex, EVP_CipherInit_ex,
11       EVP_CipherInit_ex2, EVP_CipherUpdate, EVP_CipherFinal_ex,
12       EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl, EVP_EncryptInit,
13       EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal, EVP_CipherInit,
14       EVP_CipherFinal, EVP_Cipher, EVP_get_cipherbyname, EVP_get_cipherbynid,
15       EVP_get_cipherbyobj, EVP_CIPHER_is_a, EVP_CIPHER_get0_name,
16       EVP_CIPHER_get0_description, EVP_CIPHER_names_do_all,
17       EVP_CIPHER_get0_provider, EVP_CIPHER_get_nid, EVP_CIPHER_get_params,
18       EVP_CIPHER_gettable_params, EVP_CIPHER_get_block_size,
19       EVP_CIPHER_get_key_length, EVP_CIPHER_get_iv_length,
20       EVP_CIPHER_get_flags, EVP_CIPHER_get_mode, EVP_CIPHER_get_type,
21       EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_get0_cipher,
22       EVP_CIPHER_CTX_get1_cipher, EVP_CIPHER_CTX_get0_name,
23       EVP_CIPHER_CTX_get_nid, EVP_CIPHER_CTX_get_params,
24       EVP_CIPHER_gettable_ctx_params, EVP_CIPHER_CTX_gettable_params,
25       EVP_CIPHER_CTX_set_params, EVP_CIPHER_settable_ctx_params,
26       EVP_CIPHER_CTX_settable_params, EVP_CIPHER_CTX_get_block_size,
27       EVP_CIPHER_CTX_get_key_length, EVP_CIPHER_CTX_get_iv_length,
28       EVP_CIPHER_CTX_get_tag_length, EVP_CIPHER_CTX_get_app_data,
29       EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_flags,
30       EVP_CIPHER_CTX_set_flags, EVP_CIPHER_CTX_clear_flags,
31       EVP_CIPHER_CTX_test_flags, EVP_CIPHER_CTX_get_type,
32       EVP_CIPHER_CTX_get_mode, EVP_CIPHER_CTX_get_num,
33       EVP_CIPHER_CTX_set_num, EVP_CIPHER_CTX_is_encrypting,
34       EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param,
35       EVP_CIPHER_CTX_set_padding, EVP_enc_null, EVP_CIPHER_do_all_provided,
36       EVP_CIPHER_nid, EVP_CIPHER_name, EVP_CIPHER_block_size,
37       EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags,
38       EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_encrypting,
39       EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size,
40       EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length,
41       EVP_CIPHER_CTX_tag_length, EVP_CIPHER_CTX_num, EVP_CIPHER_CTX_type,
42       EVP_CIPHER_CTX_mode - EVP cipher routines
43

SYNOPSIS

45        #include <openssl/evp.h>
46
47        EVP_CIPHER *EVP_CIPHER_fetch(OSSL_LIB_CTX *ctx, const char *algorithm,
48                                     const char *properties);
49        int EVP_CIPHER_up_ref(EVP_CIPHER *cipher);
50        void EVP_CIPHER_free(EVP_CIPHER *cipher);
51        EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
52        int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
53        void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
54
55        int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
56                               ENGINE *impl, const unsigned char *key, const unsigned char *iv);
57        int EVP_EncryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
58                                const unsigned char *key, const unsigned char *iv,
59                                const OSSL_PARAM params[]);
60        int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
61                              int *outl, const unsigned char *in, int inl);
62        int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
63
64        int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
65                               ENGINE *impl, const unsigned char *key, const unsigned char *iv);
66        int EVP_DecryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
67                                const unsigned char *key, const unsigned char *iv,
68                                const OSSL_PARAM params[]);
69        int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
70                              int *outl, const unsigned char *in, int inl);
71        int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
72
73        int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
74                              ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc);
75        int EVP_CipherInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
76                               const unsigned char *key, const unsigned char *iv,
77                               int enc, const OSSL_PARAM params[]);
78        int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
79                             int *outl, const unsigned char *in, int inl);
80        int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
81
82        int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
83                            const unsigned char *key, const unsigned char *iv);
84        int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
85
86        int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
87                            const unsigned char *key, const unsigned char *iv);
88        int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
89
90        int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
91                           const unsigned char *key, const unsigned char *iv, int enc);
92        int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
93
94        int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out,
95                       const unsigned char *in, unsigned int inl);
96
97        int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
98        int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
99        int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int cmd, int p1, void *p2);
100        int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
101        void EVP_CIPHER_CTX_set_flags(EVP_CIPHER_CTX *ctx, int flags);
102        void EVP_CIPHER_CTX_clear_flags(EVP_CIPHER_CTX *ctx, int flags);
103        int EVP_CIPHER_CTX_test_flags(const EVP_CIPHER_CTX *ctx, int flags);
104
105        const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
106        const EVP_CIPHER *EVP_get_cipherbynid(int nid);
107        const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
108
109        int EVP_CIPHER_get_nid(const EVP_CIPHER *e);
110        int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name);
111        int EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher,
112                                    void (*fn)(const char *name, void *data),
113                                    void *data);
114        const char *EVP_CIPHER_get0_name(const EVP_CIPHER *cipher);
115        const char *EVP_CIPHER_get0_description(const EVP_CIPHER *cipher);
116        const OSSL_PROVIDER *EVP_CIPHER_get0_provider(const EVP_CIPHER *cipher);
117        int EVP_CIPHER_get_block_size(const EVP_CIPHER *e);
118        int EVP_CIPHER_get_key_length(const EVP_CIPHER *e);
119        int EVP_CIPHER_get_iv_length(const EVP_CIPHER *e);
120        unsigned long EVP_CIPHER_get_flags(const EVP_CIPHER *e);
121        unsigned long EVP_CIPHER_get_mode(const EVP_CIPHER *e);
122        int EVP_CIPHER_get_type(const EVP_CIPHER *cipher);
123
124        const EVP_CIPHER *EVP_CIPHER_CTX_get0_cipher(const EVP_CIPHER_CTX *ctx);
125        EVP_CIPHER *EVP_CIPHER_CTX_get1_cipher(const EVP_CIPHER_CTX *ctx);
126        int EVP_CIPHER_CTX_get_nid(const EVP_CIPHER_CTX *ctx);
127        const char *EVP_CIPHER_CTX_get0_name(const EVP_CIPHER_CTX *ctx);
128
129        int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]);
130        int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]);
131        int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]);
132        const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher);
133        const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher);
134        const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher);
135        const OSSL_PARAM *EVP_CIPHER_CTX_settable_params(EVP_CIPHER_CTX *ctx);
136        const OSSL_PARAM *EVP_CIPHER_CTX_gettable_params(EVP_CIPHER_CTX *ctx);
137        int EVP_CIPHER_CTX_get_block_size(const EVP_CIPHER_CTX *ctx);
138        int EVP_CIPHER_CTX_get_key_length(const EVP_CIPHER_CTX *ctx);
139        int EVP_CIPHER_CTX_get_iv_length(const EVP_CIPHER_CTX *ctx);
140        int EVP_CIPHER_CTX_get_tag_length(const EVP_CIPHER_CTX *ctx);
141        void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
142        void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
143        int EVP_CIPHER_CTX_get_type(const EVP_CIPHER_CTX *ctx);
144        int EVP_CIPHER_CTX_get_mode(const EVP_CIPHER_CTX *ctx);
145        int EVP_CIPHER_CTX_get_num(const EVP_CIPHER_CTX *ctx);
146        int EVP_CIPHER_CTX_set_num(EVP_CIPHER_CTX *ctx, int num);
147        int EVP_CIPHER_CTX_is_encrypting(const EVP_CIPHER_CTX *ctx);
148
149        int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
150        int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
151
152        void EVP_CIPHER_do_all_provided(OSSL_LIB_CTX *libctx,
153                                        void (*fn)(EVP_CIPHER *cipher, void *arg),
154                                        void *arg);
155
156        #define EVP_CIPHER_nid EVP_CIPHER_get_nid
157        #define EVP_CIPHER_name EVP_CIPHER_get0_name
158        #define EVP_CIPHER_block_size EVP_CIPHER_get_block_size
159        #define EVP_CIPHER_key_length EVP_CIPHER_get_key_length
160        #define EVP_CIPHER_iv_length EVP_CIPHER_get_iv_length
161        #define EVP_CIPHER_flags EVP_CIPHER_get_flags
162        #define EVP_CIPHER_mode EVP_CIPHER_get_mode
163        #define EVP_CIPHER_type EVP_CIPHER_get_type
164        #define EVP_CIPHER_CTX_encrypting EVP_CIPHER_CTX_is_encrypting
165        #define EVP_CIPHER_CTX_nid EVP_CIPHER_CTX_get_nid
166        #define EVP_CIPHER_CTX_block_size EVP_CIPHER_CTX_get_block_size
167        #define EVP_CIPHER_CTX_key_length EVP_CIPHER_CTX_get_key_length
168        #define EVP_CIPHER_CTX_iv_length EVP_CIPHER_CTX_get_iv_length
169        #define EVP_CIPHER_CTX_tag_length EVP_CIPHER_CTX_get_tag_length
170        #define EVP_CIPHER_CTX_num EVP_CIPHER_CTX_get_num
171        #define EVP_CIPHER_CTX_type EVP_CIPHER_CTX_get_type
172        #define EVP_CIPHER_CTX_mode EVP_CIPHER_CTX_get_mode
173
174       The following function has been deprecated since OpenSSL 3.0, and can
175       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
176       version value, see openssl_user_macros(7):
177
178        const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
179
180       The following function has been deprecated since OpenSSL 1.1.0, and can
181       be hidden entirely by defining OPENSSL_API_COMPAT with a suitable
182       version value, see openssl_user_macros(7):
183
184        int EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx);
185

DESCRIPTION

187       The EVP cipher routines are a high-level interface to certain symmetric
188       ciphers.
189
190       The EVP_CIPHER type is a structure for cipher method implementation.
191
192       EVP_CIPHER_fetch()
193           Fetches the cipher implementation for the given algorithm from any
194           provider offering it, within the criteria given by the properties.
195           See "ALGORITHM FETCHING" in crypto(7) for further information.
196
197           The returned value must eventually be freed with EVP_CIPHER_free().
198
199           Fetched EVP_CIPHER structures are reference counted.
200
201       EVP_CIPHER_up_ref()
202           Increments the reference count for an EVP_CIPHER structure.
203
204       EVP_CIPHER_free()
205           Decrements the reference count for the fetched EVP_CIPHER
206           structure.  If the reference count drops to 0 then the structure is
207           freed.
208
209       EVP_CIPHER_CTX_new()
210           Allocates and returns a cipher context.
211
212       EVP_CIPHER_CTX_free()
213           Clears all information from a cipher context and frees any
214           allocated memory associated with it, including ctx itself. This
215           function should be called after all operations using a cipher are
216           complete so sensitive information does not remain in memory.
217
218       EVP_CIPHER_CTX_ctrl()
219           This is a legacy method. EVP_CIPHER_CTX_set_params() and
220           EVP_CIPHER_CTX_get_params() is the mechanism that should be used to
221           set and get parameters that are used by providers.
222
223           Performs cipher-specific control actions on context ctx. The
224           control command is indicated in cmd and any additional arguments in
225           p1 and p2.  EVP_CIPHER_CTX_ctrl() must be called after
226           EVP_CipherInit_ex2(). Other restrictions may apply depending on the
227           control type and cipher implementation.
228
229           If this function happens to be used with a fetched EVP_CIPHER, it
230           will translate the controls that are known to OpenSSL into
231           OSSL_PARAM(3) parameters with keys defined by OpenSSL and call
232           EVP_CIPHER_CTX_get_params() or EVP_CIPHER_CTX_set_params() as is
233           appropriate for each control command.
234
235           See "CONTROLS" below for more information, including what
236           translations are being done.
237
238       EVP_CIPHER_get_params()
239           Retrieves the requested list of algorithm params from a CIPHER
240           cipher.  See "PARAMETERS" below for more information.
241
242       EVP_CIPHER_CTX_get_params()
243           Retrieves the requested list of params from CIPHER context ctx.
244           See "PARAMETERS" below for more information.
245
246       EVP_CIPHER_CTX_set_params()
247           Sets the list of params into a CIPHER context ctx.  See
248           "PARAMETERS" below for more information.
249
250       EVP_CIPHER_gettable_params()
251           Get a constant OSSL_PARAM array that describes the retrievable
252           parameters that can be used with EVP_CIPHER_get_params().  See
253           OSSL_PARAM(3) for the use of OSSL_PARAM as a parameter descriptor.
254
255       EVP_CIPHER_gettable_ctx_params() and EVP_CIPHER_CTX_gettable_params()
256           Get a constant OSSL_PARAM array that describes the retrievable
257           parameters that can be used with EVP_CIPHER_CTX_get_params().
258           EVP_CIPHER_gettable_ctx_params() returns the parameters that can be
259           retrieved from the algorithm, whereas
260           EVP_CIPHER_CTX_gettable_params() returns the parameters that can be
261           retrieved in the context's current state.  See OSSL_PARAM(3) for
262           the use of OSSL_PARAM as a parameter descriptor.
263
264       EVP_CIPHER_settable_ctx_params() and EVP_CIPHER_CTX_settable_params()
265           Get a constant OSSL_PARAM array that describes the settable
266           parameters that can be used with EVP_CIPHER_CTX_set_params().
267           EVP_CIPHER_settable_ctx_params() returns the parameters that can be
268           set from the algorithm, whereas EVP_CIPHER_CTX_settable_params()
269           returns the parameters that can be set in the context's current
270           state.  See OSSL_PARAM(3) for the use of OSSL_PARAM as a parameter
271           descriptor.
272
273       EVP_EncryptInit_ex2()
274           Sets up cipher context ctx for encryption with cipher type. type is
275           typically supplied by calling EVP_CIPHER_fetch(). type may also be
276           set using legacy functions such as EVP_aes_256_cbc(), but this is
277           not recommended for new applications. key is the symmetric key to
278           use and iv is the IV to use (if necessary), the actual number of
279           bytes used for the key and IV depends on the cipher. The parameters
280           params will be set on the context after initialisation. It is
281           possible to set all parameters to NULL except type in an initial
282           call and supply the remaining parameters in subsequent calls, all
283           of which have type set to NULL. This is done when the default
284           cipher parameters are not appropriate.  For EVP_CIPH_GCM_MODE the
285           IV will be generated internally if it is not specified.
286
287       EVP_EncryptInit_ex()
288           This legacy function is similar to EVP_EncryptInit_ex2() when impl
289           is NULL.  The implementation of the type from the impl engine will
290           be used if it exists.
291
292       EVP_EncryptUpdate()
293           Encrypts inl bytes from the buffer in and writes the encrypted
294           version to out. This function can be called multiple times to
295           encrypt successive blocks of data. The amount of data written
296           depends on the block alignment of the encrypted data.  For most
297           ciphers and modes, the amount of data written can be anything from
298           zero bytes to (inl + cipher_block_size - 1) bytes.  For wrap cipher
299           modes, the amount of data written can be anything from zero bytes
300           to (inl + cipher_block_size) bytes.  For stream ciphers, the amount
301           of data written can be anything from zero bytes to inl bytes.
302           Thus, out should contain sufficient room for the operation being
303           performed.  The actual number of bytes written is placed in outl.
304           It also checks if in and out are partially overlapping, and if they
305           are 0 is returned to indicate failure.
306
307           If padding is enabled (the default) then EVP_EncryptFinal_ex()
308           encrypts the "final" data, that is any data that remains in a
309           partial block.  It uses standard block padding (aka PKCS padding)
310           as described in the NOTES section, below. The encrypted final data
311           is written to out which should have sufficient space for one cipher
312           block. The number of bytes written is placed in outl. After this
313           function is called the encryption operation is finished and no
314           further calls to EVP_EncryptUpdate() should be made.
315
316           If padding is disabled then EVP_EncryptFinal_ex() will not encrypt
317           any more data and it will return an error if any data remains in a
318           partial block: that is if the total data length is not a multiple
319           of the block size.
320
321       EVP_DecryptInit_ex2(), EVP_DecryptInit_ex(), EVP_DecryptUpdate() and
322       EVP_DecryptFinal_ex()
323           These functions are the corresponding decryption operations.
324           EVP_DecryptFinal() will return an error code if padding is enabled
325           and the final block is not correctly formatted. The parameters and
326           restrictions are identical to the encryption operations except that
327           if padding is enabled the decrypted data buffer out passed to
328           EVP_DecryptUpdate() should have sufficient room for (inl +
329           cipher_block_size) bytes unless the cipher block size is 1 in which
330           case inl bytes is sufficient.
331
332       EVP_CipherInit_ex2(), EVP_CipherInit_ex(), EVP_CipherUpdate() and
333       EVP_CipherFinal_ex()
334           These functions can be used for decryption or encryption. The
335           operation performed depends on the value of the enc parameter. It
336           should be set to 1 for encryption, 0 for decryption and -1 to leave
337           the value unchanged (the actual value of 'enc' being supplied in a
338           previous call).
339
340       EVP_CIPHER_CTX_reset()
341           Clears all information from a cipher context and free up any
342           allocated memory associated with it, except the ctx itself. This
343           function should be called anytime ctx is reused by another
344           EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal() series of
345           calls.
346
347       EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit()
348           Behave in a similar way to EVP_EncryptInit_ex(),
349           EVP_DecryptInit_ex() and EVP_CipherInit_ex() except if the type is
350           not a fetched cipher they use the default implementation of the
351           type.
352
353       EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal()
354           Identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
355           EVP_CipherFinal_ex(). In previous releases they also cleaned up the
356           ctx, but this is no longer done and EVP_CIPHER_CTX_cleanup() must
357           be called to free any context resources.
358
359       EVP_Cipher()
360           Encrypts or decrypts a maximum inl amount of bytes from in and
361           leaves the result in out.
362
363           For legacy ciphers - If the cipher doesn't have the flag
364           EVP_CIPH_FLAG_CUSTOM_CIPHER set, then inl must be a multiple of
365           EVP_CIPHER_get_block_size().  If it isn't, the result is undefined.
366           If the cipher has that flag set, then inl can be any size.
367
368           Due to the constraints of the API contract of this function it
369           shouldn't be used in applications, please consider using
370           EVP_CipherUpdate() and EVP_CipherFinal_ex() instead.
371
372       EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
373           Returns an EVP_CIPHER structure when passed a cipher name, a cipher
374           NID or an ASN1_OBJECT structure respectively.
375
376           EVP_get_cipherbyname() will return NULL for algorithms such as
377           "AES-128-SIV", "AES-128-CBC-CTS" and "CAMELLIA-128-CBC-CTS" which
378           were previously only accessible via low level interfaces.
379
380           The EVP_get_cipherbyname() function is present for backwards
381           compatibility with OpenSSL prior to version 3 and is different to
382           the EVP_CIPHER_fetch() function since it does not attempt to
383           "fetch" an implementation of the cipher.  Additionally, it only
384           knows about ciphers that are built-in to OpenSSL and have an
385           associated NID. Similarly EVP_get_cipherbynid() and
386           EVP_get_cipherbyobj() also return objects without an associated
387           implementation.
388
389           When the cipher objects returned by these functions are used (such
390           as in a call to EVP_EncryptInit_ex()) an implementation of the
391           cipher will be implicitly fetched from the loaded providers. This
392           fetch could fail if no suitable implementation is available. Use
393           EVP_CIPHER_fetch() instead to explicitly fetch the algorithm and an
394           associated implementation from a provider.
395
396           See "ALGORITHM FETCHING" in crypto(7) for more information about
397           fetching.
398
399           The cipher objects returned from these functions do not need to be
400           freed with EVP_CIPHER_free().
401
402       EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid()
403           Return the NID of a cipher when passed an EVP_CIPHER or
404           EVP_CIPHER_CTX structure.  The actual NID value is an internal
405           value which may not have a corresponding OBJECT IDENTIFIER.
406
407       EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and
408       EVP_CIPHER_CTX_test_flags()
409           Sets, clears and tests ctx flags.  See "FLAGS" below for more
410           information.
411
412           For provided ciphers EVP_CIPHER_CTX_set_flags() should be called
413           only after the fetched cipher has been assigned to the ctx. It is
414           recommended to use "PARAMETERS" instead.
415
416       EVP_CIPHER_CTX_set_padding()
417           Enables or disables padding. This function should be called after
418           the context is set up for encryption or decryption with
419           EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2() or
420           EVP_CipherInit_ex2(). By default encryption operations are padded
421           using standard block padding and the padding is checked and removed
422           when decrypting. If the pad parameter is zero then no padding is
423           performed, the total amount of data encrypted or decrypted must
424           then be a multiple of the block size or an error will occur.
425
426       EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length()
427           Return the key length of a cipher when passed an EVP_CIPHER or
428           EVP_CIPHER_CTX structure. The constant EVP_MAX_KEY_LENGTH is the
429           maximum key length for all ciphers. Note: although
430           EVP_CIPHER_get_key_length() is fixed for a given cipher, the value
431           of EVP_CIPHER_CTX_get_key_length() may be different for variable
432           key length ciphers.
433
434       EVP_CIPHER_CTX_set_key_length()
435           Sets the key length of the cipher context.  If the cipher is a
436           fixed length cipher then attempting to set the key length to any
437           value other than the fixed value is an error.
438
439       EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length()
440           Return the IV length of a cipher when passed an EVP_CIPHER or
441           EVP_CIPHER_CTX. It will return zero if the cipher does not use an
442           IV.  The constant EVP_MAX_IV_LENGTH is the maximum IV length for
443           all ciphers.
444
445       EVP_CIPHER_CTX_get_tag_length()
446           Returns the tag length of an AEAD cipher when passed a
447           EVP_CIPHER_CTX. It will return zero if the cipher does not support
448           a tag. It returns a default value if the tag length has not been
449           set.
450
451       EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size()
452           Return the block size of a cipher when passed an EVP_CIPHER or
453           EVP_CIPHER_CTX structure. The constant EVP_MAX_BLOCK_LENGTH is also
454           the maximum block length for all ciphers.
455
456       EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type()
457           Return the type of the passed cipher or context. This "type" is the
458           actual NID of the cipher OBJECT IDENTIFIER and as such it ignores
459           the cipher parameters (40 bit RC2 and 128 bit RC2 have the same
460           NID). If the cipher does not have an object identifier or does not
461           have ASN1 support this function will return NID_undef.
462
463       EVP_CIPHER_is_a()
464           Returns 1 if cipher is an implementation of an algorithm that's
465           identifiable with name, otherwise 0. If cipher is a legacy cipher
466           (it's the return value from the likes of EVP_aes128() rather than
467           the result of an EVP_CIPHER_fetch()), only cipher names registered
468           with the default library context (see OSSL_LIB_CTX(3)) will be
469           considered.
470
471       EVP_CIPHER_get0_name() and EVP_CIPHER_CTX_get0_name()
472           Return the name of the passed cipher or context.  For fetched
473           ciphers with multiple names, only one of them is returned. See also
474           EVP_CIPHER_names_do_all().
475
476       EVP_CIPHER_names_do_all()
477           Traverses all names for the cipher, and calls fn with each name and
478           data.  This is only useful with fetched EVP_CIPHERs.
479
480       EVP_CIPHER_get0_description()
481           Returns a description of the cipher, meant for display and human
482           consumption.  The description is at the discretion of the cipher
483           implementation.
484
485       EVP_CIPHER_get0_provider()
486           Returns an OSSL_PROVIDER pointer to the provider that implements
487           the given EVP_CIPHER.
488
489       EVP_CIPHER_CTX_get0_cipher()
490           Returns the EVP_CIPHER structure when passed an EVP_CIPHER_CTX
491           structure.  EVP_CIPHER_CTX_get1_cipher() is the same except the
492           ownership is passed to the caller.
493
494       EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode()
495           Return the block cipher mode: EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE,
496           EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, EVP_CIPH_CTR_MODE,
497           EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
498           EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE.  If the
499           cipher is a stream cipher then EVP_CIPH_STREAM_CIPHER is returned.
500
501       EVP_CIPHER_get_flags()
502           Returns any flags associated with the cipher. See "FLAGS" for a
503           list of currently defined flags.
504
505       EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num()
506           Gets or sets the cipher specific "num" parameter for the associated
507           ctx.  Built-in ciphers typically use this to track how much of the
508           current underlying block has been "used" already.
509
510       EVP_CIPHER_CTX_is_encrypting()
511           Reports whether the ctx is being used for encryption or decryption.
512
513       EVP_CIPHER_CTX_flags()
514           A deprecated macro calling
515           "EVP_CIPHER_get_flags(EVP_CIPHER_CTX_get0_cipher(ctx))".  Do not
516           use.
517
518       EVP_CIPHER_param_to_asn1()
519           Sets the AlgorithmIdentifier "parameter" based on the passed
520           cipher. This will typically include any parameters and an IV. The
521           cipher IV (if any) must be set when this call is made. This call
522           should be made before the cipher is actually "used" (before any
523           EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example).  This
524           function may fail if the cipher does not have any ASN1 support.
525
526       EVP_CIPHER_asn1_to_param()
527           Sets the cipher parameters based on an ASN1 AlgorithmIdentifier
528           "parameter".  The precise effect depends on the cipher. In the case
529           of RC2, for example, it will set the IV and effective key length.
530           This function should be called after the base cipher type is set
531           but before the key is set. For example EVP_CipherInit() will be
532           called with the IV and key set to NULL, EVP_CIPHER_asn1_to_param()
533           will be called and finally EVP_CipherInit() again with all
534           parameters except the key set to NULL. It is possible for this
535           function to fail if the cipher does not have any ASN1 support or
536           the parameters cannot be set (for example the RC2 effective key
537           length is not supported.
538
539       EVP_CIPHER_CTX_rand_key()
540           Generates a random key of the appropriate length based on the
541           cipher context.  The EVP_CIPHER can provide its own random key
542           generation routine to support keys of a specific form. key must
543           point to a buffer at least as big as the value returned by
544           EVP_CIPHER_CTX_get_key_length().
545
546       EVP_CIPHER_do_all_provided()
547           Traverses all ciphers implemented by all activated providers in the
548           given library context libctx, and for each of the implementations,
549           calls the given function fn with the implementation method and the
550           given arg as argument.
551

PARAMETERS

553       See OSSL_PARAM(3) for information about passing parameters.
554
555   Gettable EVP_CIPHER parameters
556       When EVP_CIPHER_fetch() is called it internally calls
557       EVP_CIPHER_get_params() and caches the results.
558
559       EVP_CIPHER_get_params() can be used with the following OSSL_PARAM keys:
560
561       "mode" (OSSL_CIPHER_PARAM_MODE) <unsigned integer>
562           Gets the mode for the associated cipher algorithm cipher.  See
563           "EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode()" for a list of
564           valid modes.  Use EVP_CIPHER_get_mode() to retrieve the cached
565           value.
566
567       "keylen" (OSSL_CIPHER_PARAM_KEYLEN) <unsigned integer>
568           Gets the key length for the associated cipher algorithm cipher.
569           Use EVP_CIPHER_get_key_length() to retrieve the cached value.
570
571       "ivlen" (OSSL_CIPHER_PARAM_IVLEN) <unsigned integer>
572           Gets the IV length for the associated cipher algorithm cipher.  Use
573           EVP_CIPHER_get_iv_length() to retrieve the cached value.
574
575       "blocksize" (OSSL_CIPHER_PARAM_BLOCK_SIZE) <unsigned integer>
576           Gets the block size for the associated cipher algorithm cipher.
577           The block size should be 1 for stream ciphers.  Note that the block
578           size for a cipher may be different to the block size for the
579           underlying encryption/decryption primitive.  For example AES in CTR
580           mode has a block size of 1 (because it operates like a stream
581           cipher), even though AES has a block size of 16.  Use
582           EVP_CIPHER_get_block_size() to retreive the cached value.
583
584       "aead" (OSSL_CIPHER_PARAM_AEAD) <integer>
585           Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0.
586           Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) to
587           retrieve the cached value.
588
589       "custom-iv" (OSSL_CIPHER_PARAM_CUSTOM_IV) <integer>
590           Gets 1 if the cipher algorithm cipher has a custom IV, otherwise it
591           gets 0.  Storing and initializing the IV is left entirely to the
592           implementation, if a custom IV is used.  Use
593           (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_CUSTOM_IV) to retrieve the
594           cached value.
595
596       "cts" (OSSL_CIPHER_PARAM_CTS) <integer>
597           Gets 1 if the cipher algorithm cipher uses ciphertext stealing,
598           otherwise it gets 0.  This is currently used to indicate that the
599           cipher is a one shot that only allows a single call to
600           EVP_CipherUpdate().  Use (EVP_CIPHER_get_flags(cipher) &
601           EVP_CIPH_FLAG_CTS) to retrieve the cached value.
602
603       "tls-multi" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK) <integer>
604           Gets 1 if the cipher algorithm cipher supports interleaving of
605           crypto blocks, otherwise it gets 0. The interleaving is an
606           optimization only applicable to certain TLS ciphers.  Use
607           (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK) to
608           retrieve the cached value.
609
610       "has-randkey" (OSSL_CIPHER_PARAM_HAS_RANDKEY) <integer>
611           Gets 1 if the cipher algorithm cipher supports the gettable
612           EVP_CIPHER_CTX parameter OSSL_CIPHER_PARAM_RANDOM_KEY. Only DES and
613           3DES set this to 1, all other OpenSSL ciphers return 0.
614
615   Gettable and Settable EVP_CIPHER_CTX parameters
616       The following OSSL_PARAM keys can be used with both
617       EVP_CIPHER_CTX_get_params() and EVP_CIPHER_CTX_set_params().
618
619       "padding" (OSSL_CIPHER_PARAM_PADDING) <unsigned integer>
620           Gets or sets the padding mode for the cipher context ctx.  Padding
621           is enabled if the value is 1, and disabled if the value is 0.  See
622           also EVP_CIPHER_CTX_set_padding().
623
624       "num" (OSSL_CIPHER_PARAM_NUM) <unsigned integer>
625           Gets or sets the cipher specific "num" parameter for the cipher
626           context ctx.  Built-in ciphers typically use this to track how much
627           of the current underlying block has been "used" already.  See also
628           EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num().
629
630       "keylen" (OSSL_CIPHER_PARAM_KEYLEN) <unsigned integer>
631           Gets or sets the key length for the cipher context ctx.  The length
632           of the "keylen" parameter should not exceed that of a size_t.  See
633           also EVP_CIPHER_CTX_get_key_length() and
634           EVP_CIPHER_CTX_set_key_length().
635
636       "tag" (OSSL_CIPHER_PARAM_AEAD_TAG) <octet string>
637           Gets or sets the AEAD tag for the associated cipher context ctx.
638           See "AEAD Interface" in EVP_EncryptInit(3).
639
640       "keybits" (OSSL_CIPHER_PARAM_RC2_KEYBITS) <unsigned integer>
641           Gets or sets the effective keybits used for a RC2 cipher.  The
642           length of the "keybits" parameter should not exceed that of a
643           size_t.
644
645       "rounds" (OSSL_CIPHER_PARAM_ROUNDS) <unsigned integer>
646           Gets or sets the number of rounds to be used for a cipher.  This is
647           used by the RC5 cipher.
648
649       "alg_id_param" (OSSL_CIPHER_PARAM_ALGORITHM_ID_PARAMS) <octet string>
650           Used to pass the DER encoded AlgorithmIdentifier parameter to or
651           from the cipher implementation.  Functions like
652           EVP_CIPHER_param_to_asn1(3) and EVP_CIPHER_asn1_to_param(3) use
653           this parameter for any implementation that has the flag
654           EVP_CIPH_FLAG_CUSTOM_ASN1 set.
655
656       "cts_mode" (OSSL_CIPHER_PARAM_CTS_MODE) <UTF8 string>
657           Gets or sets the cipher text stealing mode. For all modes the
658           output size is the same as the input size. The input length must be
659           greater than or equal to the block size. (The block size for AES
660           and CAMELLIA is 16 bytes).
661
662           Valid values for the mode are:
663
664           "CS1"
665               The NIST variant of cipher text stealing.  For input lengths
666               that are multiples of the block size it is equivalent to using
667               a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher otherwise the
668               second last cipher text block is a partial block.
669
670           "CS2"
671               For input lengths that are multiples of the block size it is
672               equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC"
673               cipher, otherwise it is the same as "CS3" mode.
674
675           "CS3"
676               The Kerberos5 variant of cipher text stealing which always
677               swaps the last cipher text block with the previous block (which
678               may be a partial or full block depending on the input length).
679               If the input length is exactly one full block then this is
680               equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC"
681               cipher.
682
683           The default is "CS1".  This is only supported for
684           "AES-128-CBC-CTS", "AES-192-CBC-CTS", "AES-256-CBC-CTS",
685           "CAMELLIA-128-CBC-CTS", "CAMELLIA-192-CBC-CTS" and
686           "CAMELLIA-256-CBC-CTS".
687
688       "tls1multi_interleave" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE)
689       <unsigned integer>
690           Sets or gets the number of records being sent in one go for a tls1
691           multiblock cipher operation (either 4 or 8 records).
692
693   Gettable EVP_CIPHER_CTX parameters
694       The following OSSL_PARAM keys can be used with
695       EVP_CIPHER_CTX_get_params():
696
697       "ivlen" (OSSL_CIPHER_PARAM_IVLEN and <OSSL_CIPHER_PARAM_AEAD_IVLEN)
698       <unsigned integer>
699           Gets the IV length for the cipher context ctx.  The length of the
700           "ivlen" parameter should not exceed that of a size_t.  See also
701           EVP_CIPHER_CTX_get_iv_length().
702
703       "iv" (OSSL_CIPHER_PARAM_IV) <octet string OR octet ptr>
704           Gets the IV used to initialize the associated cipher context ctx.
705           See also EVP_CIPHER_CTX_get_original_iv().
706
707       "updated-iv" (OSSL_CIPHER_PARAM_UPDATED_IV) <octet string OR octet ptr>
708           Gets the updated pseudo-IV state for the associated cipher context,
709           e.g., the previous ciphertext block for CBC mode or the iteratively
710           encrypted IV value for OFB mode.  Note that octet pointer access is
711           deprecated and is provided only for backwards compatibility with
712           historical libcrypto APIs.  See also
713           EVP_CIPHER_CTX_get_updated_iv().
714
715       "randkey" (OSSL_CIPHER_PARAM_RANDOM_KEY) <octet string>
716           Gets an implementation specific randomly generated key for the
717           associated cipher context ctx. This is currently only supported by
718           DES and 3DES (which set the key to odd parity).
719
720       "taglen" (OSSL_CIPHER_PARAM_AEAD_TAGLEN) <unsigned integer>
721           Gets the tag length to be used for an AEAD cipher for the
722           associated cipher context ctx. It gets a default value if it has
723           not been set.  The length of the "taglen" parameter should not
724           exceed that of a size_t.  See also EVP_CIPHER_CTX_get_tag_length().
725
726       "tlsaadpad" (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD) <unsigned integer>
727           Gets the length of the tag that will be added to a TLS record for
728           the AEAD tag for the associated cipher context ctx.  The length of
729           the "tlsaadpad" parameter should not exceed that of a size_t.
730
731       "tlsivgen" (OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN) <octet string>
732           Gets the invocation field generated for encryption.  Can only be
733           called after "tlsivfixed" is set.  This is only used for GCM mode.
734
735       "tls1multi_enclen" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN)
736       <unsigned integer>
737           Get the total length of the record returned from the
738           "tls1multi_enc" operation.
739
740       "tls1multi_maxbufsz" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE)
741       <unsigned integer>
742           Gets the maximum record length for a TLS1 multiblock cipher
743           operation.  The length of the "tls1multi_maxbufsz" parameter should
744           not exceed that of a size_t.
745
746       "tls1multi_aadpacklen" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN)
747       <unsigned integer>
748           Gets the result of running the "tls1multi_aad" operation.
749
750       "tls-mac" (OSSL_CIPHER_PARAM_TLS_MAC) <octet ptr>
751           Used to pass the TLS MAC data.
752
753   Settable EVP_CIPHER_CTX parameters
754       The following OSSL_PARAM keys can be used with
755       EVP_CIPHER_CTX_set_params():
756
757       "mackey" (OSSL_CIPHER_PARAM_AEAD_MAC_KEY) <octet string>
758           Sets the MAC key used by composite AEAD ciphers such as
759           AES-CBC-HMAC-SHA256.
760
761       "speed" (OSSL_CIPHER_PARAM_SPEED) <unsigned integer>
762           Sets the speed option for the associated cipher context. This is
763           only supported by AES SIV ciphers which disallow multiple
764           operations by default.  Setting "speed" to 1 allows another encrypt
765           or decrypt operation to be performed. This is used for performance
766           testing.
767
768       "use-bits" (OSSL_CIPHER_PARAM_USE_BITS) <unsigned integer>
769           Determines if the input length inl passed to EVP_EncryptUpdate(),
770           EVP_DecryptUpdate() and EVP_CipherUpdate() is the number of bits or
771           number of bytes.  Setting "use-bits" to 1 uses bits. The default is
772           in bytes.  This is only used for CFB1 ciphers.
773
774           This can be set using EVP_CIPHER_CTX_set_flags(ctx,
775           EVP_CIPH_FLAG_LENGTH_BITS).
776
777       "tls-version" (OSSL_CIPHER_PARAM_TLS_VERSION) <integer>
778           Sets the TLS version.
779
780       "tls-mac-size" (OSSL_CIPHER_PARAM_TLS_MAC_SIZE) <unsigned integer>
781           Set the TLS MAC size.
782
783       "tlsaad" (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD) <octet string>
784           Sets TLSv1.2 AAD information for the associated cipher context ctx.
785           TLSv1.2 AAD information is always 13 bytes in length and is as
786           defined for the "additional_data" field described in section
787           6.2.3.3 of RFC5246.
788
789       "tlsivfixed" (OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED) <octet string>
790           Sets the fixed portion of an IV for an AEAD cipher used in a TLS
791           record encryption/ decryption for the associated cipher context.
792           TLS record encryption/decryption always occurs "in place" so that
793           the input and output buffers are always the same memory location.
794           AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an
795           explicit part that varies with every record.  Setting a TLS fixed
796           IV changes a cipher to encrypt/decrypt TLS records.  TLS records
797           are encrypted/decrypted using a single OSSL_FUNC_cipher_cipher call
798           per record.  For a record decryption the first bytes of the input
799           buffer will be the explicit part of the IV and the final bytes of
800           the input buffer will be the AEAD tag.  The length of the explicit
801           part of the IV and the tag length will depend on the cipher in use
802           and will be defined in the RFC for the relevant ciphersuite.  In
803           order to allow for "in place" decryption the plaintext output
804           should be written to the same location in the output buffer that
805           the ciphertext payload was read from, i.e. immediately after the
806           explicit IV.
807
808           When encrypting a record the first bytes of the input buffer should
809           be empty to allow space for the explicit IV, as will the final
810           bytes where the tag will be written.  The length of the input
811           buffer will include the length of the explicit IV, the payload, and
812           the tag bytes.  The cipher implementation should generate the
813           explicit IV and write it to the beginning of the output buffer, do
814           "in place" encryption of the payload and write that to the output
815           buffer, and finally add the tag onto the end of the output buffer.
816
817           Whether encrypting or decrypting the value written to *outl in the
818           OSSL_FUNC_cipher_cipher call should be the length of the payload
819           excluding the explicit IV length and the tag length.
820
821       "tlsivinv" (OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV) <octet string>
822           Sets the invocation field used for decryption.  Can only be called
823           after "tlsivfixed" is set.  This is only used for GCM mode.
824
825       "tls1multi_enc" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC) <octet string>
826           Triggers a multiblock TLS1 encrypt operation for a TLS1 aware
827           cipher that supports sending 4 or 8 records in one go.  The cipher
828           performs both the MAC and encrypt stages and constructs the record
829           headers itself.  "tls1multi_enc" supplies the output buffer for the
830           encrypt operation, "tls1multi_encin" & "tls1multi_interleave" must
831           also be set in order to supply values to the encrypt operation.
832
833       "tls1multi_encin" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN) <octet
834       string>
835           Supplies the data to encrypt for a TLS1 multiblock cipher
836           operation.
837
838       "tls1multi_maxsndfrag"
839       (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT) <unsigned
840       integer>
841           Sets the maximum send fragment size for a TLS1 multiblock cipher
842           operation.  It must be set before using "tls1multi_maxbufsz".  The
843           length of the "tls1multi_maxsndfrag" parameter should not exceed
844           that of a size_t.
845
846       "tls1multi_aad" (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD) <octet string>
847           Sets the authenticated additional data used by a TLS1 multiblock
848           cipher operation.  The supplied data consists of 13 bytes of record
849           data containing: Bytes 0-7: The sequence number of the first record
850           Byte 8: The record type Byte 9-10: The protocol version Byte 11-12:
851           Input length (Always 0)
852
853           "tls1multi_interleave" must also be set for this operation.
854

CONTROLS

856       The Mappings from EVP_CIPHER_CTX_ctrl() identifiers to PARAMETERS are
857       listed in the following section. See the "PARAMETERS" section for more
858       details.
859
860       EVP_CIPHER_CTX_ctrl() can be used to send the following standard
861       controls:
862
863       EVP_CTRL_AEAD_SET_IVLEN and EVP_CTRL_GET_IVLEN
864           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
865           and EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3)
866           item with the key "ivlen" (OSSL_CIPHER_PARAM_IVLEN).
867
868       EVP_CTRL_AEAD_SET_IV_FIXED
869           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
870           gets called with an OSSL_PARAM(3) item with the key "tlsivfixed"
871           (OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED).
872
873       EVP_CTRL_AEAD_SET_MAC_KEY
874           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
875           gets called with an OSSL_PARAM(3) item with the key "mackey"
876           (OSSL_CIPHER_PARAM_AEAD_MAC_KEY).
877
878       EVP_CTRL_AEAD_SET_TAG and EVP_CTRL_AEAD_GET_TAG
879           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
880           and EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3)
881           item with the key "tag" (OSSL_CIPHER_PARAM_AEAD_TAG).
882
883       EVP_CTRL_CCM_SET_L
884           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
885           gets called with an OSSL_PARAM(3) item with the key "ivlen"
886           (OSSL_CIPHER_PARAM_IVLEN) with a value of (15 - L)
887
888       EVP_CTRL_COPY
889           There is no OSSL_PARAM mapping for this. Use EVP_CIPHER_CTX_copy()
890           instead.
891
892       EVP_CTRL_GCM_SET_IV_INV
893           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
894           gets called with an OSSL_PARAM(3) item with the key "tlsivinv"
895           (OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV).
896
897       EVP_CTRL_RAND_KEY
898           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
899           gets called with an OSSL_PARAM(3) item with the key "randkey"
900           (OSSL_CIPHER_PARAM_RANDOM_KEY).
901
902       EVP_CTRL_SET_KEY_LENGTH
903           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
904           gets called with an OSSL_PARAM(3) item with the key "keylen"
905           (OSSL_CIPHER_PARAM_KEYLEN).
906
907       EVP_CTRL_SET_RC2_KEY_BITS and EVP_CTRL_GET_RC2_KEY_BITS
908           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
909           and EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3)
910           item with the key "keybits" (OSSL_CIPHER_PARAM_RC2_KEYBITS).
911
912       EVP_CTRL_SET_RC5_ROUNDS and EVP_CTRL_GET_RC5_ROUNDS
913           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
914           and EVP_CIPHER_CTX_get_params() get called with an OSSL_PARAM(3)
915           item with the key "rounds" (OSSL_CIPHER_PARAM_ROUNDS).
916
917       EVP_CTRL_SET_SPEED
918           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
919           gets called with an OSSL_PARAM(3) item with the key "speed"
920           (OSSL_CIPHER_PARAM_SPEED).
921
922       EVP_CTRL_GCM_IV_GEN
923           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_get_params()
924           gets called with an OSSL_PARAM(3) item with the key "tlsivgen"
925           (OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN).
926
927       EVP_CTRL_AEAD_TLS1_AAD
928           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
929           get called with an OSSL_PARAM(3) item with the key "tlsaadpad"
930           (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD) followed by
931           EVP_CIPHER_CTX_get_params() with a key of "tlsaadpad"
932           (OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD).
933
934       EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE
935           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
936           gets called with an OSSL_PARAM(3) item with the key
937           OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT followed by
938           EVP_CIPHER_CTX_get_params() with a key of "tls1multi_maxbufsz"
939           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE).
940
941       EVP_CTRL_TLS1_1_MULTIBLOCK_AAD
942           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
943           gets called with OSSL_PARAM(3) items with the keys "tls1multi_aad"
944           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD) and "tls1multi_interleave"
945           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE) followed by
946           EVP_CIPHER_CTX_get_params() with keys of "tls1multi_aadpacklen"
947           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN) and
948           "tls1multi_interleave"
949           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE).
950
951       EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT
952           When used with a fetched EVP_CIPHER, EVP_CIPHER_CTX_set_params()
953           gets called with OSSL_PARAM(3) items with the keys "tls1multi_enc"
954           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC), "tls1multi_encin"
955           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN) and
956           "tls1multi_interleave"
957           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE), followed by
958           EVP_CIPHER_CTX_get_params() with a key of "tls1multi_enclen"
959           (OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN).
960

FLAGS

962       EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and
963       EVP_CIPHER_CTX_test_flags().  can be used to manipulate and test these
964       EVP_CIPHER_CTX flags:
965
966       EVP_CIPH_NO_PADDING
967           Used by EVP_CIPHER_CTX_set_padding().
968
969           See also "Gettable and Settable EVP_CIPHER_CTX parameters"
970           "padding"
971
972       EVP_CIPH_FLAG_LENGTH_BITS
973           See "Settable EVP_CIPHER_CTX parameters" "use-bits".
974
975       EVP_CIPHER_CTX_FLAG_WRAP_ALLOW
976           Used for Legacy purposes only. This flag needed to be set to
977           indicate the cipher handled wrapping.
978
979       EVP_CIPHER_flags() uses the following flags that have mappings to
980       "Gettable EVP_CIPHER parameters":
981
982       EVP_CIPH_FLAG_AEAD_CIPHER
983           See "Gettable EVP_CIPHER parameters" "aead".
984
985       EVP_CIPH_CUSTOM_IV
986           See "Gettable EVP_CIPHER parameters" "custom-iv".
987
988       EVP_CIPH_FLAG_CTS
989           See "Gettable EVP_CIPHER parameters" "cts".
990
991       EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK;
992           See "Gettable EVP_CIPHER parameters" "tls-multi".
993
994       EVP_CIPH_RAND_KEY
995           See "Gettable EVP_CIPHER parameters" "has-randkey".
996
997       EVP_CIPHER_flags() uses the following flags for legacy purposes only:
998
999       EVP_CIPH_VARIABLE_LENGTH
1000       EVP_CIPH_FLAG_CUSTOM_CIPHER
1001       EVP_CIPH_ALWAYS_CALL_INIT
1002       EVP_CIPH_CTRL_INIT
1003       EVP_CIPH_CUSTOM_KEY_LENGTH
1004       EVP_CIPH_CUSTOM_COPY
1005       EVP_CIPH_FLAG_DEFAULT_ASN1
1006           See EVP_CIPHER_meth_set_flags(3) for further information related to
1007           the above flags.
1008

RETURN VALUES

1010       EVP_CIPHER_fetch() returns a pointer to a EVP_CIPHER for success and
1011       NULL for failure.
1012
1013       EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise.
1014
1015       EVP_CIPHER_CTX_new() returns a pointer to a newly created
1016       EVP_CIPHER_CTX for success and NULL for failure.
1017
1018       EVP_EncryptInit_ex2(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
1019       return 1 for success and 0 for failure.
1020
1021       EVP_DecryptInit_ex2() and EVP_DecryptUpdate() return 1 for success and
1022       0 for failure.  EVP_DecryptFinal_ex() returns 0 if the decrypt failed
1023       or 1 for success.
1024
1025       EVP_CipherInit_ex2() and EVP_CipherUpdate() return 1 for success and 0
1026       for failure.  EVP_CipherFinal_ex() returns 0 for a decryption failure
1027       or 1 for success.
1028
1029       EVP_Cipher() returns the amount of encrypted / decrypted bytes, or -1
1030       on failure if the flag EVP_CIPH_FLAG_CUSTOM_CIPHER is set for the
1031       cipher.  EVP_Cipher() returns 1 on success or 0 on failure, if the flag
1032       EVP_CIPH_FLAG_CUSTOM_CIPHER is not set for the cipher.
1033
1034       EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
1035
1036       EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
1037       return an EVP_CIPHER structure or NULL on error.
1038
1039       EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() return a NID.
1040
1041       EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() return
1042       the block size.
1043
1044       EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() return
1045       the key length.
1046
1047       EVP_CIPHER_CTX_set_padding() always returns 1.
1048
1049       EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() return
1050       the IV length or zero if the cipher does not use an IV.
1051
1052       EVP_CIPHER_CTX_get_tag_length() return the tag length or zero if the
1053       cipher does not use a tag.
1054
1055       EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() return the NID of
1056       the cipher's OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT
1057       IDENTIFIER.
1058
1059       EVP_CIPHER_CTX_cipher() returns an EVP_CIPHER structure.
1060
1061       EVP_CIPHER_CTX_get_num() returns a nonnegative num value or
1062       EVP_CTRL_RET_UNSUPPORTED if the implementation does not support the
1063       call or on any other error.
1064
1065       EVP_CIPHER_CTX_set_num() returns 1 on success and 0 if the
1066       implementation does not support the call or on any other error.
1067
1068       EVP_CIPHER_CTX_is_encrypting() returns 1 if the ctx is set up for
1069       encryption 0 otherwise.
1070
1071       EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return
1072       greater than zero for success and zero or a negative number on failure.
1073
1074       EVP_CIPHER_CTX_rand_key() returns 1 for success.
1075
1076       EVP_CIPHER_names_do_all() returns 1 if the callback was called for all
1077       names.  A return value of 0 means that the callback was not called for
1078       any names.
1079

CIPHER LISTING

1081       All algorithms have a fixed key length unless otherwise stated.
1082
1083       Refer to "SEE ALSO" for the full list of ciphers available through the
1084       EVP interface.
1085
1086       EVP_enc_null()
1087           Null cipher: does nothing.
1088

AEAD INTERFACE

1090       The EVP interface for Authenticated Encryption with Associated Data
1091       (AEAD) modes are subtly altered and several additional ctrl operations
1092       are supported depending on the mode specified.
1093
1094       To specify additional authenticated data (AAD), a call to
1095       EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should
1096       be made with the output parameter out set to NULL.
1097
1098       When decrypting, the return value of EVP_DecryptFinal() or
1099       EVP_CipherFinal() indicates whether the operation was successful. If it
1100       does not indicate success, the authentication operation has failed and
1101       any output data MUST NOT be used as it is corrupted.
1102
1103   GCM and OCB Modes
1104       The following ctrls are supported in GCM and OCB modes.
1105
1106       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
1107           Sets the IV length. This call can only be made before specifying an
1108           IV. If not called a default IV length is used.
1109
1110           For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB
1111           mode the maximum is 15.
1112
1113       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
1114           Writes "taglen" bytes of the tag value to the buffer indicated by
1115           "tag".  This call can only be made when encrypting data and after
1116           all data has been processed (e.g. after an EVP_EncryptFinal()
1117           call).
1118
1119           For OCB, "taglen" must either be 16 or the value previously set via
1120           EVP_CTRL_AEAD_SET_TAG.
1121
1122       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
1123           When decrypting, this call sets the expected tag to "taglen" bytes
1124           from "tag".  "taglen" must be between 1 and 16 inclusive.  The tag
1125           must be set prior to any call to EVP_DecryptFinal() or
1126           EVP_DecryptFinal_ex().
1127
1128           For GCM, this call is only valid when decrypting data.
1129
1130           For OCB, this call is valid when decrypting data to set the
1131           expected tag, and when encrypting to set the desired tag length.
1132
1133           In OCB mode, calling this when encrypting with "tag" set to "NULL"
1134           sets the tag length. The tag length can only be set before
1135           specifying an IV. If this is not called prior to setting the IV
1136           during encryption, then a default tag length is used.
1137
1138           For OCB AES, the default tag length is 16 (i.e. 128 bits).  It is
1139           also the maximum tag length for OCB.
1140
1141   CCM Mode
1142       The EVP interface for CCM mode is similar to that of the GCM mode but
1143       with a few additional requirements and different ctrl values.
1144
1145       For CCM mode, the total plaintext or ciphertext length MUST be passed
1146       to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with
1147       the output and input parameters (in and out) set to NULL and the length
1148       passed in the inl parameter.
1149
1150       The following ctrls are supported in CCM mode.
1151
1152       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
1153           This call is made to set the expected CCM tag value when decrypting
1154           or the length of the tag (with the "tag" parameter set to NULL)
1155           when encrypting.  The tag length is often referred to as M. If not
1156           set a default value is used (12 for AES). When decrypting, the tag
1157           needs to be set before passing in data to be decrypted, but as in
1158           GCM and OCB mode, it can be set after passing additional
1159           authenticated data (see "AEAD INTERFACE").
1160
1161       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
1162           Sets the CCM L value. If not set a default is used (8 for AES).
1163
1164       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
1165           Sets the CCM nonce (IV) length. This call can only be made before
1166           specifying a nonce value. The nonce length is given by 15 - L so it
1167           is 7 by default for AES.
1168
1169   SIV Mode
1170       For SIV mode ciphers the behaviour of the EVP interface is subtly
1171       altered and several additional ctrl operations are supported.
1172
1173       To specify any additional authenticated data (AAD) and/or a Nonce, a
1174       call to EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate()
1175       should be made with the output parameter out set to NULL.
1176
1177       RFC5297 states that the Nonce is the last piece of AAD before the
1178       actual encrypt/decrypt takes place. The API does not differentiate the
1179       Nonce from other AAD.
1180
1181       When decrypting the return value of EVP_DecryptFinal() or
1182       EVP_CipherFinal() indicates if the operation was successful. If it does
1183       not indicate success the authentication operation has failed and any
1184       output data MUST NOT be used as it is corrupted.
1185
1186       The API does not store the the SIV (Synthetic Initialization Vector) in
1187       the cipher text. Instead, it is stored as the tag within the
1188       EVP_CIPHER_CTX.  The SIV must be retrieved from the context after
1189       encryption, and set into the context before decryption.
1190
1191       This differs from RFC5297 in that the cipher output from encryption,
1192       and the cipher input to decryption, does not contain the SIV. This also
1193       means that the plain text and cipher text lengths are identical.
1194
1195       The following ctrls are supported in SIV mode, and are used to get and
1196       set the Synthetic Initialization Vector:
1197
1198       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
1199           Writes taglen bytes of the tag value (the Synthetic Initialization
1200           Vector) to the buffer indicated by tag. This call can only be made
1201           when encrypting data and after all data has been processed (e.g.
1202           after an EVP_EncryptFinal() call). For SIV mode the taglen must be
1203           16.
1204
1205       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
1206           Sets the expected tag (the Synthetic Initialization Vector) to
1207           taglen bytes from tag. This call is only legal when decrypting data
1208           and must be made before any data is processed (e.g. before any
1209           EVP_DecryptUpdate() calls). For SIV mode the taglen must be 16.
1210
1211       SIV mode makes two passes over the input data, thus, only one call to
1212       EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should
1213       be made with out set to a non-NULL value. A call to EVP_DecryptFinal()
1214       or EVP_CipherFinal() is not required, but will indicate if the update
1215       operation succeeded.
1216
1217   ChaCha20-Poly1305
1218       The following ctrls are supported for the ChaCha20-Poly1305 AEAD
1219       algorithm.
1220
1221       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
1222           Sets the nonce length. This call can only be made before specifying
1223           the nonce.  If not called a default nonce length of 12 (i.e. 96
1224           bits) is used. The maximum nonce length is 12 bytes (i.e. 96-bits).
1225           If a nonce of less than 12 bytes is set then the nonce is
1226           automatically padded with leading 0 bytes to make it 12 bytes in
1227           length.
1228
1229       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
1230           Writes "taglen" bytes of the tag value to the buffer indicated by
1231           "tag".  This call can only be made when encrypting data and after
1232           all data has been processed (e.g. after an EVP_EncryptFinal()
1233           call).
1234
1235           "taglen" specified here must be 16 (POLY1305_BLOCK_SIZE, i.e.
1236           128-bits) or less.
1237
1238       EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
1239           Sets the expected tag to "taglen" bytes from "tag".  The tag length
1240           can only be set before specifying an IV.  "taglen" must be between
1241           1 and 16 (POLY1305_BLOCK_SIZE) inclusive.  This call is only valid
1242           when decrypting data.
1243

NOTES

1245       Where possible the EVP interface to symmetric ciphers should be used in
1246       preference to the low-level interfaces. This is because the code then
1247       becomes transparent to the cipher used and much more flexible.
1248       Additionally, the EVP interface will ensure the use of platform
1249       specific cryptographic acceleration such as AES-NI (the low-level
1250       interfaces do not provide the guarantee).
1251
1252       PKCS padding works by adding n padding bytes of value n to make the
1253       total length of the encrypted data a multiple of the block size.
1254       Padding is always added so if the data is already a multiple of the
1255       block size n will equal the block size. For example if the block size
1256       is 8 and 11 bytes are to be encrypted then 5 padding bytes of value 5
1257       will be added.
1258
1259       When decrypting the final block is checked to see if it has the correct
1260       form.
1261
1262       Although the decryption operation can produce an error if padding is
1263       enabled, it is not a strong test that the input data or key is correct.
1264       A random block has better than 1 in 256 chance of being of the correct
1265       format and problems with the input data earlier on will not produce a
1266       final decrypt error.
1267
1268       If padding is disabled then the decryption operation will always
1269       succeed if the total amount of data decrypted is a multiple of the
1270       block size.
1271
1272       The functions EVP_EncryptInit(), EVP_EncryptInit_ex(),
1273       EVP_EncryptFinal(), EVP_DecryptInit(), EVP_DecryptInit_ex(),
1274       EVP_CipherInit(), EVP_CipherInit_ex() and EVP_CipherFinal() are
1275       obsolete but are retained for compatibility with existing code. New
1276       code should use EVP_EncryptInit_ex2(), EVP_EncryptFinal_ex(),
1277       EVP_DecryptInit_ex2(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex2() and
1278       EVP_CipherFinal_ex() because they can reuse an existing context without
1279       allocating and freeing it up on each call.
1280
1281       There are some differences between functions EVP_CipherInit() and
1282       EVP_CipherInit_ex(), significant in some circumstances.
1283       EVP_CipherInit() fills the passed context object with zeros.  As a
1284       consequence, EVP_CipherInit() does not allow step-by-step
1285       initialization of the ctx when the key and iv are passed in separate
1286       calls. It also means that the flags set for the CTX are removed, and it
1287       is especially important for the EVP_CIPHER_CTX_FLAG_WRAP_ALLOW flag
1288       treated specially in EVP_CipherInit_ex().
1289
1290       EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as
1291       macros.
1292

BUGS

1294       EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal
1295       ciphers with default key lengths. If custom ciphers exceed these values
1296       the results are unpredictable. This is because it has become standard
1297       practice to define a generic key as a fixed unsigned char array
1298       containing EVP_MAX_KEY_LENGTH bytes.
1299
1300       The ASN1 code is incomplete (and sometimes inaccurate) it has only been
1301       tested for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC
1302       mode.
1303

EXAMPLES

1305       Encrypt a string using IDEA:
1306
1307        int do_crypt(char *outfile)
1308        {
1309            unsigned char outbuf[1024];
1310            int outlen, tmplen;
1311            /*
1312             * Bogus key and IV: we'd normally set these from
1313             * another source.
1314             */
1315            unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
1316            unsigned char iv[] = {1,2,3,4,5,6,7,8};
1317            char intext[] = "Some Crypto Text";
1318            EVP_CIPHER_CTX *ctx;
1319            FILE *out;
1320
1321            ctx = EVP_CIPHER_CTX_new();
1322            EVP_EncryptInit_ex2(ctx, EVP_idea_cbc(), key, iv, NULL);
1323
1324            if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
1325                /* Error */
1326                EVP_CIPHER_CTX_free(ctx);
1327                return 0;
1328            }
1329            /*
1330             * Buffer passed to EVP_EncryptFinal() must be after data just
1331             * encrypted to avoid overwriting it.
1332             */
1333            if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
1334                /* Error */
1335                EVP_CIPHER_CTX_free(ctx);
1336                return 0;
1337            }
1338            outlen += tmplen;
1339            EVP_CIPHER_CTX_free(ctx);
1340            /*
1341             * Need binary mode for fopen because encrypted data is
1342             * binary data. Also cannot use strlen() on it because
1343             * it won't be NUL terminated and may contain embedded
1344             * NULs.
1345             */
1346            out = fopen(outfile, "wb");
1347            if (out == NULL) {
1348                /* Error */
1349                return 0;
1350            }
1351            fwrite(outbuf, 1, outlen, out);
1352            fclose(out);
1353            return 1;
1354        }
1355
1356       The ciphertext from the above example can be decrypted using the
1357       openssl utility with the command line (shown on two lines for clarity):
1358
1359        openssl idea -d \
1360            -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
1361
1362       General encryption and decryption function example using FILE I/O and
1363       AES128 with a 128-bit key:
1364
1365        int do_crypt(FILE *in, FILE *out, int do_encrypt)
1366        {
1367            /* Allow enough space in output buffer for additional block */
1368            unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
1369            int inlen, outlen;
1370            EVP_CIPHER_CTX *ctx;
1371            /*
1372             * Bogus key and IV: we'd normally set these from
1373             * another source.
1374             */
1375            unsigned char key[] = "0123456789abcdeF";
1376            unsigned char iv[] = "1234567887654321";
1377
1378            /* Don't set key or IV right away; we want to check lengths */
1379            ctx = EVP_CIPHER_CTX_new();
1380            EVP_CipherInit_ex2(ctx, EVP_aes_128_cbc(), NULL, NULL,
1381                               do_encrypt, NULL);
1382            OPENSSL_assert(EVP_CIPHER_CTX_get_key_length(ctx) == 16);
1383            OPENSSL_assert(EVP_CIPHER_CTX_get_iv_length(ctx) == 16);
1384
1385            /* Now we can set key and IV */
1386            EVP_CipherInit_ex2(ctx, NULL, key, iv, do_encrypt, NULL);
1387
1388            for (;;) {
1389                inlen = fread(inbuf, 1, 1024, in);
1390                if (inlen <= 0)
1391                    break;
1392                if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
1393                    /* Error */
1394                    EVP_CIPHER_CTX_free(ctx);
1395                    return 0;
1396                }
1397                fwrite(outbuf, 1, outlen, out);
1398            }
1399            if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
1400                /* Error */
1401                EVP_CIPHER_CTX_free(ctx);
1402                return 0;
1403            }
1404            fwrite(outbuf, 1, outlen, out);
1405
1406            EVP_CIPHER_CTX_free(ctx);
1407            return 1;
1408        }
1409
1410       Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext
1411       stealing.
1412
1413        int encrypt(const unsigned char *key, const unsigned char *iv,
1414                    const unsigned char *msg, size_t msg_len, unsigned char *out)
1415        {
1416           /*
1417            * This assumes that key size is 32 bytes and the iv is 16 bytes.
1418            * For ciphertext stealing mode the length of the ciphertext "out" will be
1419            * the same size as the plaintext size "msg_len".
1420            * The "msg_len" can be any size >= 16.
1421            */
1422            int ret = 0, encrypt = 1, outlen, len;
1423            EVP_CIPHER_CTX *ctx = NULL;
1424            EVP_CIPHER *cipher = NULL;
1425            OSSL_PARAM params[2];
1426
1427            ctx = EVP_CIPHER_CTX_new();
1428            cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL);
1429            if (ctx == NULL || cipher == NULL)
1430                goto err;
1431
1432            /*
1433             * The default is "CS1" so this is not really needed,
1434             * but would be needed to set either "CS2" or "CS3".
1435             */
1436            params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE,
1437                                                         "CS1", 0);
1438            params[1] = OSSL_PARAM_construct_end();
1439
1440            if (!EVP_CipherInit_ex2(ctx, cipher, key, iv, encrypt, params))
1441                goto err;
1442
1443            /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */
1444            if (!EVP_CipherUpdate(ctx, encrypted, &outlen, msg, msglen))
1445                goto err;
1446             if (!EVP_CipherFinal_ex(ctx, encrypted + outlen, &len))
1447                goto err;
1448            ret = 1;
1449        err:
1450            EVP_CIPHER_free(cipher);
1451            EVP_CIPHER_CTX_free(ctx);
1452            return ret;
1453        }
1454

SEE ALSO

1456       evp(7), property(7), "ALGORITHM FETCHING" in crypto(7),
1457       provider-cipher(7), life_cycle-cipher(7)
1458
1459       Supported ciphers are listed in:
1460
1461       EVP_aes_128_gcm(3), EVP_aria_128_gcm(3), EVP_bf_cbc(3),
1462       EVP_camellia_128_ecb(3), EVP_cast5_cbc(3), EVP_chacha20(3),
1463       EVP_des_cbc(3), EVP_desx_cbc(3), EVP_idea_cbc(3), EVP_rc2_cbc(3),
1464       EVP_rc4(3), EVP_rc5_32_12_16_cbc(3), EVP_seed_cbc(3), EVP_sm4_cbc(3),
1465

HISTORY

1467       Support for OCB mode was added in OpenSSL 1.1.0.
1468
1469       EVP_CIPHER_CTX was made opaque in OpenSSL 1.1.0.  As a result,
1470       EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
1471       disappeared.  EVP_CIPHER_CTX_init() remains as an alias for
1472       EVP_CIPHER_CTX_reset().
1473
1474       The EVP_CIPHER_CTX_cipher() function was deprecated in OpenSSL 3.0; use
1475       EVP_CIPHER_CTX_get0_cipher() instead.
1476
1477       The EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2(), EVP_CipherInit_ex2(),
1478       EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(),
1479       EVP_CIPHER_CTX_get0_cipher(), EVP_CIPHER_CTX_get1_cipher(),
1480       EVP_CIPHER_get_params(), EVP_CIPHER_CTX_set_params(),
1481       EVP_CIPHER_CTX_get_params(), EVP_CIPHER_gettable_params(),
1482       EVP_CIPHER_settable_ctx_params(), EVP_CIPHER_gettable_ctx_params(),
1483       EVP_CIPHER_CTX_settable_params() and EVP_CIPHER_CTX_gettable_params()
1484       functions were added in 3.0.
1485
1486       The EVP_CIPHER_nid(), EVP_CIPHER_name(), EVP_CIPHER_block_size(),
1487       EVP_CIPHER_key_length(), EVP_CIPHER_iv_length(), EVP_CIPHER_flags(),
1488       EVP_CIPHER_mode(), EVP_CIPHER_type(), EVP_CIPHER_CTX_nid(),
1489       EVP_CIPHER_CTX_block_size(), EVP_CIPHER_CTX_key_length(),
1490       EVP_CIPHER_CTX_iv_length(), EVP_CIPHER_CTX_tag_length(),
1491       EVP_CIPHER_CTX_num(), EVP_CIPHER_CTX_type(), and EVP_CIPHER_CTX_mode()
1492       functions were renamed to include "get" or "get0" in their names in
1493       OpenSSL 3.0, respectively. The old names are kept as non-deprecated
1494       alias macros.
1495
1496       The EVP_CIPHER_CTX_encrypting() function was renamed to
1497       EVP_CIPHER_CTX_is_encrypting() in OpenSSL 3.0. The old name is kept as
1498       non-deprecated alias macro.
1499
1500       The EVP_CIPHER_CTX_flags() macro was deprecated in OpenSSL 1.1.0.
1501
1503       Copyright 2000-2022 The OpenSSL Project Authors. All Rights Reserved.
1504
1505       Licensed under the Apache License 2.0 (the "License").  You may not use
1506       this file except in compliance with the License.  You can obtain a copy
1507       in the file LICENSE in the source distribution or at
1508       <https://www.openssl.org/source/license.html>.
1509
1510
1511
15123.0.5                             2022-11-01            EVP_ENCRYPTINIT(3ossl)
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