17 EVP_CIPHER_CTX_set_key_length,
29 EVP_CIPHER_block_size,
30 EVP_CIPHER_key_length,
35 EVP_CIPHER_CTX_cipher,
37 EVP_CIPHER_CTX_block_size,
38 EVP_CIPHER_CTX_key_length,
39 EVP_CIPHER_CTX_iv_length,
40 EVP_CIPHER_CTX_get_app_data,
41 EVP_CIPHER_CTX_set_app_data,
45 EVP_CIPHER_param_to_asn1,
46 EVP_CIPHER_asn1_to_param,
47 EVP_CIPHER_CTX_set_padding,
55 #include <openssl/evp.h>
57 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
58 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
59 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
61 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
62 ENGINE *impl, unsigned char *key, unsigned char *iv);
63 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
64 int *outl, const unsigned char *in, int inl);
65 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
67 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
68 ENGINE *impl, unsigned char *key, unsigned char *iv);
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);
73 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
74 ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
75 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
76 int *outl, unsigned char *in, int inl);
77 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
79 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
80 unsigned char *key, unsigned char *iv);
81 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl);
83 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
84 unsigned char *key, unsigned char *iv);
85 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
87 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
88 unsigned char *key, unsigned char *iv, int enc);
89 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl);
91 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
92 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
93 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
94 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key);
96 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
97 const EVP_CIPHER *EVP_get_cipherbynid(int nid);
98 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a);
100 int EVP_CIPHER_nid(const EVP_CIPHER *e);
101 int EVP_CIPHER_block_size(const EVP_CIPHER *e);
102 int EVP_CIPHER_key_length(const EVP_CIPHER *e)
103 int EVP_CIPHER_key_length(const EVP_CIPHER *e);
104 int EVP_CIPHER_iv_length(const EVP_CIPHER *e);
105 unsigned long EVP_CIPHER_flags(const EVP_CIPHER *e);
106 unsigned long EVP_CIPHER_mode(const EVP_CIPHER *e);
107 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
109 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
110 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
111 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
112 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
113 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
114 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
115 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
116 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
117 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
119 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
120 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
124 The EVP cipher routines are a high level interface to certain
127 EVP_CIPHER_CTX_new() creates a cipher context.
129 EVP_CIPHER_CTX_free() clears all information from a cipher context
130 and free up any allocated memory associate with it, including B<ctx>
131 itself. This function should be called after all operations using a
132 cipher are complete so sensitive information does not remain in
135 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
136 with cipher B<type> from ENGINE B<impl>. B<ctx> must be created
137 before calling this function. B<type> is normally supplied
138 by a function such as EVP_aes_256_cbc(). If B<impl> is NULL then the
139 default implementation is used. B<key> is the symmetric key to use
140 and B<iv> is the IV to use (if necessary), the actual number of bytes
141 used for the key and IV depends on the cipher. It is possible to set
142 all parameters to NULL except B<type> in an initial call and supply
143 the remaining parameters in subsequent calls, all of which have B<type>
144 set to NULL. This is done when the default cipher parameters are not
147 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
148 writes the encrypted version to B<out>. This function can be called
149 multiple times to encrypt successive blocks of data. The amount
150 of data written depends on the block alignment of the encrypted data:
151 as a result the amount of data written may be anything from zero bytes
152 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
153 room. The actual number of bytes written is placed in B<outl>. It also
154 checks if B<in> and B<out> are partially overlapping, and if they are
155 0 is returned to indicate failure.
157 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
158 the "final" data, that is any data that remains in a partial block.
159 It uses standard block padding (aka PKCS padding) as described in
160 the NOTES section, below. The encrypted
161 final data is written to B<out> which should have sufficient space for
162 one cipher block. The number of bytes written is placed in B<outl>. After
163 this function is called the encryption operation is finished and no further
164 calls to EVP_EncryptUpdate() should be made.
166 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
167 data and it will return an error if any data remains in a partial block:
168 that is if the total data length is not a multiple of the block size.
170 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
171 corresponding decryption operations. EVP_DecryptFinal() will return an
172 error code if padding is enabled and the final block is not correctly
173 formatted. The parameters and restrictions are identical to the encryption
174 operations except that if padding is enabled the decrypted data buffer B<out>
175 passed to EVP_DecryptUpdate() should have sufficient room for
176 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
177 which case B<inl> bytes is sufficient.
179 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
180 functions that can be used for decryption or encryption. The operation
181 performed depends on the value of the B<enc> parameter. It should be set
182 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
183 (the actual value of 'enc' being supplied in a previous call).
185 EVP_CIPHER_CTX_reset() clears all information from a cipher context
186 and free up any allocated memory associate with it, except the B<ctx>
187 itself. This function should be called anytime B<ctx> is to be reused
188 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
191 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
192 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
193 EVP_CipherInit_ex() except the B<ctx> parameter does not need to be
194 initialized and they always use the default cipher implementation.
196 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
197 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
198 EVP_CipherFinal_ex(). In previous releases they also cleaned up
199 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
200 must be called to free any context resources.
202 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
203 return an EVP_CIPHER structure when passed a cipher name, a NID or an
204 ASN1_OBJECT structure.
206 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
207 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
208 value is an internal value which may not have a corresponding OBJECT
211 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
212 function should be called after the context is set up for encryption
213 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
214 EVP_CipherInit_ex(). By default encryption operations are padded using
215 standard block padding and the padding is checked and removed when
216 decrypting. If the B<pad> parameter is zero then no padding is
217 performed, the total amount of data encrypted or decrypted must then
218 be a multiple of the block size or an error will occur.
220 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
221 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
222 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
223 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
224 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
225 for variable key length ciphers.
227 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
228 If the cipher is a fixed length cipher then attempting to set the key
229 length to any value other than the fixed value is an error.
231 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
232 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
233 It will return zero if the cipher does not use an IV. The constant
234 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
236 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
237 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
238 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
239 length for all ciphers.
241 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
242 cipher or context. This "type" is the actual NID of the cipher OBJECT
243 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
244 128 bit RC2 have the same NID. If the cipher does not have an object
245 identifier or does not have ASN1 support this function will return
248 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
249 an B<EVP_CIPHER_CTX> structure.
251 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
252 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
253 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
254 EVP_CIPH_WRAP_MODE or EVP_CIPH_OCB_MODE. If the cipher is a stream cipher then
255 EVP_CIPH_STREAM_CIPHER is returned.
257 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
258 on the passed cipher. This will typically include any parameters and an
259 IV. The cipher IV (if any) must be set when this call is made. This call
260 should be made before the cipher is actually "used" (before any
261 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
262 may fail if the cipher does not have any ASN1 support.
264 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
265 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
266 In the case of RC2, for example, it will set the IV and effective key length.
267 This function should be called after the base cipher type is set but before
268 the key is set. For example EVP_CipherInit() will be called with the IV and
269 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
270 EVP_CipherInit() again with all parameters except the key set to NULL. It is
271 possible for this function to fail if the cipher does not have any ASN1 support
272 or the parameters cannot be set (for example the RC2 effective key length
275 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
278 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
279 based on the cipher context. The EVP_CIPHER can provide its own random key
280 generation routine to support keys of a specific form. B<Key> must point to a
281 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
285 EVP_CIPHER_CTX_new() returns a pointer to a newly created
286 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
288 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
289 return 1 for success and 0 for failure.
291 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
292 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
294 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
295 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
297 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
299 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
300 return an B<EVP_CIPHER> structure or NULL on error.
302 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
304 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
307 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
310 EVP_CIPHER_CTX_set_padding() always returns 1.
312 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
313 length or zero if the cipher does not use an IV.
315 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
316 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
318 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
320 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
321 than zero for success and zero or a negative number.
323 EVP_CIPHER_CTX_rand_key() returns 1 for success.
325 =head1 CIPHER LISTING
327 All algorithms have a fixed key length unless otherwise stated.
329 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
336 Null cipher: does nothing.
340 =head1 AEAD Interface
342 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
343 modes are subtly altered and several additional I<ctrl> operations are supported
344 depending on the mode specified.
346 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
347 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
348 parameter B<out> set to B<NULL>.
350 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
351 indicates whether the operation was successful. If it does not indicate success,
352 the authentication operation has failed and any output data B<MUST NOT> be used
355 =head2 GCM and OCB Modes
357 The following I<ctrl>s are supported in GCM and OCB modes.
361 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
363 Sets the IV length. This call can only be made before specifying an IV. If
364 not called a default IV length is used.
366 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
369 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
371 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
372 This call can only be made when encrypting data and B<after> all data has been
373 processed (e.g. after an EVP_EncryptFinal() call).
375 For OCB, C<taglen> must either be 16 or the value previously set via
376 B<EVP_CTRL_AEAD_SET_TAG>.
378 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
380 Sets the expected tag to C<taglen> bytes from C<tag>.
381 The tag length can only be set before specifying an IV.
382 C<taglen> must be between 1 and 16 inclusive.
384 For GCM, this call is only valid when decrypting data.
386 For OCB, this call is valid when decrypting data to set the expected tag,
387 and before encryption to set the desired tag length.
389 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
390 tag length. If this is not called prior to encryption, a default tag length is
393 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
394 maximum tag length for OCB.
400 The EVP interface for CCM mode is similar to that of the GCM mode but with a
401 few additional requirements and different I<ctrl> values.
403 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
404 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
405 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
406 the B<inl> parameter.
408 The following I<ctrl>s are supported in CCM mode.
412 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
414 This call is made to set the expected B<CCM> tag value when decrypting or
415 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
416 The tag length is often referred to as B<M>. If not set a default value is
419 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
421 Sets the CCM B<L> value. If not set a default is used (8 for AES).
423 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
425 Sets the CCM nonce (IV) length. This call can only be made before specifying an
426 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
431 =head2 ChaCha20-Poly1305
433 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
437 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
439 Sets the nonce length. This call can only be made before specifying the nonce.
440 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
441 nonce length is 16 (B<CHACHA_CTR_SIZE>, i.e. 128-bits).
443 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
445 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
446 This call can only be made when encrypting data and B<after> all data has been
447 processed (e.g. after an EVP_EncryptFinal() call).
449 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
452 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
454 Sets the expected tag to C<taglen> bytes from C<tag>.
455 The tag length can only be set before specifying an IV.
456 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
457 This call is only valid when decrypting data.
463 Where possible the B<EVP> interface to symmetric ciphers should be used in
464 preference to the low level interfaces. This is because the code then becomes
465 transparent to the cipher used and much more flexible. Additionally, the
466 B<EVP> interface will ensure the use of platform specific cryptographic
467 acceleration such as AES-NI (the low level interfaces do not provide the
470 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
471 length of the encrypted data a multiple of the block size. Padding is always
472 added so if the data is already a multiple of the block size B<n> will equal
473 the block size. For example if the block size is 8 and 11 bytes are to be
474 encrypted then 5 padding bytes of value 5 will be added.
476 When decrypting the final block is checked to see if it has the correct form.
478 Although the decryption operation can produce an error if padding is enabled,
479 it is not a strong test that the input data or key is correct. A random block
480 has better than 1 in 256 chance of being of the correct format and problems with
481 the input data earlier on will not produce a final decrypt error.
483 If padding is disabled then the decryption operation will always succeed if
484 the total amount of data decrypted is a multiple of the block size.
486 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
487 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
488 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
489 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
490 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
491 existing context without allocating and freeing it up on each call.
493 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
497 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
498 ciphers with default key lengths. If custom ciphers exceed these values the
499 results are unpredictable. This is because it has become standard practice to
500 define a generic key as a fixed unsigned char array containing
501 B<EVP_MAX_KEY_LENGTH> bytes.
503 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
504 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
508 Encrypt a string using IDEA:
510 int do_crypt(char *outfile)
512 unsigned char outbuf[1024];
515 * Bogus key and IV: we'd normally set these from
518 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
519 unsigned char iv[] = {1,2,3,4,5,6,7,8};
520 char intext[] = "Some Crypto Text";
524 ctx = EVP_CIPHER_CTX_new();
525 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
527 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
529 EVP_CIPHER_CTX_free(ctx);
533 * Buffer passed to EVP_EncryptFinal() must be after data just
534 * encrypted to avoid overwriting it.
536 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
538 EVP_CIPHER_CTX_free(ctx);
542 EVP_CIPHER_CTX_free(ctx);
544 * Need binary mode for fopen because encrypted data is
545 * binary data. Also cannot use strlen() on it because
546 * it won't be NUL terminated and may contain embedded
549 out = fopen(outfile, "wb");
554 fwrite(outbuf, 1, outlen, out);
559 The ciphertext from the above example can be decrypted using the B<openssl>
560 utility with the command line (shown on two lines for clarity):
563 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
565 General encryption and decryption function example using FILE I/O and AES128
568 int do_crypt(FILE *in, FILE *out, int do_encrypt)
570 /* Allow enough space in output buffer for additional block */
571 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
575 * Bogus key and IV: we'd normally set these from
578 unsigned char key[] = "0123456789abcdeF";
579 unsigned char iv[] = "1234567887654321";
581 /* Don't set key or IV right away; we want to check lengths */
582 ctx = EVP_CIPHER_CTX_new();
583 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
585 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
586 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
588 /* Now we can set key and IV */
589 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
592 inlen = fread(inbuf, 1, 1024, in);
595 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
597 EVP_CIPHER_CTX_free(ctx);
600 fwrite(outbuf, 1, outlen, out);
602 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
604 EVP_CIPHER_CTX_free(ctx);
607 fwrite(outbuf, 1, outlen, out);
609 EVP_CIPHER_CTX_free(ctx);
618 Supported ciphers are listed in:
637 Support for OCB mode was added in OpenSSL 1.1.0
639 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
640 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
641 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
642 EVP_CIPHER_CTX_reset().
646 Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
648 Licensed under the OpenSSL license (the "License"). You may not use
649 this file except in compliance with the License. You can obtain a copy
650 in the file LICENSE in the source distribution or at
651 L<https://www.openssl.org/source/license.html>.