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 they always use the default cipher implementation.
195 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
196 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
197 EVP_CipherFinal_ex(). In previous releases they also cleaned up
198 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
199 must be called to free any context resources.
201 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
202 return an EVP_CIPHER structure when passed a cipher name, a NID or an
203 ASN1_OBJECT structure.
205 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
206 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
207 value is an internal value which may not have a corresponding OBJECT
210 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
211 function should be called after the context is set up for encryption
212 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
213 EVP_CipherInit_ex(). By default encryption operations are padded using
214 standard block padding and the padding is checked and removed when
215 decrypting. If the B<pad> parameter is zero then no padding is
216 performed, the total amount of data encrypted or decrypted must then
217 be a multiple of the block size or an error will occur.
219 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
220 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
221 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
222 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
223 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
224 for variable key length ciphers.
226 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
227 If the cipher is a fixed length cipher then attempting to set the key
228 length to any value other than the fixed value is an error.
230 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
231 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
232 It will return zero if the cipher does not use an IV. The constant
233 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
235 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
236 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
237 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
238 length for all ciphers.
240 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
241 cipher or context. This "type" is the actual NID of the cipher OBJECT
242 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
243 128 bit RC2 have the same NID. If the cipher does not have an object
244 identifier or does not have ASN1 support this function will return
247 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
248 an B<EVP_CIPHER_CTX> structure.
250 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
251 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE,
252 EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE,
253 EVP_CIPH_WRAP_MODE or EVP_CIPH_OCB_MODE. If the cipher is a stream cipher then
254 EVP_CIPH_STREAM_CIPHER is returned.
256 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
257 on the passed cipher. This will typically include any parameters and an
258 IV. The cipher IV (if any) must be set when this call is made. This call
259 should be made before the cipher is actually "used" (before any
260 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
261 may fail if the cipher does not have any ASN1 support.
263 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
264 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
265 In the case of RC2, for example, it will set the IV and effective key length.
266 This function should be called after the base cipher type is set but before
267 the key is set. For example EVP_CipherInit() will be called with the IV and
268 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
269 EVP_CipherInit() again with all parameters except the key set to NULL. It is
270 possible for this function to fail if the cipher does not have any ASN1 support
271 or the parameters cannot be set (for example the RC2 effective key length
274 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
277 EVP_CIPHER_CTX_rand_key() generates a random key of the appropriate length
278 based on the cipher context. The EVP_CIPHER can provide its own random key
279 generation routine to support keys of a specific form. B<Key> must point to a
280 buffer at least as big as the value returned by EVP_CIPHER_CTX_key_length().
284 EVP_CIPHER_CTX_new() returns a pointer to a newly created
285 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
287 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
288 return 1 for success and 0 for failure.
290 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
291 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
293 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
294 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
296 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
298 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
299 return an B<EVP_CIPHER> structure or NULL on error.
301 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
303 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
306 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
309 EVP_CIPHER_CTX_set_padding() always returns 1.
311 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
312 length or zero if the cipher does not use an IV.
314 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
315 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
317 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
319 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
320 than zero for success and zero or a negative number.
322 EVP_CIPHER_CTX_rand_key() returns 1 for success.
324 =head1 CIPHER LISTING
326 All algorithms have a fixed key length unless otherwise stated.
328 Refer to L<SEE ALSO> for the full list of ciphers available through the EVP
335 Null cipher: does nothing.
339 =head1 AEAD Interface
341 The EVP interface for Authenticated Encryption with Associated Data (AEAD)
342 modes are subtly altered and several additional I<ctrl> operations are supported
343 depending on the mode specified.
345 To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(),
346 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
347 parameter B<out> set to B<NULL>.
349 When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal()
350 indicates whether the operation was successful. If it does not indicate success,
351 the authentication operation has failed and any output data B<MUST NOT> be used
354 =head2 GCM and OCB Modes
356 The following I<ctrl>s are supported in GCM and OCB modes.
360 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
362 Sets the IV length. This call can only be made before specifying an IV. If
363 not called a default IV length is used.
365 For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the
368 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
370 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
371 This call can only be made when encrypting data and B<after> all data has been
372 processed (e.g. after an EVP_EncryptFinal() call).
374 For OCB, C<taglen> must either be 16 or the value previously set via
375 B<EVP_CTRL_AEAD_SET_TAG>.
377 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
379 Sets the expected tag to C<taglen> bytes from C<tag>.
380 The tag length can only be set before specifying an IV.
381 C<taglen> must be between 1 and 16 inclusive.
383 For GCM, this call is only valid when decrypting data.
385 For OCB, this call is valid when decrypting data to set the expected tag,
386 and before encryption to set the desired tag length.
388 In OCB mode, calling this before encryption with C<tag> set to C<NULL> sets the
389 tag length. If this is not called prior to encryption, a default tag length is
392 For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the
393 maximum tag length for OCB.
399 The EVP interface for CCM mode is similar to that of the GCM mode but with a
400 few additional requirements and different I<ctrl> values.
402 For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to
403 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
404 and input parameters (B<in> and B<out>) set to B<NULL> and the length passed in
405 the B<inl> parameter.
407 The following I<ctrl>s are supported in CCM mode.
411 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
413 This call is made to set the expected B<CCM> tag value when decrypting or
414 the length of the tag (with the C<tag> parameter set to NULL) when encrypting.
415 The tag length is often referred to as B<M>. If not set a default value is
418 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL)
420 Sets the CCM B<L> value. If not set a default is used (8 for AES).
422 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
424 Sets the CCM nonce (IV) length. This call can only be made before specifying an
425 nonce value. The nonce length is given by B<15 - L> so it is 7 by default for
430 =head2 ChaCha20-Poly1305
432 The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm.
436 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL)
438 Sets the nonce length. This call can only be made before specifying the nonce.
439 If not called a default nonce length of 12 (i.e. 96 bits) is used. The maximum
440 nonce length is 16 (B<CHACHA_CTR_SIZE>, i.e. 128-bits).
442 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag)
444 Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>.
445 This call can only be made when encrypting data and B<after> all data has been
446 processed (e.g. after an EVP_EncryptFinal() call).
448 C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or
451 =item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag)
453 Sets the expected tag to C<taglen> bytes from C<tag>.
454 The tag length can only be set before specifying an IV.
455 C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive.
456 This call is only valid when decrypting data.
462 Where possible the B<EVP> interface to symmetric ciphers should be used in
463 preference to the low level interfaces. This is because the code then becomes
464 transparent to the cipher used and much more flexible. Additionally, the
465 B<EVP> interface will ensure the use of platform specific cryptographic
466 acceleration such as AES-NI (the low level interfaces do not provide the
469 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
470 length of the encrypted data a multiple of the block size. Padding is always
471 added so if the data is already a multiple of the block size B<n> will equal
472 the block size. For example if the block size is 8 and 11 bytes are to be
473 encrypted then 5 padding bytes of value 5 will be added.
475 When decrypting the final block is checked to see if it has the correct form.
477 Although the decryption operation can produce an error if padding is enabled,
478 it is not a strong test that the input data or key is correct. A random block
479 has better than 1 in 256 chance of being of the correct format and problems with
480 the input data earlier on will not produce a final decrypt error.
482 If padding is disabled then the decryption operation will always succeed if
483 the total amount of data decrypted is a multiple of the block size.
485 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
486 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
487 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
488 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
489 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
490 existing context without allocating and freeing it up on each call.
492 EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros.
496 B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal
497 ciphers with default key lengths. If custom ciphers exceed these values the
498 results are unpredictable. This is because it has become standard practice to
499 define a generic key as a fixed unsigned char array containing
500 B<EVP_MAX_KEY_LENGTH> bytes.
502 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
503 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
507 Encrypt a string using IDEA:
509 int do_crypt(char *outfile)
511 unsigned char outbuf[1024];
514 * Bogus key and IV: we'd normally set these from
517 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
518 unsigned char iv[] = {1,2,3,4,5,6,7,8};
519 char intext[] = "Some Crypto Text";
523 ctx = EVP_CIPHER_CTX_new();
524 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
526 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) {
528 EVP_CIPHER_CTX_free(ctx);
532 * Buffer passed to EVP_EncryptFinal() must be after data just
533 * encrypted to avoid overwriting it.
535 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) {
537 EVP_CIPHER_CTX_free(ctx);
541 EVP_CIPHER_CTX_free(ctx);
543 * Need binary mode for fopen because encrypted data is
544 * binary data. Also cannot use strlen() on it because
545 * it won't be NUL terminated and may contain embedded
548 out = fopen(outfile, "wb");
553 fwrite(outbuf, 1, outlen, out);
558 The ciphertext from the above example can be decrypted using the B<openssl>
559 utility with the command line (shown on two lines for clarity):
562 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename
564 General encryption and decryption function example using FILE I/O and AES128
567 int do_crypt(FILE *in, FILE *out, int do_encrypt)
569 /* Allow enough space in output buffer for additional block */
570 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
574 * Bogus key and IV: we'd normally set these from
577 unsigned char key[] = "0123456789abcdeF";
578 unsigned char iv[] = "1234567887654321";
580 /* Don't set key or IV right away; we want to check lengths */
581 ctx = EVP_CIPHER_CTX_new();
582 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
584 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
585 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
587 /* Now we can set key and IV */
588 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
591 inlen = fread(inbuf, 1, 1024, in);
594 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) {
596 EVP_CIPHER_CTX_free(ctx);
599 fwrite(outbuf, 1, outlen, out);
601 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) {
603 EVP_CIPHER_CTX_free(ctx);
606 fwrite(outbuf, 1, outlen, out);
608 EVP_CIPHER_CTX_free(ctx);
617 Supported ciphers are listed in:
636 Support for OCB mode was added in OpenSSL 1.1.0
638 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
639 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
640 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
641 EVP_CIPHER_CTX_reset().
645 Copyright 2000-2018 The OpenSSL Project Authors. All Rights Reserved.
647 Licensed under the OpenSSL license (the "License"). You may not use
648 this file except in compliance with the License. You can obtain a copy
649 in the file LICENSE in the source distribution or at
650 L<https://www.openssl.org/source/license.html>.