5 EVP_CIPHER_CTX_new, EVP_CIPHER_CTX_reset, EVP_CIPHER_CTX_free,
6 EVP_EncryptInit_ex, EVP_EncryptUpdate, EVP_EncryptFinal_ex,
7 EVP_DecryptInit_ex, EVP_DecryptUpdate, EVP_DecryptFinal_ex,
8 EVP_CipherInit_ex, EVP_CipherUpdate, EVP_CipherFinal_ex,
9 EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl, EVP_EncryptInit,
10 EVP_EncryptFinal, EVP_DecryptInit, EVP_DecryptFinal,
11 EVP_CipherInit, EVP_CipherFinal, EVP_get_cipherbyname,
12 EVP_get_cipherbynid, EVP_get_cipherbyobj, EVP_CIPHER_nid,
13 EVP_CIPHER_block_size, EVP_CIPHER_key_length, EVP_CIPHER_iv_length,
14 EVP_CIPHER_flags, EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher,
15 EVP_CIPHER_CTX_nid, EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length,
16 EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data,
17 EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags,
18 EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1, EVP_CIPHER_asn1_to_param,
19 EVP_CIPHER_CTX_set_padding, EVP_enc_null, EVP_des_cbc, EVP_des_ecb,
20 EVP_des_cfb, EVP_des_ofb, EVP_des_ede_cbc, EVP_des_ede, EVP_des_ede_ofb,
21 EVP_des_ede_cfb, EVP_des_ede3_cbc, EVP_des_ede3, EVP_des_ede3_ofb,
22 EVP_des_ede3_cfb, EVP_desx_cbc, EVP_rc4, EVP_rc4_40, EVP_idea_cbc,
23 EVP_idea_ecb, EVP_idea_cfb, EVP_idea_ofb, EVP_rc2_cbc,
24 EVP_rc2_ecb, EVP_rc2_cfb, EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc,
25 EVP_bf_cbc, EVP_bf_ecb, EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc,
26 EVP_cast5_ecb, EVP_cast5_cfb, EVP_cast5_ofb, EVP_rc5_32_12_16_cbc,
27 EVP_rc5_32_12_16_ecb, EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ofb,
28 EVP_aes_128_cbc, EVP_aes_128_ecb, EVP_aes_128_cfb, EVP_aes_128_ofb,
29 EVP_aes_192_cbc, EVP_aes_192_ecb, EVP_aes_192_cfb, EVP_aes_192_ofb,
30 EVP_aes_256_cbc, EVP_aes_256_ecb, EVP_aes_256_cfb, EVP_aes_256_ofb,
31 EVP_aes_128_gcm, EVP_aes_192_gcm, EVP_aes_256_gcm,
32 EVP_aes_128_ccm, EVP_aes_192_ccm, EVP_aes_256_ccm - EVP cipher routines
38 #include <openssl/evp.h>
40 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void);
41 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx);
42 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx);
44 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
45 ENGINE *impl, unsigned char *key, unsigned char *iv);
46 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
47 int *outl, unsigned char *in, int inl);
48 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
51 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
52 ENGINE *impl, unsigned char *key, unsigned char *iv);
53 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
54 int *outl, unsigned char *in, int inl);
55 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
58 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
59 ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
60 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
61 int *outl, unsigned char *in, int inl);
62 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
65 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
66 unsigned char *key, unsigned char *iv);
67 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
70 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
71 unsigned char *key, unsigned char *iv);
72 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
75 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
76 unsigned char *key, unsigned char *iv, int enc);
77 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
80 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
81 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
82 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
84 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
85 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
86 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
88 #define EVP_CIPHER_nid(e) ((e)->nid)
89 #define EVP_CIPHER_block_size(e) ((e)->block_size)
90 #define EVP_CIPHER_key_length(e) ((e)->key_len)
91 #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
92 #define EVP_CIPHER_flags(e) ((e)->flags)
93 #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
94 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
96 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx);
97 int EVP_CIPHER_CTX_nid(const EVP_CIPHER_CTX *ctx);
98 int EVP_CIPHER_CTX_block_size(const EVP_CIPHER_CTX *ctx);
99 int EVP_CIPHER_CTX_key_length(const EVP_CIPHER_CTX *ctx);
100 int EVP_CIPHER_CTX_iv_length(const EVP_CIPHER_CTX *ctx);
101 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx);
102 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data);
103 int EVP_CIPHER_CTX_type(const EVP_CIPHER_CTX *ctx);
104 int EVP_CIPHER_CTX_mode(const EVP_CIPHER_CTX *ctx);
106 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
107 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
111 The EVP cipher routines are a high level interface to certain
114 EVP_CIPHER_CTX_new() creates a cipher context.
116 EVP_CIPHER_CTX_free() clears all information from a cipher context
117 and free up any allocated memory associate with it, including B<ctx>
118 itself. This function should be called after all operations using a
119 cipher are complete so sensitive information does not remain in
122 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
123 with cipher B<type> from ENGINE B<impl>. B<ctx> must be created
124 before calling this function. B<type> is normally supplied
125 by a function such as EVP_aes_256_cbc(). If B<impl> is NULL then the
126 default implementation is used. B<key> is the symmetric key to use
127 and B<iv> is the IV to use (if necessary), the actual number of bytes
128 used for the key and IV depends on the cipher. It is possible to set
129 all parameters to NULL except B<type> in an initial call and supply
130 the remaining parameters in subsequent calls, all of which have B<type>
131 set to NULL. This is done when the default cipher parameters are not
134 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
135 writes the encrypted version to B<out>. This function can be called
136 multiple times to encrypt successive blocks of data. The amount
137 of data written depends on the block alignment of the encrypted data:
138 as a result the amount of data written may be anything from zero bytes
139 to (inl + cipher_block_size - 1) so B<out> should contain sufficient
140 room. The actual number of bytes written is placed in B<outl>. It also
141 checks if B<in> and B<out> are partially overlapping, and if they are
142 0 is returned to indicate failure.
144 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
145 the "final" data, that is any data that remains in a partial block.
146 It uses standard block padding (aka PKCS padding) as described in
147 the NOTES section, below. The encrypted
148 final data is written to B<out> which should have sufficient space for
149 one cipher block. The number of bytes written is placed in B<outl>. After
150 this function is called the encryption operation is finished and no further
151 calls to EVP_EncryptUpdate() should be made.
153 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
154 data and it will return an error if any data remains in a partial block:
155 that is if the total data length is not a multiple of the block size.
157 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
158 corresponding decryption operations. EVP_DecryptFinal() will return an
159 error code if padding is enabled and the final block is not correctly
160 formatted. The parameters and restrictions are identical to the encryption
161 operations except that if padding is enabled the decrypted data buffer B<out>
162 passed to EVP_DecryptUpdate() should have sufficient room for
163 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
164 which case B<inl> bytes is sufficient.
166 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
167 functions that can be used for decryption or encryption. The operation
168 performed depends on the value of the B<enc> parameter. It should be set
169 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
170 (the actual value of 'enc' being supplied in a previous call).
172 EVP_CIPHER_CTX_reset() clears all information from a cipher context
173 and free up any allocated memory associate with it, except the B<ctx>
174 itself. This function should be called anytime B<ctx> is to be reused
175 for another EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal()
178 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
179 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
180 EVP_CipherInit_ex() except the B<ctx> parameter does not need to be
181 initialized and they always use the default cipher implementation.
183 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
184 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
185 EVP_CipherFinal_ex(). In previous releases they also cleaned up
186 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
187 must be called to free any context resources.
189 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
190 return an EVP_CIPHER structure when passed a cipher name, a NID or an
191 ASN1_OBJECT structure.
193 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
194 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
195 value is an internal value which may not have a corresponding OBJECT
198 EVP_CIPHER_CTX_set_padding() enables or disables padding. This
199 function should be called after the context is set up for encryption
200 or decryption with EVP_EncryptInit_ex(), EVP_DecryptInit_ex() or
201 EVP_CipherInit_ex(). By default encryption operations are padded using
202 standard block padding and the padding is checked and removed when
203 decrypting. If the B<pad> parameter is zero then no padding is
204 performed, the total amount of data encrypted or decrypted must then
205 be a multiple of the block size or an error will occur.
207 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
208 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
209 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
210 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
211 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
212 for variable key length ciphers.
214 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
215 If the cipher is a fixed length cipher then attempting to set the key
216 length to any value other than the fixed value is an error.
218 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
219 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
220 It will return zero if the cipher does not use an IV. The constant
221 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
223 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
224 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
225 structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the maximum block
226 length for all ciphers.
228 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
229 cipher or context. This "type" is the actual NID of the cipher OBJECT
230 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
231 128 bit RC2 have the same NID. If the cipher does not have an object
232 identifier or does not have ASN1 support this function will return
235 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
236 an B<EVP_CIPHER_CTX> structure.
238 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
239 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or
240 EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then
241 EVP_CIPH_STREAM_CIPHER is returned.
243 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
244 on the passed cipher. This will typically include any parameters and an
245 IV. The cipher IV (if any) must be set when this call is made. This call
246 should be made before the cipher is actually "used" (before any
247 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
248 may fail if the cipher does not have any ASN1 support.
250 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
251 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
252 In the case of RC2, for example, it will set the IV and effective key length.
253 This function should be called after the base cipher type is set but before
254 the key is set. For example EVP_CipherInit() will be called with the IV and
255 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
256 EVP_CipherInit() again with all parameters except the key set to NULL. It is
257 possible for this function to fail if the cipher does not have any ASN1 support
258 or the parameters cannot be set (for example the RC2 effective key length
261 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
266 EVP_CIPHER_CTX_new() returns a pointer to a newly created
267 B<EVP_CIPHER_CTX> for success and B<NULL> for failure.
269 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
270 return 1 for success and 0 for failure.
272 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
273 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
275 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
276 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
278 EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure.
280 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
281 return an B<EVP_CIPHER> structure or NULL on error.
283 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
285 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
288 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
291 EVP_CIPHER_CTX_set_padding() always returns 1.
293 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
294 length or zero if the cipher does not use an IV.
296 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
297 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
299 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
301 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater
302 than zero for success and zero or a negative number.
304 =head1 CIPHER LISTING
306 All algorithms have a fixed key length unless otherwise stated.
312 Null cipher: does nothing.
314 =item EVP_aes_128_cbc(), EVP_aes_128_ecb(), EVP_aes_128_cfb(), EVP_aes_128_ofb()
316 AES with a 128-bit key in CBC, ECB, CFB and OFB modes respectively.
318 =item EVP_aes_192_cbc(), EVP_aes_192_ecb(), EVP_aes_192_cfb(), EVP_aes_192_ofb()
320 AES with a 192-bit key in CBC, ECB, CFB and OFB modes respectively.
322 =item EVP_aes_256_cbc(), EVP_aes_256_ecb(), EVP_aes_256_cfb(), EVP_aes_256_ofb()
324 AES with a 256-bit key in CBC, ECB, CFB and OFB modes respectively.
326 =item EVP_des_cbc(), EVP_des_ecb(), EVP_des_cfb(), EVP_des_ofb()
328 DES in CBC, ECB, CFB and OFB modes respectively.
330 =item EVP_des_ede_cbc(), EVP_des_ede(), EVP_des_ede_ofb(), EVP_des_ede_cfb()
332 Two key triple DES in CBC, ECB, CFB and OFB modes respectively.
334 =item EVP_des_ede3_cbc(), EVP_des_ede3(), EVP_des_ede3_ofb(), EVP_des_ede3_cfb()
336 Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
340 DESX algorithm in CBC mode.
344 RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.
348 RC4 stream cipher with 40 bit key length.
349 This is obsolete and new code should use EVP_rc4()
350 and the EVP_CIPHER_CTX_set_key_length() function.
352 =item EVP_idea_cbc() EVP_idea_ecb(), EVP_idea_cfb(), EVP_idea_ofb()
354 IDEA encryption algorithm in CBC, ECB, CFB and OFB modes respectively.
356 =item EVP_rc2_cbc(), EVP_rc2_ecb(), EVP_rc2_cfb(), EVP_rc2_ofb()
358 RC2 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
359 length cipher with an additional parameter called "effective key bits" or "effective key length".
360 By default both are set to 128 bits.
362 =item EVP_rc2_40_cbc(), EVP_rc2_64_cbc()
364 RC2 algorithm in CBC mode with a default key length and effective key length of 40 and 64 bits.
365 These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and
366 EVP_CIPHER_CTX_ctrl() to set the key length and effective key length.
368 =item EVP_bf_cbc(), EVP_bf_ecb(), EVP_bf_cfb(), EVP_bf_ofb()
370 Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
373 =item EVP_cast5_cbc(), EVP_cast5_ecb(), EVP_cast5_cfb(), EVP_cast5_ofb()
375 CAST encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
378 =item EVP_rc5_32_12_16_cbc(), EVP_rc5_32_12_16_ecb(), EVP_rc5_32_12_16_cfb(), EVP_rc5_32_12_16_ofb()
380 RC5 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key length
381 cipher with an additional "number of rounds" parameter. By default the key length is set to 128
384 =item EVP_aes_128_gcm(), EVP_aes_192_gcm(), EVP_aes_256_gcm()
386 AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively.
387 These ciphers require additional control operations to function correctly: see
388 the L</GCM and OCB Modes> section below for details.
390 =item EVP_aes_128_ocb(void), EVP_aes_192_ocb(void), EVP_aes_256_ocb(void)
392 Offset Codebook Mode (OCB) for 128, 192 and 256 bit keys respectively.
393 These ciphers require additional control operations to function correctly: see
394 the L</GCM and OCB Modes> section below for details.
396 =item EVP_aes_128_ccm(), EVP_aes_192_ccm(), EVP_aes_256_ccm()
398 AES Counter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys respectively.
399 These ciphers require additional control operations to function correctly: see
400 CCM mode section below for details.
404 =head1 GCM and OCB Modes
406 For GCM and OCB mode ciphers the behaviour of the EVP interface is subtly
407 altered and several additional ctrl operations are supported.
409 To specify any additional authenticated data (AAD) a call to EVP_CipherUpdate(),
410 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
411 parameter B<out> set to B<NULL>.
413 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
414 indicates if the operation was successful. If it does not indicate success
415 the authentication operation has failed and any output data B<MUST NOT>
416 be used as it is corrupted.
418 The following ctrls are supported in both GCM and OCB modes:
420 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
422 Sets the IV length: this call can only be made before specifying an IV. If
423 not called a default IV length is used. For GCM AES and OCB AES the default is
424 12 (i.e. 96 bits). For OCB mode the maximum is 15.
426 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag);
428 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
429 This call can only be made when encrypting data and B<after> all data has been
430 processed (e.g. after an EVP_EncryptFinal() call). For OCB mode the taglen must
431 either be 16 or the value previously set via EVP_CTRL_OCB_SET_TAGLEN.
433 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
435 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
436 when decrypting data and must be made B<before> any data is processed (e.g.
437 before any EVP_DecryptUpdate() call). For OCB mode the taglen must
438 either be 16 or the value previously set via EVP_CTRL_AEAD_SET_TAG.
440 In OCB mode calling this with B<tag> set to NULL sets the tag length. The tag
441 length can only be set before specifying an IV. If not called a default tag
442 length is used. For OCB AES the default is 16 (i.e. 128 bits). This is also the
443 maximum tag length for OCB.
445 See L</EXAMPLES> below for an example of the use of GCM mode.
449 The behaviour of CCM mode ciphers is similar to GCM mode but with a few
450 additional requirements and different ctrl values.
452 Like GCM and OCB modes any additional authenticated data (AAD) is passed by calling
453 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
454 parameter B<out> set to B<NULL>. Additionally the total plaintext or ciphertext
455 length B<MUST> be passed to EVP_CipherUpdate(), EVP_EncryptUpdate() or
456 EVP_DecryptUpdate() with the output and input parameters (B<in> and B<out>)
457 set to B<NULL> and the length passed in the B<inl> parameter.
459 The following ctrls are supported in CCM mode:
461 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag);
463 This call is made to set the expected B<CCM> tag value when decrypting or
464 the length of the tag (with the B<tag> parameter set to NULL) when encrypting.
465 The tag length is often referred to as B<M>. If not set a default value is
468 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL);
470 Sets the CCM B<L> value. If not set a default is used (8 for AES).
472 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL);
474 Sets the CCM nonce (IV) length: this call can only be made before specifying
475 an nonce value. The nonce length is given by B<15 - L> so it is 7 by default
482 Where possible the B<EVP> interface to symmetric ciphers should be used in
483 preference to the low level interfaces. This is because the code then becomes
484 transparent to the cipher used and much more flexible. Additionally, the
485 B<EVP> interface will ensure the use of platform specific cryptographic
486 acceleration such as AES-NI (the low level interfaces do not provide the
489 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
490 length of the encrypted data a multiple of the block size. Padding is always
491 added so if the data is already a multiple of the block size B<n> will equal
492 the block size. For example if the block size is 8 and 11 bytes are to be
493 encrypted then 5 padding bytes of value 5 will be added.
495 When decrypting the final block is checked to see if it has the correct form.
497 Although the decryption operation can produce an error if padding is enabled,
498 it is not a strong test that the input data or key is correct. A random block
499 has better than 1 in 256 chance of being of the correct format and problems with
500 the input data earlier on will not produce a final decrypt error.
502 If padding is disabled then the decryption operation will always succeed if
503 the total amount of data decrypted is a multiple of the block size.
505 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
506 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
507 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
508 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
509 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
510 existing context without allocating and freeing it up on each call.
514 For RC5 the number of rounds can currently only be set to 8, 12 or 16. This is
515 a limitation of the current RC5 code rather than the EVP interface.
517 EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with
518 default key lengths. If custom ciphers exceed these values the results are
519 unpredictable. This is because it has become standard practice to define a
520 generic key as a fixed unsigned char array containing EVP_MAX_KEY_LENGTH bytes.
522 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
523 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
527 Encrypt a string using IDEA:
529 int do_crypt(char *outfile)
531 unsigned char outbuf[1024];
533 /* Bogus key and IV: we'd normally set these from
536 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
537 unsigned char iv[] = {1,2,3,4,5,6,7,8};
538 char intext[] = "Some Crypto Text";
542 ctx = EVP_CIPHER_CTX_new();
543 EVP_EncryptInit_ex(ctx, EVP_idea_cbc(), NULL, key, iv);
545 if(!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext)))
550 /* Buffer passed to EVP_EncryptFinal() must be after data just
551 * encrypted to avoid overwriting it.
553 if(!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen))
559 EVP_CIPHER_CTX_free(ctx);
560 /* Need binary mode for fopen because encrypted data is
561 * binary data. Also cannot use strlen() on it because
562 * it wont be null terminated and may contain embedded
565 out = fopen(outfile, "wb");
566 fwrite(outbuf, 1, outlen, out);
571 The ciphertext from the above example can be decrypted using the B<openssl>
572 utility with the command line (shown on two lines for clarity):
574 openssl idea -d <filename
575 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
577 General encryption and decryption function example using FILE I/O and AES128
580 int do_crypt(FILE *in, FILE *out, int do_encrypt)
582 /* Allow enough space in output buffer for additional block */
583 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
586 /* Bogus key and IV: we'd normally set these from
589 unsigned char key[] = "0123456789abcdeF";
590 unsigned char iv[] = "1234567887654321";
592 /* Don't set key or IV right away; we want to check lengths */
593 ctx = EVP_CIPHER_CTX_new();
594 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
596 OPENSSL_assert(EVP_CIPHER_CTX_key_length(ctx) == 16);
597 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(ctx) == 16);
599 /* Now we can set key and IV */
600 EVP_CipherInit_ex(ctx, NULL, NULL, key, iv, do_encrypt);
604 inlen = fread(inbuf, 1, 1024, in);
605 if(inlen <= 0) break;
606 if(!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen))
609 EVP_CIPHER_CTX_free(ctx);
612 fwrite(outbuf, 1, outlen, out);
614 if(!EVP_CipherFinal_ex(ctx, outbuf, &outlen))
617 EVP_CIPHER_CTX_free(ctx);
620 fwrite(outbuf, 1, outlen, out);
622 EVP_CIPHER_CTX_free(ctx);
633 Support for OCB mode was added in OpenSSL 1.1.0
635 B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result,
636 EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup()
637 disappeared. EVP_CIPHER_CTX_init() remains as an alias for
638 EVP_CIPHER_CTX_reset().
642 Copyright 2000-2016 The OpenSSL Project Authors. All Rights Reserved.
644 Licensed under the OpenSSL license (the "License"). You may not use
645 this file except in compliance with the License. You can obtain a copy
646 in the file LICENSE in the source distribution or at
647 L<https://www.openssl.org/source/license.html>.