5 EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate,
6 EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate,
7 EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate,
8 EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length,
9 EVP_CIPHER_CTX_ctrl, EVP_CIPHER_CTX_cleanup, 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_idea_cbc, 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
36 #include <openssl/evp.h>
38 void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
40 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
41 ENGINE *impl, unsigned char *key, unsigned char *iv);
42 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
43 int *outl, unsigned char *in, int inl);
44 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
47 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
48 ENGINE *impl, unsigned char *key, unsigned char *iv);
49 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
50 int *outl, unsigned char *in, int inl);
51 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
54 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
55 ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
56 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
57 int *outl, unsigned char *in, int inl);
58 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
61 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
62 unsigned char *key, unsigned char *iv);
63 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
66 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
67 unsigned char *key, unsigned char *iv);
68 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
71 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
72 unsigned char *key, unsigned char *iv, int enc);
73 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
76 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
77 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
78 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
79 int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
81 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
82 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
83 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
85 #define EVP_CIPHER_nid(e) ((e)->nid)
86 #define EVP_CIPHER_block_size(e) ((e)->block_size)
87 #define EVP_CIPHER_key_length(e) ((e)->key_len)
88 #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
89 #define EVP_CIPHER_flags(e) ((e)->flags)
90 #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
91 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
93 #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
94 #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
95 #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
96 #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
97 #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
98 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
99 #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
100 #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
101 #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
102 #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
104 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
105 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
109 The EVP cipher routines are a high level interface to certain
112 EVP_CIPHER_CTX_init() initializes cipher contex B<ctx>.
114 EVP_EncryptInit_ex() sets up cipher context B<ctx> for encryption
115 with cipher B<type> from ENGINE B<impl>. B<ctx> must be initialized
116 before calling this function. B<type> is normally supplied
117 by a function such as EVP_des_cbc(). If B<impl> is NULL then the
118 default implementation is used. B<key> is the symmetric key to use
119 and B<iv> is the IV to use (if necessary), the actual number of bytes
120 used for the key and IV depends on the cipher. It is possible to set
121 all parameters to NULL except B<type> in an initial call and supply
122 the remaining parameters in subsequent calls, all of which have B<type>
123 set to NULL. This is done when the default cipher parameters are not
126 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
127 writes the encrypted version to B<out>. This function can be called
128 multiple times to encrypt successive blocks of data. The amount
129 of data written depends on the block alignment of the encrypted data:
130 as a result the amount of data written may be anything from zero bytes
131 to (inl + cipher_block_size - 1) so B<outl> should contain sufficient
132 room. The actual number of bytes written is placed in B<outl>.
134 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
135 the "final" data, that is any data that remains in a partial block.
136 It uses L<standard block padding|/NOTES> (aka PKCS padding). The encrypted
137 final data is written to B<out> which should have sufficient space for
138 one cipher block. The number of bytes written is placed in B<outl>. After
139 this function is called the encryption operation is finished and no further
140 calls to EVP_EncryptUpdate() should be made.
142 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more
143 data and it will return an error if any data remains in a partial block:
144 that is if the total data length is not a multiple of the block size.
146 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are the
147 corresponding decryption operations. EVP_DecryptFinal() will return an
148 error code if padding is enabled and the final block is not correctly
149 formatted. The parameters and restrictions are identical to the encryption
150 operations except that if padding is enabled the decrypted data buffer B<out>
151 passed to EVP_DecryptUpdate() should have sufficient room for
152 (B<inl> + cipher_block_size) bytes unless the cipher block size is 1 in
153 which case B<inl> bytes is sufficient.
155 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
156 functions that can be used for decryption or encryption. The operation
157 performed depends on the value of the B<enc> parameter. It should be set
158 to 1 for encryption, 0 for decryption and -1 to leave the value unchanged
159 (the actual value of 'enc' being supplied in a previous call).
161 EVP_CIPHER_CTX_cleanup() clears all information from a cipher context
162 and free up any allocated memory associate with it. It should be called
163 after all operations using a cipher are complete so sensitive information
164 does not remain in memory.
166 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
167 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and
168 EVP_CipherInit_ex() except the B<ctx> parameter does not need to be
169 initialized and they always use the default cipher implementation.
171 EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() are
172 identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and
173 EVP_CipherFinal_ex(). In previous releases they also cleaned up
174 the B<ctx>, but this is no longer done and EVP_CIPHER_CTX_clean()
175 must be called to free any context resources.
177 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
178 return an EVP_CIPHER structure when passed a cipher name, a NID or an
179 ASN1_OBJECT structure.
181 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
182 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
183 value is an internal value which may not have a corresponding OBJECT
186 EVP_CIPHER_CTX_set_padding() enables or disables padding. By default
187 encryption operations are padded using standard block padding and the
188 padding is checked and removed when decrypting. If the B<pad> parameter
189 is zero then no padding is performed, the total amount of data encrypted
190 or decrypted must then be a multiple of the block size or an error will
193 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
194 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
195 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
196 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
197 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
198 for variable key length ciphers.
200 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
201 If the cipher is a fixed length cipher then attempting to set the key
202 length to any value other than the fixed value is an error.
204 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
205 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
206 It will return zero if the cipher does not use an IV. The constant
207 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
209 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
210 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
211 structure. The constant B<EVP_MAX_IV_LENGTH> is also the maximum block
212 length for all ciphers.
214 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
215 cipher or context. This "type" is the actual NID of the cipher OBJECT
216 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
217 128 bit RC2 have the same NID. If the cipher does not have an object
218 identifier or does not have ASN1 support this function will return
221 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
222 an B<EVP_CIPHER_CTX> structure.
224 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
225 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or
226 EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then
227 EVP_CIPH_STREAM_CIPHER is returned.
229 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
230 on the passed cipher. This will typically include any parameters and an
231 IV. The cipher IV (if any) must be set when this call is made. This call
232 should be made before the cipher is actually "used" (before any
233 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
234 may fail if the cipher does not have any ASN1 support.
236 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
237 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
238 In the case of RC2, for example, it will set the IV and effective key length.
239 This function should be called after the base cipher type is set but before
240 the key is set. For example EVP_CipherInit() will be called with the IV and
241 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
242 EVP_CipherInit() again with all parameters except the key set to NULL. It is
243 possible for this function to fail if the cipher does not have any ASN1 support
244 or the parameters cannot be set (for example the RC2 effective key length
247 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
252 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
253 return 1 for success and 0 for failure.
255 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
256 EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success.
258 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0 for failure.
259 EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success.
261 EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure.
263 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
264 return an B<EVP_CIPHER> structure or NULL on error.
266 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
268 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
271 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
274 EVP_CIPHER_CTX_set_padding() always returns 1.
276 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
277 length or zero if the cipher does not use an IV.
279 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
280 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
282 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
284 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for
285 success or zero for failure.
287 =head1 CIPHER LISTING
289 All algorithms have a fixed key length unless otherwise stated.
295 Null cipher: does nothing.
297 =item EVP_aes_128_cbc(), EVP_aes_128_ecb(), EVP_aes_128_cfb(), EVP_aes_128_ofb()
299 AES with a 128-bit key in CBC, ECB, CFB and OFB modes respectively.
301 =item EVP_aes_192_cbc(), EVP_aes_192_ecb(), EVP_aes_192_cfb(), EVP_aes_192_ofb()
303 AES with a 192-bit key in CBC, ECB, CFB and OFB modes respectively.
305 =item EVP_aes_256_cbc(), EVP_aes_256_ecb(), EVP_aes_256_cfb(), EVP_aes_256_ofb()
307 AES with a 256-bit key in CBC, ECB, CFB and OFB modes respectively.
309 =item EVP_des_cbc(), EVP_des_ecb(), EVP_des_cfb(), EVP_des_ofb()
311 DES in CBC, ECB, CFB and OFB modes respectively.
313 =item EVP_des_ede_cbc(), EVP_des_ede(), EVP_des_ede_ofb(), EVP_des_ede_cfb()
315 Two key triple DES in CBC, ECB, CFB and OFB modes respectively.
317 =item EVP_des_ede3_cbc(), EVP_des_ede3(), EVP_des_ede3_ofb(), EVP_des_ede3_cfb()
319 Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
323 DESX algorithm in CBC mode.
327 RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.
331 RC4 stream cipher with 40 bit key length.
332 This is obsolete and new code should use EVP_rc4()
333 and the EVP_CIPHER_CTX_set_key_length() function.
335 =item EVP_idea_cbc() EVP_idea_ecb(), EVP_idea_cfb(), EVP_idea_ofb(), EVP_idea_cbc()
337 IDEA encryption algorithm in CBC, ECB, CFB and OFB modes respectively.
339 =item EVP_rc2_cbc(), EVP_rc2_ecb(), EVP_rc2_cfb(), EVP_rc2_ofb()
341 RC2 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
342 length cipher with an additional parameter called "effective key bits" or "effective key length".
343 By default both are set to 128 bits.
345 =item EVP_rc2_40_cbc(), EVP_rc2_64_cbc()
347 RC2 algorithm in CBC mode with a default key length and effective key length of 40 and 64 bits.
348 These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and
349 EVP_CIPHER_CTX_ctrl() to set the key length and effective key length.
351 =item EVP_bf_cbc(), EVP_bf_ecb(), EVP_bf_cfb(), EVP_bf_ofb()
353 Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
356 =item EVP_cast5_cbc(), EVP_cast5_ecb(), EVP_cast5_cfb(), EVP_cast5_ofb()
358 CAST encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
361 =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()
363 RC5 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key length
364 cipher with an additional "number of rounds" parameter. By default the key length is set to 128
367 =item EVP_aes_128_gcm(), EVP_aes_192_gcm(), EVP_aes_256_gcm()
369 AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys respectively.
370 These ciphers require additional control operations to function correctly: see
371 L<GCM mode> section below for details.
373 =item EVP_aes_128_ccm(), EVP_aes_192_ccm(), EVP_aes_256_ccm()
375 AES Counter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys respectively.
376 These ciphers require additional control operations to function correctly: see
377 CCM mode section below for details.
383 For GCM mode ciphers the behaviour of the EVP interface is subtly altered and
384 several GCM specific ctrl operations are supported.
386 To specify any additional authenticated data (AAD) a call to EVP_CipherUpdate(),
387 EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output
388 parameter B<out> set to B<NULL>.
390 When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal()
391 indicates if the operation was successful. If it does not indicate success
392 the authentication operation has failed and any output data B<MUST NOT>
393 be used as it is corrupted.
395 The following ctrls are supported in GCM mode:
397 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, ivlen, NULL);
399 Sets the GCM IV length: this call can only be made before specifying an IV. If
400 not called a default IV length is used (96 bits for AES).
402 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, taglen, tag);
404 Writes B<taglen> bytes of the tag value to the buffer indicated by B<tag>.
405 This call can only be made when encrypting data and B<after> all data has been
406 processed (e.g. after an EVP_EncryptFinal() call).
408 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, taglen, tag);
410 Sets the expected tag to B<taglen> bytes from B<tag>. This call is only legal
411 when decrypting data and must be made B<before> any data is processed (e.g.
412 before any EVP_DecryptUpdate() call).
414 See L<EXAMPLES> below for an example of the use of GCM mode.
418 The behaviour of CCM mode ciphers is similar to CCM mode but with a few
419 additional requirements and different ctrl values.
421 Like GCM mode any additional authenticated data (AAD) is passed by calling
422 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output
423 parameter B<out> set to B<NULL>. Additionally the total plaintext or ciphertext
424 length B<MUST> be passed to EVP_CipherUpdate(), EVP_EncryptUpdate() or
425 EVP_DecryptUpdate() with the output and input parameters (B<in> and B<out>)
426 set to B<NULL> and the length passed in the B<inl> parameter.
428 The following ctrls are supported in CCM mode:
430 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_TAG, taglen, tag);
432 This call is made to set the expected B<CCM> tag value when decrypting or
433 the length of the tag (with the B<tag> parameter set to NULL) when encrypting.
434 The tag length is often referred to as B<M>. If not set a default value is
437 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL);
439 Sets the CCM B<L> value. If not set a default is used (8 for AES).
441 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_IVLEN, ivlen, NULL);
443 Sets the CCM nonce (IV) length: this call can only be made before specifying
444 an nonce value. The nonce length is given by B<15 - L> so it is 7 by default
451 Where possible the B<EVP> interface to symmetric ciphers should be used in
452 preference to the low level interfaces. This is because the code then becomes
453 transparent to the cipher used and much more flexible. Additionally, the
454 B<EVP> interface will ensure the use of platform specific cryptographic
455 acceleration such as AES-NI (the low level interfaces do not provide the
458 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
459 length of the encrypted data a multiple of the block size. Padding is always
460 added so if the data is already a multiple of the block size B<n> will equal
461 the block size. For example if the block size is 8 and 11 bytes are to be
462 encrypted then 5 padding bytes of value 5 will be added.
464 When decrypting the final block is checked to see if it has the correct form.
466 Although the decryption operation can produce an error if padding is enabled,
467 it is not a strong test that the input data or key is correct. A random block
468 has better than 1 in 256 chance of being of the correct format and problems with
469 the input data earlier on will not produce a final decrypt error.
471 If padding is disabled then the decryption operation will always succeed if
472 the total amount of data decrypted is a multiple of the block size.
474 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
475 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained for
476 compatibility with existing code. New code should use EVP_EncryptInit_ex(),
477 EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(),
478 EVP_CipherInit_ex() and EVP_CipherFinal_ex() because they can reuse an
479 existing context without allocating and freeing it up on each call.
483 For RC5 the number of rounds can currently only be set to 8, 12 or 16. This is
484 a limitation of the current RC5 code rather than the EVP interface.
486 EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with
487 default key lengths. If custom ciphers exceed these values the results are
488 unpredictable. This is because it has become standard practice to define a
489 generic key as a fixed unsigned char array containing EVP_MAX_KEY_LENGTH bytes.
491 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
492 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
496 Encrypt a string using IDEA:
498 int do_crypt(char *outfile)
500 unsigned char outbuf[1024];
502 /* Bogus key and IV: we'd normally set these from
505 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
506 unsigned char iv[] = {1,2,3,4,5,6,7,8};
507 char intext[] = "Some Crypto Text";
511 EVP_CIPHER_CTX_init(&ctx);
512 EVP_EncryptInit_ex(&ctx, EVP_idea_cbc(), NULL, key, iv);
514 if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
519 /* Buffer passed to EVP_EncryptFinal() must be after data just
520 * encrypted to avoid overwriting it.
522 if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen))
528 EVP_CIPHER_CTX_cleanup(&ctx);
529 /* Need binary mode for fopen because encrypted data is
530 * binary data. Also cannot use strlen() on it because
531 * it wont be null terminated and may contain embedded
534 out = fopen(outfile, "wb");
535 fwrite(outbuf, 1, outlen, out);
540 The ciphertext from the above example can be decrypted using the B<openssl>
541 utility with the command line (shown on two lines for clarity):
543 openssl idea -d <filename
544 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
546 General encryption and decryption function example using FILE I/O and AES128
549 int do_crypt(FILE *in, FILE *out, int do_encrypt)
551 /* Allow enough space in output buffer for additional block */
552 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
555 /* Bogus key and IV: we'd normally set these from
558 unsigned char key[] = "0123456789abcdeF";
559 unsigned char iv[] = "1234567887654321";
561 /* Don't set key or IV right away; we want to check lengths */
562 EVP_CIPHER_CTX_init(&ctx);
563 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
565 OPENSSL_assert(EVP_CIPHER_CTX_key_length(&ctx) == 16);
566 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(&ctx) == 16);
568 /* Now we can set key and IV */
569 EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
573 inlen = fread(inbuf, 1, 1024, in);
574 if(inlen <= 0) break;
575 if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
578 EVP_CIPHER_CTX_cleanup(&ctx);
581 fwrite(outbuf, 1, outlen, out);
583 if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
586 EVP_CIPHER_CTX_cleanup(&ctx);
589 fwrite(outbuf, 1, outlen, out);
591 EVP_CIPHER_CTX_cleanup(&ctx);
602 EVP_CIPHER_CTX_init(), EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(),
603 EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex(),
604 EVP_CipherFinal_ex() and EVP_CIPHER_CTX_set_padding() appeared in
607 IDEA appeared in OpenSSL 0.9.7 but was often disabled due to
608 patent concerns; the last patents expired in 2012.