1EVP_EncryptInit(3) OpenSSL EVP_EncryptInit(3)
2
6 EVP_CIPHER_CTX_init, EVP_EncryptInit_ex, EVP_EncryptUpdate,
7 EVP_EncryptFinal_ex, EVP_DecryptInit_ex, EVP_DecryptUpdate,
8 EVP_DecryptFinal_ex, EVP_CipherInit_ex, EVP_CipherUpdate,
9 EVP_CipherFinal_ex, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl,
10 EVP_CIPHER_CTX_cleanup, EVP_EncryptInit, EVP_EncryptFinal,
11 EVP_DecryptInit, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherFinal,
12 EVP_get_cipherbyname, EVP_get_cipherbynid, EVP_get_cipherbyobj,
13 EVP_CIPHER_nid, EVP_CIPHER_block_size, EVP_CIPHER_key_length,
14 EVP_CIPHER_iv_length, EVP_CIPHER_flags, EVP_CIPHER_mode,
15 EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid,
16 EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length,
17 EVP_CIPHER_CTX_iv_length, EVP_CIPHER_CTX_get_app_data,
18 EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type, EVP_CIPHER_CTX_flags,
19 EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1,
20 EVP_CIPHER_asn1_to_param, EVP_CIPHER_CTX_set_padding, EVP_enc_null,
21 EVP_des_cbc, EVP_des_ecb, EVP_des_cfb, EVP_des_ofb, EVP_des_ede_cbc,
22 EVP_des_ede, EVP_des_ede_ofb, EVP_des_ede_cfb, EVP_des_ede3_cbc,
23 EVP_des_ede3, EVP_des_ede3_ofb, EVP_des_ede3_cfb, EVP_desx_cbc,
24 EVP_rc4, EVP_rc4_40, EVP_idea_cbc, EVP_idea_ecb, EVP_idea_cfb,
25 EVP_idea_ofb, EVP_idea_cbc, EVP_rc2_cbc, EVP_rc2_ecb, EVP_rc2_cfb,
26 EVP_rc2_ofb, EVP_rc2_40_cbc, EVP_rc2_64_cbc, EVP_bf_cbc, EVP_bf_ecb,
27 EVP_bf_cfb, EVP_bf_ofb, EVP_cast5_cbc, EVP_cast5_ecb, EVP_cast5_cfb,
28 EVP_cast5_ofb, EVP_rc5_32_12_16_cbc, EVP_rc5_32_12_16_ecb,
29 EVP_rc5_32_12_16_cfb, EVP_rc5_32_12_16_ofb, EVP_aes_128_gcm,
30 EVP_aes_192_gcm, EVP_aes_256_gcm, EVP_aes_128_ccm, EVP_aes_192_ccm,
31 EVP_aes_256_ccm - EVP cipher routines
32
34 #include <openssl/evp.h>
35 void EVP_CIPHER_CTX_init(EVP_CIPHER_CTX *a);
37 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
39 ENGINE *impl, unsigned char *key, unsigned char *iv);
40 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
41 int *outl, unsigned char *in, int inl);
42 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out,
43 int *outl);
44 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
46 ENGINE *impl, unsigned char *key, unsigned char *iv);
47 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
48 int *outl, unsigned char *in, int inl);
49 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
50 int *outl);
51 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
53 ENGINE *impl, unsigned char *key, unsigned char *iv, int enc);
54 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
55 int *outl, unsigned char *in, int inl);
56 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm,
57 int *outl);
58 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
60 unsigned char *key, unsigned char *iv);
61 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
62 int *outl);
63 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
65 unsigned char *key, unsigned char *iv);
66 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
67 int *outl);
68 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
70 unsigned char *key, unsigned char *iv, int enc);
71 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
72 int *outl);
73 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding);
75 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
76 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
77 int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
78 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
80 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
81 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
82 #define EVP_CIPHER_nid(e) ((e)->nid)
84 #define EVP_CIPHER_block_size(e) ((e)->block_size)
85 #define EVP_CIPHER_key_length(e) ((e)->key_len)
86 #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
87 #define EVP_CIPHER_flags(e) ((e)->flags)
88 #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
89 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
90 #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
92 #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
93 #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
94 #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
95 #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
96 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
97 #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
98 #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
99 #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
100 #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
101 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
103 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
104 const EVP_CIPHER *EVP_des_ede3(void);
106 const EVP_CIPHER *EVP_des_ede3_ecb(void);
107 const EVP_CIPHER *EVP_des_ede3_cfb64(void);
108 const EVP_CIPHER *EVP_des_ede3_cfb1(void);
109 const EVP_CIPHER *EVP_des_ede3_cfb8(void);
110 const EVP_CIPHER *EVP_des_ede3_ofb(void);
111 const EVP_CIPHER *EVP_des_ede3_cbc(void);
112 const EVP_CIPHER *EVP_aes_128_ecb(void);
113 const EVP_CIPHER *EVP_aes_128_cbc(void);
114 const EVP_CIPHER *EVP_aes_128_cfb1(void);
115 const EVP_CIPHER *EVP_aes_128_cfb8(void);
116 const EVP_CIPHER *EVP_aes_128_cfb128(void);
117 const EVP_CIPHER *EVP_aes_128_ofb(void);
118 const EVP_CIPHER *EVP_aes_192_ecb(void);
119 const EVP_CIPHER *EVP_aes_192_cbc(void);
120 const EVP_CIPHER *EVP_aes_192_cfb1(void);
121 const EVP_CIPHER *EVP_aes_192_cfb8(void);
122 const EVP_CIPHER *EVP_aes_192_cfb128(void);
123 const EVP_CIPHER *EVP_aes_192_ofb(void);
124 const EVP_CIPHER *EVP_aes_256_ecb(void);
125 const EVP_CIPHER *EVP_aes_256_cbc(void);
126 const EVP_CIPHER *EVP_aes_256_cfb1(void);
127 const EVP_CIPHER *EVP_aes_256_cfb8(void);
128 const EVP_CIPHER *EVP_aes_256_cfb128(void);
129 const EVP_CIPHER *EVP_aes_256_ofb(void);
130
132 The EVP cipher routines are a high level interface to certain symmetric
133 ciphers.
134 EVP_CIPHER_CTX_init() initializes cipher contex ctx.
136 EVP_EncryptInit_ex() sets up cipher context ctx for encryption with
138 cipher type from ENGINE impl. ctx must be initialized before calling
139 this function. type is normally supplied by a function such as
140 EVP_aes_256_cbc(). If impl is NULL then the default implementation is
141 used. key is the symmetric key to use and iv is the IV to use (if
142 necessary), the actual number of bytes used for the key and IV depends
143 on the cipher. It is possible to set all parameters to NULL except type
144 in an initial call and supply the remaining parameters in subsequent
145 calls, all of which have type set to NULL. This is done when the
146 default cipher parameters are not appropriate.
147 EVP_EncryptUpdate() encrypts inl bytes from the buffer in and writes
149 the encrypted version to out. This function can be called multiple
150 times to encrypt successive blocks of data. The amount of data written
151 depends on the block alignment of the encrypted data: as a result the
152 amount of data written may be anything from zero bytes to (inl +
153 cipher_block_size - 1) so out should contain sufficient room. The
154 actual number of bytes written is placed in outl.
155 If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts
157 the "final" data, that is any data that remains in a partial block. It
158 uses standard block padding (aka PKCS padding). The encrypted final
159 data is written to out which should have sufficient space for one
160 cipher block. The number of bytes written is placed in outl. After this
161 function is called the encryption operation is finished and no further
162 calls to EVP_EncryptUpdate() should be made.
163 If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any
165 more data and it will return an error if any data remains in a partial
166 block: that is if the total data length is not a multiple of the block
167 size.
168 EVP_DecryptInit_ex(), EVP_DecryptUpdate() and EVP_DecryptFinal_ex() are
170 the corresponding decryption operations. EVP_DecryptFinal() will return
171 an error code if padding is enabled and the final block is not
172 correctly formatted. The parameters and restrictions are identical to
173 the encryption operations except that if padding is enabled the
174 decrypted data buffer out passed to EVP_DecryptUpdate() should have
175 sufficient room for (inl + cipher_block_size) bytes unless the cipher
176 block size is 1 in which case inl bytes is sufficient.
177 EVP_CipherInit_ex(), EVP_CipherUpdate() and EVP_CipherFinal_ex() are
179 functions that can be used for decryption or encryption. The operation
180 performed depends on the value of the enc parameter. It should be set
181 to 1 for encryption, 0 for decryption and -1 to leave the value
182 unchanged (the actual value of 'enc' being supplied in a previous
183 call).
184 EVP_CIPHER_CTX_cleanup() clears all information from a cipher context
186 and free up any allocated memory associate with it. It should be called
187 after all operations using a cipher are complete so sensitive
188 information does not remain in memory.
189 EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() behave in a
191 similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex and
192 EVP_CipherInit_ex() except the ctx parameter does not need to be
193 initialized and they always use the default cipher implementation.
194 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 the
198 ctx, but this is no longer done and EVP_CIPHER_CTX_clean() must be
199 called to free any context resources.
200 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.
204 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher
206 when passed an EVP_CIPHER or EVP_CIPHER_CTX structure. The actual NID
207 value is an internal value which may not have a corresponding OBJECT
208 IDENTIFIER.
209 EVP_CIPHER_CTX_set_padding() enables or disables padding. By default
211 encryption operations are padded using standard block padding and the
212 padding is checked and removed when decrypting. If the pad parameter is
213 zero then no padding is performed, the total amount of data encrypted
214 or decrypted must then be a multiple of the block size or an error will
215 occur.
216 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
218 length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
219 structure. The constant EVP_MAX_KEY_LENGTH is the maximum key length
220 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
221 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
222 for variable key length ciphers.
223 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
225 If the cipher is a fixed length cipher then attempting to set the key
226 length to any value other than the fixed value is an error.
227 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
229 length of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX. It
230 will return zero if the cipher does not use an IV. The constant
231 EVP_MAX_IV_LENGTH is the maximum IV length for all ciphers.
232 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the
234 block size of a cipher when passed an EVP_CIPHER or EVP_CIPHER_CTX
235 structure. The constant EVP_MAX_IV_LENGTH is also the maximum block
236 length for all ciphers.
237 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the
239 passed cipher or context. This "type" is the actual NID of the cipher
240 OBJECT IDENTIFIER as such it ignores the cipher parameters and 40 bit
241 RC2 and 128 bit RC2 have the same NID. If the cipher does not have an
242 object identifier or does not have ASN1 support this function will
243 return NID_undef.
244 EVP_CIPHER_CTX_cipher() returns the EVP_CIPHER structure when passed an
246 EVP_CIPHER_CTX structure.
247 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher
249 mode: EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or
250 EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then
251 EVP_CIPH_STREAM_CIPHER is returned.
252 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter"
254 based on the passed cipher. This will typically include any parameters
255 and an IV. The cipher IV (if any) must be set when this call is made.
256 This call should be made before the cipher is actually "used" (before
257 any EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This
258 function may fail if the cipher does not have any ASN1 support.
259 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
261 AlgorithmIdentifier "parameter". The precise effect depends on the
262 cipher In the case of RC2, for example, it will set the IV and
263 effective key length. This function should be called after the base
264 cipher type is set but before the key is set. For example
265 EVP_CipherInit() will be called with the IV and key set to NULL,
266 EVP_CIPHER_asn1_to_param() will be called and finally EVP_CipherInit()
267 again with all parameters except the key set to NULL. It is possible
268 for this function to fail if the cipher does not have any ASN1 support
269 or the parameters cannot be set (for example the RC2 effective key
270 length is not supported.
271 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be
273 determined and set.
274
276 EVP_EncryptInit_ex(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex()
277 return 1 for success and 0 for failure.
278 EVP_DecryptInit_ex() and EVP_DecryptUpdate() return 1 for success and 0
280 for failure. EVP_DecryptFinal_ex() returns 0 if the decrypt failed or
281 1 for success.
282 EVP_CipherInit_ex() and EVP_CipherUpdate() return 1 for success and 0
284 for failure. EVP_CipherFinal_ex() returns 0 for a decryption failure
285 or 1 for success.
286 EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure.
288 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
290 return an EVP_CIPHER structure or NULL on error.
291 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
293 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the
295 block size.
296 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
298 length.
299 EVP_CIPHER_CTX_set_padding() always returns 1.
301 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
303 length or zero if the cipher does not use an IV.
304 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the
306 cipher's OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT
307 IDENTIFIER.
308 EVP_CIPHER_CTX_cipher() returns an EVP_CIPHER structure.
310 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for
312 success or zero for failure.
313
315 All algorithms have a fixed key length unless otherwise stated.
316 EVP_enc_null()
318 Null cipher: does nothing.
319 EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void),
321 EVP_des_ofb(void)
322 DES in CBC, ECB, CFB and OFB modes respectively.
323 EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void),
325 EVP_des_ede_cfb(void)
326 Two key triple DES in CBC, ECB, CFB and OFB modes respectively.
327 EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void),
329 EVP_des_ede3_cfb(void)
330 Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
331 EVP_desx_cbc(void)
333 DESX algorithm in CBC mode.
334 EVP_aes_128_cbc(void), EVP_aes_128_ecb(), EVP_aes_128_ofb(void),
336 EVP_aes_128_cfb1(void), EVP_aes_128_cfb8(void),
337 EVP_aes_128_cfb128(void)
338 AES with 128 bit key length in CBC, ECB, OFB and CFB modes
339 respectively.
340 EVP_aes_192_cbc(void), EVP_aes_192_ecb(), EVP_aes_192_ofb(void),
342 EVP_aes_192_cfb1(void), EVP_aes_192_cfb8(void),
343 EVP_aes_192_cfb128(void)
344 AES with 192 bit key length in CBC, ECB, OFB and CFB modes
345 respectively.
346 EVP_aes_256_cbc(void), EVP_aes_256_ecb(), EVP_aes_256_ofb(void),
348 EVP_aes_256_cfb1(void), EVP_aes_256_cfb8(void),
349 EVP_aes_256_cfb128(void)
350 AES with 256 bit key length in CBC, ECB, OFB and CFB modes
351 respectively.
352 EVP_rc4(void)
354 RC4 stream cipher. This is a variable key length cipher with
355 default key length 128 bits.
356 EVP_rc4_40(void)
358 RC4 stream cipher with 40 bit key length. This is obsolete and new
359 code should use EVP_rc4() and the EVP_CIPHER_CTX_set_key_length()
360 function.
361 EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void),
363 EVP_idea_ofb(void), EVP_idea_cbc(void)
364 IDEA encryption algorithm in CBC, ECB, CFB and OFB modes
365 respectively.
366 EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void),
368 EVP_rc2_ofb(void)
369 RC2 encryption algorithm in CBC, ECB, CFB and OFB modes
370 respectively. This is a variable key length cipher with an
371 additional parameter called "effective key bits" or "effective key
372 length". By default both are set to 128 bits.
373 EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)
375 RC2 algorithm in CBC mode with a default key length and effective
376 key length of 40 and 64 bits. These are obsolete and new code
377 should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and
378 EVP_CIPHER_CTX_ctrl() to set the key length and effective key
379 length.
380 EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);
382 Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes
383 respectively. This is a variable key length cipher.
384 EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void),
386 EVP_cast5_ofb(void)
387 CAST encryption algorithm in CBC, ECB, CFB and OFB modes
388 respectively. This is a variable key length cipher.
389 EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void),
391 EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)
392 RC5 encryption algorithm in CBC, ECB, CFB and OFB modes
393 respectively. This is a variable key length cipher with an
394 additional "number of rounds" parameter. By default the key length
395 is set to 128 bits and 12 rounds.
396 EVP_aes_128_gcm(void), EVP_aes_192_gcm(void), EVP_aes_256_gcm(void)
398 AES Galois Counter Mode (GCM) for 128, 192 and 256 bit keys
399 respectively. These ciphers require additional control operations
400 to function correctly: see "GCM mode" section below for details.
401 EVP_aes_128_ccm(void), EVP_aes_192_ccm(void), EVP_aes_256_ccm(void)
403 AES Counter with CBC-MAC Mode (CCM) for 128, 192 and 256 bit keys
404 respectively. These ciphers require additional control operations
405 to function correctly: see CCM mode section below for details.
406
408 For GCM mode ciphers the behaviour of the EVP interface is subtly
409 altered and several GCM specific ctrl operations are supported.
410 To specify any additional authenticated data (AAD) a call to
412 EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should
413 be made with the output parameter out set to NULL.
414 When decrypting the return value of EVP_DecryptFinal() or
416 EVP_CipherFinal() indicates if the operation was successful. If it does
417 not indicate success the authentication operation has failed and any
418 output data MUST NOT be used as it is corrupted.
419 The following ctrls are supported in GCM mode:
421 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_IVLEN, ivlen, NULL);
423 Sets the GCM IV length: this call can only be made before specifying an
425 IV. If not called a default IV length is used (96 bits for AES).
426 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_GET_TAG, taglen, tag);
428 Writes taglen bytes of the tag value to the buffer indicated by tag.
430 This call can only be made when encrypting data and after all data has
431 been processed (e.g. after an EVP_EncryptFinal() call).
432 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GCM_SET_TAG, taglen, tag);
434 Sets the expected tag to taglen bytes from tag. This call is only legal
436 when decrypting data and must be made before any data is processed
437 (e.g. before any EVP_DecryptUpdate() call).
438 See EXAMPLES below for an example of the use of GCM mode.
440
442 The behaviour of CCM mode ciphers is similar to CCM mode but with a few
443 additional requirements and different ctrl values.
444 Like GCM mode any additional authenticated data (AAD) is passed by
446 calling EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate()
447 with the output parameter out set to NULL. Additionally the total
448 plaintext or ciphertext length MUST be passed to EVP_CipherUpdate(),
449 EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output and input
450 parameters (in and out) set to NULL and the length passed in the inl
451 parameter.
452 The following ctrls are supported in CCM mode:
454 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_TAG, taglen, tag);
456 This call is made to set the expected CCM tag value when decrypting or
458 the length of the tag (with the tag parameter set to NULL) when
459 encrypting. The tag length is often referred to as M. If not set a
460 default value is used (12 for AES).
461 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL);
463 Sets the CCM L value. If not set a default is used (8 for AES).
465 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_IVLEN, ivlen, NULL);
467 Sets the CCM nonce (IV) length: this call can only be made before
469 specifying an nonce value. The nonce length is given by 15 - L so it is
470 7 by default for AES.
471
473 Where possible the EVP interface to symmetric ciphers should be used in
474 preference to the low level interfaces. This is because the code then
475 becomes transparent to the cipher used and much more flexible.
476 Additionally, the EVP interface will ensure the use of platform
477 specific cryptographic acceleration such as AES-NI (the low level
478 interfaces do not provide the guarantee).
479 PKCS padding works by adding n padding bytes of value n to make the
481 total length of the encrypted data a multiple of the block size.
482 Padding is always added so if the data is already a multiple of the
483 block size n will equal the block size. For example if the block size
484 is 8 and 11 bytes are to be encrypted then 5 padding bytes of value 5
485 will be added.
486 When decrypting the final block is checked to see if it has the correct
488 form.
489 Although the decryption operation can produce an error if padding is
491 enabled, it is not a strong test that the input data or key is correct.
492 A random block has better than 1 in 256 chance of being of the correct
493 format and problems with the input data earlier on will not produce a
494 final decrypt error.
495 If padding is disabled then the decryption operation will always
497 succeed if the total amount of data decrypted is a multiple of the
498 block size.
499 The functions EVP_EncryptInit(), EVP_EncryptFinal(), EVP_DecryptInit(),
501 EVP_CipherInit() and EVP_CipherFinal() are obsolete but are retained
502 for compatibility with existing code. New code should use
503 EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex(),
504 EVP_DecryptFinal_ex(), EVP_CipherInit_ex() and EVP_CipherFinal_ex()
505 because they can reuse an existing context without allocating and
506 freeing it up on each call.
507
509 For RC5 the number of rounds can currently only be set to 8, 12 or 16.
510 This is a limitation of the current RC5 code rather than the EVP
511 interface.
512 EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal
514 ciphers with default key lengths. If custom ciphers exceed these values
515 the results are unpredictable. This is because it has become standard
516 practice to define a generic key as a fixed unsigned char array
517 containing EVP_MAX_KEY_LENGTH bytes.
518 The ASN1 code is incomplete (and sometimes inaccurate) it has only been
520 tested for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC
521 mode.
522
524 Encrypt a string using IDEA:
525 int do_crypt(char *outfile)
527 {
528 unsigned char outbuf[1024];
529 int outlen, tmplen;
530 /* Bogus key and IV: we'd normally set these from
531 * another source.
532 */
533 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
534 unsigned char iv[] = {1,2,3,4,5,6,7,8};
535 char intext[] = "Some Crypto Text";
536 EVP_CIPHER_CTX ctx;
537 FILE *out;
538 EVP_CIPHER_CTX_init(&ctx);
540 EVP_EncryptInit_ex(&ctx, EVP_idea_cbc(), NULL, key, iv);
541 if(!EVP_EncryptUpdate(&ctx, outbuf, &outlen, intext, strlen(intext)))
543 {
544 /* Error */
545 return 0;
546 }
547 /* Buffer passed to EVP_EncryptFinal() must be after data just
548 * encrypted to avoid overwriting it.
549 */
550 if(!EVP_EncryptFinal_ex(&ctx, outbuf + outlen, &tmplen))
551 {
552 /* Error */
553 return 0;
554 }
555 outlen += tmplen;
556 EVP_CIPHER_CTX_cleanup(&ctx);
557 /* Need binary mode for fopen because encrypted data is
558 * binary data. Also cannot use strlen() on it because
559 * it wont be null terminated and may contain embedded
560 * nulls.
561 */
562 out = fopen(outfile, "wb");
563 fwrite(outbuf, 1, outlen, out);
564 fclose(out);
565 return 1;
566 }
567 The ciphertext from the above example can be decrypted using the
569 openssl utility with the command line (shown on two lines for clarity):
570 openssl idea -d <filename
572 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708
573 General encryption and decryption function example using FILE I/O and
575 AES128 with a 128-bit key:
576 int do_crypt(FILE *in, FILE *out, int do_encrypt)
578 {
579 /* Allow enough space in output buffer for additional block */
580 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH];
581 int inlen, outlen;
582 EVP_CIPHER_CTX ctx;
583 /* Bogus key and IV: we'd normally set these from
584 * another source.
585 */
586 unsigned char key[] = "0123456789abcdeF";
587 unsigned char iv[] = "1234567887654321";
588 /* Don't set key or IV right away; we want to check lengths */
590 EVP_CIPHER_CTX_init(&ctx);
591 EVP_CipherInit_ex(&ctx, EVP_aes_128_cbc(), NULL, NULL, NULL,
592 do_encrypt);
593 OPENSSL_assert(EVP_CIPHER_CTX_key_length(&ctx) == 16);
594 OPENSSL_assert(EVP_CIPHER_CTX_iv_length(&ctx) == 16);
595 /* Now we can set key and IV */
597 EVP_CipherInit_ex(&ctx, NULL, NULL, key, iv, do_encrypt);
598 for(;;)
600 {
601 inlen = fread(inbuf, 1, 1024, in);
602 if(inlen <= 0) break;
603 if(!EVP_CipherUpdate(&ctx, outbuf, &outlen, inbuf, inlen))
604 {
605 /* Error */
606 EVP_CIPHER_CTX_cleanup(&ctx);
607 return 0;
608 }
609 fwrite(outbuf, 1, outlen, out);
610 }
611 if(!EVP_CipherFinal_ex(&ctx, outbuf, &outlen))
612 {
613 /* Error */
614 EVP_CIPHER_CTX_cleanup(&ctx);
615 return 0;
616 }
617 fwrite(outbuf, 1, outlen, out);
618 EVP_CIPHER_CTX_cleanup(&ctx);
620 return 1;
621 }
622
624 evp(3)
625
627 EVP_CIPHER_CTX_init(), EVP_EncryptInit_ex(), EVP_EncryptFinal_ex(),
628 EVP_DecryptInit_ex(), EVP_DecryptFinal_ex(), EVP_CipherInit_ex(),
629 EVP_CipherFinal_ex() and EVP_CIPHER_CTX_set_padding() appeared in
630 OpenSSL 0.9.7.
631 IDEA appeared in OpenSSL 0.9.7 but was often disabled due to patent
633 concerns; the last patents expired in 2012.
6341.0.2k 2019-03-12 EVP_EncryptInit(3)