5 EVP_EncryptInit, EVP_EncryptUpdate, EVP_EncryptFinal, EVP_DecryptInit,
6 EVP_DecryptUpdate, EVP_DecryptFinal, EVP_CipherInit, EVP_CipherUpdate,
7 EVP_CipherFinal, EVP_CIPHER_CTX_set_key_length, EVP_CIPHER_CTX_ctrl,
8 EVP_CIPHER_CTX_cleanup, EVP_get_cipherbyname, EVP_get_cipherbynid,
9 EVP_get_cipherbyobj, EVP_CIPHER_nid, EVP_CIPHER_block_size,
10 EVP_CIPHER_key_length, EVP_CIPHER_iv_length, EVP_CIPHER_flags,
11 EVP_CIPHER_mode, EVP_CIPHER_type, EVP_CIPHER_CTX_cipher, EVP_CIPHER_CTX_nid,
12 EVP_CIPHER_CTX_block_size, EVP_CIPHER_CTX_key_length, EVP_CIPHER_CTX_iv_length,
13 EVP_CIPHER_CTX_get_app_data, EVP_CIPHER_CTX_set_app_data, EVP_CIPHER_CTX_type,
14 EVP_CIPHER_CTX_flags, EVP_CIPHER_CTX_mode, EVP_CIPHER_param_to_asn1,
15 EVP_CIPHER_asn1_to_param - EVP cipher routines
19 #include <openssl/evp.h>
21 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
22 unsigned char *key, unsigned char *iv);
23 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
24 int *outl, unsigned char *in, int inl);
25 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out,
28 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
29 unsigned char *key, unsigned char *iv);
30 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
31 int *outl, unsigned char *in, int inl);
32 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
35 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type,
36 unsigned char *key, unsigned char *iv, int enc);
37 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out,
38 int *outl, unsigned char *in, int inl);
39 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm,
42 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen);
43 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int type, int arg, void *ptr);
44 int EVP_CIPHER_CTX_cleanup(EVP_CIPHER_CTX *a);
46 const EVP_CIPHER *EVP_get_cipherbyname(const char *name);
47 #define EVP_get_cipherbynid(a) EVP_get_cipherbyname(OBJ_nid2sn(a))
48 #define EVP_get_cipherbyobj(a) EVP_get_cipherbynid(OBJ_obj2nid(a))
50 #define EVP_CIPHER_nid(e) ((e)->nid)
51 #define EVP_CIPHER_block_size(e) ((e)->block_size)
52 #define EVP_CIPHER_key_length(e) ((e)->key_len)
53 #define EVP_CIPHER_iv_length(e) ((e)->iv_len)
54 #define EVP_CIPHER_flags(e) ((e)->flags)
55 #define EVP_CIPHER_mode(e) ((e)->flags) & EVP_CIPH_MODE)
56 int EVP_CIPHER_type(const EVP_CIPHER *ctx);
58 #define EVP_CIPHER_CTX_cipher(e) ((e)->cipher)
59 #define EVP_CIPHER_CTX_nid(e) ((e)->cipher->nid)
60 #define EVP_CIPHER_CTX_block_size(e) ((e)->cipher->block_size)
61 #define EVP_CIPHER_CTX_key_length(e) ((e)->key_len)
62 #define EVP_CIPHER_CTX_iv_length(e) ((e)->cipher->iv_len)
63 #define EVP_CIPHER_CTX_get_app_data(e) ((e)->app_data)
64 #define EVP_CIPHER_CTX_set_app_data(e,d) ((e)->app_data=(char *)(d))
65 #define EVP_CIPHER_CTX_type(c) EVP_CIPHER_type(EVP_CIPHER_CTX_cipher(c))
66 #define EVP_CIPHER_CTX_flags(e) ((e)->cipher->flags)
67 #define EVP_CIPHER_CTX_mode(e) ((e)->cipher->flags & EVP_CIPH_MODE)
69 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
70 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type);
74 The EVP cipher routines are a high level interface to certain
77 EVP_EncryptInit() initializes a cipher context B<ctx> for encryption
78 with cipher B<type>. B<type> is normally supplied by a function such
79 as EVP_des_cbc() . B<key> is the symmetric key to use and B<iv> is the
80 IV to use (if necessary), the actual number of bytes used for the
81 key and IV depends on the cipher. It is possible to set all parameters
82 to NULL except B<type> in an initial call and supply the remaining
83 parameters in subsequent calls, all of which have B<type> set to NULL.
84 This is done when the default cipher parameters are not appropriate.
86 EVP_EncryptUpdate() encrypts B<inl> bytes from the buffer B<in> and
87 writes the encrypted version to B<out>. This function can be called
88 multiple times to encrypt successive blocks of data. The amount
89 of data written depends on the block alignment of the encrypted data:
90 as a result the amount of data written may be anything from zero bytes
91 to (inl + cipher_block_size - 1) so B<outl> should contain sufficient
92 room. The actual number of bytes written is placed in B<outl>.
94 EVP_EncryptFinal() encrypts the "final" data, that is any data that
95 remains in a partial block. It uses L<standard block padding|/NOTES> (aka PKCS
96 padding). The encrypted final data is written to B<out> which should
97 have sufficient space for one cipher block. The number of bytes written
98 is placed in B<outl>. After this function is called the encryption operation
99 is finished and no further calls to EVP_EncryptUpdate() should be made.
101 EVP_DecryptInit(), EVP_DecryptUpdate() and EVP_DecryptFinal() are the
102 corresponding decryption operations. EVP_DecryptFinal() will return an
103 error code if the final block is not correctly formatted. The parameters
104 and restrictions are identical to the encryption operations except that
105 the decrypted data buffer B<out> passed to EVP_DecryptUpdate() should
106 have sufficient room for (B<inl> + cipher_block_size) bytes unless the
107 cipher block size is 1 in which case B<inl> bytes is sufficient.
109 EVP_CipherInit(), EVP_CipherUpdate() and EVP_CipherFinal() are functions
110 that can be used for decryption or encryption. The operation performed
111 depends on the value of the B<enc> parameter. It should be set to 1 for
112 encryption, 0 for decryption and -1 to leave the value unchanged (the
113 actual value of 'enc' being supplied in a previous call).
115 EVP_CIPHER_CTX_cleanup() clears all information from a cipher context.
116 It should be called after all operations using a cipher are complete
117 so sensitive information does not remain in memory.
119 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
120 return an EVP_CIPHER structure when passed a cipher name, a NID or an
121 ASN1_OBJECT structure.
123 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return the NID of a cipher when
124 passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> structure. The actual NID
125 value is an internal value which may not have a corresponding OBJECT
128 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
129 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
130 structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum key length
131 for all ciphers. Note: although EVP_CIPHER_key_length() is fixed for a
132 given cipher, the value of EVP_CIPHER_CTX_key_length() may be different
133 for variable key length ciphers.
135 EVP_CIPHER_CTX_set_key_length() sets the key length of the cipher ctx.
136 If the cipher is a fixed length cipher then attempting to set the key
137 length to any value other than the fixed value is an error.
139 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
140 length of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>.
141 It will return zero if the cipher does not use an IV. The constant
142 B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers.
144 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
145 size of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX>
146 structure. The constant B<EVP_MAX_IV_LENGTH> is also the maximum block
147 length for all ciphers.
149 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the type of the passed
150 cipher or context. This "type" is the actual NID of the cipher OBJECT
151 IDENTIFIER as such it ignores the cipher parameters and 40 bit RC2 and
152 128 bit RC2 have the same NID. If the cipher does not have an object
153 identifier or does not have ASN1 support this function will return
156 EVP_CIPHER_CTX_cipher() returns the B<EVP_CIPHER> structure when passed
157 an B<EVP_CIPHER_CTX> structure.
159 EVP_CIPHER_mode() and EVP_CIPHER_CTX_mode() return the block cipher mode:
160 EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE or
161 EVP_CIPH_OFB_MODE. If the cipher is a stream cipher then
162 EVP_CIPH_STREAM_CIPHER is returned.
164 EVP_CIPHER_param_to_asn1() sets the AlgorithmIdentifier "parameter" based
165 on the passed cipher. This will typically include any parameters and an
166 IV. The cipher IV (if any) must be set when this call is made. This call
167 should be made before the cipher is actually "used" (before any
168 EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). This function
169 may fail if the cipher does not have any ASN1 support.
171 EVP_CIPHER_asn1_to_param() sets the cipher parameters based on an ASN1
172 AlgorithmIdentifier "parameter". The precise effect depends on the cipher
173 In the case of RC2, for example, it will set the IV and effective key length.
174 This function should be called after the base cipher type is set but before
175 the key is set. For example EVP_CipherInit() will be called with the IV and
176 key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally
177 EVP_CipherInit() again with all parameters except the key set to NULL. It is
178 possible for this function to fail if the cipher does not have any ASN1 support
179 or the parameters cannot be set (for example the RC2 effective key length
182 EVP_CIPHER_CTX_ctrl() allows various cipher specific parameters to be determined
183 and set. Currently only the RC2 effective key length and the number of rounds of
188 EVP_EncryptInit(), EVP_EncryptUpdate() and EVP_EncryptFinal() return 1 for success
191 EVP_DecryptInit() and EVP_DecryptUpdate() return 1 for success and 0 for failure.
192 EVP_DecryptFinal() returns 0 if the decrypt failed or 1 for success.
194 EVP_CipherInit() and EVP_CipherUpdate() return 1 for success and 0 for failure.
195 EVP_CipherFinal() returns 1 for a decryption failure or 1 for success.
197 EVP_CIPHER_CTX_cleanup() returns 1 for success and 0 for failure.
199 EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj()
200 return an B<EVP_CIPHER> structure or NULL on error.
202 EVP_CIPHER_nid() and EVP_CIPHER_CTX_nid() return a NID.
204 EVP_CIPHER_block_size() and EVP_CIPHER_CTX_block_size() return the block
207 EVP_CIPHER_key_length() and EVP_CIPHER_CTX_key_length() return the key
210 EVP_CIPHER_iv_length() and EVP_CIPHER_CTX_iv_length() return the IV
211 length or zero if the cipher does not use an IV.
213 EVP_CIPHER_type() and EVP_CIPHER_CTX_type() return the NID of the cipher's
214 OBJECT IDENTIFIER or NID_undef if it has no defined OBJECT IDENTIFIER.
216 EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure.
218 EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return 1 for
219 success or zero for failure.
221 =head1 CIPHER LISTING
223 All algorithms have a fixed key length unless otherwise stated.
229 Null cipher: does nothing.
231 =item EVP_des_cbc(void), EVP_des_ecb(void), EVP_des_cfb(void), EVP_des_ofb(void)
233 DES in CBC, ECB, CFB and OFB modes respectively.
235 =item EVP_des_ede_cbc(void), EVP_des_ede(), EVP_des_ede_ofb(void), EVP_des_ede_cfb(void)
237 Two key triple DES in CBC, ECB, CFB and OFB modes respectively.
239 =item EVP_des_ede3_cbc(void), EVP_des_ede3(), EVP_des_ede3_ofb(void), EVP_des_ede3_cfb(void)
241 Three key triple DES in CBC, ECB, CFB and OFB modes respectively.
243 =item EVP_desx_cbc(void)
245 DESX algorithm in CBC mode.
249 RC4 stream cipher. This is a variable key length cipher with default key length 128 bits.
251 =item EVP_rc4_40(void)
253 RC4 stream cipher with 40 bit key length. This is obsolete and new code should use EVP_rc4()
254 and the EVP_CIPHER_CTX_set_key_length() function.
256 =item EVP_idea_cbc() EVP_idea_ecb(void), EVP_idea_cfb(void), EVP_idea_ofb(void), EVP_idea_cbc(void)
258 IDEA encryption algorithm in CBC, ECB, CFB and OFB modes respectively.
260 =item EVP_rc2_cbc(void), EVP_rc2_ecb(void), EVP_rc2_cfb(void), EVP_rc2_ofb(void)
262 RC2 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
263 length cipher with an additional parameter called "effective key bits" or "effective key length".
264 By default both are set to 128 bits.
266 =item EVP_rc2_40_cbc(void), EVP_rc2_64_cbc(void)
268 RC2 algorithm in CBC mode with a default key length and effective key length of 40 and 64 bits.
269 These are obsolete and new code should use EVP_rc2_cbc(), EVP_CIPHER_CTX_set_key_length() and
270 EVP_CIPHER_CTX_ctrl() to set the key length and effective key length.
272 =item EVP_bf_cbc(void), EVP_bf_ecb(void), EVP_bf_cfb(void), EVP_bf_ofb(void);
274 Blowfish encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
277 =item EVP_cast5_cbc(void), EVP_cast5_ecb(void), EVP_cast5_cfb(void), EVP_cast5_ofb(void)
279 CAST encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key
282 =item EVP_rc5_32_12_16_cbc(void), EVP_rc5_32_12_16_ecb(void), EVP_rc5_32_12_16_cfb(void), EVP_rc5_32_12_16_ofb(void)
284 RC5 encryption algorithm in CBC, ECB, CFB and OFB modes respectively. This is a variable key length
285 cipher with an additional "number of rounds" parameter. By default the key length is set to 128
292 Where possible the B<EVP> interface to symmetric ciphers should be used in
293 preference to the low level interfaces. This is because the code then becomes
294 transparent to the cipher used and much more flexible.
296 PKCS padding works by adding B<n> padding bytes of value B<n> to make the total
297 length of the encrypted data a multiple of the block size. Padding is always
298 added so if the data is already a multiple of the block size B<n> will equal
299 the block size. For example if the block size is 8 and 11 bytes are to be
300 encrypted then 5 padding bytes of value 5 will be added.
302 When decrypting the final block is checked to see if it has the correct form.
304 Although the decryption operation can produce an error, it is not a strong
305 test that the input data or key is correct. A random block has better than
306 1 in 256 chance of being of the correct format and problems with the
307 input data earlier on will not produce a final decrypt error.
309 The functions EVP_EncryptInit(), EVP_EncryptUpdate(), EVP_EncryptFinal(),
310 EVP_DecryptInit(), EVP_DecryptUpdate(), EVP_CipherInit() and EVP_CipherUpdate()
311 and EVP_CIPHER_CTX_cleanup() did not return errors in OpenSSL version 0.9.5a or
312 earlier. Software only versions of encryption algorithms will never return
313 error codes for these functions, unless there is a programming error (for example
314 and attempt to set the key before the cipher is set in EVP_EncryptInit() ).
318 For RC5 the number of rounds can currently only be set to 8, 12 or 16. This is
319 a limitation of the current RC5 code rather than the EVP interface.
321 It should be possible to disable PKCS padding: currently it isn't.
323 EVP_MAX_KEY_LENGTH and EVP_MAX_IV_LENGTH only refer to the internal ciphers with
324 default key lengths. If custom ciphers exceed these values the results are
325 unpredictable. This is because it has become standard practice to define a
326 generic key as a fixed unsigned char array containing EVP_MAX_KEY_LENGTH bytes.
328 The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested
329 for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode.
333 Get the number of rounds used in RC5:
336 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC5_ROUNDS, 0, &i);
338 Get the RC2 effective key length:
341 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_GET_RC2_KEY_BITS, 0, &i);
343 Set the number of rounds used in RC5:
346 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC5_ROUNDS, i, NULL);
348 Set the number of rounds used in RC2:
351 EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_SET_RC2_KEY_BITS, i, NULL);