1=pod 2 3=head1 NAME 4 5EVP_CIPHER_fetch, 6EVP_CIPHER_up_ref, 7EVP_CIPHER_free, 8EVP_CIPHER_CTX_new, 9EVP_CIPHER_CTX_reset, 10EVP_CIPHER_CTX_free, 11EVP_EncryptInit_ex, 12EVP_EncryptInit_ex2, 13EVP_EncryptUpdate, 14EVP_EncryptFinal_ex, 15EVP_DecryptInit_ex, 16EVP_DecryptInit_ex2, 17EVP_DecryptUpdate, 18EVP_DecryptFinal_ex, 19EVP_CipherInit_ex, 20EVP_CipherInit_ex2, 21EVP_CipherUpdate, 22EVP_CipherFinal_ex, 23EVP_CIPHER_CTX_set_key_length, 24EVP_CIPHER_CTX_ctrl, 25EVP_EncryptInit, 26EVP_EncryptFinal, 27EVP_DecryptInit, 28EVP_DecryptFinal, 29EVP_CipherInit, 30EVP_CipherFinal, 31EVP_Cipher, 32EVP_get_cipherbyname, 33EVP_get_cipherbynid, 34EVP_get_cipherbyobj, 35EVP_CIPHER_is_a, 36EVP_CIPHER_get0_name, 37EVP_CIPHER_get0_description, 38EVP_CIPHER_names_do_all, 39EVP_CIPHER_get0_provider, 40EVP_CIPHER_get_nid, 41EVP_CIPHER_get_params, 42EVP_CIPHER_gettable_params, 43EVP_CIPHER_get_block_size, 44EVP_CIPHER_get_key_length, 45EVP_CIPHER_get_iv_length, 46EVP_CIPHER_get_flags, 47EVP_CIPHER_get_mode, 48EVP_CIPHER_get_type, 49EVP_CIPHER_CTX_cipher, 50EVP_CIPHER_CTX_get0_cipher, 51EVP_CIPHER_CTX_get1_cipher, 52EVP_CIPHER_CTX_get0_name, 53EVP_CIPHER_CTX_get_nid, 54EVP_CIPHER_CTX_get_params, 55EVP_CIPHER_gettable_ctx_params, 56EVP_CIPHER_CTX_gettable_params, 57EVP_CIPHER_CTX_set_params, 58EVP_CIPHER_settable_ctx_params, 59EVP_CIPHER_CTX_settable_params, 60EVP_CIPHER_CTX_get_block_size, 61EVP_CIPHER_CTX_get_key_length, 62EVP_CIPHER_CTX_get_iv_length, 63EVP_CIPHER_CTX_get_tag_length, 64EVP_CIPHER_CTX_get_app_data, 65EVP_CIPHER_CTX_set_app_data, 66EVP_CIPHER_CTX_flags, 67EVP_CIPHER_CTX_set_flags, 68EVP_CIPHER_CTX_clear_flags, 69EVP_CIPHER_CTX_test_flags, 70EVP_CIPHER_CTX_get_type, 71EVP_CIPHER_CTX_get_mode, 72EVP_CIPHER_CTX_get_num, 73EVP_CIPHER_CTX_set_num, 74EVP_CIPHER_CTX_is_encrypting, 75EVP_CIPHER_param_to_asn1, 76EVP_CIPHER_asn1_to_param, 77EVP_CIPHER_CTX_set_padding, 78EVP_enc_null, 79EVP_CIPHER_do_all_provided, 80EVP_CIPHER_nid, 81EVP_CIPHER_name, 82EVP_CIPHER_block_size, 83EVP_CIPHER_key_length, 84EVP_CIPHER_iv_length, 85EVP_CIPHER_flags, 86EVP_CIPHER_mode, 87EVP_CIPHER_type, 88EVP_CIPHER_CTX_encrypting, 89EVP_CIPHER_CTX_nid, 90EVP_CIPHER_CTX_block_size, 91EVP_CIPHER_CTX_key_length, 92EVP_CIPHER_CTX_iv_length, 93EVP_CIPHER_CTX_tag_length, 94EVP_CIPHER_CTX_num, 95EVP_CIPHER_CTX_type, 96EVP_CIPHER_CTX_mode 97- EVP cipher routines 98 99=head1 SYNOPSIS 100 101=for openssl generic 102 103 #include <openssl/evp.h> 104 105 EVP_CIPHER *EVP_CIPHER_fetch(OSSL_LIB_CTX *ctx, const char *algorithm, 106 const char *properties); 107 int EVP_CIPHER_up_ref(EVP_CIPHER *cipher); 108 void EVP_CIPHER_free(EVP_CIPHER *cipher); 109 EVP_CIPHER_CTX *EVP_CIPHER_CTX_new(void); 110 int EVP_CIPHER_CTX_reset(EVP_CIPHER_CTX *ctx); 111 void EVP_CIPHER_CTX_free(EVP_CIPHER_CTX *ctx); 112 113 int EVP_EncryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 114 ENGINE *impl, const unsigned char *key, const unsigned char *iv); 115 int EVP_EncryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 116 const unsigned char *key, const unsigned char *iv, 117 const OSSL_PARAM params[]); 118 int EVP_EncryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, 119 int *outl, const unsigned char *in, int inl); 120 int EVP_EncryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl); 121 122 int EVP_DecryptInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 123 ENGINE *impl, const unsigned char *key, const unsigned char *iv); 124 int EVP_DecryptInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 125 const unsigned char *key, const unsigned char *iv, 126 const OSSL_PARAM params[]); 127 int EVP_DecryptUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, 128 int *outl, const unsigned char *in, int inl); 129 int EVP_DecryptFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); 130 131 int EVP_CipherInit_ex(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 132 ENGINE *impl, const unsigned char *key, const unsigned char *iv, int enc); 133 int EVP_CipherInit_ex2(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 134 const unsigned char *key, const unsigned char *iv, 135 int enc, const OSSL_PARAM params[]); 136 int EVP_CipherUpdate(EVP_CIPHER_CTX *ctx, unsigned char *out, 137 int *outl, const unsigned char *in, int inl); 138 int EVP_CipherFinal_ex(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); 139 140 int EVP_EncryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 141 const unsigned char *key, const unsigned char *iv); 142 int EVP_EncryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *out, int *outl); 143 144 int EVP_DecryptInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 145 const unsigned char *key, const unsigned char *iv); 146 int EVP_DecryptFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); 147 148 int EVP_CipherInit(EVP_CIPHER_CTX *ctx, const EVP_CIPHER *type, 149 const unsigned char *key, const unsigned char *iv, int enc); 150 int EVP_CipherFinal(EVP_CIPHER_CTX *ctx, unsigned char *outm, int *outl); 151 152 int EVP_Cipher(EVP_CIPHER_CTX *ctx, unsigned char *out, 153 const unsigned char *in, unsigned int inl); 154 155 int EVP_CIPHER_CTX_set_padding(EVP_CIPHER_CTX *x, int padding); 156 int EVP_CIPHER_CTX_set_key_length(EVP_CIPHER_CTX *x, int keylen); 157 int EVP_CIPHER_CTX_ctrl(EVP_CIPHER_CTX *ctx, int cmd, int p1, void *p2); 158 int EVP_CIPHER_CTX_rand_key(EVP_CIPHER_CTX *ctx, unsigned char *key); 159 void EVP_CIPHER_CTX_set_flags(EVP_CIPHER_CTX *ctx, int flags); 160 void EVP_CIPHER_CTX_clear_flags(EVP_CIPHER_CTX *ctx, int flags); 161 int EVP_CIPHER_CTX_test_flags(const EVP_CIPHER_CTX *ctx, int flags); 162 163 const EVP_CIPHER *EVP_get_cipherbyname(const char *name); 164 const EVP_CIPHER *EVP_get_cipherbynid(int nid); 165 const EVP_CIPHER *EVP_get_cipherbyobj(const ASN1_OBJECT *a); 166 167 int EVP_CIPHER_get_nid(const EVP_CIPHER *e); 168 int EVP_CIPHER_is_a(const EVP_CIPHER *cipher, const char *name); 169 int EVP_CIPHER_names_do_all(const EVP_CIPHER *cipher, 170 void (*fn)(const char *name, void *data), 171 void *data); 172 const char *EVP_CIPHER_get0_name(const EVP_CIPHER *cipher); 173 const char *EVP_CIPHER_get0_description(const EVP_CIPHER *cipher); 174 const OSSL_PROVIDER *EVP_CIPHER_get0_provider(const EVP_CIPHER *cipher); 175 int EVP_CIPHER_get_block_size(const EVP_CIPHER *e); 176 int EVP_CIPHER_get_key_length(const EVP_CIPHER *e); 177 int EVP_CIPHER_get_iv_length(const EVP_CIPHER *e); 178 unsigned long EVP_CIPHER_get_flags(const EVP_CIPHER *e); 179 unsigned long EVP_CIPHER_get_mode(const EVP_CIPHER *e); 180 int EVP_CIPHER_get_type(const EVP_CIPHER *cipher); 181 182 const EVP_CIPHER *EVP_CIPHER_CTX_get0_cipher(const EVP_CIPHER_CTX *ctx); 183 EVP_CIPHER *EVP_CIPHER_CTX_get1_cipher(const EVP_CIPHER_CTX *ctx); 184 int EVP_CIPHER_CTX_get_nid(const EVP_CIPHER_CTX *ctx); 185 const char *EVP_CIPHER_CTX_get0_name(const EVP_CIPHER_CTX *ctx); 186 187 int EVP_CIPHER_get_params(EVP_CIPHER *cipher, OSSL_PARAM params[]); 188 int EVP_CIPHER_CTX_set_params(EVP_CIPHER_CTX *ctx, const OSSL_PARAM params[]); 189 int EVP_CIPHER_CTX_get_params(EVP_CIPHER_CTX *ctx, OSSL_PARAM params[]); 190 const OSSL_PARAM *EVP_CIPHER_gettable_params(const EVP_CIPHER *cipher); 191 const OSSL_PARAM *EVP_CIPHER_settable_ctx_params(const EVP_CIPHER *cipher); 192 const OSSL_PARAM *EVP_CIPHER_gettable_ctx_params(const EVP_CIPHER *cipher); 193 const OSSL_PARAM *EVP_CIPHER_CTX_settable_params(EVP_CIPHER_CTX *ctx); 194 const OSSL_PARAM *EVP_CIPHER_CTX_gettable_params(EVP_CIPHER_CTX *ctx); 195 int EVP_CIPHER_CTX_get_block_size(const EVP_CIPHER_CTX *ctx); 196 int EVP_CIPHER_CTX_get_key_length(const EVP_CIPHER_CTX *ctx); 197 int EVP_CIPHER_CTX_get_iv_length(const EVP_CIPHER_CTX *ctx); 198 int EVP_CIPHER_CTX_get_tag_length(const EVP_CIPHER_CTX *ctx); 199 void *EVP_CIPHER_CTX_get_app_data(const EVP_CIPHER_CTX *ctx); 200 void EVP_CIPHER_CTX_set_app_data(const EVP_CIPHER_CTX *ctx, void *data); 201 int EVP_CIPHER_CTX_get_type(const EVP_CIPHER_CTX *ctx); 202 int EVP_CIPHER_CTX_get_mode(const EVP_CIPHER_CTX *ctx); 203 int EVP_CIPHER_CTX_get_num(const EVP_CIPHER_CTX *ctx); 204 int EVP_CIPHER_CTX_set_num(EVP_CIPHER_CTX *ctx, int num); 205 int EVP_CIPHER_CTX_is_encrypting(const EVP_CIPHER_CTX *ctx); 206 207 int EVP_CIPHER_param_to_asn1(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 208 int EVP_CIPHER_asn1_to_param(EVP_CIPHER_CTX *c, ASN1_TYPE *type); 209 210 void EVP_CIPHER_do_all_provided(OSSL_LIB_CTX *libctx, 211 void (*fn)(EVP_CIPHER *cipher, void *arg), 212 void *arg); 213 214 #define EVP_CIPHER_nid EVP_CIPHER_get_nid 215 #define EVP_CIPHER_name EVP_CIPHER_get0_name 216 #define EVP_CIPHER_block_size EVP_CIPHER_get_block_size 217 #define EVP_CIPHER_key_length EVP_CIPHER_get_key_length 218 #define EVP_CIPHER_iv_length EVP_CIPHER_get_iv_length 219 #define EVP_CIPHER_flags EVP_CIPHER_get_flags 220 #define EVP_CIPHER_mode EVP_CIPHER_get_mode 221 #define EVP_CIPHER_type EVP_CIPHER_get_type 222 #define EVP_CIPHER_CTX_encrypting EVP_CIPHER_CTX_is_encrypting 223 #define EVP_CIPHER_CTX_nid EVP_CIPHER_CTX_get_nid 224 #define EVP_CIPHER_CTX_block_size EVP_CIPHER_CTX_get_block_size 225 #define EVP_CIPHER_CTX_key_length EVP_CIPHER_CTX_get_key_length 226 #define EVP_CIPHER_CTX_iv_length EVP_CIPHER_CTX_get_iv_length 227 #define EVP_CIPHER_CTX_tag_length EVP_CIPHER_CTX_get_tag_length 228 #define EVP_CIPHER_CTX_num EVP_CIPHER_CTX_get_num 229 #define EVP_CIPHER_CTX_type EVP_CIPHER_CTX_get_type 230 #define EVP_CIPHER_CTX_mode EVP_CIPHER_CTX_get_mode 231 232The following function has been deprecated since OpenSSL 3.0, and can be 233hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 234see L<openssl_user_macros(7)>: 235 236 const EVP_CIPHER *EVP_CIPHER_CTX_cipher(const EVP_CIPHER_CTX *ctx); 237 238The following function has been deprecated since OpenSSL 1.1.0, and can be 239hidden entirely by defining B<OPENSSL_API_COMPAT> with a suitable version value, 240see L<openssl_user_macros(7)>: 241 242 int EVP_CIPHER_CTX_flags(const EVP_CIPHER_CTX *ctx); 243 244=head1 DESCRIPTION 245 246The EVP cipher routines are a high-level interface to certain 247symmetric ciphers. 248 249The B<EVP_CIPHER> type is a structure for cipher method implementation. 250 251=over 4 252 253=item EVP_CIPHER_fetch() 254 255Fetches the cipher implementation for the given I<algorithm> from any provider 256offering it, within the criteria given by the I<properties>. 257See L<crypto(7)/ALGORITHM FETCHING> for further information. 258 259The returned value must eventually be freed with EVP_CIPHER_free(). 260 261Fetched B<EVP_CIPHER> structures are reference counted. 262 263=item EVP_CIPHER_up_ref() 264 265Increments the reference count for an B<EVP_CIPHER> structure. 266 267=item EVP_CIPHER_free() 268 269Decrements the reference count for the fetched B<EVP_CIPHER> structure. 270If the reference count drops to 0 then the structure is freed. 271If the argument is NULL, nothing is done. 272 273=item EVP_CIPHER_CTX_new() 274 275Allocates and returns a cipher context. 276 277=item EVP_CIPHER_CTX_free() 278 279Clears all information from a cipher context and frees any allocated memory 280associated with it, including I<ctx> itself. This function should be called 281after all operations using a cipher are complete so sensitive information does 282not remain in memory. If the argument is NULL, nothing is done. 283 284=item EVP_CIPHER_CTX_ctrl() 285 286I<This is a legacy method.> EVP_CIPHER_CTX_set_params() and 287EVP_CIPHER_CTX_get_params() is the mechanism that should be used to set and get 288parameters that are used by providers. 289 290Performs cipher-specific control actions on context I<ctx>. The control command 291is indicated in I<cmd> and any additional arguments in I<p1> and I<p2>. 292EVP_CIPHER_CTX_ctrl() must be called after EVP_CipherInit_ex2(). Other restrictions 293may apply depending on the control type and cipher implementation. 294 295If this function happens to be used with a fetched B<EVP_CIPHER>, it will 296translate the controls that are known to OpenSSL into L<OSSL_PARAM(3)> 297parameters with keys defined by OpenSSL and call EVP_CIPHER_CTX_get_params() or 298EVP_CIPHER_CTX_set_params() as is appropriate for each control command. 299 300See L</CONTROLS> below for more information, including what translations are 301being done. 302 303=item EVP_CIPHER_get_params() 304 305Retrieves the requested list of algorithm I<params> from a CIPHER I<cipher>. 306See L</PARAMETERS> below for more information. 307 308=item EVP_CIPHER_CTX_get_params() 309 310Retrieves the requested list of I<params> from CIPHER context I<ctx>. 311See L</PARAMETERS> below for more information. 312 313=item EVP_CIPHER_CTX_set_params() 314 315Sets the list of I<params> into a CIPHER context I<ctx>. 316See L</PARAMETERS> below for more information. 317 318=item EVP_CIPHER_gettable_params() 319 320Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters 321that can be used with EVP_CIPHER_get_params(). 322 323=item EVP_CIPHER_gettable_ctx_params() and EVP_CIPHER_CTX_gettable_params() 324 325Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters 326that can be used with EVP_CIPHER_CTX_get_params(). 327EVP_CIPHER_gettable_ctx_params() returns the parameters that can be retrieved 328from the algorithm, whereas EVP_CIPHER_CTX_gettable_params() returns the 329parameters that can be retrieved in the context's current state. 330 331=item EVP_CIPHER_settable_ctx_params() and EVP_CIPHER_CTX_settable_params() 332 333Get a constant L<OSSL_PARAM(3)> array that describes the settable parameters 334that can be used with EVP_CIPHER_CTX_set_params(). 335EVP_CIPHER_settable_ctx_params() returns the parameters that can be set from the 336algorithm, whereas EVP_CIPHER_CTX_settable_params() returns the parameters that 337can be set in the context's current state. 338 339=item EVP_EncryptInit_ex2() 340 341Sets up cipher context I<ctx> for encryption with cipher I<type>. I<type> is 342typically supplied by calling EVP_CIPHER_fetch(). I<type> may also be set 343using legacy functions such as EVP_aes_256_cbc(), but this is not recommended 344for new applications. I<key> is the symmetric key to use and I<iv> is the IV to 345use (if necessary), the actual number of bytes used for the key and IV depends 346on the cipher. The parameters I<params> will be set on the context after 347initialisation. It is possible to set all parameters to NULL except I<type> in 348an initial call and supply the remaining parameters in subsequent calls, all of 349which have I<type> set to NULL. This is done when the default cipher parameters 350are not appropriate. 351For B<EVP_CIPH_GCM_MODE> the IV will be generated internally if it is not 352specified. 353 354=item EVP_EncryptInit_ex() 355 356This legacy function is similar to EVP_EncryptInit_ex2() when I<impl> is NULL. 357The implementation of the I<type> from the I<impl> engine will be used if it 358exists. 359 360=item EVP_EncryptUpdate() 361 362Encrypts I<inl> bytes from the buffer I<in> and writes the encrypted version to 363I<out>. The pointers I<out> and I<in> may point to the same location, in which 364case the encryption will be done in-place. However, in-place encryption is 365guaranteed to work only if the encryption context (I<ctx>) has processed data in 366multiples of the block size. If the context contains an incomplete data block 367from previous operations, in-place encryption will fail. 368 369If I<out> and I<in> point to different locations, the two buffers must be 370disjoint, otherwise the operation might fail or the outcome might be undefined. 371 372This function can be called multiple times to encrypt successive blocks 373of data. The amount of data written depends on the block alignment of the 374encrypted data. 375For most ciphers and modes, the amount of data written can be anything 376from zero bytes to (inl + cipher_block_size - 1) bytes. 377For wrap cipher modes, the amount of data written can be anything 378from zero bytes to (inl + cipher_block_size) bytes. 379For stream ciphers, the amount of data written can be anything from zero 380bytes to inl bytes. 381Thus, the buffer pointed to by I<out> must contain sufficient room for the 382operation being performed. 383The actual number of bytes written is placed in I<outl>. 384 385If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts 386the "final" data, that is any data that remains in a partial block. 387It uses standard block padding (aka PKCS padding) as described in 388the NOTES section, below. The encrypted 389final data is written to I<out> which should have sufficient space for 390one cipher block. The number of bytes written is placed in I<outl>. After 391this function is called the encryption operation is finished and no further 392calls to EVP_EncryptUpdate() should be made. 393 394If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more 395data and it will return an error if any data remains in a partial block: 396that is if the total data length is not a multiple of the block size. 397 398=item EVP_DecryptInit_ex2(), EVP_DecryptInit_ex(), EVP_DecryptUpdate() 399and EVP_DecryptFinal_ex() 400 401These functions are the corresponding decryption operations. 402EVP_DecryptFinal() will return an error code if padding is enabled and the 403final block is not correctly formatted. The parameters and restrictions are 404identical to the encryption operations except that if padding is enabled the 405decrypted data buffer I<out> passed to EVP_DecryptUpdate() should have 406sufficient room for (I<inl> + cipher_block_size) bytes unless the cipher block 407size is 1 in which case I<inl> bytes is sufficient. 408 409=item EVP_CipherInit_ex2(), EVP_CipherInit_ex(), EVP_CipherUpdate() and 410EVP_CipherFinal_ex() 411 412These functions can be used for decryption or encryption. The operation 413performed depends on the value of the I<enc> parameter. It should be set to 1 414for encryption, 0 for decryption and -1 to leave the value unchanged 415(the actual value of 'enc' being supplied in a previous call). 416 417=item EVP_CIPHER_CTX_reset() 418 419Clears all information from a cipher context and free up any allocated memory 420associated with it, except the I<ctx> itself. This function should be called 421anytime I<ctx> is reused by another 422EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal() series of calls. 423 424=item EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() 425 426Behave in a similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and 427EVP_CipherInit_ex() except if the I<type> is not a fetched cipher they use the 428default implementation of the I<type>. 429 430=item EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() 431 432Identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and 433EVP_CipherFinal_ex(). In previous releases they also cleaned up 434the I<ctx>, but this is no longer done and EVP_CIPHER_CTX_cleanup() 435must be called to free any context resources. 436 437=item EVP_Cipher() 438 439Encrypts or decrypts a maximum I<inl> amount of bytes from I<in> and leaves the 440result in I<out>. 441 442For legacy ciphers - If the cipher doesn't have the flag 443B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set, then I<inl> must be a multiple of 444EVP_CIPHER_get_block_size(). If it isn't, the result is undefined. If the cipher 445has that flag set, then I<inl> can be any size. 446 447Due to the constraints of the API contract of this function it shouldn't be used 448in applications, please consider using EVP_CipherUpdate() and 449EVP_CipherFinal_ex() instead. 450 451=item EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 452 453Returns an B<EVP_CIPHER> structure when passed a cipher name, a cipher B<NID> or 454an B<ASN1_OBJECT> structure respectively. 455 456EVP_get_cipherbyname() will return NULL for algorithms such as "AES-128-SIV", 457"AES-128-CBC-CTS" and "CAMELLIA-128-CBC-CTS" which were previously only 458accessible via low level interfaces. 459 460The EVP_get_cipherbyname() function is present for backwards compatibility with 461OpenSSL prior to version 3 and is different to the EVP_CIPHER_fetch() function 462since it does not attempt to "fetch" an implementation of the cipher. 463Additionally, it only knows about ciphers that are built-in to OpenSSL and have 464an associated NID. Similarly EVP_get_cipherbynid() and EVP_get_cipherbyobj() 465also return objects without an associated implementation. 466 467When the cipher objects returned by these functions are used (such as in a call 468to EVP_EncryptInit_ex()) an implementation of the cipher will be implicitly 469fetched from the loaded providers. This fetch could fail if no suitable 470implementation is available. Use EVP_CIPHER_fetch() instead to explicitly fetch 471the algorithm and an associated implementation from a provider. 472 473See L<crypto(7)/ALGORITHM FETCHING> for more information about fetching. 474 475The cipher objects returned from these functions do not need to be freed with 476EVP_CIPHER_free(). 477 478=item EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() 479 480Return the NID of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 481structure. The actual NID value is an internal value which may not have a 482corresponding OBJECT IDENTIFIER. 483 484=item EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags() 485 486Sets, clears and tests I<ctx> flags. See L</FLAGS> below for more information. 487 488For provided ciphers EVP_CIPHER_CTX_set_flags() should be called only after the 489fetched cipher has been assigned to the I<ctx>. It is recommended to use 490L</PARAMETERS> instead. 491 492=item EVP_CIPHER_CTX_set_padding() 493 494Enables or disables padding. This function should be called after the context 495is set up for encryption or decryption with EVP_EncryptInit_ex2(), 496EVP_DecryptInit_ex2() or EVP_CipherInit_ex2(). By default encryption operations 497are padded using standard block padding and the padding is checked and removed 498when decrypting. If the I<pad> parameter is zero then no padding is 499performed, the total amount of data encrypted or decrypted must then 500be a multiple of the block size or an error will occur. 501 502=item EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() 503 504Return the key length of a cipher when passed an B<EVP_CIPHER> or 505B<EVP_CIPHER_CTX> structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum 506key length for all ciphers. Note: although EVP_CIPHER_get_key_length() is fixed for 507a given cipher, the value of EVP_CIPHER_CTX_get_key_length() may be different for 508variable key length ciphers. 509 510=item EVP_CIPHER_CTX_set_key_length() 511 512Sets the key length of the cipher context. 513If the cipher is a fixed length cipher then attempting to set the key 514length to any value other than the fixed value is an error. 515 516=item EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() 517 518Return the IV length of a cipher when passed an B<EVP_CIPHER> or 519B<EVP_CIPHER_CTX>. It will return zero if the cipher does not use an IV. 520The constant B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers. 521 522=item EVP_CIPHER_CTX_get_tag_length() 523 524Returns the tag length of an AEAD cipher when passed a B<EVP_CIPHER_CTX>. It will 525return zero if the cipher does not support a tag. It returns a default value if 526the tag length has not been set. 527 528=item EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() 529 530Return the block size of a cipher when passed an B<EVP_CIPHER> or 531B<EVP_CIPHER_CTX> structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the 532maximum block length for all ciphers. 533 534=item EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() 535 536Return the type of the passed cipher or context. This "type" is the actual NID 537of the cipher OBJECT IDENTIFIER and as such it ignores the cipher parameters 538(40 bit RC2 and 128 bit RC2 have the same NID). If the cipher does not have an 539object identifier or does not have ASN1 support this function will return 540B<NID_undef>. 541 542=item EVP_CIPHER_is_a() 543 544Returns 1 if I<cipher> is an implementation of an algorithm that's identifiable 545with I<name>, otherwise 0. If I<cipher> is a legacy cipher (it's the return 546value from the likes of EVP_aes128() rather than the result of an 547EVP_CIPHER_fetch()), only cipher names registered with the default library 548context (see L<OSSL_LIB_CTX(3)>) will be considered. 549 550=item EVP_CIPHER_get0_name() and EVP_CIPHER_CTX_get0_name() 551 552Return the name of the passed cipher or context. For fetched ciphers with 553multiple names, only one of them is returned. See also EVP_CIPHER_names_do_all(). 554 555=item EVP_CIPHER_names_do_all() 556 557Traverses all names for the I<cipher>, and calls I<fn> with each name and 558I<data>. This is only useful with fetched B<EVP_CIPHER>s. 559 560=item EVP_CIPHER_get0_description() 561 562Returns a description of the cipher, meant for display and human consumption. 563The description is at the discretion of the cipher implementation. 564 565=item EVP_CIPHER_get0_provider() 566 567Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given 568B<EVP_CIPHER>. 569 570=item EVP_CIPHER_CTX_get0_cipher() 571 572Returns the B<EVP_CIPHER> structure when passed an B<EVP_CIPHER_CTX> structure. 573EVP_CIPHER_CTX_get1_cipher() is the same except the ownership is passed to 574the caller. 575 576=item EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode() 577 578Return the block cipher mode: 579EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, 580EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE, 581EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. 582If the cipher is a stream cipher then EVP_CIPH_STREAM_CIPHER is returned. 583 584=item EVP_CIPHER_get_flags() 585 586Returns any flags associated with the cipher. See L</FLAGS> 587for a list of currently defined flags. 588 589=item EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num() 590 591Gets or sets the cipher specific "num" parameter for the associated I<ctx>. 592Built-in ciphers typically use this to track how much of the current underlying block 593has been "used" already. 594 595=item EVP_CIPHER_CTX_is_encrypting() 596 597Reports whether the I<ctx> is being used for encryption or decryption. 598 599=item EVP_CIPHER_CTX_flags() 600 601A deprecated macro calling C<EVP_CIPHER_get_flags(EVP_CIPHER_CTX_get0_cipher(ctx))>. 602Do not use. 603 604=item EVP_CIPHER_param_to_asn1() 605 606Sets the AlgorithmIdentifier "parameter" based on the passed cipher. This will 607typically include any parameters and an IV. The cipher IV (if any) must be set 608when this call is made. This call should be made before the cipher is actually 609"used" (before any EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). 610This function may fail if the cipher does not have any ASN1 support. 611 612=item EVP_CIPHER_asn1_to_param() 613 614Sets the cipher parameters based on an ASN1 AlgorithmIdentifier "parameter". 615The precise effect depends on the cipher. In the case of B<RC2>, for example, 616it will set the IV and effective key length. 617This function should be called after the base cipher type is set but before 618the key is set. For example EVP_CipherInit() will be called with the IV and 619key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally 620EVP_CipherInit() again with all parameters except the key set to NULL. It is 621possible for this function to fail if the cipher does not have any ASN1 support 622or the parameters cannot be set (for example the RC2 effective key length 623is not supported. 624 625=item EVP_CIPHER_CTX_rand_key() 626 627Generates a random key of the appropriate length based on the cipher context. 628The B<EVP_CIPHER> can provide its own random key generation routine to support 629keys of a specific form. I<key> must point to a buffer at least as big as the 630value returned by EVP_CIPHER_CTX_get_key_length(). 631 632=item EVP_CIPHER_do_all_provided() 633 634Traverses all ciphers implemented by all activated providers in the given 635library context I<libctx>, and for each of the implementations, calls the given 636function I<fn> with the implementation method and the given I<arg> as argument. 637 638=back 639 640=head1 PARAMETERS 641 642See L<OSSL_PARAM(3)> for information about passing parameters. 643 644=head2 Gettable EVP_CIPHER parameters 645 646When EVP_CIPHER_fetch() is called it internally calls EVP_CIPHER_get_params() 647and caches the results. 648 649EVP_CIPHER_get_params() can be used with the following L<OSSL_PARAM(3)> keys: 650 651=over 4 652 653=item "mode" (B<OSSL_CIPHER_PARAM_MODE>) <unsigned integer> 654 655Gets the mode for the associated cipher algorithm I<cipher>. 656See L</EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode()> for a list of valid modes. 657Use EVP_CIPHER_get_mode() to retrieve the cached value. 658 659=item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer> 660 661Gets the key length for the associated cipher algorithm I<cipher>. 662Use EVP_CIPHER_get_key_length() to retrieve the cached value. 663 664=item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) <unsigned integer> 665 666Gets the IV length for the associated cipher algorithm I<cipher>. 667Use EVP_CIPHER_get_iv_length() to retrieve the cached value. 668 669=item "blocksize" (B<OSSL_CIPHER_PARAM_BLOCK_SIZE>) <unsigned integer> 670 671Gets the block size for the associated cipher algorithm I<cipher>. 672The block size should be 1 for stream ciphers. 673Note that the block size for a cipher may be different to the block size for 674the underlying encryption/decryption primitive. 675For example AES in CTR mode has a block size of 1 (because it operates like a 676stream cipher), even though AES has a block size of 16. 677Use EVP_CIPHER_get_block_size() to retrieve the cached value. 678 679=item "aead" (B<OSSL_CIPHER_PARAM_AEAD>) <integer> 680 681Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0. 682Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) to retrieve the 683cached value. 684 685=item "custom-iv" (B<OSSL_CIPHER_PARAM_CUSTOM_IV>) <integer> 686 687Gets 1 if the cipher algorithm I<cipher> has a custom IV, otherwise it gets 0. 688Storing and initializing the IV is left entirely to the implementation, if a 689custom IV is used. 690Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_CUSTOM_IV) to retrieve the 691cached value. 692 693=item "cts" (B<OSSL_CIPHER_PARAM_CTS>) <integer> 694 695Gets 1 if the cipher algorithm I<cipher> uses ciphertext stealing, 696otherwise it gets 0. 697This is currently used to indicate that the cipher is a one shot that only 698allows a single call to EVP_CipherUpdate(). 699Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_CTS) to retrieve the 700cached value. 701 702=item "tls-multi" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK>) <integer> 703 704Gets 1 if the cipher algorithm I<cipher> supports interleaving of crypto blocks, 705otherwise it gets 0. The interleaving is an optimization only applicable to certain 706TLS ciphers. 707Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK) to retrieve the 708cached value. 709 710=item "has-randkey" (B<OSSL_CIPHER_PARAM_HAS_RANDKEY>) <integer> 711 712Gets 1 if the cipher algorithm I<cipher> supports the gettable EVP_CIPHER_CTX 713parameter B<OSSL_CIPHER_PARAM_RANDOM_KEY>. Only DES and 3DES set this to 1, 714all other OpenSSL ciphers return 0. 715 716=back 717 718=head2 Gettable and Settable EVP_CIPHER_CTX parameters 719 720The following L<OSSL_PARAM(3)> keys can be used with both EVP_CIPHER_CTX_get_params() 721and EVP_CIPHER_CTX_set_params(). 722 723=over 4 724 725=item "padding" (B<OSSL_CIPHER_PARAM_PADDING>) <unsigned integer> 726 727Gets or sets the padding mode for the cipher context I<ctx>. 728Padding is enabled if the value is 1, and disabled if the value is 0. 729See also EVP_CIPHER_CTX_set_padding(). 730 731=item "num" (B<OSSL_CIPHER_PARAM_NUM>) <unsigned integer> 732 733Gets or sets the cipher specific "num" parameter for the cipher context I<ctx>. 734Built-in ciphers typically use this to track how much of the current underlying 735block has been "used" already. 736See also EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num(). 737 738=item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer> 739 740Gets or sets the key length for the cipher context I<ctx>. 741The length of the "keylen" parameter should not exceed that of a B<size_t>. 742See also EVP_CIPHER_CTX_get_key_length() and EVP_CIPHER_CTX_set_key_length(). 743 744=item "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>) <octet string> 745 746Gets or sets the AEAD tag for the associated cipher context I<ctx>. 747See L<EVP_EncryptInit(3)/AEAD Interface>. 748 749=item "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>) <unsigned integer> 750 751Gets or sets the effective keybits used for a RC2 cipher. 752The length of the "keybits" parameter should not exceed that of a B<size_t>. 753 754=item "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>) <unsigned integer> 755 756Gets or sets the number of rounds to be used for a cipher. 757This is used by the RC5 cipher. 758 759=item "alg_id_param" (B<OSSL_CIPHER_PARAM_ALGORITHM_ID_PARAMS>) <octet string> 760 761Used to pass the DER encoded AlgorithmIdentifier parameter to or from 762the cipher implementation. Functions like L<EVP_CIPHER_param_to_asn1(3)> 763and L<EVP_CIPHER_asn1_to_param(3)> use this parameter for any implementation 764that has the flag B<EVP_CIPH_FLAG_CUSTOM_ASN1> set. 765 766=item "cts_mode" (B<OSSL_CIPHER_PARAM_CTS_MODE>) <UTF8 string> 767 768Gets or sets the cipher text stealing mode. For all modes the output size is the 769same as the input size. The input length must be greater than or equal to the 770block size. (The block size for AES and CAMELLIA is 16 bytes). 771 772Valid values for the mode are: 773 774=over 4 775 776=item "CS1" 777 778The NIST variant of cipher text stealing. 779For input lengths that are multiples of the block size it is equivalent to 780using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher otherwise the second last 781cipher text block is a partial block. 782 783=item "CS2" 784 785For input lengths that are multiples of the block size it is equivalent to 786using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher, otherwise it is the same as 787"CS3" mode. 788 789=item "CS3" 790 791The Kerberos5 variant of cipher text stealing which always swaps the last 792cipher text block with the previous block (which may be a partial or full block 793depending on the input length). If the input length is exactly one full block 794then this is equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher. 795 796=back 797 798The default is "CS1". 799This is only supported for "AES-128-CBC-CTS", "AES-192-CBC-CTS", "AES-256-CBC-CTS", 800"CAMELLIA-128-CBC-CTS", "CAMELLIA-192-CBC-CTS" and "CAMELLIA-256-CBC-CTS". 801 802=item "tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) <unsigned integer> 803 804Sets or gets the number of records being sent in one go for a tls1 multiblock 805cipher operation (either 4 or 8 records). 806 807=back 808 809=head2 Gettable EVP_CIPHER_CTX parameters 810 811The following L<OSSL_PARAM(3)> keys can be used with EVP_CIPHER_CTX_get_params(): 812 813=over 4 814 815=item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN> and <B<OSSL_CIPHER_PARAM_AEAD_IVLEN>) <unsigned integer> 816 817Gets the IV length for the cipher context I<ctx>. 818The length of the "ivlen" parameter should not exceed that of a B<size_t>. 819See also EVP_CIPHER_CTX_get_iv_length(). 820 821=item "iv" (B<OSSL_CIPHER_PARAM_IV>) <octet string OR octet ptr> 822 823Gets the IV used to initialize the associated cipher context I<ctx>. 824See also EVP_CIPHER_CTX_get_original_iv(). 825 826=item "updated-iv" (B<OSSL_CIPHER_PARAM_UPDATED_IV>) <octet string OR octet ptr> 827 828Gets the updated pseudo-IV state for the associated cipher context, e.g., 829the previous ciphertext block for CBC mode or the iteratively encrypted IV 830value for OFB mode. Note that octet pointer access is deprecated and is 831provided only for backwards compatibility with historical libcrypto APIs. 832See also EVP_CIPHER_CTX_get_updated_iv(). 833 834=item "randkey" (B<OSSL_CIPHER_PARAM_RANDOM_KEY>) <octet string> 835 836Gets an implementation specific randomly generated key for the associated 837cipher context I<ctx>. This is currently only supported by DES and 3DES (which set 838the key to odd parity). 839 840=item "taglen" (B<OSSL_CIPHER_PARAM_AEAD_TAGLEN>) <unsigned integer> 841 842Gets the tag length to be used for an AEAD cipher for the associated cipher 843context I<ctx>. It gets a default value if it has not been set. 844The length of the "taglen" parameter should not exceed that of a B<size_t>. 845See also EVP_CIPHER_CTX_get_tag_length(). 846 847=item "tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>) <unsigned integer> 848 849Gets the length of the tag that will be added to a TLS record for the AEAD 850tag for the associated cipher context I<ctx>. 851The length of the "tlsaadpad" parameter should not exceed that of a B<size_t>. 852 853=item "tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>) <octet string> 854 855Gets the invocation field generated for encryption. 856Can only be called after "tlsivfixed" is set. 857This is only used for GCM mode. 858 859=item "tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>) <unsigned integer> 860 861Get the total length of the record returned from the "tls1multi_enc" operation. 862 863=item "tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>) <unsigned integer> 864 865Gets the maximum record length for a TLS1 multiblock cipher operation. 866The length of the "tls1multi_maxbufsz" parameter should not exceed that of a B<size_t>. 867 868=item "tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) <unsigned integer> 869 870Gets the result of running the "tls1multi_aad" operation. 871 872=item "tls-mac" (B<OSSL_CIPHER_PARAM_TLS_MAC>) <octet ptr> 873 874Used to pass the TLS MAC data. 875 876=back 877 878=head2 Settable EVP_CIPHER_CTX parameters 879 880The following L<OSSL_PARAM(3)> keys can be used with EVP_CIPHER_CTX_set_params(): 881 882=over 4 883 884=item "mackey" (B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>) <octet string> 885 886Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256. 887 888=item "speed" (B<OSSL_CIPHER_PARAM_SPEED>) <unsigned integer> 889 890Sets the speed option for the associated cipher context. This is only supported 891by AES SIV ciphers which disallow multiple operations by default. 892Setting "speed" to 1 allows another encrypt or decrypt operation to be 893performed. This is used for performance testing. 894 895=item "use-bits" (B<OSSL_CIPHER_PARAM_USE_BITS>) <unsigned integer> 896 897Determines if the input length I<inl> passed to EVP_EncryptUpdate(), 898EVP_DecryptUpdate() and EVP_CipherUpdate() is the number of bits or number of bytes. 899Setting "use-bits" to 1 uses bits. The default is in bytes. 900This is only used for B<CFB1> ciphers. 901 902This can be set using EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS). 903 904=item "tls-version" (B<OSSL_CIPHER_PARAM_TLS_VERSION>) <integer> 905 906Sets the TLS version. 907 908=item "tls-mac-size" (B<OSSL_CIPHER_PARAM_TLS_MAC_SIZE>) <unsigned integer> 909 910Set the TLS MAC size. 911 912=item "tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) <octet string> 913 914Sets TLSv1.2 AAD information for the associated cipher context I<ctx>. 915TLSv1.2 AAD information is always 13 bytes in length and is as defined for the 916"additional_data" field described in section 6.2.3.3 of RFC5246. 917 918=item "tlsivfixed" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>) <octet string> 919 920Sets the fixed portion of an IV for an AEAD cipher used in a TLS record 921encryption/ decryption for the associated cipher context. 922TLS record encryption/decryption always occurs "in place" so that the input and 923output buffers are always the same memory location. 924AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part 925that varies with every record. 926Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records. 927TLS records are encrypted/decrypted using a single OSSL_FUNC_cipher_cipher call per 928record. 929For a record decryption the first bytes of the input buffer will be the explicit 930part of the IV and the final bytes of the input buffer will be the AEAD tag. 931The length of the explicit part of the IV and the tag length will depend on the 932cipher in use and will be defined in the RFC for the relevant ciphersuite. 933In order to allow for "in place" decryption the plaintext output should be 934written to the same location in the output buffer that the ciphertext payload 935was read from, i.e. immediately after the explicit IV. 936 937When encrypting a record the first bytes of the input buffer should be empty to 938allow space for the explicit IV, as will the final bytes where the tag will 939be written. 940The length of the input buffer will include the length of the explicit IV, the 941payload, and the tag bytes. 942The cipher implementation should generate the explicit IV and write it to the 943beginning of the output buffer, do "in place" encryption of the payload and 944write that to the output buffer, and finally add the tag onto the end of the 945output buffer. 946 947Whether encrypting or decrypting the value written to I<*outl> in the 948OSSL_FUNC_cipher_cipher call should be the length of the payload excluding the explicit 949IV length and the tag length. 950 951=item "tlsivinv" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>) <octet string> 952 953Sets the invocation field used for decryption. 954Can only be called after "tlsivfixed" is set. 955This is only used for GCM mode. 956 957=item "tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>) <octet string> 958 959Triggers a multiblock TLS1 encrypt operation for a TLS1 aware cipher that 960supports sending 4 or 8 records in one go. 961The cipher performs both the MAC and encrypt stages and constructs the record 962headers itself. 963"tls1multi_enc" supplies the output buffer for the encrypt operation, 964"tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply 965values to the encrypt operation. 966 967=item "tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) <octet string> 968 969Supplies the data to encrypt for a TLS1 multiblock cipher operation. 970 971=item "tls1multi_maxsndfrag" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT>) <unsigned integer> 972 973Sets the maximum send fragment size for a TLS1 multiblock cipher operation. 974It must be set before using "tls1multi_maxbufsz". 975The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a B<size_t>. 976 977=item "tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) <octet string> 978 979Sets the authenticated additional data used by a TLS1 multiblock cipher operation. 980The supplied data consists of 13 bytes of record data containing: 981Bytes 0-7: The sequence number of the first record 982Byte 8: The record type 983Byte 9-10: The protocol version 984Byte 11-12: Input length (Always 0) 985 986"tls1multi_interleave" must also be set for this operation. 987 988=back 989 990=head1 CONTROLS 991 992The Mappings from EVP_CIPHER_CTX_ctrl() identifiers to PARAMETERS are listed 993in the following section. See the L</PARAMETERS> section for more details. 994 995EVP_CIPHER_CTX_ctrl() can be used to send the following standard controls: 996 997=over 4 998 999=item EVP_CTRL_AEAD_SET_IVLEN and EVP_CTRL_GET_IVLEN 1000 1001When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1002EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1003key "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>). 1004 1005=item EVP_CTRL_AEAD_SET_IV_FIXED 1006 1007When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1008with an L<OSSL_PARAM(3)> item with the key "tlsivfixed" 1009(B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>). 1010 1011=item EVP_CTRL_AEAD_SET_MAC_KEY 1012 1013When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1014with an L<OSSL_PARAM(3)> item with the key "mackey" 1015(B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>). 1016 1017=item EVP_CTRL_AEAD_SET_TAG and EVP_CTRL_AEAD_GET_TAG 1018 1019When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1020EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1021key "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>). 1022 1023=item EVP_CTRL_CCM_SET_L 1024 1025When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1026with an L<OSSL_PARAM(3)> item with the key "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) 1027with a value of (15 - L) 1028 1029=item EVP_CTRL_COPY 1030 1031There is no OSSL_PARAM mapping for this. Use EVP_CIPHER_CTX_copy() instead. 1032 1033=item EVP_CTRL_GCM_SET_IV_INV 1034 1035When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1036with an L<OSSL_PARAM(3)> item with the key "tlsivinv" 1037(B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>). 1038 1039=item EVP_CTRL_RAND_KEY 1040 1041When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1042with an L<OSSL_PARAM(3)> item with the key "randkey" 1043(B<OSSL_CIPHER_PARAM_RANDOM_KEY>). 1044 1045=item EVP_CTRL_SET_KEY_LENGTH 1046 1047When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1048with an L<OSSL_PARAM(3)> item with the key "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>). 1049 1050=item EVP_CTRL_SET_RC2_KEY_BITS and EVP_CTRL_GET_RC2_KEY_BITS 1051 1052When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1053EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1054key "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>). 1055 1056=item EVP_CTRL_SET_RC5_ROUNDS and EVP_CTRL_GET_RC5_ROUNDS 1057 1058When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1059EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1060key "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>). 1061 1062=item EVP_CTRL_SET_SPEED 1063 1064When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1065with an L<OSSL_PARAM(3)> item with the key "speed" (B<OSSL_CIPHER_PARAM_SPEED>). 1066 1067=item EVP_CTRL_GCM_IV_GEN 1068 1069When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_get_params() gets called 1070with an L<OSSL_PARAM(3)> item with the key 1071"tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>). 1072 1073=item EVP_CTRL_AEAD_TLS1_AAD 1074 1075When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() get called 1076with an L<OSSL_PARAM(3)> item with the key 1077"tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) 1078followed by EVP_CIPHER_CTX_get_params() with a key of 1079"tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>). 1080 1081=item EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE 1082 1083When used with a fetched B<EVP_CIPHER>, 1084EVP_CIPHER_CTX_set_params() gets called with an L<OSSL_PARAM(3)> item with the 1085key OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT 1086followed by EVP_CIPHER_CTX_get_params() with a key of 1087"tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>). 1088 1089=item EVP_CTRL_TLS1_1_MULTIBLOCK_AAD 1090 1091When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1092with L<OSSL_PARAM(3)> items with the keys 1093"tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) and 1094"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) 1095followed by EVP_CIPHER_CTX_get_params() with keys of 1096"tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) and 1097"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>). 1098 1099=item EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT 1100 1101When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1102with L<OSSL_PARAM(3)> items with the keys 1103"tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>), 1104"tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) and 1105"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>), 1106followed by EVP_CIPHER_CTX_get_params() with a key of 1107"tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>). 1108 1109=back 1110 1111=head1 FLAGS 1112 1113EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags(). 1114can be used to manipulate and test these B<EVP_CIPHER_CTX> flags: 1115 1116=over 4 1117 1118=item EVP_CIPH_NO_PADDING 1119 1120Used by EVP_CIPHER_CTX_set_padding(). 1121 1122See also L</Gettable and Settable EVP_CIPHER_CTX parameters> "padding" 1123 1124=item EVP_CIPH_FLAG_LENGTH_BITS 1125 1126See L</Settable EVP_CIPHER_CTX parameters> "use-bits". 1127 1128=item EVP_CIPHER_CTX_FLAG_WRAP_ALLOW 1129 1130Used for Legacy purposes only. This flag needed to be set to indicate the 1131cipher handled wrapping. 1132 1133=back 1134 1135EVP_CIPHER_flags() uses the following flags that 1136have mappings to L</Gettable EVP_CIPHER parameters>: 1137 1138=over 4 1139 1140=item EVP_CIPH_FLAG_AEAD_CIPHER 1141 1142See L</Gettable EVP_CIPHER parameters> "aead". 1143 1144=item EVP_CIPH_CUSTOM_IV 1145 1146See L</Gettable EVP_CIPHER parameters> "custom-iv". 1147 1148=item EVP_CIPH_FLAG_CTS 1149 1150See L</Gettable EVP_CIPHER parameters> "cts". 1151 1152=item EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK; 1153 1154See L</Gettable EVP_CIPHER parameters> "tls-multi". 1155 1156=item EVP_CIPH_RAND_KEY 1157 1158See L</Gettable EVP_CIPHER parameters> "has-randkey". 1159 1160=back 1161 1162EVP_CIPHER_flags() uses the following flags for legacy purposes only: 1163 1164=over 4 1165 1166=item EVP_CIPH_VARIABLE_LENGTH 1167 1168=item EVP_CIPH_FLAG_CUSTOM_CIPHER 1169 1170=item EVP_CIPH_ALWAYS_CALL_INIT 1171 1172=item EVP_CIPH_CTRL_INIT 1173 1174=item EVP_CIPH_CUSTOM_KEY_LENGTH 1175 1176=item EVP_CIPH_CUSTOM_COPY 1177 1178=item EVP_CIPH_FLAG_DEFAULT_ASN1 1179 1180See L<EVP_CIPHER_meth_set_flags(3)> for further information related to the above 1181flags. 1182 1183=back 1184 1185=head1 RETURN VALUES 1186 1187EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success 1188and B<NULL> for failure. 1189 1190EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise. 1191 1192EVP_CIPHER_CTX_new() returns a pointer to a newly created 1193B<EVP_CIPHER_CTX> for success and B<NULL> for failure. 1194 1195EVP_EncryptInit_ex2(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex() 1196return 1 for success and 0 for failure. 1197 1198EVP_DecryptInit_ex2() and EVP_DecryptUpdate() return 1 for success and 0 for failure. 1199EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success. 1200 1201EVP_CipherInit_ex2() and EVP_CipherUpdate() return 1 for success and 0 for failure. 1202EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success. 1203 1204EVP_Cipher() returns 1 on success or 0 on failure, if the flag 1205B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher. 1206EVP_Cipher() returns the number of bytes written to I<out> for encryption / decryption, or 1207the number of bytes authenticated in a call specifying AAD for an AEAD cipher, if the flag 1208B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the cipher. 1209 1210EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure. 1211 1212EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 1213return an B<EVP_CIPHER> structure or NULL on error. 1214 1215EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() return a NID. 1216 1217EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() return the 1218block size. 1219 1220EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() return the key 1221length. 1222 1223EVP_CIPHER_CTX_set_padding() always returns 1. 1224 1225EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() return the IV 1226length or zero if the cipher does not use an IV. 1227 1228EVP_CIPHER_CTX_get_tag_length() return the tag length or zero if the cipher 1229does not use a tag. 1230 1231EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() return the NID of the 1232cipher's OBJECT IDENTIFIER or NID_undef if it has no defined 1233OBJECT IDENTIFIER. 1234 1235EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure. 1236 1237EVP_CIPHER_CTX_get_num() returns a nonnegative num value or 1238B<EVP_CTRL_RET_UNSUPPORTED> if the implementation does not support the call 1239or on any other error. 1240 1241EVP_CIPHER_CTX_set_num() returns 1 on success and 0 if the implementation 1242does not support the call or on any other error. 1243 1244EVP_CIPHER_CTX_is_encrypting() returns 1 if the I<ctx> is set up for encryption 12450 otherwise. 1246 1247EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater 1248than zero for success and zero or a negative number on failure. 1249 1250EVP_CIPHER_CTX_rand_key() returns 1 for success and zero or a negative number 1251for failure. 1252 1253EVP_CIPHER_names_do_all() returns 1 if the callback was called for all names. 1254A return value of 0 means that the callback was not called for any names. 1255 1256=head1 CIPHER LISTING 1257 1258All algorithms have a fixed key length unless otherwise stated. 1259 1260Refer to L</SEE ALSO> for the full list of ciphers available through the EVP 1261interface. 1262 1263=over 4 1264 1265=item EVP_enc_null() 1266 1267Null cipher: does nothing. 1268 1269=back 1270 1271=head1 AEAD INTERFACE 1272 1273The EVP interface for Authenticated Encryption with Associated Data (AEAD) 1274modes are subtly altered and several additional I<ctrl> operations are supported 1275depending on the mode specified. 1276 1277To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(), 1278EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output 1279parameter I<out> set to B<NULL>. In this case, on success, the parameter 1280I<outl> is set to the number of bytes authenticated. 1281 1282When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal() 1283indicates whether the operation was successful. If it does not indicate success, 1284the authentication operation has failed and any output data B<MUST NOT> be used 1285as it is corrupted. 1286 1287=head2 GCM and OCB Modes 1288 1289The following I<ctrl>s are supported in GCM and OCB modes. 1290 1291=over 4 1292 1293=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1294 1295Sets the IV length. This call can only be made before specifying an IV. If 1296not called a default IV length is used. 1297 1298For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the 1299maximum is 15. 1300 1301=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag) 1302 1303Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>. 1304This call can only be made when encrypting data and B<after> all data has been 1305processed (e.g. after an EVP_EncryptFinal() call). 1306 1307For OCB, C<taglen> must either be 16 or the value previously set via 1308B<EVP_CTRL_AEAD_SET_TAG>. 1309 1310=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1311 1312When decrypting, this call sets the expected tag to C<taglen> bytes from C<tag>. 1313C<taglen> must be between 1 and 16 inclusive. 1314The tag must be set prior to any call to EVP_DecryptFinal() or 1315EVP_DecryptFinal_ex(). 1316 1317For GCM, this call is only valid when decrypting data. 1318 1319For OCB, this call is valid when decrypting data to set the expected tag, 1320and when encrypting to set the desired tag length. 1321 1322In OCB mode, calling this when encrypting with C<tag> set to C<NULL> sets the 1323tag length. The tag length can only be set before specifying an IV. If this is 1324not called prior to setting the IV during encryption, then a default tag length 1325is used. 1326 1327For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the 1328maximum tag length for OCB. 1329 1330=back 1331 1332=head2 CCM Mode 1333 1334The EVP interface for CCM mode is similar to that of the GCM mode but with a 1335few additional requirements and different I<ctrl> values. 1336 1337For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to 1338EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output 1339and input parameters (I<in> and I<out>) set to B<NULL> and the length passed in 1340the I<inl> parameter. 1341 1342The following I<ctrl>s are supported in CCM mode. 1343 1344=over 4 1345 1346=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1347 1348This call is made to set the expected B<CCM> tag value when decrypting or 1349the length of the tag (with the C<tag> parameter set to NULL) when encrypting. 1350The tag length is often referred to as B<M>. If not set a default value is 1351used (12 for AES). When decrypting, the tag needs to be set before passing 1352in data to be decrypted, but as in GCM and OCB mode, it can be set after 1353passing additional authenticated data (see L</AEAD INTERFACE>). 1354 1355=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL) 1356 1357Sets the CCM B<L> value. If not set a default is used (8 for AES). 1358 1359=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1360 1361Sets the CCM nonce (IV) length. This call can only be made before specifying a 1362nonce value. The nonce length is given by B<15 - L> so it is 7 by default for 1363AES. 1364 1365=back 1366 1367=head2 SIV Mode 1368 1369For SIV mode ciphers the behaviour of the EVP interface is subtly 1370altered and several additional ctrl operations are supported. 1371 1372To specify any additional authenticated data (AAD) and/or a Nonce, a call to 1373EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made 1374with the output parameter I<out> set to B<NULL>. 1375 1376RFC5297 states that the Nonce is the last piece of AAD before the actual 1377encrypt/decrypt takes place. The API does not differentiate the Nonce from 1378other AAD. 1379 1380When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal() 1381indicates if the operation was successful. If it does not indicate success 1382the authentication operation has failed and any output data B<MUST NOT> 1383be used as it is corrupted. 1384 1385The API does not store the the SIV (Synthetic Initialization Vector) in 1386the cipher text. Instead, it is stored as the tag within the EVP_CIPHER_CTX. 1387The SIV must be retrieved from the context after encryption, and set into 1388the context before decryption. 1389 1390This differs from RFC5297 in that the cipher output from encryption, and 1391the cipher input to decryption, does not contain the SIV. This also means 1392that the plain text and cipher text lengths are identical. 1393 1394The following ctrls are supported in SIV mode, and are used to get and set 1395the Synthetic Initialization Vector: 1396 1397=over 4 1398 1399=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag); 1400 1401Writes I<taglen> bytes of the tag value (the Synthetic Initialization Vector) 1402to the buffer indicated by I<tag>. This call can only be made when encrypting 1403data and B<after> all data has been processed (e.g. after an EVP_EncryptFinal() 1404call). For SIV mode the taglen must be 16. 1405 1406=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag); 1407 1408Sets the expected tag (the Synthetic Initialization Vector) to I<taglen> 1409bytes from I<tag>. This call is only legal when decrypting data and must be 1410made B<before> any data is processed (e.g. before any EVP_DecryptUpdate() 1411calls). For SIV mode the taglen must be 16. 1412 1413=back 1414 1415SIV mode makes two passes over the input data, thus, only one call to 1416EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made 1417with I<out> set to a non-B<NULL> value. A call to EVP_DecryptFinal() or 1418EVP_CipherFinal() is not required, but will indicate if the update 1419operation succeeded. 1420 1421=head2 ChaCha20-Poly1305 1422 1423The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm. 1424 1425=over 4 1426 1427=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1428 1429Sets the nonce length. This call is now redundant since the only valid value 1430is the default length of 12 (i.e. 96 bits). 1431Prior to OpenSSL 3.0 a nonce of less than 12 bytes could be used to automatically 1432pad the iv with leading 0 bytes to make it 12 bytes in length. 1433 1434=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag) 1435 1436Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>. 1437This call can only be made when encrypting data and B<after> all data has been 1438processed (e.g. after an EVP_EncryptFinal() call). 1439 1440C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or 1441less. 1442 1443=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1444 1445Sets the expected tag to C<taglen> bytes from C<tag>. 1446The tag length can only be set before specifying an IV. 1447C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive. 1448This call is only valid when decrypting data. 1449 1450=back 1451 1452=head1 NOTES 1453 1454Where possible the B<EVP> interface to symmetric ciphers should be used in 1455preference to the low-level interfaces. This is because the code then becomes 1456transparent to the cipher used and much more flexible. Additionally, the 1457B<EVP> interface will ensure the use of platform specific cryptographic 1458acceleration such as AES-NI (the low-level interfaces do not provide the 1459guarantee). 1460 1461PKCS padding works by adding B<n> padding bytes of value B<n> to make the total 1462length of the encrypted data a multiple of the block size. Padding is always 1463added so if the data is already a multiple of the block size B<n> will equal 1464the block size. For example if the block size is 8 and 11 bytes are to be 1465encrypted then 5 padding bytes of value 5 will be added. 1466 1467When decrypting the final block is checked to see if it has the correct form. 1468 1469Although the decryption operation can produce an error if padding is enabled, 1470it is not a strong test that the input data or key is correct. A random block 1471has better than 1 in 256 chance of being of the correct format and problems with 1472the input data earlier on will not produce a final decrypt error. 1473 1474If padding is disabled then the decryption operation will always succeed if 1475the total amount of data decrypted is a multiple of the block size. 1476 1477The functions EVP_EncryptInit(), EVP_EncryptInit_ex(), 1478EVP_EncryptFinal(), EVP_DecryptInit(), EVP_DecryptInit_ex(), 1479EVP_CipherInit(), EVP_CipherInit_ex() and EVP_CipherFinal() are obsolete 1480but are retained for compatibility with existing code. New code should 1481use EVP_EncryptInit_ex2(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex2(), 1482EVP_DecryptFinal_ex(), EVP_CipherInit_ex2() and EVP_CipherFinal_ex() 1483because they can reuse an existing context without allocating and freeing 1484it up on each call. 1485 1486There are some differences between functions EVP_CipherInit() and 1487EVP_CipherInit_ex(), significant in some circumstances. EVP_CipherInit() fills 1488the passed context object with zeros. As a consequence, EVP_CipherInit() does 1489not allow step-by-step initialization of the ctx when the I<key> and I<iv> are 1490passed in separate calls. It also means that the flags set for the CTX are 1491removed, and it is especially important for the 1492B<EVP_CIPHER_CTX_FLAG_WRAP_ALLOW> flag treated specially in 1493EVP_CipherInit_ex(). 1494 1495Ignoring failure returns of the B<EVP_CIPHER_CTX> initialization functions can 1496lead to subsequent undefined behavior when calling the functions that update or 1497finalize the context. The only valid calls on the B<EVP_CIPHER_CTX> when 1498initialization fails are calls that attempt another initialization of the 1499context or release the context. 1500 1501EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros. 1502 1503=head1 BUGS 1504 1505B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal 1506ciphers with default key lengths. If custom ciphers exceed these values the 1507results are unpredictable. This is because it has become standard practice to 1508define a generic key as a fixed unsigned char array containing 1509B<EVP_MAX_KEY_LENGTH> bytes. 1510 1511The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested 1512for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode. 1513 1514=head1 EXAMPLES 1515 1516Encrypt a string using IDEA: 1517 1518 int do_crypt(char *outfile) 1519 { 1520 unsigned char outbuf[1024]; 1521 int outlen, tmplen; 1522 /* 1523 * Bogus key and IV: we'd normally set these from 1524 * another source. 1525 */ 1526 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}; 1527 unsigned char iv[] = {1,2,3,4,5,6,7,8}; 1528 char intext[] = "Some Crypto Text"; 1529 EVP_CIPHER_CTX *ctx; 1530 FILE *out; 1531 1532 ctx = EVP_CIPHER_CTX_new(); 1533 if (!EVP_EncryptInit_ex2(ctx, EVP_idea_cbc(), key, iv, NULL)) { 1534 /* Error */ 1535 EVP_CIPHER_CTX_free(ctx); 1536 return 0; 1537 } 1538 1539 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) { 1540 /* Error */ 1541 EVP_CIPHER_CTX_free(ctx); 1542 return 0; 1543 } 1544 /* 1545 * Buffer passed to EVP_EncryptFinal() must be after data just 1546 * encrypted to avoid overwriting it. 1547 */ 1548 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) { 1549 /* Error */ 1550 EVP_CIPHER_CTX_free(ctx); 1551 return 0; 1552 } 1553 outlen += tmplen; 1554 EVP_CIPHER_CTX_free(ctx); 1555 /* 1556 * Need binary mode for fopen because encrypted data is 1557 * binary data. Also cannot use strlen() on it because 1558 * it won't be NUL terminated and may contain embedded 1559 * NULs. 1560 */ 1561 out = fopen(outfile, "wb"); 1562 if (out == NULL) { 1563 /* Error */ 1564 return 0; 1565 } 1566 fwrite(outbuf, 1, outlen, out); 1567 fclose(out); 1568 return 1; 1569 } 1570 1571The ciphertext from the above example can be decrypted using the B<openssl> 1572utility with the command line (shown on two lines for clarity): 1573 1574 openssl idea -d \ 1575 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename 1576 1577General encryption and decryption function example using FILE I/O and AES128 1578with a 128-bit key: 1579 1580 int do_crypt(FILE *in, FILE *out, int do_encrypt) 1581 { 1582 /* Allow enough space in output buffer for additional block */ 1583 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; 1584 int inlen, outlen; 1585 EVP_CIPHER_CTX *ctx; 1586 /* 1587 * Bogus key and IV: we'd normally set these from 1588 * another source. 1589 */ 1590 unsigned char key[] = "0123456789abcdeF"; 1591 unsigned char iv[] = "1234567887654321"; 1592 1593 /* Don't set key or IV right away; we want to check lengths */ 1594 ctx = EVP_CIPHER_CTX_new(); 1595 if (!EVP_CipherInit_ex2(ctx, EVP_aes_128_cbc(), NULL, NULL, 1596 do_encrypt, NULL)) { 1597 /* Error */ 1598 EVP_CIPHER_CTX_free(ctx); 1599 return 0; 1600 } 1601 OPENSSL_assert(EVP_CIPHER_CTX_get_key_length(ctx) == 16); 1602 OPENSSL_assert(EVP_CIPHER_CTX_get_iv_length(ctx) == 16); 1603 1604 /* Now we can set key and IV */ 1605 if (!EVP_CipherInit_ex2(ctx, NULL, key, iv, do_encrypt, NULL)) { 1606 /* Error */ 1607 EVP_CIPHER_CTX_free(ctx); 1608 return 0; 1609 } 1610 1611 for (;;) { 1612 inlen = fread(inbuf, 1, 1024, in); 1613 if (inlen <= 0) 1614 break; 1615 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) { 1616 /* Error */ 1617 EVP_CIPHER_CTX_free(ctx); 1618 return 0; 1619 } 1620 fwrite(outbuf, 1, outlen, out); 1621 } 1622 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) { 1623 /* Error */ 1624 EVP_CIPHER_CTX_free(ctx); 1625 return 0; 1626 } 1627 fwrite(outbuf, 1, outlen, out); 1628 1629 EVP_CIPHER_CTX_free(ctx); 1630 return 1; 1631 } 1632 1633Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext stealing. 1634 1635 int encrypt(const unsigned char *key, const unsigned char *iv, 1636 const unsigned char *msg, size_t msg_len, unsigned char *out) 1637 { 1638 /* 1639 * This assumes that key size is 32 bytes and the iv is 16 bytes. 1640 * For ciphertext stealing mode the length of the ciphertext "out" will be 1641 * the same size as the plaintext size "msg_len". 1642 * The "msg_len" can be any size >= 16. 1643 */ 1644 int ret = 0, encrypt = 1, outlen, len; 1645 EVP_CIPHER_CTX *ctx = NULL; 1646 EVP_CIPHER *cipher = NULL; 1647 OSSL_PARAM params[2]; 1648 1649 ctx = EVP_CIPHER_CTX_new(); 1650 cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL); 1651 if (ctx == NULL || cipher == NULL) 1652 goto err; 1653 1654 /* 1655 * The default is "CS1" so this is not really needed, 1656 * but would be needed to set either "CS2" or "CS3". 1657 */ 1658 params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE, 1659 "CS1", 0); 1660 params[1] = OSSL_PARAM_construct_end(); 1661 1662 if (!EVP_CipherInit_ex2(ctx, cipher, key, iv, encrypt, params)) 1663 goto err; 1664 1665 /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */ 1666 if (!EVP_CipherUpdate(ctx, out, &outlen, msg, msg_len)) 1667 goto err; 1668 if (!EVP_CipherFinal_ex(ctx, out + outlen, &len)) 1669 goto err; 1670 ret = 1; 1671 err: 1672 EVP_CIPHER_free(cipher); 1673 EVP_CIPHER_CTX_free(ctx); 1674 return ret; 1675 } 1676 1677=head1 SEE ALSO 1678 1679L<evp(7)>, 1680L<property(7)>, 1681L<crypto(7)/ALGORITHM FETCHING>, 1682L<provider-cipher(7)>, 1683L<life_cycle-cipher(7)> 1684 1685Supported ciphers are listed in: 1686 1687L<EVP_aes_128_gcm(3)>, 1688L<EVP_aria_128_gcm(3)>, 1689L<EVP_bf_cbc(3)>, 1690L<EVP_camellia_128_ecb(3)>, 1691L<EVP_cast5_cbc(3)>, 1692L<EVP_chacha20(3)>, 1693L<EVP_des_cbc(3)>, 1694L<EVP_desx_cbc(3)>, 1695L<EVP_idea_cbc(3)>, 1696L<EVP_rc2_cbc(3)>, 1697L<EVP_rc4(3)>, 1698L<EVP_rc5_32_12_16_cbc(3)>, 1699L<EVP_seed_cbc(3)>, 1700L<EVP_sm4_cbc(3)>, 1701 1702=head1 HISTORY 1703 1704Support for OCB mode was added in OpenSSL 1.1.0. 1705 1706B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result, 1707EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup() 1708disappeared. EVP_CIPHER_CTX_init() remains as an alias for 1709EVP_CIPHER_CTX_reset(). 1710 1711The EVP_CIPHER_CTX_cipher() function was deprecated in OpenSSL 3.0; use 1712EVP_CIPHER_CTX_get0_cipher() instead. 1713 1714The EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2(), EVP_CipherInit_ex2(), 1715EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(), 1716EVP_CIPHER_CTX_get0_cipher(), EVP_CIPHER_CTX_get1_cipher(), 1717EVP_CIPHER_get_params(), EVP_CIPHER_CTX_set_params(), 1718EVP_CIPHER_CTX_get_params(), EVP_CIPHER_gettable_params(), 1719EVP_CIPHER_settable_ctx_params(), EVP_CIPHER_gettable_ctx_params(), 1720EVP_CIPHER_CTX_settable_params() and EVP_CIPHER_CTX_gettable_params() 1721functions were added in 3.0. 1722 1723The EVP_CIPHER_nid(), EVP_CIPHER_name(), EVP_CIPHER_block_size(), 1724EVP_CIPHER_key_length(), EVP_CIPHER_iv_length(), EVP_CIPHER_flags(), 1725EVP_CIPHER_mode(), EVP_CIPHER_type(), EVP_CIPHER_CTX_nid(), 1726EVP_CIPHER_CTX_block_size(), EVP_CIPHER_CTX_key_length(), 1727EVP_CIPHER_CTX_iv_length(), EVP_CIPHER_CTX_tag_length(), 1728EVP_CIPHER_CTX_num(), EVP_CIPHER_CTX_type(), and EVP_CIPHER_CTX_mode() 1729functions were renamed to include C<get> or C<get0> in their names in 1730OpenSSL 3.0, respectively. The old names are kept as non-deprecated 1731alias macros. 1732 1733The EVP_CIPHER_CTX_encrypting() function was renamed to 1734EVP_CIPHER_CTX_is_encrypting() in OpenSSL 3.0. The old name is kept as 1735non-deprecated alias macro. 1736 1737The EVP_CIPHER_CTX_flags() macro was deprecated in OpenSSL 1.1.0. 1738 1739=head1 COPYRIGHT 1740 1741Copyright 2000-2024 The OpenSSL Project Authors. All Rights Reserved. 1742 1743Licensed under the Apache License 2.0 (the "License"). You may not use 1744this file except in compliance with the License. You can obtain a copy 1745in the file LICENSE in the source distribution or at 1746L<https://www.openssl.org/source/license.html>. 1747 1748=cut 1749