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. 271 272=item EVP_CIPHER_CTX_new() 273 274Allocates and returns a cipher context. 275 276=item EVP_CIPHER_CTX_free() 277 278Clears all information from a cipher context and frees any allocated memory 279associated with it, including I<ctx> itself. This function should be called after 280all operations using a cipher are complete so sensitive information does not 281remain in memory. 282 283=item EVP_CIPHER_CTX_ctrl() 284 285I<This is a legacy method.> EVP_CIPHER_CTX_set_params() and 286EVP_CIPHER_CTX_get_params() is the mechanism that should be used to set and get 287parameters that are used by providers. 288 289Performs cipher-specific control actions on context I<ctx>. The control command 290is indicated in I<cmd> and any additional arguments in I<p1> and I<p2>. 291EVP_CIPHER_CTX_ctrl() must be called after EVP_CipherInit_ex2(). Other restrictions 292may apply depending on the control type and cipher implementation. 293 294If this function happens to be used with a fetched B<EVP_CIPHER>, it will 295translate the controls that are known to OpenSSL into L<OSSL_PARAM(3)> 296parameters with keys defined by OpenSSL and call EVP_CIPHER_CTX_get_params() or 297EVP_CIPHER_CTX_set_params() as is appropriate for each control command. 298 299See L</CONTROLS> below for more information, including what translations are 300being done. 301 302=item EVP_CIPHER_get_params() 303 304Retrieves the requested list of algorithm I<params> from a CIPHER I<cipher>. 305See L</PARAMETERS> below for more information. 306 307=item EVP_CIPHER_CTX_get_params() 308 309Retrieves the requested list of I<params> from CIPHER context I<ctx>. 310See L</PARAMETERS> below for more information. 311 312=item EVP_CIPHER_CTX_set_params() 313 314Sets the list of I<params> into a CIPHER context I<ctx>. 315See L</PARAMETERS> below for more information. 316 317=item EVP_CIPHER_gettable_params() 318 319Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters 320that can be used with EVP_CIPHER_get_params(). 321 322=item EVP_CIPHER_gettable_ctx_params() and EVP_CIPHER_CTX_gettable_params() 323 324Get a constant L<OSSL_PARAM(3)> array that describes the retrievable parameters 325that can be used with EVP_CIPHER_CTX_get_params(). 326EVP_CIPHER_gettable_ctx_params() returns the parameters that can be retrieved 327from the algorithm, whereas EVP_CIPHER_CTX_gettable_params() returns the 328parameters that can be retrieved in the context's current state. 329 330=item EVP_CIPHER_settable_ctx_params() and EVP_CIPHER_CTX_settable_params() 331 332Get a constant L<OSSL_PARAM(3)> array that describes the settable parameters 333that can be used with EVP_CIPHER_CTX_set_params(). 334EVP_CIPHER_settable_ctx_params() returns the parameters that can be set from the 335algorithm, whereas EVP_CIPHER_CTX_settable_params() returns the parameters that 336can be set in the context's current state. 337 338=item EVP_EncryptInit_ex2() 339 340Sets up cipher context I<ctx> for encryption with cipher I<type>. I<type> is 341typically supplied by calling EVP_CIPHER_fetch(). I<type> may also be set 342using legacy functions such as EVP_aes_256_cbc(), but this is not recommended 343for new applications. I<key> is the symmetric key to use and I<iv> is the IV to 344use (if necessary), the actual number of bytes used for the key and IV depends 345on the cipher. The parameters I<params> will be set on the context after 346initialisation. It is possible to set all parameters to NULL except I<type> in 347an initial call and supply the remaining parameters in subsequent calls, all of 348which have I<type> set to NULL. This is done when the default cipher parameters 349are not appropriate. 350For B<EVP_CIPH_GCM_MODE> the IV will be generated internally if it is not 351specified. 352 353=item EVP_EncryptInit_ex() 354 355This legacy function is similar to EVP_EncryptInit_ex2() when I<impl> is NULL. 356The implementation of the I<type> from the I<impl> engine will be used if it 357exists. 358 359=item EVP_EncryptUpdate() 360 361Encrypts I<inl> bytes from the buffer I<in> and writes the encrypted version to 362I<out>. This function can be called multiple times to encrypt successive blocks 363of data. The amount of data written depends on the block alignment of the 364encrypted data. 365For most ciphers and modes, the amount of data written can be anything 366from zero bytes to (inl + cipher_block_size - 1) bytes. 367For wrap cipher modes, the amount of data written can be anything 368from zero bytes to (inl + cipher_block_size) bytes. 369For stream ciphers, the amount of data written can be anything from zero 370bytes to inl bytes. 371Thus, I<out> should contain sufficient room for the operation being performed. 372The actual number of bytes written is placed in I<outl>. It also 373checks if I<in> and I<out> are partially overlapping, and if they are 3740 is returned to indicate failure. 375 376If padding is enabled (the default) then EVP_EncryptFinal_ex() encrypts 377the "final" data, that is any data that remains in a partial block. 378It uses standard block padding (aka PKCS padding) as described in 379the NOTES section, below. The encrypted 380final data is written to I<out> which should have sufficient space for 381one cipher block. The number of bytes written is placed in I<outl>. After 382this function is called the encryption operation is finished and no further 383calls to EVP_EncryptUpdate() should be made. 384 385If padding is disabled then EVP_EncryptFinal_ex() will not encrypt any more 386data and it will return an error if any data remains in a partial block: 387that is if the total data length is not a multiple of the block size. 388 389=item EVP_DecryptInit_ex2(), EVP_DecryptInit_ex(), EVP_DecryptUpdate() 390and EVP_DecryptFinal_ex() 391 392These functions are the corresponding decryption operations. 393EVP_DecryptFinal() will return an error code if padding is enabled and the 394final block is not correctly formatted. The parameters and restrictions are 395identical to the encryption operations except that if padding is enabled the 396decrypted data buffer I<out> passed to EVP_DecryptUpdate() should have 397sufficient room for (I<inl> + cipher_block_size) bytes unless the cipher block 398size is 1 in which case I<inl> bytes is sufficient. 399 400=item EVP_CipherInit_ex2(), EVP_CipherInit_ex(), EVP_CipherUpdate() and 401EVP_CipherFinal_ex() 402 403These functions can be used for decryption or encryption. The operation 404performed depends on the value of the I<enc> parameter. It should be set to 1 405for encryption, 0 for decryption and -1 to leave the value unchanged 406(the actual value of 'enc' being supplied in a previous call). 407 408=item EVP_CIPHER_CTX_reset() 409 410Clears all information from a cipher context and free up any allocated memory 411associated with it, except the I<ctx> itself. This function should be called 412anytime I<ctx> is reused by another 413EVP_CipherInit() / EVP_CipherUpdate() / EVP_CipherFinal() series of calls. 414 415=item EVP_EncryptInit(), EVP_DecryptInit() and EVP_CipherInit() 416 417Behave in a similar way to EVP_EncryptInit_ex(), EVP_DecryptInit_ex() and 418EVP_CipherInit_ex() except if the I<type> is not a fetched cipher they use the 419default implementation of the I<type>. 420 421=item EVP_EncryptFinal(), EVP_DecryptFinal() and EVP_CipherFinal() 422 423Identical to EVP_EncryptFinal_ex(), EVP_DecryptFinal_ex() and 424EVP_CipherFinal_ex(). In previous releases they also cleaned up 425the I<ctx>, but this is no longer done and EVP_CIPHER_CTX_cleanup() 426must be called to free any context resources. 427 428=item EVP_Cipher() 429 430Encrypts or decrypts a maximum I<inl> amount of bytes from I<in> and leaves the 431result in I<out>. 432 433For legacy ciphers - If the cipher doesn't have the flag 434B<EVP_CIPH_FLAG_CUSTOM_CIPHER> set, then I<inl> must be a multiple of 435EVP_CIPHER_get_block_size(). If it isn't, the result is undefined. If the cipher 436has that flag set, then I<inl> can be any size. 437 438Due to the constraints of the API contract of this function it shouldn't be used 439in applications, please consider using EVP_CipherUpdate() and 440EVP_CipherFinal_ex() instead. 441 442=item EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 443 444Returns an B<EVP_CIPHER> structure when passed a cipher name, a cipher B<NID> or 445an B<ASN1_OBJECT> structure respectively. 446 447EVP_get_cipherbyname() will return NULL for algorithms such as "AES-128-SIV", 448"AES-128-CBC-CTS" and "CAMELLIA-128-CBC-CTS" which were previously only 449accessible via low level interfaces. 450 451The EVP_get_cipherbyname() function is present for backwards compatibility with 452OpenSSL prior to version 3 and is different to the EVP_CIPHER_fetch() function 453since it does not attempt to "fetch" an implementation of the cipher. 454Additionally, it only knows about ciphers that are built-in to OpenSSL and have 455an associated NID. Similarly EVP_get_cipherbynid() and EVP_get_cipherbyobj() 456also return objects without an associated implementation. 457 458When the cipher objects returned by these functions are used (such as in a call 459to EVP_EncryptInit_ex()) an implementation of the cipher will be implicitly 460fetched from the loaded providers. This fetch could fail if no suitable 461implementation is available. Use EVP_CIPHER_fetch() instead to explicitly fetch 462the algorithm and an associated implementation from a provider. 463 464See L<crypto(7)/ALGORITHM FETCHING> for more information about fetching. 465 466The cipher objects returned from these functions do not need to be freed with 467EVP_CIPHER_free(). 468 469=item EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() 470 471Return the NID of a cipher when passed an B<EVP_CIPHER> or B<EVP_CIPHER_CTX> 472structure. The actual NID value is an internal value which may not have a 473corresponding OBJECT IDENTIFIER. 474 475=item EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags() 476 477Sets, clears and tests I<ctx> flags. See L</FLAGS> below for more information. 478 479For provided ciphers EVP_CIPHER_CTX_set_flags() should be called only after the 480fetched cipher has been assigned to the I<ctx>. It is recommended to use 481L</PARAMETERS> instead. 482 483=item EVP_CIPHER_CTX_set_padding() 484 485Enables or disables padding. This function should be called after the context 486is set up for encryption or decryption with EVP_EncryptInit_ex2(), 487EVP_DecryptInit_ex2() or EVP_CipherInit_ex2(). By default encryption operations 488are padded using standard block padding and the padding is checked and removed 489when decrypting. If the I<pad> parameter is zero then no padding is 490performed, the total amount of data encrypted or decrypted must then 491be a multiple of the block size or an error will occur. 492 493=item EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() 494 495Return the key length of a cipher when passed an B<EVP_CIPHER> or 496B<EVP_CIPHER_CTX> structure. The constant B<EVP_MAX_KEY_LENGTH> is the maximum 497key length for all ciphers. Note: although EVP_CIPHER_get_key_length() is fixed for 498a given cipher, the value of EVP_CIPHER_CTX_get_key_length() may be different for 499variable key length ciphers. 500 501=item EVP_CIPHER_CTX_set_key_length() 502 503Sets the key length of the cipher context. 504If the cipher is a fixed length cipher then attempting to set the key 505length to any value other than the fixed value is an error. 506 507=item EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() 508 509Return the IV length of a cipher when passed an B<EVP_CIPHER> or 510B<EVP_CIPHER_CTX>. It will return zero if the cipher does not use an IV. 511The constant B<EVP_MAX_IV_LENGTH> is the maximum IV length for all ciphers. 512 513=item EVP_CIPHER_CTX_get_tag_length() 514 515Returns the tag length of an AEAD cipher when passed a B<EVP_CIPHER_CTX>. It will 516return zero if the cipher does not support a tag. It returns a default value if 517the tag length has not been set. 518 519=item EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() 520 521Return the block size of a cipher when passed an B<EVP_CIPHER> or 522B<EVP_CIPHER_CTX> structure. The constant B<EVP_MAX_BLOCK_LENGTH> is also the 523maximum block length for all ciphers. 524 525=item EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() 526 527Return the type of the passed cipher or context. This "type" is the actual NID 528of the cipher OBJECT IDENTIFIER and as such it ignores the cipher parameters 529(40 bit RC2 and 128 bit RC2 have the same NID). If the cipher does not have an 530object identifier or does not have ASN1 support this function will return 531B<NID_undef>. 532 533=item EVP_CIPHER_is_a() 534 535Returns 1 if I<cipher> is an implementation of an algorithm that's identifiable 536with I<name>, otherwise 0. If I<cipher> is a legacy cipher (it's the return 537value from the likes of EVP_aes128() rather than the result of an 538EVP_CIPHER_fetch()), only cipher names registered with the default library 539context (see L<OSSL_LIB_CTX(3)>) will be considered. 540 541=item EVP_CIPHER_get0_name() and EVP_CIPHER_CTX_get0_name() 542 543Return the name of the passed cipher or context. For fetched ciphers with 544multiple names, only one of them is returned. See also EVP_CIPHER_names_do_all(). 545 546=item EVP_CIPHER_names_do_all() 547 548Traverses all names for the I<cipher>, and calls I<fn> with each name and 549I<data>. This is only useful with fetched B<EVP_CIPHER>s. 550 551=item EVP_CIPHER_get0_description() 552 553Returns a description of the cipher, meant for display and human consumption. 554The description is at the discretion of the cipher implementation. 555 556=item EVP_CIPHER_get0_provider() 557 558Returns an B<OSSL_PROVIDER> pointer to the provider that implements the given 559B<EVP_CIPHER>. 560 561=item EVP_CIPHER_CTX_get0_cipher() 562 563Returns the B<EVP_CIPHER> structure when passed an B<EVP_CIPHER_CTX> structure. 564EVP_CIPHER_CTX_get1_cipher() is the same except the ownership is passed to 565the caller. 566 567=item EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode() 568 569Return the block cipher mode: 570EVP_CIPH_ECB_MODE, EVP_CIPH_CBC_MODE, EVP_CIPH_CFB_MODE, EVP_CIPH_OFB_MODE, 571EVP_CIPH_CTR_MODE, EVP_CIPH_GCM_MODE, EVP_CIPH_CCM_MODE, EVP_CIPH_XTS_MODE, 572EVP_CIPH_WRAP_MODE, EVP_CIPH_OCB_MODE or EVP_CIPH_SIV_MODE. 573If the cipher is a stream cipher then EVP_CIPH_STREAM_CIPHER is returned. 574 575=item EVP_CIPHER_get_flags() 576 577Returns any flags associated with the cipher. See L</FLAGS> 578for a list of currently defined flags. 579 580=item EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num() 581 582Gets or sets the cipher specific "num" parameter for the associated I<ctx>. 583Built-in ciphers typically use this to track how much of the current underlying block 584has been "used" already. 585 586=item EVP_CIPHER_CTX_is_encrypting() 587 588Reports whether the I<ctx> is being used for encryption or decryption. 589 590=item EVP_CIPHER_CTX_flags() 591 592A deprecated macro calling C<EVP_CIPHER_get_flags(EVP_CIPHER_CTX_get0_cipher(ctx))>. 593Do not use. 594 595=item EVP_CIPHER_param_to_asn1() 596 597Sets the AlgorithmIdentifier "parameter" based on the passed cipher. This will 598typically include any parameters and an IV. The cipher IV (if any) must be set 599when this call is made. This call should be made before the cipher is actually 600"used" (before any EVP_EncryptUpdate(), EVP_DecryptUpdate() calls for example). 601This function may fail if the cipher does not have any ASN1 support. 602 603=item EVP_CIPHER_asn1_to_param() 604 605Sets the cipher parameters based on an ASN1 AlgorithmIdentifier "parameter". 606The precise effect depends on the cipher. In the case of B<RC2>, for example, 607it will set the IV and effective key length. 608This function should be called after the base cipher type is set but before 609the key is set. For example EVP_CipherInit() will be called with the IV and 610key set to NULL, EVP_CIPHER_asn1_to_param() will be called and finally 611EVP_CipherInit() again with all parameters except the key set to NULL. It is 612possible for this function to fail if the cipher does not have any ASN1 support 613or the parameters cannot be set (for example the RC2 effective key length 614is not supported. 615 616=item EVP_CIPHER_CTX_rand_key() 617 618Generates a random key of the appropriate length based on the cipher context. 619The B<EVP_CIPHER> can provide its own random key generation routine to support 620keys of a specific form. I<key> must point to a buffer at least as big as the 621value returned by EVP_CIPHER_CTX_get_key_length(). 622 623=item EVP_CIPHER_do_all_provided() 624 625Traverses all ciphers implemented by all activated providers in the given 626library context I<libctx>, and for each of the implementations, calls the given 627function I<fn> with the implementation method and the given I<arg> as argument. 628 629=back 630 631=head1 PARAMETERS 632 633See L<OSSL_PARAM(3)> for information about passing parameters. 634 635=head2 Gettable EVP_CIPHER parameters 636 637When EVP_CIPHER_fetch() is called it internally calls EVP_CIPHER_get_params() 638and caches the results. 639 640EVP_CIPHER_get_params() can be used with the following L<OSSL_PARAM(3)> keys: 641 642=over 4 643 644=item "mode" (B<OSSL_CIPHER_PARAM_MODE>) <unsigned integer> 645 646Gets the mode for the associated cipher algorithm I<cipher>. 647See L</EVP_CIPHER_get_mode() and EVP_CIPHER_CTX_get_mode()> for a list of valid modes. 648Use EVP_CIPHER_get_mode() to retrieve the cached value. 649 650=item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer> 651 652Gets the key length for the associated cipher algorithm I<cipher>. 653Use EVP_CIPHER_get_key_length() to retrieve the cached value. 654 655=item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) <unsigned integer> 656 657Gets the IV length for the associated cipher algorithm I<cipher>. 658Use EVP_CIPHER_get_iv_length() to retrieve the cached value. 659 660=item "blocksize" (B<OSSL_CIPHER_PARAM_BLOCK_SIZE>) <unsigned integer> 661 662Gets the block size for the associated cipher algorithm I<cipher>. 663The block size should be 1 for stream ciphers. 664Note that the block size for a cipher may be different to the block size for 665the underlying encryption/decryption primitive. 666For example AES in CTR mode has a block size of 1 (because it operates like a 667stream cipher), even though AES has a block size of 16. 668Use EVP_CIPHER_get_block_size() to retrieve the cached value. 669 670=item "aead" (B<OSSL_CIPHER_PARAM_AEAD>) <integer> 671 672Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0. 673Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) to retrieve the 674cached value. 675 676=item "custom-iv" (B<OSSL_CIPHER_PARAM_CUSTOM_IV>) <integer> 677 678Gets 1 if the cipher algorithm I<cipher> has a custom IV, otherwise it gets 0. 679Storing and initializing the IV is left entirely to the implementation, if a 680custom IV is used. 681Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_CUSTOM_IV) to retrieve the 682cached value. 683 684=item "cts" (B<OSSL_CIPHER_PARAM_CTS>) <integer> 685 686Gets 1 if the cipher algorithm I<cipher> uses ciphertext stealing, 687otherwise it gets 0. 688This is currently used to indicate that the cipher is a one shot that only 689allows a single call to EVP_CipherUpdate(). 690Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_CTS) to retrieve the 691cached value. 692 693=item "tls-multi" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK>) <integer> 694 695Gets 1 if the cipher algorithm I<cipher> supports interleaving of crypto blocks, 696otherwise it gets 0. The interleaving is an optimization only applicable to certain 697TLS ciphers. 698Use (EVP_CIPHER_get_flags(cipher) & EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK) to retrieve the 699cached value. 700 701=item "has-randkey" (B<OSSL_CIPHER_PARAM_HAS_RANDKEY>) <integer> 702 703Gets 1 if the cipher algorithm I<cipher> supports the gettable EVP_CIPHER_CTX 704parameter B<OSSL_CIPHER_PARAM_RANDOM_KEY>. Only DES and 3DES set this to 1, 705all other OpenSSL ciphers return 0. 706 707=back 708 709=head2 Gettable and Settable EVP_CIPHER_CTX parameters 710 711The following L<OSSL_PARAM(3)> keys can be used with both EVP_CIPHER_CTX_get_params() 712and EVP_CIPHER_CTX_set_params(). 713 714=over 4 715 716=item "padding" (B<OSSL_CIPHER_PARAM_PADDING>) <unsigned integer> 717 718Gets or sets the padding mode for the cipher context I<ctx>. 719Padding is enabled if the value is 1, and disabled if the value is 0. 720See also EVP_CIPHER_CTX_set_padding(). 721 722=item "num" (B<OSSL_CIPHER_PARAM_NUM>) <unsigned integer> 723 724Gets or sets the cipher specific "num" parameter for the cipher context I<ctx>. 725Built-in ciphers typically use this to track how much of the current underlying 726block has been "used" already. 727See also EVP_CIPHER_CTX_get_num() and EVP_CIPHER_CTX_set_num(). 728 729=item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer> 730 731Gets or sets the key length for the cipher context I<ctx>. 732The length of the "keylen" parameter should not exceed that of a B<size_t>. 733See also EVP_CIPHER_CTX_get_key_length() and EVP_CIPHER_CTX_set_key_length(). 734 735=item "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>) <octet string> 736 737Gets or sets the AEAD tag for the associated cipher context I<ctx>. 738See L<EVP_EncryptInit(3)/AEAD Interface>. 739 740=item "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>) <unsigned integer> 741 742Gets or sets the effective keybits used for a RC2 cipher. 743The length of the "keybits" parameter should not exceed that of a B<size_t>. 744 745=item "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>) <unsigned integer> 746 747Gets or sets the number of rounds to be used for a cipher. 748This is used by the RC5 cipher. 749 750=item "alg_id_param" (B<OSSL_CIPHER_PARAM_ALGORITHM_ID_PARAMS>) <octet string> 751 752Used to pass the DER encoded AlgorithmIdentifier parameter to or from 753the cipher implementation. Functions like L<EVP_CIPHER_param_to_asn1(3)> 754and L<EVP_CIPHER_asn1_to_param(3)> use this parameter for any implementation 755that has the flag B<EVP_CIPH_FLAG_CUSTOM_ASN1> set. 756 757=item "cts_mode" (B<OSSL_CIPHER_PARAM_CTS_MODE>) <UTF8 string> 758 759Gets or sets the cipher text stealing mode. For all modes the output size is the 760same as the input size. The input length must be greater than or equal to the 761block size. (The block size for AES and CAMELLIA is 16 bytes). 762 763Valid values for the mode are: 764 765=over 4 766 767=item "CS1" 768 769The NIST variant of cipher text stealing. 770For input lengths that are multiples of the block size it is equivalent to 771using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher otherwise the second last 772cipher text block is a partial block. 773 774=item "CS2" 775 776For input lengths that are multiples of the block size it is equivalent to 777using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher, otherwise it is the same as 778"CS3" mode. 779 780=item "CS3" 781 782The Kerberos5 variant of cipher text stealing which always swaps the last 783cipher text block with the previous block (which may be a partial or full block 784depending on the input length). If the input length is exactly one full block 785then this is equivalent to using a "AES-XXX-CBC" or "CAMELLIA-XXX-CBC" cipher. 786 787=back 788 789The default is "CS1". 790This is only supported for "AES-128-CBC-CTS", "AES-192-CBC-CTS", "AES-256-CBC-CTS", 791"CAMELLIA-128-CBC-CTS", "CAMELLIA-192-CBC-CTS" and "CAMELLIA-256-CBC-CTS". 792 793=item "tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) <unsigned integer> 794 795Sets or gets the number of records being sent in one go for a tls1 multiblock 796cipher operation (either 4 or 8 records). 797 798=back 799 800=head2 Gettable EVP_CIPHER_CTX parameters 801 802The following L<OSSL_PARAM(3)> keys can be used with EVP_CIPHER_CTX_get_params(): 803 804=over 4 805 806=item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN> and <B<OSSL_CIPHER_PARAM_AEAD_IVLEN>) <unsigned integer> 807 808Gets the IV length for the cipher context I<ctx>. 809The length of the "ivlen" parameter should not exceed that of a B<size_t>. 810See also EVP_CIPHER_CTX_get_iv_length(). 811 812=item "iv" (B<OSSL_CIPHER_PARAM_IV>) <octet string OR octet ptr> 813 814Gets the IV used to initialize the associated cipher context I<ctx>. 815See also EVP_CIPHER_CTX_get_original_iv(). 816 817=item "updated-iv" (B<OSSL_CIPHER_PARAM_UPDATED_IV>) <octet string OR octet ptr> 818 819Gets the updated pseudo-IV state for the associated cipher context, e.g., 820the previous ciphertext block for CBC mode or the iteratively encrypted IV 821value for OFB mode. Note that octet pointer access is deprecated and is 822provided only for backwards compatibility with historical libcrypto APIs. 823See also EVP_CIPHER_CTX_get_updated_iv(). 824 825=item "randkey" (B<OSSL_CIPHER_PARAM_RANDOM_KEY>) <octet string> 826 827Gets an implementation specific randomly generated key for the associated 828cipher context I<ctx>. This is currently only supported by DES and 3DES (which set 829the key to odd parity). 830 831=item "taglen" (B<OSSL_CIPHER_PARAM_AEAD_TAGLEN>) <unsigned integer> 832 833Gets the tag length to be used for an AEAD cipher for the associated cipher 834context I<ctx>. It gets a default value if it has not been set. 835The length of the "taglen" parameter should not exceed that of a B<size_t>. 836See also EVP_CIPHER_CTX_get_tag_length(). 837 838=item "tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>) <unsigned integer> 839 840Gets the length of the tag that will be added to a TLS record for the AEAD 841tag for the associated cipher context I<ctx>. 842The length of the "tlsaadpad" parameter should not exceed that of a B<size_t>. 843 844=item "tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>) <octet string> 845 846Gets the invocation field generated for encryption. 847Can only be called after "tlsivfixed" is set. 848This is only used for GCM mode. 849 850=item "tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>) <unsigned integer> 851 852Get the total length of the record returned from the "tls1multi_enc" operation. 853 854=item "tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>) <unsigned integer> 855 856Gets the maximum record length for a TLS1 multiblock cipher operation. 857The length of the "tls1multi_maxbufsz" parameter should not exceed that of a B<size_t>. 858 859=item "tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) <unsigned integer> 860 861Gets the result of running the "tls1multi_aad" operation. 862 863=item "tls-mac" (B<OSSL_CIPHER_PARAM_TLS_MAC>) <octet ptr> 864 865Used to pass the TLS MAC data. 866 867=back 868 869=head2 Settable EVP_CIPHER_CTX parameters 870 871The following L<OSSL_PARAM(3)> keys can be used with EVP_CIPHER_CTX_set_params(): 872 873=over 4 874 875=item "mackey" (B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>) <octet string> 876 877Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256. 878 879=item "speed" (B<OSSL_CIPHER_PARAM_SPEED>) <unsigned integer> 880 881Sets the speed option for the associated cipher context. This is only supported 882by AES SIV ciphers which disallow multiple operations by default. 883Setting "speed" to 1 allows another encrypt or decrypt operation to be 884performed. This is used for performance testing. 885 886=item "use-bits" (B<OSSL_CIPHER_PARAM_USE_BITS>) <unsigned integer> 887 888Determines if the input length I<inl> passed to EVP_EncryptUpdate(), 889EVP_DecryptUpdate() and EVP_CipherUpdate() is the number of bits or number of bytes. 890Setting "use-bits" to 1 uses bits. The default is in bytes. 891This is only used for B<CFB1> ciphers. 892 893This can be set using EVP_CIPHER_CTX_set_flags(ctx, EVP_CIPH_FLAG_LENGTH_BITS). 894 895=item "tls-version" (B<OSSL_CIPHER_PARAM_TLS_VERSION>) <integer> 896 897Sets the TLS version. 898 899=item "tls-mac-size" (B<OSSL_CIPHER_PARAM_TLS_MAC_SIZE>) <unsigned integer> 900 901Set the TLS MAC size. 902 903=item "tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) <octet string> 904 905Sets TLSv1.2 AAD information for the associated cipher context I<ctx>. 906TLSv1.2 AAD information is always 13 bytes in length and is as defined for the 907"additional_data" field described in section 6.2.3.3 of RFC5246. 908 909=item "tlsivfixed" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>) <octet string> 910 911Sets the fixed portion of an IV for an AEAD cipher used in a TLS record 912encryption/ decryption for the associated cipher context. 913TLS record encryption/decryption always occurs "in place" so that the input and 914output buffers are always the same memory location. 915AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part 916that varies with every record. 917Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records. 918TLS records are encrypted/decrypted using a single OSSL_FUNC_cipher_cipher call per 919record. 920For a record decryption the first bytes of the input buffer will be the explicit 921part of the IV and the final bytes of the input buffer will be the AEAD tag. 922The length of the explicit part of the IV and the tag length will depend on the 923cipher in use and will be defined in the RFC for the relevant ciphersuite. 924In order to allow for "in place" decryption the plaintext output should be 925written to the same location in the output buffer that the ciphertext payload 926was read from, i.e. immediately after the explicit IV. 927 928When encrypting a record the first bytes of the input buffer should be empty to 929allow space for the explicit IV, as will the final bytes where the tag will 930be written. 931The length of the input buffer will include the length of the explicit IV, the 932payload, and the tag bytes. 933The cipher implementation should generate the explicit IV and write it to the 934beginning of the output buffer, do "in place" encryption of the payload and 935write that to the output buffer, and finally add the tag onto the end of the 936output buffer. 937 938Whether encrypting or decrypting the value written to I<*outl> in the 939OSSL_FUNC_cipher_cipher call should be the length of the payload excluding the explicit 940IV length and the tag length. 941 942=item "tlsivinv" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>) <octet string> 943 944Sets the invocation field used for decryption. 945Can only be called after "tlsivfixed" is set. 946This is only used for GCM mode. 947 948=item "tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>) <octet string> 949 950Triggers a multiblock TLS1 encrypt operation for a TLS1 aware cipher that 951supports sending 4 or 8 records in one go. 952The cipher performs both the MAC and encrypt stages and constructs the record 953headers itself. 954"tls1multi_enc" supplies the output buffer for the encrypt operation, 955"tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply 956values to the encrypt operation. 957 958=item "tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) <octet string> 959 960Supplies the data to encrypt for a TLS1 multiblock cipher operation. 961 962=item "tls1multi_maxsndfrag" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT>) <unsigned integer> 963 964Sets the maximum send fragment size for a TLS1 multiblock cipher operation. 965It must be set before using "tls1multi_maxbufsz". 966The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a B<size_t>. 967 968=item "tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) <octet string> 969 970Sets the authenticated additional data used by a TLS1 multiblock cipher operation. 971The supplied data consists of 13 bytes of record data containing: 972Bytes 0-7: The sequence number of the first record 973Byte 8: The record type 974Byte 9-10: The protocol version 975Byte 11-12: Input length (Always 0) 976 977"tls1multi_interleave" must also be set for this operation. 978 979=back 980 981=head1 CONTROLS 982 983The Mappings from EVP_CIPHER_CTX_ctrl() identifiers to PARAMETERS are listed 984in the following section. See the L</PARAMETERS> section for more details. 985 986EVP_CIPHER_CTX_ctrl() can be used to send the following standard controls: 987 988=over 4 989 990=item EVP_CTRL_AEAD_SET_IVLEN and EVP_CTRL_GET_IVLEN 991 992When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 993EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 994key "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>). 995 996=item EVP_CTRL_AEAD_SET_IV_FIXED 997 998When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 999with an L<OSSL_PARAM(3)> item with the key "tlsivfixed" 1000(B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>). 1001 1002=item EVP_CTRL_AEAD_SET_MAC_KEY 1003 1004When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1005with an L<OSSL_PARAM(3)> item with the key "mackey" 1006(B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>). 1007 1008=item EVP_CTRL_AEAD_SET_TAG and EVP_CTRL_AEAD_GET_TAG 1009 1010When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1011EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1012key "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>). 1013 1014=item EVP_CTRL_CCM_SET_L 1015 1016When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1017with an L<OSSL_PARAM(3)> item with the key "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) 1018with a value of (15 - L) 1019 1020=item EVP_CTRL_COPY 1021 1022There is no OSSL_PARAM mapping for this. Use EVP_CIPHER_CTX_copy() instead. 1023 1024=item EVP_CTRL_GCM_SET_IV_INV 1025 1026When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1027with an L<OSSL_PARAM(3)> item with the key "tlsivinv" 1028(B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>). 1029 1030=item EVP_CTRL_RAND_KEY 1031 1032When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1033with an L<OSSL_PARAM(3)> item with the key "randkey" 1034(B<OSSL_CIPHER_PARAM_RANDOM_KEY>). 1035 1036=item EVP_CTRL_SET_KEY_LENGTH 1037 1038When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1039with an L<OSSL_PARAM(3)> item with the key "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>). 1040 1041=item EVP_CTRL_SET_RC2_KEY_BITS and EVP_CTRL_GET_RC2_KEY_BITS 1042 1043When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1044EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1045key "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>). 1046 1047=item EVP_CTRL_SET_RC5_ROUNDS and EVP_CTRL_GET_RC5_ROUNDS 1048 1049When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() and 1050EVP_CIPHER_CTX_get_params() get called with an L<OSSL_PARAM(3)> item with the 1051key "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>). 1052 1053=item EVP_CTRL_SET_SPEED 1054 1055When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1056with an L<OSSL_PARAM(3)> item with the key "speed" (B<OSSL_CIPHER_PARAM_SPEED>). 1057 1058=item EVP_CTRL_GCM_IV_GEN 1059 1060When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_get_params() gets called 1061with an L<OSSL_PARAM(3)> item with the key 1062"tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>). 1063 1064=item EVP_CTRL_AEAD_TLS1_AAD 1065 1066When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() get called 1067with an L<OSSL_PARAM(3)> item with the key 1068"tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) 1069followed by EVP_CIPHER_CTX_get_params() with a key of 1070"tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>). 1071 1072=item EVP_CTRL_TLS1_1_MULTIBLOCK_MAX_BUFSIZE 1073 1074When used with a fetched B<EVP_CIPHER>, 1075EVP_CIPHER_CTX_set_params() gets called with an L<OSSL_PARAM(3)> item with the 1076key OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT 1077followed by EVP_CIPHER_CTX_get_params() with a key of 1078"tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>). 1079 1080=item EVP_CTRL_TLS1_1_MULTIBLOCK_AAD 1081 1082When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1083with L<OSSL_PARAM(3)> items with the keys 1084"tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) and 1085"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) 1086followed by EVP_CIPHER_CTX_get_params() with keys of 1087"tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) and 1088"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>). 1089 1090=item EVP_CTRL_TLS1_1_MULTIBLOCK_ENCRYPT 1091 1092When used with a fetched B<EVP_CIPHER>, EVP_CIPHER_CTX_set_params() gets called 1093with L<OSSL_PARAM(3)> items with the keys 1094"tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>), 1095"tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) and 1096"tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>), 1097followed by EVP_CIPHER_CTX_get_params() with a key of 1098"tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>). 1099 1100=back 1101 1102=head1 FLAGS 1103 1104EVP_CIPHER_CTX_set_flags(), EVP_CIPHER_CTX_clear_flags() and EVP_CIPHER_CTX_test_flags(). 1105can be used to manipulate and test these B<EVP_CIPHER_CTX> flags: 1106 1107=over 4 1108 1109=item EVP_CIPH_NO_PADDING 1110 1111Used by EVP_CIPHER_CTX_set_padding(). 1112 1113See also L</Gettable and Settable EVP_CIPHER_CTX parameters> "padding" 1114 1115=item EVP_CIPH_FLAG_LENGTH_BITS 1116 1117See L</Settable EVP_CIPHER_CTX parameters> "use-bits". 1118 1119=item EVP_CIPHER_CTX_FLAG_WRAP_ALLOW 1120 1121Used for Legacy purposes only. This flag needed to be set to indicate the 1122cipher handled wrapping. 1123 1124=back 1125 1126EVP_CIPHER_flags() uses the following flags that 1127have mappings to L</Gettable EVP_CIPHER parameters>: 1128 1129=over 4 1130 1131=item EVP_CIPH_FLAG_AEAD_CIPHER 1132 1133See L</Gettable EVP_CIPHER parameters> "aead". 1134 1135=item EVP_CIPH_CUSTOM_IV 1136 1137See L</Gettable EVP_CIPHER parameters> "custom-iv". 1138 1139=item EVP_CIPH_FLAG_CTS 1140 1141See L</Gettable EVP_CIPHER parameters> "cts". 1142 1143=item EVP_CIPH_FLAG_TLS1_1_MULTIBLOCK; 1144 1145See L</Gettable EVP_CIPHER parameters> "tls-multi". 1146 1147=item EVP_CIPH_RAND_KEY 1148 1149See L</Gettable EVP_CIPHER parameters> "has-randkey". 1150 1151=back 1152 1153EVP_CIPHER_flags() uses the following flags for legacy purposes only: 1154 1155=over 4 1156 1157=item EVP_CIPH_VARIABLE_LENGTH 1158 1159=item EVP_CIPH_FLAG_CUSTOM_CIPHER 1160 1161=item EVP_CIPH_ALWAYS_CALL_INIT 1162 1163=item EVP_CIPH_CTRL_INIT 1164 1165=item EVP_CIPH_CUSTOM_KEY_LENGTH 1166 1167=item EVP_CIPH_CUSTOM_COPY 1168 1169=item EVP_CIPH_FLAG_DEFAULT_ASN1 1170 1171See L<EVP_CIPHER_meth_set_flags(3)> for further information related to the above 1172flags. 1173 1174=back 1175 1176=head1 RETURN VALUES 1177 1178EVP_CIPHER_fetch() returns a pointer to a B<EVP_CIPHER> for success 1179and B<NULL> for failure. 1180 1181EVP_CIPHER_up_ref() returns 1 for success or 0 otherwise. 1182 1183EVP_CIPHER_CTX_new() returns a pointer to a newly created 1184B<EVP_CIPHER_CTX> for success and B<NULL> for failure. 1185 1186EVP_EncryptInit_ex2(), EVP_EncryptUpdate() and EVP_EncryptFinal_ex() 1187return 1 for success and 0 for failure. 1188 1189EVP_DecryptInit_ex2() and EVP_DecryptUpdate() return 1 for success and 0 for failure. 1190EVP_DecryptFinal_ex() returns 0 if the decrypt failed or 1 for success. 1191 1192EVP_CipherInit_ex2() and EVP_CipherUpdate() return 1 for success and 0 for failure. 1193EVP_CipherFinal_ex() returns 0 for a decryption failure or 1 for success. 1194 1195EVP_Cipher() returns 1 on success or 0 on failure, if the flag 1196B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is not set for the cipher. 1197EVP_Cipher() returns the number of bytes written to I<out> for encryption / decryption, or 1198the number of bytes authenticated in a call specifying AAD for an AEAD cipher, if the flag 1199B<EVP_CIPH_FLAG_CUSTOM_CIPHER> is set for the cipher. 1200 1201EVP_CIPHER_CTX_reset() returns 1 for success and 0 for failure. 1202 1203EVP_get_cipherbyname(), EVP_get_cipherbynid() and EVP_get_cipherbyobj() 1204return an B<EVP_CIPHER> structure or NULL on error. 1205 1206EVP_CIPHER_get_nid() and EVP_CIPHER_CTX_get_nid() return a NID. 1207 1208EVP_CIPHER_get_block_size() and EVP_CIPHER_CTX_get_block_size() return the 1209block size. 1210 1211EVP_CIPHER_get_key_length() and EVP_CIPHER_CTX_get_key_length() return the key 1212length. 1213 1214EVP_CIPHER_CTX_set_padding() always returns 1. 1215 1216EVP_CIPHER_get_iv_length() and EVP_CIPHER_CTX_get_iv_length() return the IV 1217length or zero if the cipher does not use an IV. 1218 1219EVP_CIPHER_CTX_get_tag_length() return the tag length or zero if the cipher 1220does not use a tag. 1221 1222EVP_CIPHER_get_type() and EVP_CIPHER_CTX_get_type() return the NID of the 1223cipher's OBJECT IDENTIFIER or NID_undef if it has no defined 1224OBJECT IDENTIFIER. 1225 1226EVP_CIPHER_CTX_cipher() returns an B<EVP_CIPHER> structure. 1227 1228EVP_CIPHER_CTX_get_num() returns a nonnegative num value or 1229B<EVP_CTRL_RET_UNSUPPORTED> if the implementation does not support the call 1230or on any other error. 1231 1232EVP_CIPHER_CTX_set_num() returns 1 on success and 0 if the implementation 1233does not support the call or on any other error. 1234 1235EVP_CIPHER_CTX_is_encrypting() returns 1 if the I<ctx> is set up for encryption 12360 otherwise. 1237 1238EVP_CIPHER_param_to_asn1() and EVP_CIPHER_asn1_to_param() return greater 1239than zero for success and zero or a negative number on failure. 1240 1241EVP_CIPHER_CTX_rand_key() returns 1 for success and zero or a negative number 1242for failure. 1243 1244EVP_CIPHER_names_do_all() returns 1 if the callback was called for all names. 1245A return value of 0 means that the callback was not called for any names. 1246 1247=head1 CIPHER LISTING 1248 1249All algorithms have a fixed key length unless otherwise stated. 1250 1251Refer to L</SEE ALSO> for the full list of ciphers available through the EVP 1252interface. 1253 1254=over 4 1255 1256=item EVP_enc_null() 1257 1258Null cipher: does nothing. 1259 1260=back 1261 1262=head1 AEAD INTERFACE 1263 1264The EVP interface for Authenticated Encryption with Associated Data (AEAD) 1265modes are subtly altered and several additional I<ctrl> operations are supported 1266depending on the mode specified. 1267 1268To specify additional authenticated data (AAD), a call to EVP_CipherUpdate(), 1269EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made with the output 1270parameter I<out> set to B<NULL>. In this case, on success, the parameter 1271I<outl> is set to the number of bytes authenticated. 1272 1273When decrypting, the return value of EVP_DecryptFinal() or EVP_CipherFinal() 1274indicates whether the operation was successful. If it does not indicate success, 1275the authentication operation has failed and any output data B<MUST NOT> be used 1276as it is corrupted. 1277 1278=head2 GCM and OCB Modes 1279 1280The following I<ctrl>s are supported in GCM and OCB modes. 1281 1282=over 4 1283 1284=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1285 1286Sets the IV length. This call can only be made before specifying an IV. If 1287not called a default IV length is used. 1288 1289For GCM AES and OCB AES the default is 12 (i.e. 96 bits). For OCB mode the 1290maximum is 15. 1291 1292=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag) 1293 1294Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>. 1295This call can only be made when encrypting data and B<after> all data has been 1296processed (e.g. after an EVP_EncryptFinal() call). 1297 1298For OCB, C<taglen> must either be 16 or the value previously set via 1299B<EVP_CTRL_AEAD_SET_TAG>. 1300 1301=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1302 1303When decrypting, this call sets the expected tag to C<taglen> bytes from C<tag>. 1304C<taglen> must be between 1 and 16 inclusive. 1305The tag must be set prior to any call to EVP_DecryptFinal() or 1306EVP_DecryptFinal_ex(). 1307 1308For GCM, this call is only valid when decrypting data. 1309 1310For OCB, this call is valid when decrypting data to set the expected tag, 1311and when encrypting to set the desired tag length. 1312 1313In OCB mode, calling this when encrypting with C<tag> set to C<NULL> sets the 1314tag length. The tag length can only be set before specifying an IV. If this is 1315not called prior to setting the IV during encryption, then a default tag length 1316is used. 1317 1318For OCB AES, the default tag length is 16 (i.e. 128 bits). It is also the 1319maximum tag length for OCB. 1320 1321=back 1322 1323=head2 CCM Mode 1324 1325The EVP interface for CCM mode is similar to that of the GCM mode but with a 1326few additional requirements and different I<ctrl> values. 1327 1328For CCM mode, the total plaintext or ciphertext length B<MUST> be passed to 1329EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() with the output 1330and input parameters (I<in> and I<out>) set to B<NULL> and the length passed in 1331the I<inl> parameter. 1332 1333The following I<ctrl>s are supported in CCM mode. 1334 1335=over 4 1336 1337=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1338 1339This call is made to set the expected B<CCM> tag value when decrypting or 1340the length of the tag (with the C<tag> parameter set to NULL) when encrypting. 1341The tag length is often referred to as B<M>. If not set a default value is 1342used (12 for AES). When decrypting, the tag needs to be set before passing 1343in data to be decrypted, but as in GCM and OCB mode, it can be set after 1344passing additional authenticated data (see L</AEAD INTERFACE>). 1345 1346=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_CCM_SET_L, ivlen, NULL) 1347 1348Sets the CCM B<L> value. If not set a default is used (8 for AES). 1349 1350=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1351 1352Sets the CCM nonce (IV) length. This call can only be made before specifying a 1353nonce value. The nonce length is given by B<15 - L> so it is 7 by default for 1354AES. 1355 1356=back 1357 1358=head2 SIV Mode 1359 1360For SIV mode ciphers the behaviour of the EVP interface is subtly 1361altered and several additional ctrl operations are supported. 1362 1363To specify any additional authenticated data (AAD) and/or a Nonce, a call to 1364EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made 1365with the output parameter I<out> set to B<NULL>. 1366 1367RFC5297 states that the Nonce is the last piece of AAD before the actual 1368encrypt/decrypt takes place. The API does not differentiate the Nonce from 1369other AAD. 1370 1371When decrypting the return value of EVP_DecryptFinal() or EVP_CipherFinal() 1372indicates if the operation was successful. If it does not indicate success 1373the authentication operation has failed and any output data B<MUST NOT> 1374be used as it is corrupted. 1375 1376The API does not store the the SIV (Synthetic Initialization Vector) in 1377the cipher text. Instead, it is stored as the tag within the EVP_CIPHER_CTX. 1378The SIV must be retrieved from the context after encryption, and set into 1379the context before decryption. 1380 1381This differs from RFC5297 in that the cipher output from encryption, and 1382the cipher input to decryption, does not contain the SIV. This also means 1383that the plain text and cipher text lengths are identical. 1384 1385The following ctrls are supported in SIV mode, and are used to get and set 1386the Synthetic Initialization Vector: 1387 1388=over 4 1389 1390=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag); 1391 1392Writes I<taglen> bytes of the tag value (the Synthetic Initialization Vector) 1393to the buffer indicated by I<tag>. This call can only be made when encrypting 1394data and B<after> all data has been processed (e.g. after an EVP_EncryptFinal() 1395call). For SIV mode the taglen must be 16. 1396 1397=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag); 1398 1399Sets the expected tag (the Synthetic Initialization Vector) to I<taglen> 1400bytes from I<tag>. This call is only legal when decrypting data and must be 1401made B<before> any data is processed (e.g. before any EVP_DecryptUpdate() 1402calls). For SIV mode the taglen must be 16. 1403 1404=back 1405 1406SIV mode makes two passes over the input data, thus, only one call to 1407EVP_CipherUpdate(), EVP_EncryptUpdate() or EVP_DecryptUpdate() should be made 1408with I<out> set to a non-B<NULL> value. A call to EVP_DecryptFinal() or 1409EVP_CipherFinal() is not required, but will indicate if the update 1410operation succeeded. 1411 1412=head2 ChaCha20-Poly1305 1413 1414The following I<ctrl>s are supported for the ChaCha20-Poly1305 AEAD algorithm. 1415 1416=over 4 1417 1418=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_IVLEN, ivlen, NULL) 1419 1420Sets the nonce length. This call is now redundant since the only valid value 1421is the default length of 12 (i.e. 96 bits). 1422Prior to OpenSSL 3.0 a nonce of less than 12 bytes could be used to automatically 1423pad the iv with leading 0 bytes to make it 12 bytes in length. 1424 1425=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_GET_TAG, taglen, tag) 1426 1427Writes C<taglen> bytes of the tag value to the buffer indicated by C<tag>. 1428This call can only be made when encrypting data and B<after> all data has been 1429processed (e.g. after an EVP_EncryptFinal() call). 1430 1431C<taglen> specified here must be 16 (B<POLY1305_BLOCK_SIZE>, i.e. 128-bits) or 1432less. 1433 1434=item EVP_CIPHER_CTX_ctrl(ctx, EVP_CTRL_AEAD_SET_TAG, taglen, tag) 1435 1436Sets the expected tag to C<taglen> bytes from C<tag>. 1437The tag length can only be set before specifying an IV. 1438C<taglen> must be between 1 and 16 (B<POLY1305_BLOCK_SIZE>) inclusive. 1439This call is only valid when decrypting data. 1440 1441=back 1442 1443=head1 NOTES 1444 1445Where possible the B<EVP> interface to symmetric ciphers should be used in 1446preference to the low-level interfaces. This is because the code then becomes 1447transparent to the cipher used and much more flexible. Additionally, the 1448B<EVP> interface will ensure the use of platform specific cryptographic 1449acceleration such as AES-NI (the low-level interfaces do not provide the 1450guarantee). 1451 1452PKCS padding works by adding B<n> padding bytes of value B<n> to make the total 1453length of the encrypted data a multiple of the block size. Padding is always 1454added so if the data is already a multiple of the block size B<n> will equal 1455the block size. For example if the block size is 8 and 11 bytes are to be 1456encrypted then 5 padding bytes of value 5 will be added. 1457 1458When decrypting the final block is checked to see if it has the correct form. 1459 1460Although the decryption operation can produce an error if padding is enabled, 1461it is not a strong test that the input data or key is correct. A random block 1462has better than 1 in 256 chance of being of the correct format and problems with 1463the input data earlier on will not produce a final decrypt error. 1464 1465If padding is disabled then the decryption operation will always succeed if 1466the total amount of data decrypted is a multiple of the block size. 1467 1468The functions EVP_EncryptInit(), EVP_EncryptInit_ex(), 1469EVP_EncryptFinal(), EVP_DecryptInit(), EVP_DecryptInit_ex(), 1470EVP_CipherInit(), EVP_CipherInit_ex() and EVP_CipherFinal() are obsolete 1471but are retained for compatibility with existing code. New code should 1472use EVP_EncryptInit_ex2(), EVP_EncryptFinal_ex(), EVP_DecryptInit_ex2(), 1473EVP_DecryptFinal_ex(), EVP_CipherInit_ex2() and EVP_CipherFinal_ex() 1474because they can reuse an existing context without allocating and freeing 1475it up on each call. 1476 1477There are some differences between functions EVP_CipherInit() and 1478EVP_CipherInit_ex(), significant in some circumstances. EVP_CipherInit() fills 1479the passed context object with zeros. As a consequence, EVP_CipherInit() does 1480not allow step-by-step initialization of the ctx when the I<key> and I<iv> are 1481passed in separate calls. It also means that the flags set for the CTX are 1482removed, and it is especially important for the 1483B<EVP_CIPHER_CTX_FLAG_WRAP_ALLOW> flag treated specially in 1484EVP_CipherInit_ex(). 1485 1486Ignoring failure returns of the B<EVP_CIPHER_CTX> initialization functions can 1487lead to subsequent undefined behavior when calling the functions that update or 1488finalize the context. The only valid calls on the B<EVP_CIPHER_CTX> when 1489initialization fails are calls that attempt another initialization of the 1490context or release the context. 1491 1492EVP_get_cipherbynid(), and EVP_get_cipherbyobj() are implemented as macros. 1493 1494=head1 BUGS 1495 1496B<EVP_MAX_KEY_LENGTH> and B<EVP_MAX_IV_LENGTH> only refer to the internal 1497ciphers with default key lengths. If custom ciphers exceed these values the 1498results are unpredictable. This is because it has become standard practice to 1499define a generic key as a fixed unsigned char array containing 1500B<EVP_MAX_KEY_LENGTH> bytes. 1501 1502The ASN1 code is incomplete (and sometimes inaccurate) it has only been tested 1503for certain common S/MIME ciphers (RC2, DES, triple DES) in CBC mode. 1504 1505=head1 EXAMPLES 1506 1507Encrypt a string using IDEA: 1508 1509 int do_crypt(char *outfile) 1510 { 1511 unsigned char outbuf[1024]; 1512 int outlen, tmplen; 1513 /* 1514 * Bogus key and IV: we'd normally set these from 1515 * another source. 1516 */ 1517 unsigned char key[] = {0,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15}; 1518 unsigned char iv[] = {1,2,3,4,5,6,7,8}; 1519 char intext[] = "Some Crypto Text"; 1520 EVP_CIPHER_CTX *ctx; 1521 FILE *out; 1522 1523 ctx = EVP_CIPHER_CTX_new(); 1524 if (!EVP_EncryptInit_ex2(ctx, EVP_idea_cbc(), key, iv, NULL)) { 1525 /* Error */ 1526 EVP_CIPHER_CTX_free(ctx); 1527 return 0; 1528 } 1529 1530 if (!EVP_EncryptUpdate(ctx, outbuf, &outlen, intext, strlen(intext))) { 1531 /* Error */ 1532 EVP_CIPHER_CTX_free(ctx); 1533 return 0; 1534 } 1535 /* 1536 * Buffer passed to EVP_EncryptFinal() must be after data just 1537 * encrypted to avoid overwriting it. 1538 */ 1539 if (!EVP_EncryptFinal_ex(ctx, outbuf + outlen, &tmplen)) { 1540 /* Error */ 1541 EVP_CIPHER_CTX_free(ctx); 1542 return 0; 1543 } 1544 outlen += tmplen; 1545 EVP_CIPHER_CTX_free(ctx); 1546 /* 1547 * Need binary mode for fopen because encrypted data is 1548 * binary data. Also cannot use strlen() on it because 1549 * it won't be NUL terminated and may contain embedded 1550 * NULs. 1551 */ 1552 out = fopen(outfile, "wb"); 1553 if (out == NULL) { 1554 /* Error */ 1555 return 0; 1556 } 1557 fwrite(outbuf, 1, outlen, out); 1558 fclose(out); 1559 return 1; 1560 } 1561 1562The ciphertext from the above example can be decrypted using the B<openssl> 1563utility with the command line (shown on two lines for clarity): 1564 1565 openssl idea -d \ 1566 -K 000102030405060708090A0B0C0D0E0F -iv 0102030405060708 <filename 1567 1568General encryption and decryption function example using FILE I/O and AES128 1569with a 128-bit key: 1570 1571 int do_crypt(FILE *in, FILE *out, int do_encrypt) 1572 { 1573 /* Allow enough space in output buffer for additional block */ 1574 unsigned char inbuf[1024], outbuf[1024 + EVP_MAX_BLOCK_LENGTH]; 1575 int inlen, outlen; 1576 EVP_CIPHER_CTX *ctx; 1577 /* 1578 * Bogus key and IV: we'd normally set these from 1579 * another source. 1580 */ 1581 unsigned char key[] = "0123456789abcdeF"; 1582 unsigned char iv[] = "1234567887654321"; 1583 1584 /* Don't set key or IV right away; we want to check lengths */ 1585 ctx = EVP_CIPHER_CTX_new(); 1586 if (!EVP_CipherInit_ex2(ctx, EVP_aes_128_cbc(), NULL, NULL, 1587 do_encrypt, NULL)) { 1588 /* Error */ 1589 EVP_CIPHER_CTX_free(ctx); 1590 return 0; 1591 } 1592 OPENSSL_assert(EVP_CIPHER_CTX_get_key_length(ctx) == 16); 1593 OPENSSL_assert(EVP_CIPHER_CTX_get_iv_length(ctx) == 16); 1594 1595 /* Now we can set key and IV */ 1596 if (!EVP_CipherInit_ex2(ctx, NULL, key, iv, do_encrypt, NULL)) { 1597 /* Error */ 1598 EVP_CIPHER_CTX_free(ctx); 1599 return 0; 1600 } 1601 1602 for (;;) { 1603 inlen = fread(inbuf, 1, 1024, in); 1604 if (inlen <= 0) 1605 break; 1606 if (!EVP_CipherUpdate(ctx, outbuf, &outlen, inbuf, inlen)) { 1607 /* Error */ 1608 EVP_CIPHER_CTX_free(ctx); 1609 return 0; 1610 } 1611 fwrite(outbuf, 1, outlen, out); 1612 } 1613 if (!EVP_CipherFinal_ex(ctx, outbuf, &outlen)) { 1614 /* Error */ 1615 EVP_CIPHER_CTX_free(ctx); 1616 return 0; 1617 } 1618 fwrite(outbuf, 1, outlen, out); 1619 1620 EVP_CIPHER_CTX_free(ctx); 1621 return 1; 1622 } 1623 1624Encryption using AES-CBC with a 256-bit key with "CS1" ciphertext stealing. 1625 1626 int encrypt(const unsigned char *key, const unsigned char *iv, 1627 const unsigned char *msg, size_t msg_len, unsigned char *out) 1628 { 1629 /* 1630 * This assumes that key size is 32 bytes and the iv is 16 bytes. 1631 * For ciphertext stealing mode the length of the ciphertext "out" will be 1632 * the same size as the plaintext size "msg_len". 1633 * The "msg_len" can be any size >= 16. 1634 */ 1635 int ret = 0, encrypt = 1, outlen, len; 1636 EVP_CIPHER_CTX *ctx = NULL; 1637 EVP_CIPHER *cipher = NULL; 1638 OSSL_PARAM params[2]; 1639 1640 ctx = EVP_CIPHER_CTX_new(); 1641 cipher = EVP_CIPHER_fetch(NULL, "AES-256-CBC-CTS", NULL); 1642 if (ctx == NULL || cipher == NULL) 1643 goto err; 1644 1645 /* 1646 * The default is "CS1" so this is not really needed, 1647 * but would be needed to set either "CS2" or "CS3". 1648 */ 1649 params[0] = OSSL_PARAM_construct_utf8_string(OSSL_CIPHER_PARAM_CTS_MODE, 1650 "CS1", 0); 1651 params[1] = OSSL_PARAM_construct_end(); 1652 1653 if (!EVP_CipherInit_ex2(ctx, cipher, key, iv, encrypt, params)) 1654 goto err; 1655 1656 /* NOTE: CTS mode does not support multiple calls to EVP_CipherUpdate() */ 1657 if (!EVP_CipherUpdate(ctx, out, &outlen, msg, msg_len)) 1658 goto err; 1659 if (!EVP_CipherFinal_ex(ctx, out + outlen, &len)) 1660 goto err; 1661 ret = 1; 1662 err: 1663 EVP_CIPHER_free(cipher); 1664 EVP_CIPHER_CTX_free(ctx); 1665 return ret; 1666 } 1667 1668=head1 SEE ALSO 1669 1670L<evp(7)>, 1671L<property(7)>, 1672L<crypto(7)/ALGORITHM FETCHING>, 1673L<provider-cipher(7)>, 1674L<life_cycle-cipher(7)> 1675 1676Supported ciphers are listed in: 1677 1678L<EVP_aes_128_gcm(3)>, 1679L<EVP_aria_128_gcm(3)>, 1680L<EVP_bf_cbc(3)>, 1681L<EVP_camellia_128_ecb(3)>, 1682L<EVP_cast5_cbc(3)>, 1683L<EVP_chacha20(3)>, 1684L<EVP_des_cbc(3)>, 1685L<EVP_desx_cbc(3)>, 1686L<EVP_idea_cbc(3)>, 1687L<EVP_rc2_cbc(3)>, 1688L<EVP_rc4(3)>, 1689L<EVP_rc5_32_12_16_cbc(3)>, 1690L<EVP_seed_cbc(3)>, 1691L<EVP_sm4_cbc(3)>, 1692 1693=head1 HISTORY 1694 1695Support for OCB mode was added in OpenSSL 1.1.0. 1696 1697B<EVP_CIPHER_CTX> was made opaque in OpenSSL 1.1.0. As a result, 1698EVP_CIPHER_CTX_reset() appeared and EVP_CIPHER_CTX_cleanup() 1699disappeared. EVP_CIPHER_CTX_init() remains as an alias for 1700EVP_CIPHER_CTX_reset(). 1701 1702The EVP_CIPHER_CTX_cipher() function was deprecated in OpenSSL 3.0; use 1703EVP_CIPHER_CTX_get0_cipher() instead. 1704 1705The EVP_EncryptInit_ex2(), EVP_DecryptInit_ex2(), EVP_CipherInit_ex2(), 1706EVP_CIPHER_fetch(), EVP_CIPHER_free(), EVP_CIPHER_up_ref(), 1707EVP_CIPHER_CTX_get0_cipher(), EVP_CIPHER_CTX_get1_cipher(), 1708EVP_CIPHER_get_params(), EVP_CIPHER_CTX_set_params(), 1709EVP_CIPHER_CTX_get_params(), EVP_CIPHER_gettable_params(), 1710EVP_CIPHER_settable_ctx_params(), EVP_CIPHER_gettable_ctx_params(), 1711EVP_CIPHER_CTX_settable_params() and EVP_CIPHER_CTX_gettable_params() 1712functions were added in 3.0. 1713 1714The EVP_CIPHER_nid(), EVP_CIPHER_name(), EVP_CIPHER_block_size(), 1715EVP_CIPHER_key_length(), EVP_CIPHER_iv_length(), EVP_CIPHER_flags(), 1716EVP_CIPHER_mode(), EVP_CIPHER_type(), EVP_CIPHER_CTX_nid(), 1717EVP_CIPHER_CTX_block_size(), EVP_CIPHER_CTX_key_length(), 1718EVP_CIPHER_CTX_iv_length(), EVP_CIPHER_CTX_tag_length(), 1719EVP_CIPHER_CTX_num(), EVP_CIPHER_CTX_type(), and EVP_CIPHER_CTX_mode() 1720functions were renamed to include C<get> or C<get0> in their names in 1721OpenSSL 3.0, respectively. The old names are kept as non-deprecated 1722alias macros. 1723 1724The EVP_CIPHER_CTX_encrypting() function was renamed to 1725EVP_CIPHER_CTX_is_encrypting() in OpenSSL 3.0. The old name is kept as 1726non-deprecated alias macro. 1727 1728The EVP_CIPHER_CTX_flags() macro was deprecated in OpenSSL 1.1.0. 1729 1730=head1 COPYRIGHT 1731 1732Copyright 2000-2023 The OpenSSL Project Authors. All Rights Reserved. 1733 1734Licensed under the Apache License 2.0 (the "License"). You may not use 1735this file except in compliance with the License. You can obtain a copy 1736in the file LICENSE in the source distribution or at 1737L<https://www.openssl.org/source/license.html>. 1738 1739=cut 1740