5 provider-cipher - The cipher library E<lt>-E<gt> provider functions
9 =for openssl multiple includes
11 #include <openssl/core_dispatch.h>
12 #include <openssl/core_names.h>
15 * None of these are actual functions, but are displayed like this for
16 * the function signatures for functions that are offered as function
17 * pointers in OSSL_DISPATCH arrays.
20 /* Context management */
21 void *OSSL_FUNC_cipher_newctx(void *provctx);
22 void OSSL_FUNC_cipher_freectx(void *cctx);
23 void *OSSL_FUNC_cipher_dupctx(void *cctx);
25 /* Encryption/decryption */
26 int OSSL_FUNC_cipher_encrypt_init(void *cctx, const unsigned char *key,
27 size_t keylen, const unsigned char *iv,
28 size_t ivlen, const OSSL_PARAM params[]);
29 int OSSL_FUNC_cipher_decrypt_init(void *cctx, const unsigned char *key,
30 size_t keylen, const unsigned char *iv,
31 size_t ivlen, const OSSL_PARAM params[]);
32 int OSSL_FUNC_cipher_update(void *cctx, unsigned char *out, size_t *outl,
33 size_t outsize, const unsigned char *in, size_t inl);
34 int OSSL_FUNC_cipher_final(void *cctx, unsigned char *out, size_t *outl,
36 int OSSL_FUNC_cipher_cipher(void *cctx, unsigned char *out, size_t *outl,
37 size_t outsize, const unsigned char *in, size_t inl);
39 /* Cipher parameter descriptors */
40 const OSSL_PARAM *OSSL_FUNC_cipher_gettable_params(void *provctx);
42 /* Cipher operation parameter descriptors */
43 const OSSL_PARAM *OSSL_FUNC_cipher_gettable_ctx_params(void *cctx,
45 const OSSL_PARAM *OSSL_FUNC_cipher_settable_ctx_params(void *cctx,
48 /* Cipher parameters */
49 int OSSL_FUNC_cipher_get_params(OSSL_PARAM params[]);
51 /* Cipher operation parameters */
52 int OSSL_FUNC_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]);
53 int OSSL_FUNC_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]);
57 This documentation is primarily aimed at provider authors. See L<provider(7)>
58 for further information.
60 The CIPHER operation enables providers to implement cipher algorithms and make
61 them available to applications via the API functions L<EVP_EncryptInit_ex(3)>,
62 L<EVP_EncryptUpdate(3)> and L<EVP_EncryptFinal(3)> (as well as the decrypt
63 equivalents and other related functions).
65 All "functions" mentioned here are passed as function pointers between
66 F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
67 B<OSSL_ALGORITHM> arrays that are returned by the provider's
68 provider_query_operation() function
69 (see L<provider-base(7)/Provider Functions>).
71 All these "functions" have a corresponding function type definition
72 named B<OSSL_{name}_fn>, and a helper function to retrieve the
73 function pointer from an B<OSSL_DISPATCH> element named
75 For example, the "function" OSSL_FUNC_cipher_newctx() has these:
77 typedef void *(OSSL_OSSL_FUNC_cipher_newctx_fn)(void *provctx);
78 static ossl_inline OSSL_OSSL_FUNC_cipher_newctx_fn
79 OSSL_FUNC_cipher_newctx(const OSSL_DISPATCH *opf);
81 B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
82 macros in L<openssl-core_dispatch.h(7)>, as follows:
84 OSSL_FUNC_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX
85 OSSL_FUNC_cipher_freectx OSSL_FUNC_CIPHER_FREECTX
86 OSSL_FUNC_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX
88 OSSL_FUNC_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT
89 OSSL_FUNC_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT
90 OSSL_FUNC_cipher_update OSSL_FUNC_CIPHER_UPDATE
91 OSSL_FUNC_cipher_final OSSL_FUNC_CIPHER_FINAL
92 OSSL_FUNC_cipher_cipher OSSL_FUNC_CIPHER_CIPHER
94 OSSL_FUNC_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS
95 OSSL_FUNC_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS
96 OSSL_FUNC_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS
98 OSSL_FUNC_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS
99 OSSL_FUNC_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS
100 OSSL_FUNC_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS
102 A cipher algorithm implementation may not implement all of these functions.
103 In order to be a consistent set of functions there must at least be a complete
104 set of "encrypt" functions, or a complete set of "decrypt" functions, or a
105 single "cipher" function.
106 In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be
108 All other functions are optional.
110 =head2 Context Management Functions
112 OSSL_FUNC_cipher_newctx() should create and return a pointer to a provider side
113 structure for holding context information during a cipher operation.
114 A pointer to this context will be passed back in a number of the other cipher
115 operation function calls.
116 The parameter I<provctx> is the provider context generated during provider
117 initialisation (see L<provider(7)>).
119 OSSL_FUNC_cipher_freectx() is passed a pointer to the provider side cipher context in
120 the I<cctx> parameter.
121 This function should free any resources associated with that context.
123 OSSL_FUNC_cipher_dupctx() should duplicate the provider side cipher context in the
124 I<cctx> parameter and return the duplicate copy.
126 =head2 Encryption/Decryption Functions
128 OSSL_FUNC_cipher_encrypt_init() initialises a cipher operation for encryption given a
129 newly created provider side cipher context in the I<cctx> parameter.
130 The key to be used is given in I<key> which is I<keylen> bytes long.
131 The IV to be used is given in I<iv> which is I<ivlen> bytes long.
132 The I<params>, if not NULL, should be set on the context in a manner similar to
133 using OSSL_FUNC_cipher_set_ctx_params().
135 OSSL_FUNC_cipher_decrypt_init() is the same as OSSL_FUNC_cipher_encrypt_init() except that it
136 initialises the context for a decryption operation.
138 OSSL_FUNC_cipher_update() is called to supply data to be encrypted/decrypted as part of
139 a previously initialised cipher operation.
140 The I<cctx> parameter contains a pointer to a previously initialised provider
142 OSSL_FUNC_cipher_update() should encrypt/decrypt I<inl> bytes of data at the location
144 The encrypted data should be stored in I<out> and the amount of data written to
145 I<*outl> which should not exceed I<outsize> bytes.
146 OSSL_FUNC_cipher_update() may be called multiple times for a single cipher operation.
147 It is the responsibility of the cipher implementation to handle input lengths
148 that are not multiples of the block length.
149 In such cases a cipher implementation will typically cache partial blocks of
150 input data until a complete block is obtained.
151 I<out> may be the same location as I<in> but it should not partially overlap.
152 The same expectations apply to I<outsize> as documented for
153 L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>.
155 OSSL_FUNC_cipher_final() completes an encryption or decryption started through previous
156 OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(), and OSSL_FUNC_cipher_update()
158 The I<cctx> parameter contains a pointer to the provider side context.
159 Any final encryption/decryption output should be written to I<out> and the
160 amount of data written to I<*outl> which should not exceed I<outsize> bytes.
161 The same expectations apply to I<outsize> as documented for
162 L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>.
164 OSSL_FUNC_cipher_cipher() performs encryption/decryption using the provider side cipher
165 context in the I<cctx> parameter that should have been previously initialised via
166 a call to OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init().
167 This should call the raw underlying cipher function without any padding.
168 This will be invoked in the provider as a result of the application calling
170 The application is responsible for ensuring that the input is a multiple of the
172 The data to be encrypted/decrypted will be in I<in>, and it will be I<inl> bytes
174 The output from the encryption/decryption should be stored in I<out> and the
175 amount of data stored should be put in I<*outl> which should be no more than
178 =head2 Cipher Parameters
180 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
183 OSSL_FUNC_cipher_get_params() gets details of the algorithm implementation
184 and stores them in I<params>.
186 OSSL_FUNC_cipher_set_ctx_params() sets cipher operation parameters for the
187 provider side cipher context I<cctx> to I<params>.
188 Any parameter settings are additional to any that were previously set.
189 Passing NULL for I<params> should return true.
191 OSSL_FUNC_cipher_get_ctx_params() gets cipher operation details details from
192 the given provider side cipher context I<cctx> and stores them in I<params>.
193 Passing NULL for I<params> should return true.
195 OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params(),
196 and OSSL_FUNC_cipher_settable_ctx_params() all return constant B<OSSL_PARAM>
197 arrays as descriptors of the parameters that OSSL_FUNC_cipher_get_params(),
198 OSSL_FUNC_cipher_get_ctx_params(), and OSSL_FUNC_cipher_set_ctx_params()
199 can handle, respectively. OSSL_FUNC_cipher_gettable_ctx_params() and
200 OSSL_FUNC_cipher_settable_ctx_params() will return the parameters associated
201 with the provider side context I<cctx> in its current state if it is
202 not NULL. Otherwise, they return the parameters associated with the
203 provider side algorithm I<provctx>.
205 Parameters currently recognised by built-in ciphers are as follows. Not all
206 parameters are relevant to, or are understood by all ciphers:
210 =item "padding" (B<OSSL_CIPHER_PARAM_PADDING>) <unsigned integer>
212 Sets the padding mode for the associated cipher ctx.
213 Setting a value of 1 will turn padding on.
214 Setting a value of 0 will turn padding off.
216 =item "mode" (B<OSSL_CIPHER_PARAM_MODE>) <unsigned integer>
218 Gets the mode for the associated cipher algorithm.
219 See L<EVP_CIPHER_mode(3)> for a list of valid modes.
221 =item "blocksize" (B<OSSL_CIPHER_PARAM_BLOCK_SIZE>) <unsigned integer>
223 Gets the block size for the associated cipher algorithm.
224 The block size should be 1 for stream ciphers.
225 Note that the block size for a cipher may be different to the block size for
226 the underlying encryption/decryption primitive.
227 For example AES in CTR mode has a block size of 1 (because it operates like a
228 stream cipher), even though AES has a block size of 16.
229 The length of the "blocksize" parameter should not exceed that of a B<size_t>.
231 =item "aead" (B<OSSL_CIPHER_PARAM_AEAD>) <integer>
233 Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0.
235 =item "custom-iv" (B<OSSL_CIPHER_PARAM_CUSTOM_IV>) <integer>
237 Gets 1 if the cipher algorithm has a custom IV, otherwise it gets 0.
238 Storing and initializing the IV is left entirely to the implementation, if a
241 =item "cts" (B<OSSL_CIPHER_PARAM_CTS>) <integer>
243 Gets 1 if the cipher algorithm uses ciphertext stealing, otherwise it gets 0.
244 This is currently used to indicate that the cipher is a one shot that only
245 allows a single call to EVP_CipherUpdate().
247 =item "tls-multi" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK>) <integer>
249 Gets 1 if the cipher algorithm supports interleaving of crypto blocks, otherwise
250 it gets 0. The interleaving is an optimization only applicable to certain
253 =item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer>
255 Gets the key length for the associated cipher algorithm.
256 This can also be used to get or set the key length for the associated cipher
258 The length of the "keylen" parameter should not exceed that of a B<size_t>.
260 =item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) <unsigned integer>
262 Gets the IV length for the associated cipher algorithm.
263 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
265 =item "iv" (B<OSSL_CIPHER_PARAM_IV>) <octet string OR octet ptr>
267 Gets the IV used to initialize the associated cipher ctx.
269 =item "updated-iv" (B<OSSL_CIPHER_PARAM_UPDATED_IV>) <octet string OR octet ptr>
271 Gets the updated pseudo-IV state for the associated cipher ctx, e.g.,
272 the previous ciphertext block for CBC mode or the iteratively encrypted IV
273 value for OFB mode. Note that octet pointer access is deprecated and is
274 provided only for backwards compatibility with historical libcrypto APIs.
276 =item "num" (B<OSSL_CIPHER_PARAM_NUM>) <unsigned integer>
278 Gets or sets the cipher specific "num" parameter for the associated cipher ctx.
279 Built-in ciphers typically use this to track how much of the current underlying
280 block has been "used" already.
282 =item "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>) <octet string>
284 Gets or sets the AEAD tag for the associated cipher ctx.
285 See L<EVP_EncryptInit(3)/AEAD Interface>.
287 =item "taglen" (B<OSSL_CIPHER_PARAM_AEAD_TAGLEN>) <unsigned integer>
289 Gets the tag length to be used for an AEAD cipher for the associated cipher ctx.
290 It gets a default value if it has not been set.
291 The length of the "taglen" parameter should not exceed that of a B<size_t>.
293 =item "tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) <octet string>
295 =for comment TODO(3.0): Consider changing this interface so that all ciphers
296 use the standard AEAD interface - rather than having this special purpose
299 Sets TLSv1.2 AAD information for the associated cipher ctx.
300 TLSv1.2 AAD information is always 13 bytes in length and is as defined for the
301 "additional_data" field described in section 6.2.3.3 of RFC5246.
303 =item "tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>) <unsigned integer>
305 Gets the length of the tag that will be added to a TLS record for the AEAD
306 tag for the associated cipher ctx.
307 The length of the "tlsaadpad" parameter should not exceed that of a B<size_t>.
309 =item "tlsivfixed" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>) <octet string>
311 =for comment TODO(3.0): This interface needs completely redesigning!
313 Sets the fixed portion of an IV for an AEAD cipher used in a TLS record
314 encryption/ decryption for the associated cipher ctx.
315 TLS record encryption/decryption always occurs "in place" so that the input and
316 output buffers are always the same memory location.
317 AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part
318 that varies with every record.
319 Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records.
320 TLS records are encrypted/decrypted using a single OSSL_FUNC_cipher_cipher call per
322 For a record decryption the first bytes of the input buffer will be the explicit
323 part of the IV and the final bytes of the input buffer will be the AEAD tag.
324 The length of the explicit part of the IV and the tag length will depend on the
325 cipher in use and will be defined in the RFC for the relevant ciphersuite.
326 In order to allow for "in place" decryption the plaintext output should be
327 written to the same location in the output buffer that the ciphertext payload
328 was read from, i.e. immediately after the explicit IV.
330 When encrypting a record the first bytes of the input buffer will be empty to
331 allow space for the explicit IV, as will the final bytes where the tag will
333 The length of the input buffer will include the length of the explicit IV, the
334 payload, and the tag bytes.
335 The cipher implementation should generate the explicit IV and write it to the
336 beginning of the output buffer, do "in place" encryption of the payload and
337 write that to the output buffer, and finally add the tag onto the end of the
340 Whether encrypting or decrypting the value written to I<*outl> in the
341 OSSL_FUNC_cipher_cipher call should be the length of the payload excluding the explicit
342 IV length and the tag length.
344 =item "ivlen" (B<OSSL_CIPHER_PARAM_AEAD_IVLEN>) <unsigned integer>
346 Sets the IV length to be used for an AEAD cipher for the associated cipher ctx.
347 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
349 =item "mackey" (B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>) <octet string>
351 Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256.
353 =item "randkey" (B<OSSL_CIPHER_PARAM_RANDOM_KEY>) <octet string>
355 Gets a implementation specific randomly generated key for the associated
356 cipher ctx. This is currently only supported by 3DES (which sets the key to
359 =item "alg_id_param" (B<OSSL_CIPHER_PARAM_ALG_ID>) <octet string>
361 Used to pass the DER encoded AlgorithmIdentifier parameter to or from
362 the cipher implementation. Functions like L<EVP_CIPHER_param_to_asn1(3)>
363 and L<EVP_CIPHER_asn1_to_param(3)> use this parameter for any implementation
364 that has the flag B<EVP_CIPH_FLAG_CUSTOM_ASN1> set.
366 =item "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>) <unsigned integer>
368 Sets or gets the number of rounds to be used for a cipher.
369 This is used by the RC5 cipher.
371 =item "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>) <unsigned integer>
373 Gets or sets the effective keybits used for a RC2 cipher.
374 The length of the "keybits" parameter should not exceed that of a B<size_t>.
376 =item "speed" (B<OSSL_CIPHER_PARAM_SPEED>) <unsigned integer>
378 Sets the speed option for the associated cipher ctx. This is only supported
379 by AES SIV ciphers which disallow multiple operations by default.
380 Setting "speed" to 1 allows another encrypt or decrypt operation to be
381 performed. This is used for performance testing.
383 =item "tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>) <octet string>
385 Gets the invocation field generated for encryption.
386 Can only be called after "tlsivfixed" is set.
387 This is only used for GCM mode.
389 =item "tlsivinv" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>) <octet string>
391 Sets the invocation field used for decryption.
392 Can only be called after "tlsivfixed" is set.
393 This is only used for GCM mode.
395 =item "tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>) <octet string>
397 Triggers a multiblock tls1 encrypt operation for a tls1 aware cipher that supports
398 sending 4 or 8 records in one go.
399 The cipher performs both the MAC and encrypt stages and constructs the record
401 "tls1multi_enc" supplies the output buffer for the encrypt operation,
402 "tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply
403 values to the encrypt operation.
405 =item "tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>) <unsigned integer>
407 Get the total length of the record returned from the "tls1multi_enc" operation.
409 =item "tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) <unsigned integer>
411 Sets or gets the number of records being sent in one go for a tls1 multiblock
412 cipher operation (either 4 or 8 records).
414 =item "tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) <octet string>
416 Supplies the data to encrypt for a tls1 multiblock cipher operation.
418 =item "tls1multi_maxsndfrag" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT>) <unsigned integer>
420 Sets the maximum send fragment size for a tls1 multiblock cipher operation.
421 It must be set before using "tls1multi_maxbufsz".
422 The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a B<size_t>.
424 =item "tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>) <unsigned integer>
426 Gets the maximum record length for a tls1 multiblock cipher operation.
427 The length of the "tls1multi_maxbufsz" parameter should not exceed that of a B<size_t>.
429 =item "tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) <octet string>
431 Sets the authenticated additional data used by a tls1 multiblock cipher operation.
432 The supplied data consists of 13 bytes of record data containing:
433 Bytes 0-7: The sequence number of the first record
434 Byte 8: The record type
435 Byte 9-10: The protocol version
436 Byte 11-12: Input length (Always 0)
438 "tls1multi_interleave" must also be set for this operation.
440 =item "tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) <unsigned integer>
442 Gets the result of running the "tls1multi_aad" operation.
444 =item "cts_mode" (B<OSSL_CIPHER_PARAM_CTS_MODE>) <utf8 string>
446 Sets the cipher text stealing mode. For all modes the output size is the same as
449 Valid values for the mode are:
455 The NIST variant of cipher text stealing.
456 For message lengths that are multiples of the block size it is equivalent to
457 using a "AES-CBC" cipher otherwise the second last cipher text block is a
462 For message lengths that are multiples of the block size it is equivalent to
463 using a "AES-CBC" cipher, otherwise it is the same as "CS3".
467 The Kerberos5 variant of cipher text stealing which always swaps the last
468 cipher text block with the previous block (which may be a partial or full block
469 depending on the input length).
473 The default is "CS1".
474 This is only supported for "AES-128-CBC-CTS", "AES-192-CBC-CTS" and "AES-256-CBC-CTS".
480 OSSL_FUNC_cipher_newctx() and OSSL_FUNC_cipher_dupctx() should return the newly created
481 provider side cipher context, or NULL on failure.
483 OSSL_FUNC_cipher_encrypt_init(), OSSL_FUNC_cipher_decrypt_init(), OSSL_FUNC_cipher_update(),
484 OSSL_FUNC_cipher_final(), OSSL_FUNC_cipher_cipher(), OSSL_FUNC_cipher_get_params(),
485 OSSL_FUNC_cipher_get_ctx_params() and OSSL_FUNC_cipher_set_ctx_params() should return 1 for
486 success or 0 on error.
488 OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params() and
489 OSSL_FUNC_cipher_settable_ctx_params() should return a constant B<OSSL_PARAM>
490 array, or NULL if none is offered.
498 The provider CIPHER interface was introduced in OpenSSL 3.0.
502 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
504 Licensed under the Apache License 2.0 (the "License"). You may not use
505 this file except in compliance with the License. You can obtain a copy
506 in the file LICENSE in the source distribution or at
507 L<https://www.openssl.org/source/license.html>.