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,
29 int OSSL_FUNC_cipher_decrypt_init(void *cctx, const unsigned char *key,
30 size_t keylen, const unsigned char *iv,
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.
133 OSSL_FUNC_cipher_decrypt_init() is the same as OSSL_FUNC_cipher_encrypt_init() except that it
134 initialises the context for a decryption operation.
136 OSSL_FUNC_cipher_update() is called to supply data to be encrypted/decrypted as part of
137 a previously initialised cipher operation.
138 The I<cctx> parameter contains a pointer to a previously initialised provider
140 OSSL_FUNC_cipher_update() should encrypt/decrypt I<inl> bytes of data at the location
142 The encrypted data should be stored in I<out> and the amount of data written to
143 I<*outl> which should not exceed I<outsize> bytes.
144 OSSL_FUNC_cipher_update() may be called multiple times for a single cipher operation.
145 It is the responsibility of the cipher implementation to handle input lengths
146 that are not multiples of the block length.
147 In such cases a cipher implementation will typically cache partial blocks of
148 input data until a complete block is obtained.
149 I<out> may be the same location as I<in> but it should not partially overlap.
150 The same expectations apply to I<outsize> as documented for
151 L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>.
153 OSSL_FUNC_cipher_final() completes an encryption or decryption started through previous
154 OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(), and OSSL_FUNC_cipher_update()
156 The I<cctx> parameter contains a pointer to the provider side context.
157 Any final encryption/decryption output should be written to I<out> and the
158 amount of data written to I<*outl> which should not exceed I<outsize> bytes.
159 The same expectations apply to I<outsize> as documented for
160 L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>.
162 OSSL_FUNC_cipher_cipher() performs encryption/decryption using the provider side cipher
163 context in the I<cctx> parameter that should have been previously initialised via
164 a call to OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init().
165 This should call the raw underlying cipher function without any padding.
166 This will be invoked in the provider as a result of the application calling
168 The application is responsible for ensuring that the input is a multiple of the
170 The data to be encrypted/decrypted will be in I<in>, and it will be I<inl> bytes
172 The output from the encryption/decryption should be stored in I<out> and the
173 amount of data stored should be put in I<*outl> which should be no more than
176 =head2 Cipher Parameters
178 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
181 OSSL_FUNC_cipher_get_params() gets details of the algorithm implementation
182 and stores them in I<params>.
184 OSSL_FUNC_cipher_set_ctx_params() sets cipher operation parameters for the
185 provider side cipher context I<cctx> to I<params>.
186 Any parameter settings are additional to any that were previously set.
188 OSSL_FUNC_cipher_get_ctx_params() gets cipher operation details details from
189 the given provider side cipher context I<cctx> and stores them in I<params>.
191 OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params(),
192 and OSSL_FUNC_cipher_settable_ctx_params() all return constant B<OSSL_PARAM>
193 arrays as descriptors of the parameters that OSSL_FUNC_cipher_get_params(),
194 OSSL_FUNC_cipher_get_ctx_params(), and OSSL_FUNC_cipher_set_ctx_params()
195 can handle, respectively. OSSL_FUNC_cipher_gettable_ctx_params() and
196 OSSL_FUNC_cipher_settable_ctx_params() will return the parameters associated
197 with the provider side context I<cctx> in its current state if it is
198 not NULL. Otherwise, they return the parameters associated with the
199 provider side algorithm I<provctx>.
201 Parameters currently recognised by built-in ciphers are as follows. Not all
202 parameters are relevant to, or are understood by all ciphers:
206 =item "padding" (B<OSSL_CIPHER_PARAM_PADDING>) <unsigned integer>
208 Sets the padding mode for the associated cipher ctx.
209 Setting a value of 1 will turn padding on.
210 Setting a value of 0 will turn padding off.
212 =item "mode" (B<OSSL_CIPHER_PARAM_MODE>) <unsigned integer>
214 Gets the mode for the associated cipher algorithm.
215 See L<EVP_CIPHER_mode(3)> for a list of valid modes.
217 =item "blocksize" (B<OSSL_CIPHER_PARAM_BLOCK_SIZE>) <unsigned integer>
219 Gets the block size for the associated cipher algorithm.
220 The block size should be 1 for stream ciphers.
221 Note that the block size for a cipher may be different to the block size for
222 the underlying encryption/decryption primitive.
223 For example AES in CTR mode has a block size of 1 (because it operates like a
224 stream cipher), even though AES has a block size of 16.
225 The length of the "blocksize" parameter should not exceed that of a B<size_t>.
227 =item "aead" (B<OSSL_CIPHER_PARAM_AEAD>) <integer>
229 Gets 1 if this is an AEAD cipher algorithm, otherwise it gets 0.
231 =item "custom-iv" (B<OSSL_CIPHER_PARAM_CUSTOM_IV>) <integer>
233 Gets 1 if the cipher algorithm has a custom IV, otherwise it gets 0.
234 Storing and initializing the IV is left entirely to the implementation, if a
237 =item "cts" (B<OSSL_CIPHER_PARAM_CTS>) <integer>
239 Gets 1 if the cipher algorithm uses ciphertext stealing, otherwise it gets 0.
240 This is currently used to indicate that the cipher is a one shot that only
241 allows a single call to EVP_CipherUpdate().
243 =item "tls-multi" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK>) <integer>
245 Gets 1 if the cipher algorithm supports interleaving of crypto blocks, otherwise
246 it gets 0. The interleaving is an optimization only applicable to certain
249 =item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer>
251 Gets the key length for the associated cipher algorithm.
252 This can also be used to get or set the key length for the associated cipher
254 The length of the "keylen" parameter should not exceed that of a B<size_t>.
256 =item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) <unsigned integer>
258 Gets the IV length for the associated cipher algorithm.
259 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
261 =item "iv" (B<OSSL_CIPHER_PARAM_IV>) <octet string OR octet ptr>
263 Gets the IV used to initialize the associated cipher ctx.
265 =item "updated-iv" (B<OSSL_CIPHER_PARAM_UPDATED_IV>) <octet string OR octet ptr>
267 Gets the updated pseudo-IV state for the associated cipher ctx, e.g.,
268 the previous ciphertext block for CBC mode or the iteratively encrypted IV
269 value for OFB mode. Note that octet pointer access is deprecated and is
270 provided only for backwards compatibility with historical libcrypto APIs.
272 =item "num" (B<OSSL_CIPHER_PARAM_NUM>) <unsigned integer>
274 Gets or sets the cipher specific "num" parameter for the associated cipher ctx.
275 Built-in ciphers typically use this to track how much of the current underlying
276 block has been "used" already.
278 =item "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>) <octet string>
280 Gets or sets the AEAD tag for the associated cipher ctx.
281 See L<EVP_EncryptInit(3)/AEAD Interface>.
283 =item "taglen" (B<OSSL_CIPHER_PARAM_AEAD_TAGLEN>) <unsigned integer>
285 Gets the tag length to be used for an AEAD cipher for the associated cipher ctx.
286 It gets a default value if it has not been set.
287 The length of the "taglen" parameter should not exceed that of a B<size_t>.
289 =item "tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) <octet string>
291 =for comment TODO(3.0): Consider changing this interface so that all ciphers
292 use the standard AEAD interface - rather than having this special purpose
295 Sets TLSv1.2 AAD information for the associated cipher ctx.
296 TLSv1.2 AAD information is always 13 bytes in length and is as defined for the
297 "additional_data" field described in section 6.2.3.3 of RFC5246.
299 =item "tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>) <unsigned integer>
301 Gets the length of the tag that will be added to a TLS record for the AEAD
302 tag for the associated cipher ctx.
303 The length of the "tlsaadpad" parameter should not exceed that of a B<size_t>.
305 =item "tlsivfixed" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>) <octet string>
307 =for comment TODO(3.0): This interface needs completely redesigning!
309 Sets the fixed portion of an IV for an AEAD cipher used in a TLS record
310 encryption/ decryption for the associated cipher ctx.
311 TLS record encryption/decryption always occurs "in place" so that the input and
312 output buffers are always the same memory location.
313 AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part
314 that varies with every record.
315 Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records.
316 TLS records are encrypted/decrypted using a single OSSL_FUNC_cipher_cipher call per
318 For a record decryption the first bytes of the input buffer will be the explicit
319 part of the IV and the final bytes of the input buffer will be the AEAD tag.
320 The length of the explicit part of the IV and the tag length will depend on the
321 cipher in use and will be defined in the RFC for the relevant ciphersuite.
322 In order to allow for "in place" decryption the plaintext output should be
323 written to the same location in the output buffer that the ciphertext payload
324 was read from, i.e. immediately after the explicit IV.
326 When encrypting a record the first bytes of the input buffer will be empty to
327 allow space for the explicit IV, as will the final bytes where the tag will
329 The length of the input buffer will include the length of the explicit IV, the
330 payload, and the tag bytes.
331 The cipher implementation should generate the explicit IV and write it to the
332 beginning of the output buffer, do "in place" encryption of the payload and
333 write that to the output buffer, and finally add the tag onto the end of the
336 Whether encrypting or decrypting the value written to I<*outl> in the
337 OSSL_FUNC_cipher_cipher call should be the length of the payload excluding the explicit
338 IV length and the tag length.
340 =item "ivlen" (B<OSSL_CIPHER_PARAM_AEAD_IVLEN>) <unsigned integer>
342 Sets the IV length to be used for an AEAD cipher for the associated cipher ctx.
343 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
345 =item "mackey" (B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>) <octet string>
347 Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256.
349 =item "randkey" (B<OSSL_CIPHER_PARAM_RANDOM_KEY>) <octet string>
351 Gets a implementation specific randomly generated key for the associated
352 cipher ctx. This is currently only supported by 3DES (which sets the key to
355 =item "alg_id_param" (B<OSSL_CIPHER_PARAM_ALG_ID>) <octet string>
357 Used to pass the DER encoded AlgorithmIdentifier parameter to or from
358 the cipher implementation. Functions like L<EVP_CIPHER_param_to_asn1(3)>
359 and L<EVP_CIPHER_asn1_to_param(3)> use this parameter for any implementation
360 that has the flag B<EVP_CIPH_FLAG_CUSTOM_ASN1> set.
362 =item "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>) <unsigned integer>
364 Sets or gets the number of rounds to be used for a cipher.
365 This is used by the RC5 cipher.
367 =item "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>) <unsigned integer>
369 Gets or sets the effective keybits used for a RC2 cipher.
370 The length of the "keybits" parameter should not exceed that of a B<size_t>.
372 =item "speed" (B<OSSL_CIPHER_PARAM_SPEED>) <unsigned integer>
374 Sets the speed option for the associated cipher ctx. This is only supported
375 by AES SIV ciphers which disallow multiple operations by default.
376 Setting "speed" to 1 allows another encrypt or decrypt operation to be
377 performed. This is used for performance testing.
379 =item "tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>) <octet string>
381 Gets the invocation field generated for encryption.
382 Can only be called after "tlsivfixed" is set.
383 This is only used for GCM mode.
385 =item "tlsivinv" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>) <octet string>
387 Sets the invocation field used for decryption.
388 Can only be called after "tlsivfixed" is set.
389 This is only used for GCM mode.
391 =item "tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>) <octet string>
393 Triggers a multiblock tls1 encrypt operation for a tls1 aware cipher that supports
394 sending 4 or 8 records in one go.
395 The cipher performs both the MAC and encrypt stages and constructs the record
397 "tls1multi_enc" supplies the output buffer for the encrypt operation,
398 "tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply
399 values to the encrypt operation.
401 =item "tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>) <unsigned integer>
403 Get the total length of the record returned from the "tls1multi_enc" operation.
405 =item "tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) <unsigned integer>
407 Sets or gets the number of records being sent in one go for a tls1 multiblock
408 cipher operation (either 4 or 8 records).
410 =item "tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) <octet string>
412 Supplies the data to encrypt for a tls1 multiblock cipher operation.
414 =item "tls1multi_maxsndfrag" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT>) <unsigned integer>
416 Sets the maximum send fragment size for a tls1 multiblock cipher operation.
417 It must be set before using "tls1multi_maxbufsz".
418 The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a B<size_t>.
420 =item "tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>) <unsigned integer>
422 Gets the maximum record length for a tls1 multiblock cipher operation.
423 The length of the "tls1multi_maxbufsz" parameter should not exceed that of a B<size_t>.
425 =item "tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) <octet string>
427 Sets the authenticated additional data used by a tls1 multiblock cipher operation.
428 The supplied data consists of 13 bytes of record data containing:
429 Bytes 0-7: The sequence number of the first record
430 Byte 8: The record type
431 Byte 9-10: The protocol version
432 Byte 11-12: Input length (Always 0)
434 "tls1multi_interleave" must also be set for this operation.
436 =item "tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) <unsigned integer>
438 Gets the result of running the "tls1multi_aad" operation.
440 =item "cts_mode" (B<OSSL_CIPHER_PARAM_CTS_MODE>) <utf8 string>
442 Sets the cipher text stealing mode. For all modes the output size is the same as
445 Valid values for the mode are:
451 The NIST variant of cipher text stealing.
452 For message lengths that are multiples of the block size it is equivalent to
453 using a "AES-CBC" cipher otherwise the second last cipher text block is a
458 For message lengths that are multiples of the block size it is equivalent to
459 using a "AES-CBC" cipher, otherwise it is the same as "CS3".
463 The Kerberos5 variant of cipher text stealing which always swaps the last
464 cipher text block with the previous block (which may be a partial or full block
465 depending on the input length).
469 The default is "CS1".
470 This is only supported for "AES-128-CBC-CTS", "AES-192-CBC-CTS" and "AES-256-CBC-CTS".
476 OSSL_FUNC_cipher_newctx() and OSSL_FUNC_cipher_dupctx() should return the newly created
477 provider side cipher context, or NULL on failure.
479 OSSL_FUNC_cipher_encrypt_init(), OSSL_FUNC_cipher_decrypt_init(), OSSL_FUNC_cipher_update(),
480 OSSL_FUNC_cipher_final(), OSSL_FUNC_cipher_cipher(), OSSL_FUNC_cipher_get_params(),
481 OSSL_FUNC_cipher_get_ctx_params() and OSSL_FUNC_cipher_set_ctx_params() should return 1 for
482 success or 0 on error.
484 OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params() and
485 OSSL_FUNC_cipher_settable_ctx_params() should return a constant B<OSSL_PARAM>
486 array, or NULL if none is offered.
494 The provider CIPHER interface was introduced in OpenSSL 3.0.
498 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
500 Licensed under the Apache License 2.0 (the "License"). You may not use
501 this file except in compliance with the License. You can obtain a copy
502 in the file LICENSE in the source distribution or at
503 L<https://www.openssl.org/source/license.html>.