5 provider-cipher - The cipher library E<lt>-E<gt> provider functions
9 =for openssl multiple includes
11 #include <openssl/core_numbers.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 *OP_cipher_newctx(void *provctx);
22 void OP_cipher_freectx(void *cctx);
23 void *OP_cipher_dupctx(void *cctx);
25 /* Encryption/decryption */
26 int OP_cipher_encrypt_init(void *cctx, const unsigned char *key,
27 size_t keylen, const unsigned char *iv,
29 int OP_cipher_decrypt_init(void *cctx, const unsigned char *key,
30 size_t keylen, const unsigned char *iv,
32 int OP_cipher_update(void *cctx, unsigned char *out, size_t *outl,
33 size_t outsize, const unsigned char *in, size_t inl);
34 int OP_cipher_final(void *cctx, unsigned char *out, size_t *outl,
36 int OP_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 *OP_cipher_gettable_params(void);
42 /* Cipher operation parameter descriptors */
43 const OSSL_PARAM *OP_cipher_gettable_ctx_params(void);
44 const OSSL_PARAM *OP_cipher_settable_ctx_params(void);
46 /* Cipher parameters */
47 int OP_cipher_get_params(OSSL_PARAM params[]);
49 /* Cipher operation parameters */
50 int OP_cipher_get_ctx_params(void *cctx, OSSL_PARAM params[]);
51 int OP_cipher_set_ctx_params(void *cctx, const OSSL_PARAM params[]);
55 This documentation is primarily aimed at provider authors. See L<provider(7)>
56 for further information.
58 The CIPHER operation enables providers to implement cipher algorithms and make
59 them available to applications via the API functions L<EVP_EncryptInit_ex(3)>,
60 L<EVP_EncryptUpdate(3)> and L<EVP_EncryptFinal(3)> (as well as the decrypt
61 equivalents and other related functions).
63 All "functions" mentioned here are passed as function pointers between
64 F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
65 B<OSSL_ALGORITHM> arrays that are returned by the provider's
66 provider_query_operation() function
67 (see L<provider-base(7)/Provider Functions>).
69 All these "functions" have a corresponding function type definition
70 named B<OSSL_{name}_fn>, and a helper function to retrieve the
71 function pointer from an B<OSSL_DISPATCH> element named
73 For example, the "function" OP_cipher_newctx() has these:
75 typedef void *(OSSL_OP_cipher_newctx_fn)(void *provctx);
76 static ossl_inline OSSL_OP_cipher_newctx_fn
77 OSSL_get_OP_cipher_newctx(const OSSL_DISPATCH *opf);
79 B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
80 macros in L<openssl-core_numbers.h(7)>, as follows:
82 OP_cipher_newctx OSSL_FUNC_CIPHER_NEWCTX
83 OP_cipher_freectx OSSL_FUNC_CIPHER_FREECTX
84 OP_cipher_dupctx OSSL_FUNC_CIPHER_DUPCTX
86 OP_cipher_encrypt_init OSSL_FUNC_CIPHER_ENCRYPT_INIT
87 OP_cipher_decrypt_init OSSL_FUNC_CIPHER_DECRYPT_INIT
88 OP_cipher_update OSSL_FUNC_CIPHER_UPDATE
89 OP_cipher_final OSSL_FUNC_CIPHER_FINAL
90 OP_cipher_cipher OSSL_FUNC_CIPHER_CIPHER
92 OP_cipher_get_params OSSL_FUNC_CIPHER_GET_PARAMS
93 OP_cipher_get_ctx_params OSSL_FUNC_CIPHER_GET_CTX_PARAMS
94 OP_cipher_set_ctx_params OSSL_FUNC_CIPHER_SET_CTX_PARAMS
96 OP_cipher_gettable_params OSSL_FUNC_CIPHER_GETTABLE_PARAMS
97 OP_cipher_gettable_ctx_params OSSL_FUNC_CIPHER_GETTABLE_CTX_PARAMS
98 OP_cipher_settable_ctx_params OSSL_FUNC_CIPHER_SETTABLE_CTX_PARAMS
100 A cipher algorithm implementation may not implement all of these functions.
101 In order to be a consistent set of functions there must at least be a complete
102 set of "encrypt" functions, or a complete set of "decrypt" functions, or a
103 single "cipher" function.
104 In all cases both the OP_cipher_newctx and OP_cipher_freectx functions must be
106 All other functions are optional.
108 =head2 Context Management Functions
110 OP_cipher_newctx() should create and return a pointer to a provider side
111 structure for holding context information during a cipher operation.
112 A pointer to this context will be passed back in a number of the other cipher
113 operation function calls.
114 The parameter I<provctx> is the provider context generated during provider
115 initialisation (see L<provider(7)>).
117 OP_cipher_freectx() is passed a pointer to the provider side cipher context in
118 the I<cctx> parameter.
119 This function should free any resources associated with that context.
121 OP_cipher_dupctx() should duplicate the provider side cipher context in the
122 I<cctx> parameter and return the duplicate copy.
124 =head2 Encryption/Decryption Functions
126 OP_cipher_encrypt_init() initialises a cipher operation for encryption given a
127 newly created provider side cipher context in the I<cctx> parameter.
128 The key to be used is given in I<key> which is I<keylen> bytes long.
129 The IV to be used is given in I<iv> which is I<ivlen> bytes long.
131 OP_cipher_decrypt_init() is the same as OP_cipher_encrypt_init() except that it
132 initialises the context for a decryption operation.
134 OP_cipher_update() is called to supply data to be encrypted/decrypted as part of
135 a previously initialised cipher operation.
136 The I<cctx> parameter contains a pointer to a previously initialised provider
138 OP_cipher_update() should encrypt/decrypt I<inl> bytes of data at the location
140 The encrypted data should be stored in I<out> and the amount of data written to
141 I<*outl> which should not exceed I<outsize> bytes.
142 OP_cipher_update() may be called multiple times for a single cipher operation.
143 It is the responsibility of the cipher implementation to handle input lengths
144 that are not multiples of the block length.
145 In such cases a cipher implementation will typically cache partial blocks of
146 input data until a complete block is obtained.
147 I<out> may be the same location as I<in> but it should not partially overlap.
148 The same expectations apply to I<outsize> as documented for
149 L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>.
151 OP_cipher_final() completes an encryption or decryption started through previous
152 OP_cipher_encrypt_init() or OP_cipher_decrypt_init(), and OP_cipher_update()
154 The I<cctx> parameter contains a pointer to the provider side context.
155 Any final encryption/decryption output should be written to I<out> and the
156 amount of data written to I<*outl> which should not exceed I<outsize> bytes.
157 The same expectations apply to I<outsize> as documented for
158 L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>.
160 OP_cipher_cipher() performs encryption/decryption using the provider side cipher
161 context in the I<cctx> parameter that should have been previously initialised via
162 a call to OP_cipher_encrypt_init() or OP_cipher_decrypt_init().
163 This should call the raw underlying cipher function without any padding.
164 This will be invoked in the provider as a result of the application calling
166 The application is responsible for ensuring that the input is a multiple of the
168 The data to be encrypted/decrypted will be in I<in>, and it will be I<inl> bytes
170 The output from the encryption/decryption should be stored in I<out> and the
171 amount of data stored should be put in I<*outl> which should be no more than
174 =head2 Cipher Parameters
176 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
179 OP_cipher_get_params() gets details of the algorithm implementation
180 and stores them in I<params>.
182 OP_cipher_set_ctx_params() sets cipher operation parameters for the
183 provider side cipher context I<cctx> to I<params>.
184 Any parameter settings are additional to any that were previously set.
186 OP_cipher_get_ctx_params() gets cipher operation details details from
187 the given provider side cipher context I<cctx> and stores them in I<params>.
189 OP_cipher_gettable_params(), OP_cipher_gettable_ctx_params(), and
190 OP_cipher_settable_ctx_params() all return constant B<OSSL_PARAM> arrays
191 as descriptors of the parameters that OP_cipher_get_params(),
192 OP_cipher_get_ctx_params(), and OP_cipher_set_ctx_params() can handle,
195 Parameters currently recognised by built-in ciphers are as follows. Not all
196 parameters are relevant to, or are understood by all ciphers:
200 =item "padding" (B<OSSL_CIPHER_PARAM_PADDING>) <unsigned integer>
202 Sets the padding mode for the associated cipher ctx.
203 Setting a value of 1 will turn padding on.
204 Setting a value of 0 will turn padding off.
206 =item "mode" (B<OSSL_CIPHER_PARAM_MODE>) <unsigned integer>
208 Gets the mode for the associated cipher algorithm.
209 See L<EVP_CIPHER_mode(3)> for a list of valid modes.
211 =item "blocksize" (B<OSSL_CIPHER_PARAM_BLOCK_SIZE>) <unsigned integer>
213 Gets the block size for the associated cipher algorithm.
214 The block size should be 1 for stream ciphers.
215 Note that the block size for a cipher may be different to the block size for
216 the underlying encryption/decryption primitive.
217 For example AES in CTR mode has a block size of 1 (because it operates like a
218 stream cipher), even though AES has a block size of 16.
219 The length of the "blocksize" parameter should not exceed that of a B<size_t>.
221 =item "flags" (B<OSSL_CIPHER_PARAM_FLAGS>) <unsigned integer>
223 Gets any flags for the associated cipher algorithm.
224 See L<EVP_CIPHER_meth_set_flags(3)> for a list of currently defined cipher
226 The length of the "flags" parameter should equal that of an
227 B<unsigned long int>.
229 =item "keylen" (B<OSSL_CIPHER_PARAM_KEYLEN>) <unsigned integer>
231 Gets the key length for the associated cipher algorithm.
232 This can also be used to get or set the key length for the associated cipher
234 The length of the "keylen" parameter should not exceed that of a B<size_t>.
236 =item "ivlen" (B<OSSL_CIPHER_PARAM_IVLEN>) <unsigned integer>
238 Gets the IV length for the associated cipher algorithm.
239 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
241 =item "iv" (B<OSSL_CIPHER_PARAM_IV>) <octet string OR octet ptr>
243 Gets the IV for the associated cipher ctx.
245 =item "num" (B<OSSL_CIPHER_PARAM_NUM>) <unsigned integer>
247 Gets or sets the cipher specific "num" parameter for the associated cipher ctx.
248 Built-in ciphers typically use this to track how much of the current underlying
249 block has been "used" already.
251 =item "tag" (B<OSSL_CIPHER_PARAM_AEAD_TAG>) <octet string>
253 Gets or sets the AEAD tag for the associated cipher ctx.
254 See L<EVP_EncryptInit(3)/AEAD Interface>.
256 =item "taglen" (B<OSSL_CIPHER_PARAM_AEAD_TAGLEN>) <unsigned integer>
258 Gets the tag length to be used for an AEAD cipher for the associated cipher ctx.
259 It returns a default value if it has not been set.
260 The length of the "taglen" parameter should not exceed that of a B<size_t>.
262 =item "tlsaad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD>) <octet string>
264 =for comment TODO(3.0): Consider changing this interface so that all ciphers
265 use the standard AEAD interface - rather than having this special purpose
268 Sets TLSv1.2 AAD information for the associated cipher ctx.
269 TLSv1.2 AAD information is always 13 bytes in length and is as defined for the
270 "additional_data" field described in section 6.2.3.3 of RFC5246.
272 =item "tlsaadpad" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_AAD_PAD>) <unsigned integer>
274 Gets the length of the tag that will be added to a TLS record for the AEAD
275 tag for the associated cipher ctx.
276 The length of the "tlsaadpad" parameter should not exceed that of a B<size_t>.
278 =item "tlsivfixed" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_IV_FIXED>) <octet string>
280 =for comment TODO(3.0): This interface needs completely redesigning!
282 Sets the fixed portion of an IV for an AEAD cipher used in a TLS record
283 encryption/ decryption for the associated cipher ctx.
284 TLS record encryption/decryption always occurs "in place" so that the input and
285 output buffers are always the same memory location.
286 AEAD IVs in TLSv1.2 consist of an implicit "fixed" part and an explicit part
287 that varies with every record.
288 Setting a TLS fixed IV changes a cipher to encrypt/decrypt TLS records.
289 TLS records are encrypted/decrypted using a single OP_cipher_cipher call per
291 For a record decryption the first bytes of the input buffer will be the explicit
292 part of the IV and the final bytes of the input buffer will be the AEAD tag.
293 The length of the explicit part of the IV and the tag length will depend on the
294 cipher in use and will be defined in the RFC for the relevant ciphersuite.
295 In order to allow for "in place" decryption the plaintext output should be
296 written to the same location in the output buffer that the ciphertext payload
297 was read from, i.e. immediately after the explicit IV.
299 When encrypting a record the first bytes of the input buffer will be empty to
300 allow space for the explicit IV, as will the final bytes where the tag will
302 The length of the input buffer will include the length of the explicit IV, the
303 payload, and the tag bytes.
304 The cipher implementation should generate the explicit IV and write it to the
305 beginning of the output buffer, do "in place" encryption of the payload and
306 write that to the output buffer, and finally add the tag onto the end of the
309 Whether encrypting or decrypting the value written to I<*outl> in the
310 OP_cipher_cipher call should be the length of the payload excluding the explicit
311 IV length and the tag length.
313 =item "ivlen" (B<OSSL_CIPHER_PARAM_AEAD_IVLEN>) <unsigned integer>
315 Sets the IV length to be used for an AEAD cipher for the associated cipher ctx.
316 The length of the "ivlen" parameter should not exceed that of a B<size_t>.
318 =item "mackey" (B<OSSL_CIPHER_PARAM_AEAD_MAC_KEY>) <octet string>
320 Sets the MAC key used by composite AEAD ciphers such as AES-CBC-HMAC-SHA256.
322 =item "randkey" (B<OSSL_CIPHER_PARAM_RANDOM_KEY>) <octet string>
324 Gets a implementation specific randomly generated key for the associated
325 cipher ctx. This is currently only supported by 3DES (which sets the key to
328 =item "alg_id_param" (B<OSSL_CIPHER_PARAM_ALG_ID>) <octet string>
330 Used to pass the DER encoded AlgorithmIdentifier parameter to or from
331 the cipher implementation. Functions like L<EVP_CIPHER_param_to_asn1(3)>
332 and L<EVP_CIPHER_asn1_to_param(3)> use this parameter for any implementation
333 that has the flag B<EVP_CIPH_FLAG_CUSTOM_ASN1> set.
335 =item "rounds" (B<OSSL_CIPHER_PARAM_ROUNDS>) <unsigned integer>
337 Sets or gets the number of rounds to be used for a cipher.
338 This is used by the RC5 cipher.
340 =item "keybits" (B<OSSL_CIPHER_PARAM_RC2_KEYBITS>) <unsigned integer>
342 Gets or sets the effective keybits used for a RC2 cipher.
343 The length of the "keybits" parameter should not exceed that of a B<size_t>.
345 =item "speed" (B<OSSL_CIPHER_PARAM_SPEED>) <unsigned integer>
347 Sets the speed option for the associated cipher ctx. This is only supported
348 by AES SIV ciphers which disallow multiple operations by default.
349 Setting "speed" to 1 allows another encrypt or decrypt operation to be
350 performed. This is used for performance testing.
352 =item "tlsivgen" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_GET_IV_GEN>) <octet string>
354 Gets the invocation field generated for encryption.
355 Can only be called after "tlsivfixed" is set.
356 This is only used for GCM mode.
358 =item "tlsivinv" (B<OSSL_CIPHER_PARAM_AEAD_TLS1_SET_IV_INV>) <octet string>
360 Sets the invocation field used for decryption.
361 Can only be called after "tlsivfixed" is set.
362 This is only used for GCM mode.
364 =item "tls1multi_enc" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC>) <octet string>
366 Triggers a multiblock tls1 encrypt operation for a tls1 aware cipher that supports
367 sending 4 or 8 records in one go.
368 The cipher performs both the MAC and encrypt stages and constructs the record
370 "tls1multi_enc" supplies the output buffer for the encrypt operation,
371 "tls1multi_encin" & "tls1multi_interleave" must also be set in order to supply
372 values to the encrypt operation.
374 =item "tls1multi_enclen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_LEN>) <unsigned integer>
376 Get the total length of the record returned from the "tls1multi_enc" operation.
378 =item "tls1multi_interleave" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_INTERLEAVE>) <unsigned integer>
380 Sets or gets the number of records being sent in one go for a tls1 multiblock
381 cipher operation (either 4 or 8 records).
383 =item "tls1multi_encin" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_ENC_IN>) <octet string>
385 Supplies the data to encrypt for a tls1 multiblock cipher operation.
387 =item "tls1multi_maxsndfrag" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_SEND_FRAGMENT>) <unsigned integer>
389 Sets the maximum send fragment size for a tls1 multiblock cipher operation.
390 It must be set before using "tls1multi_maxbufsz".
391 The length of the "tls1multi_maxsndfrag" parameter should not exceed that of a B<size_t>.
393 =item "tls1multi_maxbufsz" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_MAX_BUFSIZE>) <unsigned integer>
395 Gets the maximum record length for a tls1 multiblock cipher operation.
396 The length of the "tls1multi_maxbufsz" parameter should not exceed that of a B<size_t>.
398 =item "tls1multi_aad" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD>) <octet string>
400 Sets the authenticated additional data used by a tls1 multiblock cipher operation.
401 The supplied data consists of 13 bytes of record data containing:
402 Bytes 0-7: The sequence number of the first record
403 Byte 8: The record type
404 Byte 9-10: The protocol version
405 Byte 11-12: Input length (Always 0)
407 "tls1multi_interleave" must also be set for this operation.
409 =item "tls1multi_aadpacklen" (B<OSSL_CIPHER_PARAM_TLS1_MULTIBLOCK_AAD_PACKLEN>) <unsigned integer>
411 Gets the result of running the "tls1multi_aad" operation.
417 OP_cipher_newctx() and OP_cipher_dupctx() should return the newly created
418 provider side cipher context, or NULL on failure.
420 OP_cipher_encrypt_init(), OP_cipher_decrypt_init(), OP_cipher_update(),
421 OP_cipher_final(), OP_cipher_cipher(), OP_cipher_get_params(),
422 OP_cipher_get_ctx_params() and OP_cipher_set_ctx_params() should return 1 for
423 success or 0 on error.
425 OP_cipher_gettable_params(), OP_cipher_gettable_ctx_params() and
426 OP_cipher_settable_ctx_params() should return a constant B<OSSL_PARAM>
427 array, or NULL if none is offered.
435 The provider CIPHER interface was introduced in OpenSSL 3.0.
439 Copyright 2019-2020 The OpenSSL Project Authors. All Rights Reserved.
441 Licensed under the Apache License 2.0 (the "License"). You may not use
442 this file except in compliance with the License. You can obtain a copy
443 in the file LICENSE in the source distribution or at
444 L<https://www.openssl.org/source/license.html>.