xref: /openssl/doc/man7/provider-cipher.pod (revision 13b47155) 
1=pod
2
3=head1 NAME
4
5provider-cipher - The cipher library E<lt>-E<gt> provider functions
6
7=head1 SYNOPSIS
8
9=for openssl multiple includes
10
11 #include <openssl/core_dispatch.h>
12 #include <openssl/core_names.h>
13
14 /*
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.
18  */
19
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);
24
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,
35                            size_t outsize);
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);
38
39 /* Cipher parameter descriptors */
40 const OSSL_PARAM *OSSL_FUNC_cipher_gettable_params(void *provctx);
41
42 /* Cipher operation parameter descriptors */
43 const OSSL_PARAM *OSSL_FUNC_cipher_gettable_ctx_params(void *cctx,
44                                                        void *provctx);
45 const OSSL_PARAM *OSSL_FUNC_cipher_settable_ctx_params(void *cctx,
46                                                        void *provctx);
47
48 /* Cipher parameters */
49 int OSSL_FUNC_cipher_get_params(OSSL_PARAM params[]);
50
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[]);
54
55=head1 DESCRIPTION
56
57This documentation is primarily aimed at provider authors. See L<provider(7)>
58for further information.
59
60The CIPHER operation enables providers to implement cipher algorithms and make
61them available to applications via the API functions L<EVP_EncryptInit_ex(3)>,
62L<EVP_EncryptUpdate(3)> and L<EVP_EncryptFinal(3)> (as well as the decrypt
63equivalents and other related functions).
64
65All "functions" mentioned here are passed as function pointers between
66F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
67B<OSSL_ALGORITHM> arrays that are returned by the provider's
68provider_query_operation() function
69(see L<provider-base(7)/Provider Functions>).
70
71All these "functions" have a corresponding function type definition
72named B<OSSL_FUNC_{name}_fn>, and a helper function to retrieve the
73function pointer from an B<OSSL_DISPATCH> element named
74B<OSSL_FUNC_{name}>.
75For example, the "function" OSSL_FUNC_cipher_newctx() has these:
76
77 typedef void *(OSSL_FUNC_cipher_newctx_fn)(void *provctx);
78 static ossl_inline OSSL_FUNC_cipher_newctx_fn
79     OSSL_FUNC_cipher_newctx(const OSSL_DISPATCH *opf);
80
81B<OSSL_DISPATCH> arrays are indexed by numbers that are provided as
82macros in L<openssl-core_dispatch.h(7)>, as follows:
83
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
87
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
93
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
97
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
101
102A cipher algorithm implementation may not implement all of these functions.
103In order to be a consistent set of functions there must at least be a complete
104set of "encrypt" functions, or a complete set of "decrypt" functions, or a
105single "cipher" function.
106In all cases both the OSSL_FUNC_cipher_newctx and OSSL_FUNC_cipher_freectx functions must be
107present.
108All other functions are optional.
109
110=head2 Context Management Functions
111
112OSSL_FUNC_cipher_newctx() should create and return a pointer to a provider side
113structure for holding context information during a cipher operation.
114A pointer to this context will be passed back in a number of the other cipher
115operation function calls.
116The parameter I<provctx> is the provider context generated during provider
117initialisation (see L<provider(7)>).
118
119OSSL_FUNC_cipher_freectx() is passed a pointer to the provider side cipher context in
120the I<cctx> parameter.
121This function should free any resources associated with that context.
122
123OSSL_FUNC_cipher_dupctx() should duplicate the provider side cipher context in the
124I<cctx> parameter and return the duplicate copy.
125
126=head2 Encryption/Decryption Functions
127
128OSSL_FUNC_cipher_encrypt_init() initialises a cipher operation for encryption given a
129newly created provider side cipher context in the I<cctx> parameter.
130The key to be used is given in I<key> which is I<keylen> bytes long.
131The IV to be used is given in I<iv> which is I<ivlen> bytes long.
132The I<params>, if not NULL, should be set on the context in a manner similar to
133using OSSL_FUNC_cipher_set_ctx_params().
134
135OSSL_FUNC_cipher_decrypt_init() is the same as OSSL_FUNC_cipher_encrypt_init() except that it
136initialises the context for a decryption operation.
137
138OSSL_FUNC_cipher_update() is called to supply data to be encrypted/decrypted as part of
139a previously initialised cipher operation.
140The I<cctx> parameter contains a pointer to a previously initialised provider
141side context.
142OSSL_FUNC_cipher_update() should encrypt/decrypt I<inl> bytes of data at the location
143pointed to by I<in>.
144The encrypted data should be stored in I<out> and the amount of data written to
145I<*outl> which should not exceed I<outsize> bytes.
146OSSL_FUNC_cipher_update() may be called multiple times for a single cipher operation.
147It is the responsibility of the cipher implementation to handle input lengths
148that are not multiples of the block length.
149In such cases a cipher implementation will typically cache partial blocks of
150input data until a complete block is obtained.
151I<out> may be the same location as I<in> but it should not partially overlap.
152The same expectations apply to I<outsize> as documented for
153L<EVP_EncryptUpdate(3)> and L<EVP_DecryptUpdate(3)>.
154
155OSSL_FUNC_cipher_final() completes an encryption or decryption started through previous
156OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init(), and OSSL_FUNC_cipher_update()
157calls.
158The I<cctx> parameter contains a pointer to the provider side context.
159Any final encryption/decryption output should be written to I<out> and the
160amount of data written to I<*outl> which should not exceed I<outsize> bytes.
161The same expectations apply to I<outsize> as documented for
162L<EVP_EncryptFinal(3)> and L<EVP_DecryptFinal(3)>.
163
164OSSL_FUNC_cipher_cipher() performs encryption/decryption using the provider side cipher
165context in the I<cctx> parameter that should have been previously initialised via
166a call to OSSL_FUNC_cipher_encrypt_init() or OSSL_FUNC_cipher_decrypt_init().
167This should call the raw underlying cipher function without any padding.
168This will be invoked in the provider as a result of the application calling
169L<EVP_Cipher(3)>.
170The application is responsible for ensuring that the input is a multiple of the
171block length.
172The data to be encrypted/decrypted will be in I<in>, and it will be I<inl> bytes
173in length.
174The output from the encryption/decryption should be stored in I<out> and the
175amount of data stored should be put in I<*outl> which should be no more than
176I<outsize> bytes.
177
178=head2 Cipher Parameters
179
180See L<OSSL_PARAM(3)> for further details on the parameters structure used by
181these functions.
182
183OSSL_FUNC_cipher_get_params() gets details of the algorithm implementation
184and stores them in I<params>.
185
186OSSL_FUNC_cipher_set_ctx_params() sets cipher operation parameters for the
187provider side cipher context I<cctx> to I<params>.
188Any parameter settings are additional to any that were previously set.
189Passing NULL for I<params> should return true.
190
191OSSL_FUNC_cipher_get_ctx_params() gets cipher operation details details from
192the given provider side cipher context I<cctx> and stores them in I<params>.
193Passing NULL for I<params> should return true.
194
195OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params(),
196and OSSL_FUNC_cipher_settable_ctx_params() all return constant B<OSSL_PARAM>
197arrays as descriptors of the parameters that OSSL_FUNC_cipher_get_params(),
198OSSL_FUNC_cipher_get_ctx_params(), and OSSL_FUNC_cipher_set_ctx_params()
199can handle, respectively.  OSSL_FUNC_cipher_gettable_ctx_params() and
200OSSL_FUNC_cipher_settable_ctx_params() will return the parameters associated
201with the provider side context I<cctx> in its current state if it is
202not NULL.  Otherwise, they return the parameters associated with the
203provider side algorithm I<provctx>.
204
205Parameters currently recognised by built-in ciphers are listed in
206L<EVP_EncryptInit(3)/PARAMETERS>.
207Not all parameters are relevant to, or are understood by all ciphers.
208
209=head1 RETURN VALUES
210
211OSSL_FUNC_cipher_newctx() and OSSL_FUNC_cipher_dupctx() should return the newly created
212provider side cipher context, or NULL on failure.
213
214OSSL_FUNC_cipher_encrypt_init(), OSSL_FUNC_cipher_decrypt_init(), OSSL_FUNC_cipher_update(),
215OSSL_FUNC_cipher_final(), OSSL_FUNC_cipher_cipher(), OSSL_FUNC_cipher_get_params(),
216OSSL_FUNC_cipher_get_ctx_params() and OSSL_FUNC_cipher_set_ctx_params() should return 1 for
217success or 0 on error.
218
219OSSL_FUNC_cipher_gettable_params(), OSSL_FUNC_cipher_gettable_ctx_params() and
220OSSL_FUNC_cipher_settable_ctx_params() should return a constant B<OSSL_PARAM>
221array, or NULL if none is offered.
222
223=head1 SEE ALSO
224
225L<provider(7)>, L<OSSL_PROVIDER-FIPS(7)>, L<OSSL_PROVIDER-default(7)>,
226L<OSSL_PROVIDER-legacy(7)>,
227L<EVP_CIPHER-AES(7)>, L<EVP_CIPHER-ARIA(7)>, L<EVP_CIPHER-BLOWFISH(7)>,
228L<EVP_CIPHER-CAMELLIA(7)>, L<EVP_CIPHER-CAST(7)>, L<EVP_CIPHER-CHACHA(7)>,
229L<EVP_CIPHER-DES(7)>, L<EVP_CIPHER-IDEA(7)>, L<EVP_CIPHER-RC2(7)>,
230L<EVP_CIPHER-RC4(7)>, L<EVP_CIPHER-RC5(7)>, L<EVP_CIPHER-SEED(7)>,
231L<EVP_CIPHER-SM4(7)>,
232L<life_cycle-cipher(7)>, L<EVP_EncryptInit(3)>
233
234=head1 HISTORY
235
236The provider CIPHER interface was introduced in OpenSSL 3.0.
237
238=head1 COPYRIGHT
239
240Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
241
242Licensed under the Apache License 2.0 (the "License").  You may not use
243this file except in compliance with the License.  You can obtain a copy
244in the file LICENSE in the source distribution or at
245L<https://www.openssl.org/source/license.html>.
246
247=cut
248