5 provider-kdf - The KDF 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_kdf_newctx(void *provctx);
22 void OSSL_FUNC_kdf_freectx(void *kctx);
23 void *OSSL_FUNC_kdf_dupctx(void *src);
25 /* Encryption/decryption */
26 int OSSL_FUNC_kdf_reset(void *kctx);
27 int OSSL_FUNC_kdf_derive(void *kctx, unsigned char *key, size_t keylen,
28 const OSSL_PARAM params[]);
30 /* KDF parameter descriptors */
31 const OSSL_PARAM *OSSL_FUNC_kdf_gettable_params(void *provctx);
32 const OSSL_PARAM *OSSL_FUNC_kdf_gettable_ctx_params(void *kcxt, void *provctx);
33 const OSSL_PARAM *OSSL_FUNC_kdf_settable_ctx_params(void *kcxt, void *provctx);
36 int OSSL_FUNC_kdf_get_params(OSSL_PARAM params[]);
37 int OSSL_FUNC_kdf_get_ctx_params(void *kctx, OSSL_PARAM params[]);
38 int OSSL_FUNC_kdf_set_ctx_params(void *kctx, const OSSL_PARAM params[]);
42 This documentation is primarily aimed at provider authors. See L<provider(7)>
43 for further information.
45 The KDF operation enables providers to implement KDF algorithms and make
46 them available to applications via the API functions L<EVP_KDF_CTX_reset(3)>,
47 and L<EVP_KDF_derive(3)>.
49 All "functions" mentioned here are passed as function pointers between
50 F<libcrypto> and the provider in B<OSSL_DISPATCH> arrays via
51 B<OSSL_ALGORITHM> arrays that are returned by the provider's
52 provider_query_operation() function
53 (see L<provider-base(7)/Provider Functions>).
55 All these "functions" have a corresponding function type definition
56 named B<OSSL_{name}_fn>, and a helper function to retrieve the
57 function pointer from an B<OSSL_DISPATCH> element named
59 For example, the "function" OSSL_FUNC_kdf_newctx() has these:
61 typedef void *(OSSL_OSSL_FUNC_kdf_newctx_fn)(void *provctx);
62 static ossl_inline OSSL_OSSL_FUNC_kdf_newctx_fn
63 OSSL_FUNC_kdf_newctx(const OSSL_DISPATCH *opf);
65 B<OSSL_DISPATCH> array entries are identified by numbers that are provided as
66 macros in L<openssl-core_dispatch.h(7)>, as follows:
68 OSSL_FUNC_kdf_newctx OSSL_FUNC_KDF_NEWCTX
69 OSSL_FUNC_kdf_freectx OSSL_FUNC_KDF_FREECTX
70 OSSL_FUNC_kdf_dupctx OSSL_FUNC_KDF_DUPCTX
72 OSSL_FUNC_kdf_reset OSSL_FUNC_KDF_RESET
73 OSSL_FUNC_kdf_derive OSSL_FUNC_KDF_DERIVE
75 OSSL_FUNC_kdf_get_params OSSL_FUNC_KDF_GET_PARAMS
76 OSSL_FUNC_kdf_get_ctx_params OSSL_FUNC_KDF_GET_CTX_PARAMS
77 OSSL_FUNC_kdf_set_ctx_params OSSL_FUNC_KDF_SET_CTX_PARAMS
79 OSSL_FUNC_kdf_gettable_params OSSL_FUNC_KDF_GETTABLE_PARAMS
80 OSSL_FUNC_kdf_gettable_ctx_params OSSL_FUNC_KDF_GETTABLE_CTX_PARAMS
81 OSSL_FUNC_kdf_settable_ctx_params OSSL_FUNC_KDF_SETTABLE_CTX_PARAMS
83 A KDF algorithm implementation may not implement all of these functions.
84 In order to be a consistent set of functions, at least the following functions
85 must be implemented: OSSL_FUNC_kdf_newctx(), OSSL_FUNC_kdf_freectx(),
86 OSSL_FUNC_kdf_set_ctx_params(), OSSL_FUNC_kdf_derive().
87 All other functions are optional.
89 =head2 Context Management Functions
91 OSSL_FUNC_kdf_newctx() should create and return a pointer to a provider side
92 structure for holding context information during a KDF operation.
93 A pointer to this context will be passed back in a number of the other KDF
94 operation function calls.
95 The parameter I<provctx> is the provider context generated during provider
96 initialisation (see L<provider(7)>).
98 OSSL_FUNC_kdf_freectx() is passed a pointer to the provider side KDF context in
99 the I<kctx> parameter.
100 If it receives NULL as I<kctx> value, it should not do anything other than
102 This function should free any resources associated with that context.
104 OSSL_FUNC_kdf_dupctx() should duplicate the provider side KDF context in the
105 I<kctx> parameter and return the duplicate copy.
107 =head2 Encryption/Decryption Functions
109 OSSL_FUNC_kdf_reset() initialises a KDF operation given a provider
110 side KDF context in the I<kctx> parameter.
112 OSSL_FUNC_kdf_derive() performs the KDF operation after processing the
113 I<params> as per OSSL_FUNC_kdf_set_ctx_params().
114 The I<kctx> parameter contains a pointer to the provider side context.
115 The resulting key of the desired I<keylen> should be written to I<key>.
116 If the algorithm does not support the requested I<keylen> the function must
119 =head2 KDF Parameters
121 See L<OSSL_PARAM(3)> for further details on the parameters structure used by
124 OSSL_FUNC_kdf_get_params() gets details of parameter values associated with the
125 provider algorithm and stores them in I<params>.
127 OSSL_FUNC_kdf_set_ctx_params() sets KDF parameters associated with the given
128 provider side KDF context I<kctx> to I<params>.
129 Any parameter settings are additional to any that were previously set.
130 Passing NULL for I<params> should return true.
132 OSSL_FUNC_kdf_get_ctx_params() retrieves gettable parameter values associated
133 with the given provider side KDF context I<kctx> and stores them in I<params>.
134 Passing NULL for I<params> should return true.
136 OSSL_FUNC_kdf_gettable_params(), OSSL_FUNC_kdf_gettable_ctx_params(),
137 and OSSL_FUNC_kdf_settable_ctx_params() all return constant B<OSSL_PARAM>
138 arrays as descriptors of the parameters that OSSL_FUNC_kdf_get_params(),
139 OSSL_FUNC_kdf_get_ctx_params(), and OSSL_FUNC_kdf_set_ctx_params()
140 can handle, respectively. OSSL_FUNC_kdf_gettable_ctx_params() and
141 OSSL_FUNC_kdf_settable_ctx_params() will return the parameters associated
142 with the provider side context I<kctx> in its current state if it is
143 not NULL. Otherwise, they return the parameters associated with the
144 provider side algorithm I<provctx>.
147 Parameters currently recognised by built-in KDFs are as follows. Not all
148 parameters are relevant to, or are understood by all KDFs:
152 =item "size" (B<OSSL_KDF_PARAM_SIZE>) <unsigned integer>
154 Gets the output size from the associated KDF ctx.
155 If the algorithm produces a variable amount of output, SIZE_MAX should be
157 If the input parameters required to calculate the fixed output size have not yet
158 been supplied, 0 should be returned indicating an error.
160 =item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string>
162 Sets the key in the associated KDF ctx.
164 =item "secret" (B<OSSL_KDF_PARAM_SECRET>) <octet string>
166 Sets the secret in the associated KDF ctx.
168 =item "pass" (B<OSSL_KDF_PARAM_PASSWORD>) <octet string>
170 Sets the password in the associated KDF ctx.
172 =item "cipher" (B<OSSL_KDF_PARAM_CIPHER>) <UTF8 string>
174 =item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
176 =item "mac" (B<OSSL_KDF_PARAM_MAC>) <UTF8 string>
178 Sets the name of the underlying cipher, digest or MAC to be used.
179 It must name a suitable algorithm for the KDF that's being used.
181 =item "maclen" (B<OSSL_KDF_PARAM_MAC_SIZE>) <octet string>
183 Sets the length of the MAC in the associated KDF ctx.
185 =item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
187 Sets the properties to be queried when trying to fetch the underlying algorithm.
188 This must be given together with the algorithm naming parameter to be
191 =item "iter" (B<OSSL_KDF_PARAM_ITER>) <unsigned integer>
193 Sets the number of iterations in the associated KDF ctx.
195 =item "mode" (B<OSSL_KDF_PARAM_MODE>) <UTF8 string>
197 Sets the mode in the associated KDF ctx.
199 =item "pkcs5" (B<OSSL_KDF_PARAM_PKCS5>) <integer>
201 Enables or diables the SP800-132 compliance checks.
202 A mode of 0 enables the compliance checks.
204 The checks performed are:
208 =item - the iteration count is at least 1000.
210 =item - the salt length is at least 128 bits.
212 =item - the derived key length is at least 112 bits.
216 =item "ukm" (B<OSSL_KDF_PARAM_UKM>) <octet string>
218 Sets an optional random string that is provided by the sender called
219 "partyAInfo". In CMS this is the user keying material.
222 =item "cekalg" (B<OSSL_KDF_PARAM_CEK_ALG>) <UTF8 string>
224 Sets the CEK wrapping algorithm name in the associated KDF ctx.
226 =item "n" (B<OSSL_KDF_PARAM_SCRYPT_N>) <unsigned integer>
228 Sets the scrypt work factor parameter N in the associated KDF ctx.
230 =item "r" (B<OSSL_KDF_PARAM_SCRYPT_R>) <unsigned integer>
232 Sets the scrypt work factor parameter r in the associated KDF ctx.
234 =item "p" (B<OSSL_KDF_PARAM_SCRYPT_P>) <unsigned integer>
236 Sets the scrypt work factor parameter p in the associated KDF ctx.
238 =item "maxmem_bytes" (B<OSSL_KDF_PARAM_SCRYPT_MAXMEM>) <unsigned integer>
240 Sets the scrypt work factor parameter maxmem in the associated KDF ctx.
242 =item "info" (B<OSSL_KDF_PARAM_INFO>) <octet string>
244 Sets the optional shared info in the associated KDF ctx.
246 =item "seed" (B<OSSL_KDF_PARAM_SEED>) <octet string>
248 Sets the IV in the associated KDF ctx.
250 =item "xcghash" (B<OSSL_KDF_PARAM_SSHKDF_XCGHASH>) <octet string>
252 Sets the xcghash in the associated KDF ctx.
254 =item "session_id" (B<OSSL_KDF_PARAM_SSHKDF_SESSION_ID>) <octet string>
256 Sets the session ID in the associated KDF ctx.
258 =item "type" (B<OSSL_KDF_PARAM_SSHKDF_TYPE>) <UTF8 string>
260 Sets the SSH KDF type parameter in the associated KDF ctx.
261 There are six supported types:
265 =item EVP_KDF_SSHKDF_TYPE_INITIAL_IV_CLI_TO_SRV
267 The Initial IV from client to server.
268 A single char of value 65 (ASCII char 'A').
270 =item EVP_KDF_SSHKDF_TYPE_INITIAL_IV_SRV_TO_CLI
272 The Initial IV from server to client
273 A single char of value 66 (ASCII char 'B').
275 =item EVP_KDF_SSHKDF_TYPE_ENCRYPTION_KEY_CLI_TO_SRV
277 The Encryption Key from client to server
278 A single char of value 67 (ASCII char 'C').
280 =item EVP_KDF_SSHKDF_TYPE_ENCRYPTION_KEY_SRV_TO_CLI
282 The Encryption Key from server to client
283 A single char of value 68 (ASCII char 'D').
285 =item EVP_KDF_SSHKDF_TYPE_INTEGRITY_KEY_CLI_TO_SRV
287 The Integrity Key from client to server
288 A single char of value 69 (ASCII char 'E').
290 =item EVP_KDF_SSHKDF_TYPE_INTEGRITY_KEY_SRV_TO_CLI
292 The Integrity Key from client to server
293 A single char of value 70 (ASCII char 'F').
297 =item "constant" (B<OSSL_KDF_PARAM_CONSTANT>) <octet string>
299 Sets the constant value in the associated KDF ctx.
301 =item "id" (B<OSSL_KDF_PARAM_PKCS12_ID>) <integer>
303 Sets the intended usage of the output bits in the associated KDF ctx.
304 It is defined as per RFC 7292 section B.3.
310 OSSL_FUNC_kdf_newctx() and OSSL_FUNC_kdf_dupctx() should return the newly created
311 provider side KDF context, or NULL on failure.
313 OSSL_FUNC_kdf_derive(), OSSL_FUNC_kdf_get_params(),
314 OSSL_FUNC_kdf_get_ctx_params() and OSSL_FUNC_kdf_set_ctx_params() should return 1 for
315 success or 0 on error.
317 OSSL_FUNC_kdf_gettable_params(), OSSL_FUNC_kdf_gettable_ctx_params() and
318 OSSL_FUNC_kdf_settable_ctx_params() should return a constant B<OSSL_PARAM>
319 array, or NULL if none is offered.
327 The provider KDF interface was introduced in OpenSSL 3.0.
331 Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
333 Licensed under the Apache License 2.0 (the "License"). You may not use
334 this file except in compliance with the License. You can obtain a copy
335 in the file LICENSE in the source distribution or at
336 L<https://www.openssl.org/source/license.html>.