1EVP_KDF-KB(7ossl) OpenSSL EVP_KDF-KB(7ossl)
2
6 EVP_KDF-KB - The Key-Based EVP_KDF implementation
7
9 The EVP_KDF-KB algorithm implements the Key-Based key derivation
10 function (KBKDF). KBKDF derives a key from repeated application of a
11 keyed MAC to an input secret (and other optional values).
12 Identity
14 "KBKDF" is the name for this implementation; it can be used with the
15 EVP_KDF_fetch() function.
16 Supported parameters
18 The supported parameters are:
19 "mode" (OSSL_KDF_PARAM_MODE) <UTF8 string>
21 The mode parameter determines which flavor of KBKDF to use -
22 currently the choices are "counter" and "feedback". "counter" is
23 the default, and will be used if unspecified.
24 "mac" (OSSL_KDF_PARAM_MAC) <UTF8 string>
26 The value is either CMAC or HMAC.
27 "digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>
29 "cipher" (OSSL_KDF_PARAM_CIPHER) <UTF8 string>
30 "properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>
31 "key" (OSSL_KDF_PARAM_KEY) <octet string>
32 "salt" (OSSL_KDF_PARAM_SALT) <octet string>
33 "info (OSSL_KDF_PARAM_INFO) <octet string>
34 "seed" (OSSL_KDF_PARAM_SEED) <octet string>
35 The seed parameter is unused in counter mode.
36 "use-l" (OSSL_KDF_PARAM_KBKDF_USE_L) <integer>
38 Set to 0 to disable use of the optional Fixed Input data 'L' (see
39 SP800-108). The default value of 1 will be used if unspecified.
40 "use-separator" (OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR) <integer>
42 Set to 0 to disable use of the optional Fixed Input data 'zero
43 separator' (see SP800-108) that is placed between the Label and
44 Context. The default value of 1 will be used if unspecified.
45 "r" (OSSL_KDF_PARAM_KBKDF_R) <integer>
47 Set the fixed value 'r', indicating the length of the counter in
48 bits.
49 Supported values are 8, 16, 24, and 32. The default value of 32
51 will be used if unspecified.
52 Depending on whether mac is CMAC or HMAC, either digest or cipher is
54 required (respectively) and the other is unused.
55 The parameters key, salt, info, and seed correspond to KI, Label,
57 Context, and IV (respectively) in SP800-108. As in that document,
58 salt, info, and seed are optional and may be omitted.
59 "mac", "digest", cipher" and "properties" are described in "PARAMETERS"
61 in EVP_KDF(3).
62
64 A context for KBKDF can be obtained by calling:
65 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
67 EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
68 The output length of an KBKDF is specified via the "keylen" parameter
70 to the EVP_KDF_derive(3) function.
71 Note that currently OpenSSL only implements counter and feedback modes.
73 Other variants may be supported in the future.
74
76 This example derives 10 bytes using COUNTER-HMAC-SHA256, with KI
77 "secret", Label "label", and Context "context".
78 EVP_KDF *kdf;
80 EVP_KDF_CTX *kctx;
81 unsigned char out[10];
82 OSSL_PARAM params[6], *p = params;
83 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
85 kctx = EVP_KDF_CTX_new(kdf);
86 EVP_KDF_free(kdf);
87 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
89 "SHA2-256", 0);
90 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
91 "HMAC", 0);
92 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
93 "secret", strlen("secret"));
94 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
95 "label", strlen("label"));
96 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
97 "context", strlen("context"));
98 *p = OSSL_PARAM_construct_end();
99 if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
100 error("EVP_KDF_derive");
101 EVP_KDF_CTX_free(kctx);
103 This example derives 10 bytes using FEEDBACK-CMAC-AES256, with KI
105 "secret", Label "label", and IV "sixteen bytes iv".
106 EVP_KDF *kdf;
108 EVP_KDF_CTX *kctx;
109 unsigned char out[10];
110 OSSL_PARAM params[8], *p = params;
111 unsigned char *iv = "sixteen bytes iv";
112 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
114 kctx = EVP_KDF_CTX_new(kdf);
115 EVP_KDF_free(kdf);
116 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CIPHER, "AES256", 0);
118 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC, "CMAC", 0);
119 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MODE, "FEEDBACK", 0);
120 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
121 "secret", strlen("secret"));
122 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
123 "label", strlen("label"));
124 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
125 "context", strlen("context"));
126 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
127 iv, strlen(iv));
128 *p = OSSL_PARAM_construct_end();
129 if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
130 error("EVP_KDF_derive");
131 EVP_KDF_CTX_free(kctx);
133
135 NIST SP800-108, IETF RFC 6803, IETF RFC 8009.
136
138 EVP_KDF(3), EVP_KDF_CTX_free(3), EVP_KDF_CTX_get_kdf_size(3),
139 EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)
140
142 This functionality was added to OpenSSL 3.0.
143
145 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
146 Copyright 2019 Red Hat, Inc.
147 Licensed under the Apache License 2.0 (the "License"). You may not use
149 this file except in compliance with the License. You can obtain a copy
150 in the file LICENSE in the source distribution or at
151 <https://www.openssl.org/source/license.html>.
1523.0.5 2022-07-05 EVP_KDF-KB(7ossl)