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, HMAC, KMAC128 or KMAC256.
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. They are unused for
55 KMAC128 and KMAC256.
56 The parameters key, salt, info, and seed correspond to KI, Label,
58 Context, and IV (respectively) in SP800-108. As in that document,
59 salt, info, and seed are optional and may be omitted.
60 "mac", "digest", cipher" and "properties" are described in "PARAMETERS"
62 in EVP_KDF(3).
63
65 A context for KBKDF can be obtained by calling:
66 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
68 EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
69 The output length of an KBKDF is specified via the "keylen" parameter
71 to the EVP_KDF_derive(3) function.
72 Note that currently OpenSSL only implements counter and feedback modes.
74 Other variants may be supported in the future.
75
77 This example derives 10 bytes using COUNTER-HMAC-SHA256, with KI
78 "secret", Label "label", and Context "context".
79 EVP_KDF *kdf;
81 EVP_KDF_CTX *kctx;
82 unsigned char out[10];
83 OSSL_PARAM params[6], *p = params;
84 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
86 kctx = EVP_KDF_CTX_new(kdf);
87 EVP_KDF_free(kdf);
88 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
90 "SHA2-256", 0);
91 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
92 "HMAC", 0);
93 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
94 "secret", strlen("secret"));
95 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
96 "label", strlen("label"));
97 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
98 "context", strlen("context"));
99 *p = OSSL_PARAM_construct_end();
100 if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
101 error("EVP_KDF_derive");
102 EVP_KDF_CTX_free(kctx);
104 This example derives 10 bytes using FEEDBACK-CMAC-AES256, with KI
106 "secret", Label "label", and IV "sixteen bytes iv".
107 EVP_KDF *kdf;
109 EVP_KDF_CTX *kctx;
110 unsigned char out[10];
111 OSSL_PARAM params[8], *p = params;
112 unsigned char *iv = "sixteen bytes iv";
113 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
115 kctx = EVP_KDF_CTX_new(kdf);
116 EVP_KDF_free(kdf);
117 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CIPHER, "AES256", 0);
119 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC, "CMAC", 0);
120 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MODE, "FEEDBACK", 0);
121 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
122 "secret", strlen("secret"));
123 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
124 "label", strlen("label"));
125 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
126 "context", strlen("context"));
127 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
128 iv, strlen(iv));
129 *p = OSSL_PARAM_construct_end();
130 if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
131 error("EVP_KDF_derive");
132 EVP_KDF_CTX_free(kctx);
134
136 NIST SP800-108, IETF RFC 6803, IETF RFC 8009.
137
139 EVP_KDF(3), EVP_KDF_CTX_free(3), EVP_KDF_CTX_get_kdf_size(3),
140 EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)
141
143 This functionality was added in OpenSSL 3.0.
144 Support for KMAC was added in OpenSSL 3.1.
146
148 Copyright 2019-2022 The OpenSSL Project Authors. All Rights Reserved.
149 Copyright 2019 Red Hat, Inc.
150 Licensed under the Apache License 2.0 (the "License"). You may not use
152 this file except in compliance with the License. You can obtain a copy
153 in the file LICENSE in the source distribution or at
154 <https://www.openssl.org/source/license.html>.
1553.1.1 2023-08-31 EVP_KDF-KB(7ossl)