1EVP_KDF-KB(7ossl) OpenSSL EVP_KDF-KB(7ossl)
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6 EVP_KDF-KB - The Key-Based EVP_KDF implementation
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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).
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13 Identity
14 "KBKDF" is the name for this implementation; it can be used with the
15 EVP_KDF_fetch() function.
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17 Supported parameters
18 The supported parameters are:
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20 "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.
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25 "mac" (OSSL_KDF_PARAM_MAC) <UTF8 string>
26 The value is either CMAC or HMAC.
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28 "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.
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37 "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.
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41 "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.
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46 "r" (OSSL_KDF_PARAM_KBKDF_R) <integer>
47 Set the fixed value 'r', indicating the length of the counter in
48 bits.
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50 Supported values are 8, 16, 24, and 32. The default value of 32
51 will be used if unspecified.
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53 Depending on whether mac is CMAC or HMAC, either digest or cipher is
54 required (respectively) and the other is unused.
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56 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.
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60 "mac", "digest", cipher" and "properties" are described in "PARAMETERS"
61 in EVP_KDF(3).
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64 A context for KBKDF can be obtained by calling:
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66 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
67 EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
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69 The output length of an KBKDF is specified via the "keylen" parameter
70 to the EVP_KDF_derive(3) function.
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72 Note that currently OpenSSL only implements counter and feedback modes.
73 Other variants may be supported in the future.
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76 This example derives 10 bytes using COUNTER-HMAC-SHA256, with KI
77 "secret", Label "label", and Context "context".
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79 EVP_KDF *kdf;
80 EVP_KDF_CTX *kctx;
81 unsigned char out[10];
82 OSSL_PARAM params[6], *p = params;
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84 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
85 kctx = EVP_KDF_CTX_new(kdf);
86 EVP_KDF_free(kdf);
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88 *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");
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102 EVP_KDF_CTX_free(kctx);
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104 This example derives 10 bytes using FEEDBACK-CMAC-AES256, with KI
105 "secret", Label "label", and IV "sixteen bytes iv".
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107 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";
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113 kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
114 kctx = EVP_KDF_CTX_new(kdf);
115 EVP_KDF_free(kdf);
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117 *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");
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132 EVP_KDF_CTX_free(kctx);
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135 NIST SP800-108, IETF RFC 6803, IETF RFC 8009.
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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)
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142 This functionality was added to OpenSSL 3.0.
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145 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
146 Copyright 2019 Red Hat, Inc.
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148 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>.
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1553.0.5 2022-11-01 EVP_KDF-KB(7ossl)