1EVP_KDF-X942-ASN1(7ossl) OpenSSL EVP_KDF-X942-ASN1(7ossl)
2
6 EVP_KDF-X942-ASN1 - The X9.42-2003 asn1 EVP_KDF implementation
7
9 The EVP_KDF-X942-ASN1 algorithm implements the key derivation function
10 X942KDF-ASN1. It is used by DH KeyAgreement, to derive a key using
11 input such as a shared secret key and other info. The other info is DER
12 encoded data that contains a 32 bit counter as well as optional fields
13 for "partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo".
14 This kdf is used by Cryptographic Message Syntax (CMS).
15 Identity
17 "X942KDF-ASN1" or "X942KDF" is the name for this implementation; it can
18 be used with the EVP_KDF_fetch() function.
19 Supported parameters
21 The supported parameters are:
22 "properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>
24 "digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>
25 These parameters work as described in "PARAMETERS" in EVP_KDF(3).
26 "key" (OSSL_KDF_PARAM_KEY) <octet string>
28 The shared secret used for key derivation. This parameter sets the
29 secret.
30 "acvp-info" (OSSL_KDF_PARAM_X942_ACVPINFO) <octet string>
32 This value should not be used in production and should only be used
33 for ACVP testing. It is an optional octet string containing a
34 combined DER encoded blob of any of the optional fields related to
35 "partyu-info", "partyv-info", "supp-pubinfo" and "supp-privinfo".
36 If it is specified then none of these other fields should be used.
37 "partyu-info" (OSSL_KDF_PARAM_X942_PARTYUINFO) <octet string>
39 An optional octet string containing public info contributed by the
40 initiator.
41 "ukm" (OSSL_KDF_PARAM_UKM) <octet string>
43 An alias for "partyu-info". In CMS this is the user keying
44 material.
45 "partyv-info" (OSSL_KDF_PARAM_X942_PARTYVINFO) <octet string>
47 An optional octet string containing public info contributed by the
48 responder.
49 "supp-pubinfo" (OSSL_KDF_PARAM_X942_SUPP_PUBINFO) <octet string>
51 An optional octet string containing some additional, mutually-known
52 public information. Setting this value also sets "use-keybits" to
53 0.
54 "use-keybits" (OSSL_KDF_PARAM_X942_SUPP_PRIVINFO) <integer>
56 The default value of 1 will use the KEK key length (in bits) as the
57 "supp-pubinfo". A value of 0 disables setting the "supp-pubinfo".
58 "supp-privinfo" (OSSL_KDF_PARAM_X942_SUPP_PRIVINFO) <octet string>
60 An optional octet string containing some additional, mutually-known
61 private information.
62 "cekalg" (OSSL_KDF_PARAM_CEK_ALG) <UTF8 string>
64 This parameter sets the CEK wrapping algorithm name. Valid values
65 are "AES-128-WRAP", "AES-192-WRAP", "AES-256-WRAP" and "DES3-WRAP".
66
68 A context for X942KDF can be obtained by calling:
69 EVP_KDF *kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
71 EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
72 The output length of an X942KDF is specified via the keylen parameter
74 to the EVP_KDF_derive(3) function.
75
77 This example derives 24 bytes, with the secret key "secret" and random
78 user keying material:
79 EVP_KDF_CTX *kctx;
81 EVP_KDF_CTX *kctx;
82 unsigned char out[192/8];
83 unsignred char ukm[64];
84 OSSL_PARAM params[5], *p = params;
85 if (RAND_bytes(ukm, sizeof(ukm)) <= 0)
87 error("RAND_bytes");
88 kdf = EVP_KDF_fetch(NULL, "X942KDF", NULL);
90 if (kctx == NULL)
91 error("EVP_KDF_fetch");
92 kctx = EVP_KDF_CTX_new(kdf);
93 EVP_KDF_free(kdf);
94 if (kctx == NULL)
95 error("EVP_KDF_CTX_new");
96 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST, "SHA256", 0);
98 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SECRET,
99 "secret", (size_t)6);
100 *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_UKM, ukm, sizeof(ukm));
101 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CEK_ALG, "AES-256-WRAP, 0);
102 *p = OSSL_PARAM_construct_end();
103 if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
104 error("EVP_KDF_derive");
105 EVP_KDF_CTX_free(kctx);
107
109 ANS1 X9.42-2003 RFC 2631
110
112 EVP_KDF(3), EVP_KDF_CTX_new(3), EVP_KDF_CTX_free(3),
113 EVP_KDF_CTX_set_params(3), EVP_KDF_CTX_get_kdf_size(3),
114 EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)
115
117 This functionality was added to OpenSSL 3.0.
118
120 Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
121 Licensed under the Apache License 2.0 (the "License"). You may not use
123 this file except in compliance with the License. You can obtain a copy
124 in the file LICENSE in the source distribution or at
125 <https://www.openssl.org/source/license.html>.
1263.0.5 2022-07-05 EVP_KDF-X942-ASN1(7ossl)