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EVP_KDF-KB(7ossl)                   OpenSSL                  EVP_KDF-KB(7ossl)



NAME

       EVP_KDF-KB - The Key-Based EVP_KDF implementation


DESCRIPTION

       The EVP_KDF-KB algorithm implements the Key-Based key derivation
       function (KBKDF).  KBKDF derives a key from repeated application of a
       keyed MAC to an input secret (and other optional values).

       The output is considered to be keying material.

   Identity
       "KBKDF" is the name for this implementation; it can be used with the
       EVP_KDF_fetch() function.

   Supported parameters
       The supported parameters are:

       "mode" (OSSL_KDF_PARAM_MODE) <UTF8 string>
           The mode parameter determines which flavor of KBKDF to use -
           currently the choices are "counter" and "feedback". "counter" is
           the default, and will be used if unspecified.

       "mac" (OSSL_KDF_PARAM_MAC) <UTF8 string>
           The value is either CMAC, HMAC, KMAC128 or KMAC256.

       "digest" (OSSL_KDF_PARAM_DIGEST) <UTF8 string>
       "cipher" (OSSL_KDF_PARAM_CIPHER) <UTF8 string>
       "properties" (OSSL_KDF_PARAM_PROPERTIES) <UTF8 string>
       "key" (OSSL_KDF_PARAM_KEY) <octet string>
       "salt" (OSSL_KDF_PARAM_SALT) <octet string>
       "info (OSSL_KDF_PARAM_INFO) <octet string>
       "seed" (OSSL_KDF_PARAM_SEED) <octet string>
           The seed parameter is unused in counter mode.

       "use-l" (OSSL_KDF_PARAM_KBKDF_USE_L) <integer>
           Set to 0 to disable use of the optional Fixed Input data 'L' (see
           SP800-108).  The default value of 1 will be used if unspecified.

       "use-separator" (OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR) <integer>
           Set to 0 to disable use of the optional Fixed Input data 'zero
           separator' (see SP800-108) that is placed between the Label and
           Context.  The default value of 1 will be used if unspecified.

       "r" (OSSL_KDF_PARAM_KBKDF_R) <integer>
           Set the fixed value 'r', indicating the length of the counter in
           bits.

           Supported values are 8, 16, 24, and 32.  The default value of 32
           will be used if unspecified.

       The OpenSSL FIPS provider also supports the following parameters:

       "fips-indicator" (OSSL_KDF_PARAM_FIPS_APPROVED_INDICATOR) <integer>
           A getter that returns 1 if the operation is FIPS approved, or 0
           otherwise.  This may be used after calling EVP_KDF_derive. It
           returns 0 if "key-check" is set to 0 and the check fails.

       "key-check" (OSSL_KDF_PARAM_FIPS_KEY_CHECK) <integer>
           The default value of 1 causes an error during
           EVP_KDF_CTX_set_params() if the length of used key-derivation key
           (OSSL_KDF_PARAM_KEY) is shorter than 112 bits.  Setting this to
           zero will ignore the error and set the approved "fips-indicator" to
           0.  This option breaks FIPS compliance if it causes the approved
           "fips-indicator" to return 0.

       Depending on whether mac is CMAC or HMAC, either digest or cipher is
       required (respectively) and the other is unused. They are unused for
       KMAC128 and KMAC256.

       The parameters key, salt, info, and seed correspond to KI, Label,
       Context, and IV (respectively) in SP800-108.  As in that document,
       salt, info, and seed are optional and may be omitted.

       "mac", "digest", cipher" and "properties" are described in "PARAMETERS"
       in EVP_KDF(3).


NOTES

       A context for KBKDF can be obtained by calling:

        EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
        EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);

       The output length of an KBKDF is specified via the "keylen" parameter
       to the EVP_KDF_derive(3) function.

       Note that currently OpenSSL only implements counter and feedback modes.
       Other variants may be supported in the future.


EXAMPLES

       This example derives 10 bytes using COUNTER-HMAC-SHA256, with KI
       "secret", Label "label", and Context "context".

        EVP_KDF *kdf;
        EVP_KDF_CTX *kctx;
        unsigned char out[10];
        OSSL_PARAM params[6], *p = params;

        kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
        kctx = EVP_KDF_CTX_new(kdf);
        EVP_KDF_free(kdf);

        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
                                                "SHA2-256", 0);
        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
                                                "HMAC", 0);
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
                                                 "secret", strlen("secret"));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
                                                 "label", strlen("label"));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
                                                 "context", strlen("context"));
        *p = OSSL_PARAM_construct_end();
        if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
            error("EVP_KDF_derive");

        EVP_KDF_CTX_free(kctx);

       This example derives 10 bytes using FEEDBACK-CMAC-AES256, with KI
       "secret", Label "label", and IV "sixteen bytes iv".

        EVP_KDF *kdf;
        EVP_KDF_CTX *kctx;
        unsigned char out[10];
        OSSL_PARAM params[8], *p = params;
        unsigned char *iv = "sixteen bytes iv";

        kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
        kctx = EVP_KDF_CTX_new(kdf);
        EVP_KDF_free(kdf);

        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CIPHER, "AES256", 0);
        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC, "CMAC", 0);
        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MODE, "FEEDBACK", 0);
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
                                                 "secret", strlen("secret"));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
                                                 "label", strlen("label"));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
                                                 "context", strlen("context"));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
                                                 iv, strlen(iv));
        *p = OSSL_PARAM_construct_end();
        if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
            error("EVP_KDF_derive");

        EVP_KDF_CTX_free(kctx);


CONFORMING TO

       NIST SP800-108, IETF RFC 6803, IETF RFC 8009.


SEE ALSO

       EVP_KDF(3), EVP_KDF_CTX_free(3), EVP_KDF_CTX_get_kdf_size(3),
       EVP_KDF_derive(3), "PARAMETERS" in EVP_KDF(3)


HISTORY

       This functionality was added in OpenSSL 3.0.

       Support for KMAC was added in OpenSSL 3.1.


COPYRIGHT

       Copyright 2019-2024 The OpenSSL Project Authors. All Rights Reserved.
       Copyright 2019 Red Hat, Inc.

       Licensed under the Apache License 2.0 (the "License").  You may not use
       this file except in compliance with the License.  You can obtain a copy
       in the file LICENSE in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.4.0                             2024-10-29                 EVP_KDF-KB(7ossl)

openssl 3.4.0 - Generated Thu Nov 21 10:42:44 CST 2024
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