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c9f18e5990
Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Richard Levitte <levitte@openssl.org> (Merged from https://github.com/openssl/openssl/pull/15178)
173 lines
5.3 KiB
Plaintext
173 lines
5.3 KiB
Plaintext
=pod
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=head1 NAME
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EVP_KDF-KB - The Key-Based EVP_KDF implementation
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=head1 DESCRIPTION
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The EVP_KDF-KB algorithm implements the Key-Based key derivation function
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(KBKDF). KBKDF derives a key from repeated application of a keyed MAC to an
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input secret (and other optional values).
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=head2 Identity
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"KBKDF" is the name for this implementation; it can be used with the
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EVP_KDF_fetch() function.
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=head2 Supported parameters
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The supported parameters are:
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=over 4
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=item "mode" (B<OSSL_KDF_PARAM_MODE>) <UTF8 string>
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The mode parameter determines which flavor of KBKDF to use - currently the
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choices are "counter" and "feedback". "counter" is the default, and will be
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used if unspecified.
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=item "mac" (B<OSSL_KDF_PARAM_MAC>) <UTF8 string>
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The value is either CMAC or HMAC.
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=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
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=item "cipher" (B<OSSL_KDF_PARAM_CIPHER>) <UTF8 string>
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=item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
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=item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string>
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=item "salt" (B<OSSL_KDF_PARAM_SALT>) <octet string>
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=item "info (B<OSSL_KDF_PARAM_INFO>) <octet string>
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=item "seed" (B<OSSL_KDF_PARAM_SEED>) <octet string>
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The seed parameter is unused in counter mode.
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=item "use-l" (B<OSSL_KDF_PARAM_KBKDF_USE_L>) <integer>
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Set to B<0> to disable use of the optional Fixed Input data 'L' (see SP800-108).
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The default value of B<1> will be used if unspecified.
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=item "use-separator" (B<OSSL_KDF_PARAM_KBKDF_USE_SEPARATOR>) <integer>
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Set to B<0> to disable use of the optional Fixed Input data 'zero separator'
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(see SP800-108) that is placed between the Label and Context.
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The default value of B<1> will be used if unspecified.
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=back
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Depending on whether mac is CMAC or HMAC, either digest or cipher is required
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(respectively) and the other is unused.
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The parameters key, salt, info, and seed correspond to KI, Label, Context, and
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IV (respectively) in SP800-108. As in that document, salt, info, and seed are
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optional and may be omitted.
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"mac", "digest", cipher" and "properties" are described in
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L<EVP_KDF(3)/PARAMETERS>.
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=head1 NOTES
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A context for KBKDF can be obtained by calling:
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EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
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EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
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The output length of an KBKDF is specified via the C<keylen>
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parameter to the L<EVP_KDF_derive(3)> function.
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Note that currently OpenSSL only implements counter and feedback modes. Other
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variants may be supported in the future.
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=head1 EXAMPLES
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This example derives 10 bytes using COUNTER-HMAC-SHA256, with KI "secret",
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Label "label", and Context "context".
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char out[10];
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OSSL_PARAM params[6], *p = params;
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kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
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kctx = EVP_KDF_CTX_new(kdf);
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EVP_KDF_free(kdf);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_DIGEST,
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"SHA2-256", 0);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC,
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"HMAC", 0);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
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"secret", strlen("secret"));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
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"label", strlen("label"));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
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"context", strlen("context"));
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
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error("EVP_KDF_derive");
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EVP_KDF_CTX_free(kctx);
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This example derives 10 bytes using FEEDBACK-CMAC-AES256, with KI "secret",
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Label "label", and IV "sixteen bytes iv".
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char out[10];
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OSSL_PARAM params[8], *p = params;
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unsigned char *iv = "sixteen bytes iv";
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kdf = EVP_KDF_fetch(NULL, "KBKDF", NULL);
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kctx = EVP_KDF_CTX_new(kdf);
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EVP_KDF_free(kdf);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_CIPHER, "AES256", 0);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MAC, "CMAC", 0);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_KDF_PARAM_MODE, "FEEDBACK", 0);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
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"secret", strlen("secret"));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SALT,
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"label", strlen("label"));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_INFO,
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"context", strlen("context"));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_SEED,
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iv, strlen(iv));
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_derive(kctx, out, sizeof(out), params) <= 0)
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error("EVP_KDF_derive");
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EVP_KDF_CTX_free(kctx);
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=head1 CONFORMING TO
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NIST SP800-108, IETF RFC 6803, IETF RFC 8009.
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=head1 SEE ALSO
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L<EVP_KDF(3)>,
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L<EVP_KDF_CTX_free(3)>,
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L<EVP_KDF_CTX_get_kdf_size(3)>,
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L<EVP_KDF_derive(3)>,
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L<EVP_KDF(3)/PARAMETERS>
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=head1 HISTORY
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This functionality was added to OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2019-2021 The OpenSSL Project Authors. All Rights Reserved.
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Copyright 2019 Red Hat, Inc.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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