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Explicitely document what semantic meaning do various EVP_KDF algorithms produce. PBKDF2 produces cryptographic keys that are subject to cryptographic security measures, for example as defined in NIST SP 800-132. All other algorithms produce keying material, not subject to explicit output length checks in any known standards. Reviewed-by: Paul Dale <ppzgs1@gmail.com> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/25610)
116 lines
2.9 KiB
Plaintext
116 lines
2.9 KiB
Plaintext
=pod
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=head1 NAME
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EVP_KDF-PBKDF2 - The PBKDF2 EVP_KDF implementation
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=head1 DESCRIPTION
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Support for computing the B<PBKDF2> password-based KDF through the B<EVP_KDF>
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API.
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The EVP_KDF-PBKDF2 algorithm implements the PBKDF2 password-based key
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derivation function, as described in SP800-132; it derives a key from a password
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using a salt and iteration count.
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The output is considered to be a cryptographic key.
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=head2 Identity
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"PBKDF2" is the name for this implementation; it
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can be used with the 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 "pass" (B<OSSL_KDF_PARAM_PASSWORD>) <octet string>
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=item "salt" (B<OSSL_KDF_PARAM_SALT>) <octet string>
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=item "iter" (B<OSSL_KDF_PARAM_ITER>) <unsigned integer>
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This parameter has a default value of 2048.
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=item "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
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=item "digest" (B<OSSL_KDF_PARAM_DIGEST>) <UTF8 string>
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These parameters work as described in L<EVP_KDF(3)/PARAMETERS>.
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=item "pkcs5" (B<OSSL_KDF_PARAM_PKCS5>) <integer>
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This parameter can be used to enable or disable SP800-132 compliance checks.
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Setting the mode to 0 enables the compliance checks.
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The checks performed are:
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=over 4
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=item - the iteration count is at least 1000.
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=item - the salt length is at least 128 bits.
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=item - the derived key length is at least 112 bits.
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=back
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The default provider uses a default mode of 1 for backwards compatibility,
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and the FIPS provider uses a default mode of 0.
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This option breaks FIPS compliance if it causes the approved "fips-indicator"
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to return 0.
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=item "fips-indicator" (B<OSSL_KDF_PARAM_FIPS_APPROVED_INDICATOR>) <integer>
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This option is used by the OpenSSL FIPS provider.
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A getter that returns 1 if the operation is FIPS approved, or 0 otherwise.
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This may be used after calling EVP_KDF_derive. It returns 0 if "pkcs5"
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is set to 1 and the derived key length, salt length or iteration count test
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fails.
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=back
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=head1 NOTES
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A typical application of this algorithm is to derive keying material for an
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encryption algorithm from a password in the "pass", a salt in "salt",
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and an iteration count.
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Increasing the "iter" parameter slows down the algorithm which makes it
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harder for an attacker to perform a brute force attack using a large number
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of candidate passwords.
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No assumption is made regarding the given password; it is simply treated as a
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byte sequence.
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=head1 CONFORMING TO
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SP800-132
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=head1 SEE ALSO
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L<EVP_KDF(3)>,
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L<EVP_KDF_CTX_new(3)>,
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L<EVP_KDF_CTX_free(3)>,
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L<EVP_KDF_CTX_set_params(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 in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2018-2024 The OpenSSL Project Authors. All Rights Reserved.
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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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