4674aaf4f2
3.0.0 is a habit from pre-3.0 OpenSSL, which doesn't make sense with the new version scheme. Reviewed-by: Tim Hudson <tjh@openssl.org> (Merged from https://github.com/openssl/openssl/pull/9376)
150 lines
3.5 KiB
Text
150 lines
3.5 KiB
Text
=pod
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=head1 NAME
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EVP_KDF_X942 - The X9.42-2001 asn1 EVP_KDF implementation
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=head1 DESCRIPTION
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The EVP_KDF_X942 algorithm implements the key derivation function (X942KDF).
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X942KDF is used by Cryptographic Message Syntax (CMS) for DH KeyAgreement, to
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derive a key using input such as a shared secret key and other info. The other
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info is DER encoded data that contains a 32 bit counter.
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=head2 Numeric identity
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B<EVP_KDF_X942> is the numeric identity for this implementation; it
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can be used with the EVP_KDF_CTX_new_id() function.
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=head2 Supported controls
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The supported controls are:
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=over 4
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=item B<EVP_KDF_CTRL_SET_MD>
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This control works as described in L<EVP_KDF_CTX(3)/CONTROLS>.
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=item B<EVP_KDF_CTRL_SET_KEY>
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This control expects two arguments: C<unsigned char *secret>, C<size_t secretlen>
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The shared secret used for key derivation. This control sets the secret.
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EVP_KDF_ctrl_str() takes two type strings for this control:
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=over 4
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=item "secret"
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The value string is used as is.
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=item "hexsecret"
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The value string is expected to be a hexadecimal number, which will be
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decoded before being passed on as the control value.
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=back
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=item B<EVP_KDF_CTRL_SET_UKM>
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This control expects two arguments: C<unsigned char *ukm>, C<size_t ukmlen>
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An optional random string that is provided by the sender called "partyAInfo".
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In CMS this is the user keying material.
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EVP_KDF_ctrl_str() takes two type strings for this control:
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=over 4
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=item "ukm"
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The value string is used as is.
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=item "hexukm"
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The value string is expected to be a hexadecimal number, which will be
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decoded before being passed on as the control value.
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=back
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=item B<EVP_KDF_CTRL_SET_CEK_ALG>
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This control expects one argument: C<char *alg>
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The CEK wrapping algorithm name.
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EVP_KDF_ctrl_str() type string: "cekalg"
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The value string is used as is.
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=back
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=head1 NOTES
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A context for X942KDF can be obtained by calling:
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EVP_KDF_CTX *kctx = EVP_KDF_CTX_new_id(EVP_KDF_X942);
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The output length of an X942KDF is specified via the C<keylen>
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parameter to the L<EVP_KDF_derive(3)> function.
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=head1 EXAMPLE
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This example derives 24 bytes, with the secret key "secret" and a random user
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keying material:
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EVP_KDF_CTX *kctx;
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unsigned char out[192/8];
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unsignred char ukm[64];
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if (RAND_bytes(ukm, sizeof(ukm)) <= 0)
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error("RAND_bytes");
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kctx = EVP_KDF_CTX_new_id(EVP_KDF_X942);
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if (kctx == NULL)
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error("EVP_KDF_CTX_new_id");
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if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_MD, EVP_sha256()) <= 0)
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error("EVP_KDF_CTRL_SET_MD");
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if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_KEY, "secret", (size_t)6) <= 0)
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error("EVP_KDF_CTRL_SET_KEY");
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if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_UKM, ukm, sizeof(ukm)) <= 0)
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error("EVP_KDF_CTRL_SET_UKM");
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if (EVP_KDF_ctrl(kctx, EVP_KDF_CTRL_SET_CEK_ALG,
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SN_id_smime_alg_CMS3DESwrap) <= 0)
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error("EVP_KDF_CTRL_SET_CEK_ALG");
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if (EVP_KDF_derive(kctx, out, sizeof(out)) <= 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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RFC 2631
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=head1 SEE ALSO
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L<EVP_KDF_CTX>,
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L<EVP_KDF_CTX_new_id(3)>,
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L<EVP_KDF_CTX_free(3)>,
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L<EVP_KDF_ctrl(3)>,
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L<EVP_KDF_size(3)>,
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L<EVP_KDF_derive(3)>,
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L<EVP_KDF_CTX(3)/CONTROLS>
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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 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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