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d2f82495a2
One macro existed that was added since 1.1.1 and was undocumented. This had been added to missingmacro.txt. This is the wrong approach and so has been removed from there. There were some entries in missingcrypto.txt that don't exist as functions at all. There were also some which were in fact documented. Additionally 2 entries from missingcrypto.txt have been moved to missingmacro.txt. These entries existed in 1.1.1 and were undocumented. In master they have been deprecated and compatibility macros for them implemented. The replacement functions have been documented. An entry in missingcrypto111.txt was not in alphabetical order (and was also) duplicated, but the equivalent entry in missingcrypto.txt was in the correct place. This has been corrected to make comparisons between the files easier. Finally a function has been added to missingcrypto111.txt. This function did exist in 1.1.1 and was undocumented. Its unclear why this wasn't in missingcrypto111.txt to start with. Reviewed-by: Paul Dale <pauli@openssl.org> Reviewed-by: Tomas Mraz <tomas@openssl.org> (Merged from https://github.com/openssl/openssl/pull/15333)
116 lines
3.3 KiB
Plaintext
116 lines
3.3 KiB
Plaintext
=pod
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=head1 NAME
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EVP_KDF-KRB5KDF - The RFC3961 Krb5 KDF EVP_KDF implementation
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=head1 DESCRIPTION
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Support for computing the B<KRB5KDF> KDF through the B<EVP_KDF> API.
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The EVP_KDF-KRB5KDF algorithm implements the key derivation function defined
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in RFC 3961, section 5.1 and is used by Krb5 to derive session keys.
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Three inputs are required to perform key derivation: a cipher, (for example
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AES-128-CBC), the initial key, and a constant.
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=head2 Identity
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"KRB5KDF" is the name for this implementation;
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it 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 "properties" (B<OSSL_KDF_PARAM_PROPERTIES>) <UTF8 string>
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=item "cipher" (B<OSSL_KDF_PARAM_CIPHER>) <UTF8 string>
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=item "key" (B<OSSL_KDF_PARAM_KEY>) <octet string>
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These parameters work as described in L<EVP_KDF(3)/PARAMETERS>.
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=item "constant" (B<OSSL_KDF_PARAM_CONSTANT>) <octet string>
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This parameter sets the constant value for the KDF.
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If a value is already set, the contents are replaced.
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=back
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=head1 NOTES
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A context for KRB5KDF can be obtained by calling:
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EVP_KDF *kdf = EVP_KDF_fetch(NULL, "KRB5KDF", NULL);
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EVP_KDF_CTX *kctx = EVP_KDF_CTX_new(kdf);
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The output length of the KRB5KDF derivation is specified via the I<keylen>
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parameter to the L<EVP_KDF_derive(3)> function, and MUST match the key
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length for the chosen cipher or an error is returned. Moreover, the
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constant's length must not exceed the block size of the cipher.
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Since the KRB5KDF output length depends on the chosen cipher, calling
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L<EVP_KDF_CTX_get_kdf_size(3)> to obtain the requisite length returns the correct length
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only after the cipher is set. Prior to that B<EVP_MAX_KEY_LENGTH> is returned.
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The caller must allocate a buffer of the correct length for the chosen
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cipher, and pass that buffer to the L<EVP_KDF_derive(3)> function along
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with that length.
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=head1 EXAMPLES
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This example derives a key using the AES-128-CBC cipher:
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EVP_KDF *kdf;
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EVP_KDF_CTX *kctx;
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unsigned char key[16] = "01234...";
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unsigned char constant[] = "I'm a constant";
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unsigned char out[16];
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size_t outlen = sizeof(out);
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OSSL_PARAM params[4], *p = params;
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kdf = EVP_KDF_fetch(NULL, "KRB5KDF", 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,
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SN_aes_128_cbc,
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strlen(SN_aes_128_cbc));
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_KEY,
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key, (size_t)16);
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*p++ = OSSL_PARAM_construct_octet_string(OSSL_KDF_PARAM_CONSTANT,
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constant, strlen(constant));
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*p = OSSL_PARAM_construct_end();
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if (EVP_KDF_derive(kctx, out, outlen, params) <= 0)
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/* Error */
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EVP_KDF_CTX_free(kctx);
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=head1 CONFORMING TO
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RFC 3961
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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 2016-2021 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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