133 lines
4.6 KiB
Plaintext
133 lines
4.6 KiB
Plaintext
=pod
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=head1 NAME
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EVP_PKEY_CTX_new, EVP_PKEY_CTX_new_id, EVP_PKEY_CTX_new_from_name,
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EVP_PKEY_CTX_new_from_pkey, EVP_PKEY_CTX_dup, EVP_PKEY_CTX_free,
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EVP_PKEY_CTX_is_a
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- public key algorithm context functions
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=head1 SYNOPSIS
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#include <openssl/evp.h>
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EVP_PKEY_CTX *EVP_PKEY_CTX_new(EVP_PKEY *pkey, ENGINE *e);
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EVP_PKEY_CTX *EVP_PKEY_CTX_new_id(int id, ENGINE *e);
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EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_name(OSSL_LIB_CTX *libctx,
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const char *name,
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const char *propquery);
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EVP_PKEY_CTX *EVP_PKEY_CTX_new_from_pkey(OSSL_LIB_CTX *libctx,
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EVP_PKEY *pkey,
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const char *propquery);
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EVP_PKEY_CTX *EVP_PKEY_CTX_dup(const EVP_PKEY_CTX *ctx);
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void EVP_PKEY_CTX_free(EVP_PKEY_CTX *ctx);
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int EVP_PKEY_CTX_is_a(EVP_PKEY_CTX *ctx, const char *keytype);
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=head1 DESCRIPTION
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The EVP_PKEY_CTX_new() function allocates public key algorithm context using
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the I<pkey> key type and ENGINE I<e>.
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The EVP_PKEY_CTX_new_id() function allocates public key algorithm context
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using the key type specified by I<id> and ENGINE I<e>.
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The EVP_PKEY_CTX_new_from_name() function allocates a public key algorithm
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context using the library context I<libctx> (see L<OSSL_LIB_CTX(3)>), the
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key type specified by I<name> and the property query I<propquery>. None
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of the arguments are duplicated, so they must remain unchanged for the
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lifetime of the returned B<EVP_PKEY_CTX> or of any of its duplicates. Read
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further about the possible names in L</NOTES> below.
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The EVP_PKEY_CTX_new_from_pkey() function allocates a public key algorithm
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context using the library context I<libctx> (see L<OSSL_LIB_CTX(3)>) and the
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algorithm specified by I<pkey> and the property query I<propquery>. None of the
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arguments are duplicated, so they must remain unchanged for the lifetime of the
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returned B<EVP_PKEY_CTX> or any of its duplicates.
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EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_new_from_name() are normally
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used when no B<EVP_PKEY> structure is associated with the operations,
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for example during parameter generation or key generation for some
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algorithms.
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EVP_PKEY_CTX_dup() duplicates the context I<ctx>. It is not supported for a
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keygen operation.
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EVP_PKEY_CTX_free() frees up the context I<ctx>.
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If I<ctx> is NULL, nothing is done.
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EVP_PKEY_is_a() checks if the key type associated with I<ctx> is I<keytype>.
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=head1 NOTES
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=head2 On B<EVP_PKEY_CTX>
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The B<EVP_PKEY_CTX> structure is an opaque public key algorithm context used
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by the OpenSSL high-level public key API. Contexts B<MUST NOT> be shared between
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threads: that is it is not permissible to use the same context simultaneously
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in two threads.
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=head2 On Key Types
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We mention "key type" in this manual, which is the same
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as "algorithm" in most cases, allowing either term to be used
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interchangeably. There are algorithms where the I<key type> and the
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I<algorithm> of the operations that use the keys are not the same,
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such as EC keys being used for ECDSA and ECDH operations.
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Key types are given in two different manners:
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=over 4
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=item Legacy NID or EVP_PKEY type
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This is the I<id> used with EVP_PKEY_CTX_new_id().
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These are B<EVP_PKEY_RSA>, B<EVP_PKEY_RSA_PSS>, B<EVP_PKEY_DSA>,
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B<EVP_PKEY_DH>, B<EVP_PKEY_EC>, B<EVP_PKEY_SM2>, B<EVP_PKEY_X25519>,
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B<EVP_PKEY_X448>, and are used by legacy methods.
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=item Name strings
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This is the I<name> used with EVP_PKEY_CTX_new_from_name().
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These are names like "RSA", "DSA", and what's available depends on what
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providers are currently accessible.
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The OpenSSL providers offer a set of key types available this way, please
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see L<OSSL_PROVIDER-FIPS(7)> and L<OSSL_PROVIDER-default(7)> and related
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documentation for more information.
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=back
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=head1 RETURN VALUES
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EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id() and EVP_PKEY_CTX_dup() return either
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the newly allocated B<EVP_PKEY_CTX> structure or B<NULL> if an error occurred.
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EVP_PKEY_CTX_free() does not return a value.
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EVP_PKEY_CTX_is_a() returns 1 for true and 0 for false.
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=head1 SEE ALSO
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L<EVP_PKEY_new(3)>
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=head1 HISTORY
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The EVP_PKEY_CTX_new(), EVP_PKEY_CTX_new_id(), EVP_PKEY_CTX_dup() and
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EVP_PKEY_CTX_free() functions were added in OpenSSL 1.0.0.
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The EVP_PKEY_CTX_new_from_name() and EVP_PKEY_CTX_new_from_pkey() functions were
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added in OpenSSL 3.0.
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=head1 COPYRIGHT
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Copyright 2006-2021 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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