openssl/doc/man3/d2i_PrivateKey.pod
Richard Levitte b305452f69 Redesign the KEYMGMT libcrypto <-> provider interface - the basics
The KEYMGMT libcrypto <-> provider interface currently makes a few
assumptions:

1.  provider side domain parameters and key data isn't mutable. In
    other words, as soon as a key has been created in any (loaded,
    imported data, ...), it's set in stone.
2.  provider side domain parameters can be strictly separated from the
    key data.

This does work for the most part, but there are places where that's a
bit too rigid for the functionality that the EVP_PKEY API delivers.
Key data needs to be mutable to allow the flexibility that functions
like EVP_PKEY_copy_parameters promise, as well as to provide the
combinations of data that an EVP_PKEY is generally assumed to be able
to hold:

- domain parameters only
- public key only
- public key + private key
- domain parameters + public key
- domain parameters + public key + private key

To remedy all this, we:

1.  let go of the distinction between domain parameters and key
    material proper in the libcrypto <-> provider interface.

    As a consequence, functions that still need it gain a selection
    argument, which is a set of bits that indicate what parts of the
    key object are to be considered in a specific call.  This allows
    a reduction of very similar functions into one.

2.  Rework the libcrypto <-> provider interface so provider side key
    objects are created and destructed with a separate function, and
    get their data filled and extracted in through import and export.

(future work will see other key object constructors and other
functions to fill them with data)

Fixes #10979

squash! Redesign the KEYMGMT libcrypto <-> provider interface - the basics

Remedy 1 needs a rewrite:

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Shane Lontis <shane.lontis@oracle.com>
Reviewed-by: Paul Dale <paul.dale@oracle.com>
(Merged from https://github.com/openssl/openssl/pull/11006)
2020-02-07 09:37:56 +01:00

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=pod
=head1 NAME
d2i_PrivateKey, d2i_PublicKey, d2i_KeyParams, d2i_AutoPrivateKey,
i2d_PrivateKey, i2d_PublicKey, i2d_KeyParams, i2d_KeyParams_bio,
d2i_PrivateKey_bio, d2i_PrivateKey_fp, d2i_KeyParams_bio
- decode and encode functions for reading and saving EVP_PKEY structures
=head1 SYNOPSIS
#include <openssl/evp.h>
EVP_PKEY *d2i_PrivateKey(int type, EVP_PKEY **a, const unsigned char **pp,
long length);
EVP_PKEY *d2i_PublicKey(int type, EVP_PKEY **a, const unsigned char **pp,
long length);
EVP_PKEY *d2i_KeyParams(int type, EVP_PKEY **a, const unsigned char **pp,
long length);
EVP_PKEY *d2i_AutoPrivateKey(EVP_PKEY **a, const unsigned char **pp,
long length);
int i2d_PrivateKey(const EVP_PKEY *a, unsigned char **pp);
int i2d_PublicKey(const EVP_PKEY *a, unsigned char **pp);
int i2d_KeyParams(const EVP_PKEY *a, unsigned char **pp);
int i2d_KeyParams_bio(BIO *bp, const EVP_PKEY *pkey);
EVP_PKEY *d2i_PrivateKey_bio(BIO *bp, EVP_PKEY **a);
EVP_PKEY *d2i_PrivateKey_fp(FILE *fp, EVP_PKEY **a)
EVP_PKEY *d2i_KeyParams_bio(int type, EVP_PKEY **a, BIO *in);
=head1 DESCRIPTION
d2i_PrivateKey() decodes a private key using algorithm B<type>. It attempts to
use any key specific format or PKCS#8 unencrypted PrivateKeyInfo format. The
B<type> parameter should be a public key algorithm constant such as
B<EVP_PKEY_RSA>. An error occurs if the decoded key does not match B<type>.
d2i_PublicKey() does the same for public keys.
d2i_KeyParams() does the same for key parameters.
d2i_AutoPrivateKey() is similar to d2i_PrivateKey() except it attempts to
automatically detect the private key format.
i2d_PrivateKey() encodes B<key>. It uses a key specific format or, if none is
defined for that key type, PKCS#8 unencrypted PrivateKeyInfo format.
i2d_PublicKey() does the same for public keys.
i2d_KeyParams() does the same for key parameters.
These functions are similar to the d2i_X509() functions; see L<d2i_X509(3)>.
=head1 NOTES
All these functions use DER format and unencrypted keys. Applications wishing
to encrypt or decrypt private keys should use other functions such as
d2i_PKCS8PrivateKey() instead.
If the B<*a> is not NULL when calling d2i_PrivateKey() or d2i_AutoPrivateKey()
(i.e. an existing structure is being reused) and the key format is PKCS#8
then B<*a> will be freed and replaced on a successful call.
To decode a key with type B<EVP_PKEY_EC>, d2i_PublicKey() requires B<*a> to be
a non-NULL EVP_PKEY structure assigned an EC_KEY structure referencing the proper
EC_GROUP.
=head1 RETURN VALUES
The d2i_PrivateKey(), d2i_AutoPrivateKey(), d2i_PrivateKey_bio(), d2i_PrivateKey_fp(),
d2i_PublicKey(), d2i_KeyParams() and d2i_KeyParams_bio() functions return a valid
B<EVP_KEY> structure or B<NULL> if an error occurs. The error code can be
obtained by calling L<ERR_get_error(3)>.
i2d_PrivateKey(), i2d_PublicKey(), i2d_KeyParams() i2d_KeyParams_bio() return
the number of bytes successfully encoded or a negative value if an error occurs.
The error code can be obtained by calling L<ERR_get_error(3)>.
=head1 SEE ALSO
L<crypto(7)>,
L<d2i_PKCS8PrivateKey_bio(3)>
=head1 COPYRIGHT
Copyright 2017-2019 The OpenSSL Project Authors. All Rights Reserved.
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
L<https://www.openssl.org/source/license.html>.
=cut