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OSSL_ENCODER_CTX_new_for_pkey(3) OpenSSL OSSL_ENCODER_CTX_new_for_pkey(3)
NAME
OSSL_ENCODER_CTX_new_for_pkey, OSSL_ENCODER_CTX_set_cipher,
OSSL_ENCODER_CTX_set_passphrase, OSSL_ENCODER_CTX_set_pem_password_cb,
OSSL_ENCODER_CTX_set_passphrase_cb, OSSL_ENCODER_CTX_set_passphrase_ui
- Encoder routines to encode EVP_PKEYs
LIBRARY
libcrypto, -lcrypto
SYNOPSIS
#include <openssl/encoder.h>
OSSL_ENCODER_CTX *
OSSL_ENCODER_CTX_new_for_pkey(const EVP_PKEY *pkey, int selection,
const char *output_type,
const char *output_structure,
const char *propquery);
int OSSL_ENCODER_CTX_set_cipher(OSSL_ENCODER_CTX *ctx,
const char *cipher_name,
const char *propquery);
int OSSL_ENCODER_CTX_set_passphrase(OSSL_ENCODER_CTX *ctx,
const unsigned char *kstr,
size_t klen);
int OSSL_ENCODER_CTX_set_pem_password_cb(OSSL_ENCODER_CTX *ctx,
pem_password_cb *cb, void *cbarg);
int OSSL_ENCODER_CTX_set_passphrase_ui(OSSL_ENCODER_CTX *ctx,
const UI_METHOD *ui_method,
void *ui_data);
int OSSL_ENCODER_CTX_set_passphrase_cb(OSSL_ENCODER_CTX *ctx,
OSSL_PASSPHRASE_CALLBACK *cb,
void *cbarg);
DESCRIPTION
OSSL_ENCODER_CTX_new_for_pkey() is a utility function that creates a
OSSL_ENCODER_CTX, finds all applicable encoder implementations and sets
them up, so almost all the caller has to do next is call functions like
OSSL_ENCODER_to_bio(3). output_type determines the final output
encoding, and selection can be used to select what parts of the pkey
should be included in the output. output_type is further discussed in
"Output types" below, and selection is further described in
"Selections".
Internally, OSSL_ENCODER_CTX_new_for_pkey() uses the names from the
EVP_KEYMGMT(3) implementation associated with pkey to build a list of
applicable encoder implementations that are used to process the pkey
into the encoding named by output_type, with the outermost structure
named by output_structure if that's relevant. All these
implementations are implicitly fetched, with propquery for finer
selection.
If no suitable encoder implementation is found,
OSSL_ENCODER_CTX_new_for_pkey() still creates a OSSL_ENCODER_CTX, but
with no associated encoder (OSSL_ENCODER_CTX_get_num_encoders(3)
returns zero). This helps the caller to distinguish between an error
when creating the OSSL_ENCODER_CTX and missing encoder implementation,
and allows it to act accordingly.
OSSL_ENCODER_CTX_set_cipher() tells the implementation what cipher
should be used to encrypt encoded keys. The cipher is given by name
cipher_name. The interpretation of that cipher_name is implementation
dependent. The implementation may implement the cipher directly itself
or by other implementations, or it may choose to fetch it. If the
implementation supports fetching the cipher, then it may use propquery
as properties to be queried for when fetching. cipher_name may also be
NULL, which will result in unencrypted encoding.
OSSL_ENCODER_CTX_set_passphrase() gives the implementation a pass
phrase to use when encrypting the encoded private key. Alternatively,
a pass phrase callback may be specified with the following functions.
OSSL_ENCODER_CTX_set_pem_password_cb(),
OSSL_ENCODER_CTX_set_passphrase_ui() and
OSSL_ENCODER_CTX_set_passphrase_cb() sets up a callback method that the
implementation can use to prompt for a pass phrase, giving the caller
the choice of preferred pass phrase callback form. These are called
indirectly, through an internal OSSL_PASSPHRASE_CALLBACK(3) function.
Output types
The possible EVP_PKEY output types depends on the available
implementations.
OpenSSL has built in implementations for the following output types:
"TEXT"
The output is a human readable description of the key.
EVP_PKEY_print_private(3), EVP_PKEY_print_public(3) and
EVP_PKEY_print_params(3) use this for their output.
"DER"
The output is the DER encoding of the selection of the pkey.
"PEM"
The output is the selection of the pkey in PEM format.
Selections
selection can be any one of the values described in "Selections" in
EVP_PKEY_fromdata(3).
These are only 'hints' since the encoder implementations are free to
determine what makes sense to include in the output, and this may
depend on the desired output. For example, an EC key in a PKCS#8
structure doesn't usually include the public key.
RETURN VALUES
OSSL_ENCODER_CTX_new_for_pkey() returns a pointer to an
OSSL_ENCODER_CTX, or NULL if it couldn't be created.
OSSL_ENCODER_CTX_set_cipher(), OSSL_ENCODER_CTX_set_passphrase(),
OSSL_ENCODER_CTX_set_pem_password_cb(),
OSSL_ENCODER_CTX_set_passphrase_ui() and
OSSL_ENCODER_CTX_set_passphrase_cb() all return 1 on success, or 0 on
failure.
SEE ALSO
provider(7), OSSL_ENCODER(3), OSSL_ENCODER_CTX(3)
HISTORY
The functions described here were added in OpenSSL 3.0.
COPYRIGHT
Copyright 2019-2021 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
<https://www.openssl.org/source/license.html>.
3.0.12 2023-05-07 OSSL_ENCODER_CTX_new_for_pkey(3)