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
#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);
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.
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.
selection can be any one of the values described in EVP_PKEY_fromdata(3)/Selections.
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.
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.
provider(7), OSSL_ENCODER(3), OSSL_ENCODER_CTX(3)
The functions described here were added in OpenSSL 3.0.
Copyright 2019-2022 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.