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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)