Ubuntu Manpage: OSSL_DECODER_CTX_new_for_pkey, OSSL_DECODER_CTX_set

Provided by: libssl-doc_3.0.5-2ubuntu1_all

NAME

       OSSL_DECODER_CTX_new_for_pkey, OSSL_DECODER_CTX_set_passphrase,
       OSSL_DECODER_CTX_set_pem_password_cb, OSSL_DECODER_CTX_set_passphrase_ui,
       OSSL_DECODER_CTX_set_passphrase_cb - Decoder routines to decode EVP_PKEYs

SYNOPSIS

        #include <openssl/decoder.h>

        OSSL_DECODER_CTX *
        OSSL_DECODER_CTX_new_for_pkey(EVP_PKEY **pkey,
                                      const char *input_type,
                                      const char *input_struct,
                                      const char *keytype, int selection,
                                      OSSL_LIB_CTX *libctx, const char *propquery);

        int OSSL_DECODER_CTX_set_passphrase(OSSL_DECODER_CTX *ctx,
                                            const unsigned char *kstr,
                                            size_t klen);
        int OSSL_DECODER_CTX_set_pem_password_cb(OSSL_DECODER_CTX *ctx,
                                                 pem_password_cb *cb,
                                                 void *cbarg);
        int OSSL_DECODER_CTX_set_passphrase_ui(OSSL_DECODER_CTX *ctx,
                                               const UI_METHOD *ui_method,
                                               void *ui_data);
        int OSSL_DECODER_CTX_set_passphrase_cb(OSSL_DECODER_CTX *ctx,
                                               OSSL_PASSPHRASE_CALLBACK *cb,
                                               void *cbarg);

DESCRIPTION

OSSL_DECODER_CTX_new_for_pkey() is a utility function that creates a OSSL_DECODER_CTX,
finds all applicable decoder implementations and sets them up, so all the caller has to do
next is call functions like OSSL_DECODER_from_bio(3). The caller may use the optional
input_type, input_struct, keytype and selection to specify what the input is expected to
contain. The pkey must reference an EVP_PKEY * variable that will be set to the newly
created EVP_PKEY on succesfull decoding. The referenced variable must be initialized to
NULL before calling the function.

Internally OSSL_DECODER_CTX_new_for_pkey() searches for all available EVP_KEYMGMT(3)
implementations, and then builds a list of all potential decoder implementations that may
be able to process the encoded input into data suitable for EVP_PKEYs. All these
implementations are implicitly fetched using libctx and propquery.

The search of decoder implementations can be limited with input_type and input_struct
which specifies a starting input type and input structure. NULL is valid for both of them
and signifies that the decoder implementations will find out the input type on their own.
They are set with OSSL_DECODER_CTX_set_input_type(3) and
OSSL_DECODER_CTX_set_input_structure(3). See "Input Types" and "Input Structures" below
for further information.

The search of decoder implementations can also be limited with keytype and selection,
which specifies the expected resulting keytype and contents. NULL and zero are valid and
signify that the decoder implementations will find out the keytype and key contents on
their own from the input they get.

If no suitable decoder implementation is found, OSSL_DECODER_CTX_new_for_pkey() still
creates a OSSL_DECODER_CTX, but with no associated decoder
(OSSL_DECODER_CTX_get_num_decoders(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_DECODER_CTX_set_passphrase() gives the implementation a pass phrase to use when
decrypting the encoded private key. Alternatively, a pass phrase callback may be specified
with the following functions.

OSSL_DECODER_CTX_set_pem_password_cb(), OSSL_DECODER_CTX_set_passphrase_ui() and
OSSL_DECODER_CTX_set_passphrase_cb() set up a callback method that the implementation can
use to prompt for a pass phrase, giving the caller the choice of prefered pass phrase
callback form. These are called indirectly, through an internal OSSL_PASSPHRASE_CALLBACK
function.

The internal OSSL_PASSPHRASE_CALLBACK function caches the pass phrase, to be re-used in
all decodings that are performed in the same decoding run (for example, within one
OSSL_DECODER_from_bio(3) call).

Input Types
Available input types depend on the implementations that available providers offer, and
provider documentation should have the details.

Among the known input types that OpenSSL decoder implementations offer for EVP_PKEYs are
"DER", "PEM", "MSBLOB" and "PVK". See openssl-glossary(7) for further information on what
these input types mean.

Input Structures
Available input structures depend on the implementations that available providers offer,
and provider documentation should have the details.

Among the known input structures that OpenSSL decoder implementations offer for EVP_PKEYs
are "pkcs8" and "SubjectPublicKeyInfo".

OpenSSL decoder implementations also support the input structure "type-specific". This is
the structure used for keys encoded according to key type specific specifications. For
example, RSA keys encoded according to PKCS#1.

Selections
selection can be any one of the values described in "Selections" in EVP_PKEY_fromdata(3).
Additionally selection can also be set to 0 to indicate that the code will auto detect the
selection.

RETURN VALUES

       OSSL_DECODER_CTX_new_for_pkey() returns a pointer to a OSSL_DECODER_CTX, or NULL if it
       couldn't be created.

       OSSL_DECODER_CTX_set_passphrase(), OSSL_DECODER_CTX_set_pem_password_cb(),
       OSSL_DECODER_CTX_set_passphrase_ui() and OSSL_DECODER_CTX_set_passphrase_cb() all return 1
       on success, or 0 on failure.

HISTORY

       The functions described here were added in OpenSSL 3.0.

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