NAME¶

OSSL_ENCODER_CTX, OSSL_ENCODER_CTX_new, OSSL_ENCODER_settable_ctx_params, OSSL_ENCODER_CTX_set_params, OSSL_ENCODER_CTX_free, OSSL_ENCODER_CTX_set_selection, OSSL_ENCODER_CTX_set_output_type, OSSL_ENCODER_CTX_set_output_structure, OSSL_ENCODER_CTX_add_encoder, OSSL_ENCODER_CTX_add_extra, OSSL_ENCODER_CTX_get_num_encoders, OSSL_ENCODER_INSTANCE, OSSL_ENCODER_INSTANCE_get_encoder, OSSL_ENCODER_INSTANCE_get_encoder_ctx, OSSL_ENCODER_INSTANCE_get_output_type, OSSL_ENCODER_INSTANCE_get_output_structure, OSSL_ENCODER_CONSTRUCT, OSSL_ENCODER_CLEANUP, OSSL_ENCODER_CTX_set_construct, OSSL_ENCODER_CTX_set_construct_data, OSSL_ENCODER_CTX_set_cleanup - Encoder context routines

SYNOPSIS¶

 #include <openssl/encoder.h>
 typedef struct ossl_encoder_ctx_st OSSL_ENCODER_CTX;
 OSSL_ENCODER_CTX *OSSL_ENCODER_CTX_new();
 const OSSL_PARAM *OSSL_ENCODER_settable_ctx_params(OSSL_ENCODER *encoder);
 int OSSL_ENCODER_CTX_set_params(OSSL_ENCODER_CTX *ctx,
                                 const OSSL_PARAM params[]);
 void OSSL_ENCODER_CTX_free(OSSL_ENCODER_CTX *ctx);
 int OSSL_ENCODER_CTX_set_selection(OSSL_ENCODER_CTX *ctx, int selection);
 int OSSL_ENCODER_CTX_set_output_type(OSSL_ENCODER_CTX *ctx,
                                      const char *output_type);
 int OSSL_ENCODER_CTX_set_output_structure(OSSL_ENCODER_CTX *ctx,
                                           const char *output_structure);
 int OSSL_ENCODER_CTX_add_encoder(OSSL_ENCODER_CTX *ctx, OSSL_ENCODER *encoder);
 int OSSL_ENCODER_CTX_add_extra(OSSL_ENCODER_CTX *ctx,
                                OSSL_LIB_CTX *libctx, const char *propq);
 int OSSL_ENCODER_CTX_get_num_encoders(OSSL_ENCODER_CTX *ctx);
 typedef struct ossl_encoder_instance_st OSSL_ENCODER_INSTANCE;
 OSSL_ENCODER *
 OSSL_ENCODER_INSTANCE_get_encoder(OSSL_ENCODER_INSTANCE *encoder_inst);
 void *
 OSSL_ENCODER_INSTANCE_get_encoder_ctx(OSSL_ENCODER_INSTANCE *encoder_inst);
 const char *
 OSSL_ENCODER_INSTANCE_get_output_type(OSSL_ENCODER_INSTANCE *encoder_inst);
 const char *
 OSSL_ENCODER_INSTANCE_get_output_structure(OSSL_ENCODER_INSTANCE *encoder_inst);
 typedef const void *OSSL_ENCODER_CONSTRUCT(OSSL_ENCODER_INSTANCE *encoder_inst,
                                            void *construct_data);
 typedef void OSSL_ENCODER_CLEANUP(void *construct_data);
 int OSSL_ENCODER_CTX_set_construct(OSSL_ENCODER_CTX *ctx,
                                    OSSL_ENCODER_CONSTRUCT *construct);
 int OSSL_ENCODER_CTX_set_construct_data(OSSL_ENCODER_CTX *ctx,
                                         void *construct_data);
 int OSSL_ENCODER_CTX_set_cleanup(OSSL_ENCODER_CTX *ctx,
                                  OSSL_ENCODER_CLEANUP *cleanup);

DESCRIPTION¶

Encoding an input object to the desired encoding may be done with a chain of encoder implementations, which means that the output from one encoder may be the input for the next in the chain. The OSSL_ENCODER_CTX holds all the data about these encoders. This allows having generic format encoders such as DER to PEM, as well as more specialized encoders like RSA to DER.

The final output type must be given, and a chain of encoders must end with an implementation that produces that output type.

At the beginning of the encoding process, a constructor provided by the caller is called to ensure that there is an appropriate provider-side object to start with. The constructor is set with OSSL_ENCODER_CTX_set_construct().

OSSL_ENCODER_INSTANCE is an opaque structure that contains data about the encoder that is going to be used, and that may be useful for the constructor. There are some functions to extract data from this type, described in "Constructor" below.

RETURN VALUES¶

OSSL_ENCODER_CTX_new() returns a pointer to a OSSL_ENCODER_CTX, or NULL if the context structure couldn't be allocated.

OSSL_ENCODER_settable_ctx_params() returns an OSSL_PARAM(3) array, or NULL if none is available.

OSSL_ENCODER_CTX_set_params() returns 1 if all recognised parameters were valid, or 0 if one of them was invalid or caused some other failure in the implementation.

OSSL_ENCODER_CTX_add_encoder(), OSSL_ENCODER_CTX_add_extra(), OSSL_ENCODER_CTX_set_construct(), OSSL_ENCODER_CTX_set_construct_data() and OSSL_ENCODER_CTX_set_cleanup() return 1 on success, or 0 on failure.

OSSL_ENCODER_CTX_get_num_encoders() returns the current number of encoders. It returns 0 if ctx is NULL.

OSSL_ENCODER_INSTANCE_get_encoder() returns an OSSL_ENCODER pointer on success, or NULL on failure.

OSSL_ENCODER_INSTANCE_get_encoder_ctx() returns a provider context pointer on success, or NULL on failure.

OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the input type, if relevant. NULL is a valid returned value.

OSSL_ENCODER_INSTANCE_get_output_type() returns a string with the name of the output type.

OSSL_ENCODER_INSTANCE_get_output_structure() returns a string with the name of the output structure.

SEE ALSO¶

provider(7), OSSL_ENCODER(3)

HISTORY¶

The functions described here were added in OpenSSL 3.0.

COPYRIGHT¶

Copyright 2019-2024 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>.