NAME

       OSSL_ENCODER_to_data, OSSL_ENCODER_to_bio, OSSL_ENCODER_to_fp - Routines to perform an
       encoding

SYNOPSIS

        #include <openssl/encoder.h>

        int OSSL_ENCODER_to_data(OSSL_ENCODER_CTX *ctx, unsigned char **pdata,
                                 size_t *pdata_len);
        int OSSL_ENCODER_to_bio(OSSL_ENCODER_CTX *ctx, BIO *out);
        int OSSL_ENCODER_to_fp(OSSL_ENCODER_CTX *ctx, FILE *fp);

       Feature availability macros:

       OSSL_ENCODER_to_fp() is only available when OPENSSL_NO_STDIO is undefined.

DESCRIPTION

       OSSL_ENCODER_to_data() runs the encoding process for the context ctx, with the output
       going to the *pdata and *pdata_len.  If *pdata is NULL when OSSL_ENCODER_to_data() is
       called, a buffer will be allocated using OPENSSL_zalloc(3), and *pdata will be set to
       point at the start of that buffer, and *pdata_len will be assigned its length when
       OSSL_ENCODER_to_data() returns.  If *pdata is non-NULL when OSSL_ENCODER_to_data() is
       called, *pdata_len is assumed to have its size.  In this case, *pdata will be set to point
       after the encoded bytes, and *pdata_len will be assigned the number of remaining bytes.

       OSSL_ENCODER_to_bio() runs the encoding process for the context ctx, with the output going
       to the BIO out.

       OSSL_ENCODER_to_fp() does the same thing as OSSL_ENCODER_to_bio(), except that the output
       is going to the FILE fp.

       For OSSL_ENCODER_to_bio() and OSSL_ENCODER_to_fp(), the application is required to set up
       the BIO or FILE properly, for example to have it in text or binary mode as is appropriate
       for the encoder output type.

RETURN VALUES

       OSSL_ENCODER_to_bio(), OSSL_ENCODER_to_fp() and OSSL_ENCODER_to_data() return 1 on
       success, or 0 on failure.

EXAMPLES

       To encode a pkey as PKCS#8 with PEM format into a bio:

        OSSL_ENCODER_CTX *ectx;
        const char *format = "PEM";
        const char *structure = "PrivateKeyInfo"; /* PKCS#8 structure */
        const unsigned char *pass = "my password";

        ectx = OSSL_ENCODER_CTX_new_for_pkey(pkey,
                                             OSSL_KEYMGMT_SELECT_KEYPAIR
                                             | OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
                                             format, structure,
                                             NULL);
        if (ectx == NULL) {
            /* error: no suitable potential encoders found */
        }
        if (pass != NULL)
            OSSL_ENCODER_CTX_set_passphrase(ectx, pass, strlen(pass));
        if (OSSL_ENCODER_to_bio(ectx, bio)) {
            /* pkey was successfully encoded into the bio */
        } else {
            /* encoding failure */
        }
        OSSL_ENCODER_CTX_free(ectx);

       To encode a pkey as PKCS#8 with DER format encrypted with AES-256-CBC into a buffer:

        OSSL_ENCODER_CTX *ectx;
        const char *format = "DER";
        const char *structure = "PrivateKeyInfo"; /* PKCS#8 structure */
        const unsigned char *pass = "my password";
        unsigned char *data = NULL;
        size_t datalen;

        ectx = OSSL_ENCODER_CTX_new_for_pkey(pkey,
                                             OSSL_KEYMGMT_SELECT_KEYPAIR
                                             | OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
                                             format, structure,
                                             NULL);
        if (ectx == NULL) {
            /* error: no suitable potential encoders found */
        }
        if (pass != NULL) {
            OSSL_ENCODER_CTX_set_passphrase(ectx, pass, strlen(pass));
            OSSL_ENCODER_CTX_set_cipher(ctx, "AES-256-CBC", NULL);
        }
        if (OSSL_ENCODER_to_data(ectx, &data, &datalen)) {
            /*
             * pkey was successfully encoded into a newly allocated
             * data buffer
             */
        } else {
            /* encoding failure */
        }
        OSSL_ENCODER_CTX_free(ectx);

SEE ALSO

       provider(7), 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>.