OSSL_DECODER_from_data, OSSL_DECODER_from_bio, OSSL_DECODER_from_fp - Routines to perform a decoding

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       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>.

3.5.0                                              2025-06-04                        OSSL_DECODER_FROM_BIO(3SSL)

OSSL_DECODER_from_data()  runs  the  decoding process for the context ctx, with input coming from *pdata,
       *pdata_len bytes long.  Both *pdata and  *pdata_len  must  be  non-NULL.   When  OSSL_DECODER_from_data()
       returns,  *pdata  is updated to point at the location after what has been decoded, and *pdata_len to have
       the number of remaining bytes.

       OSSL_DECODER_from_bio() runs the decoding process for the context ctx, with the input coming from the BIOin.  Should it make a difference, it's recommended to have the BIO set in binary mode  rather  than  text
       mode.

       OSSL_DECODER_from_fp()  does  the  same thing as OSSL_DECODER_from_bio(), except that the input is coming
       from the FILEfp.

       To decode an RSA key encoded with PEM from a bio:

        OSSL_DECODER_CTX *dctx;
        EVP_PKEY *pkey = NULL;
        const char *format = "PEM";   /* NULL for any format */
        const char *structure = NULL; /* any structure */
        const char *keytype = "RSA";  /* NULL for any key */
        const unsigned char *pass = "my password";

        dctx = OSSL_DECODER_CTX_new_for_pkey(&pkey, format, structure,
                                             keytype,
                                             OSSL_KEYMGMT_SELECT_KEYPAIR,
                                             NULL, NULL);
        if (dctx == NULL) {
            /* error: no suitable potential decoders found */
        }
        if (pass != NULL)
            OSSL_DECODER_CTX_set_passphrase(dctx, pass, strlen(pass));
        if (OSSL_DECODER_from_bio(dctx, bio)) {
            /* pkey is created with the decoded data from the bio */
        } else {
            /* decoding failure */
        }
        OSSL_DECODER_CTX_free(dctx);

       To decode an EC key encoded with DER from a buffer:

        OSSL_DECODER_CTX *dctx;
        EVP_PKEY *pkey = NULL;
        const char *format = "DER";   /* NULL for any format */
        const char *structure = NULL; /* any structure */
        const char *keytype = "EC";   /* NULL for any key */
        const unsigned char *pass = NULL
        const unsigned char *data = buffer;
        size_t datalen = sizeof(buffer);

        dctx = OSSL_DECODER_CTX_new_for_pkey(&pkey, format, structure,
                                             keytype,
                                             OSSL_KEYMGMT_SELECT_KEYPAIR
                                             | OSSL_KEYMGMT_SELECT_DOMAIN_PARAMETERS,
                                             NULL, NULL);
        if (dctx == NULL) {
            /* error: no suitable potential decoders found */
        }
        if (pass != NULL)
            OSSL_DECODER_CTX_set_passphrase(dctx, pass, strlen(pass));
        if (OSSL_DECODER_from_data(dctx, &data, &datalen)) {
            /* pkey is created with the decoded data from the buffer */
        } else {
            /* decoding failure */
        }
        OSSL_DECODER_CTX_free(dctx);

       The functions described here were added in OpenSSL 3.0.

       OSSL_DECODER_from_data, OSSL_DECODER_from_bio, OSSL_DECODER_from_fp - Routines to perform a decoding

OSSL_DECODER_from_bio(), OSSL_DECODER_from_data() and OSSL_DECODER_from_fp() return 1 on success, or 0 on
       failure.

provider(7), OSSL_DECODER_CTX(3)

        #include <openssl/decoder.h>

        int OSSL_DECODER_from_bio(OSSL_DECODER_CTX *ctx, BIO *in);
        int OSSL_DECODER_from_fp(OSSL_DECODER_CTX *ctx, FILE *fp);
        int OSSL_DECODER_from_data(OSSL_DECODER_CTX *ctx, const unsigned char **pdata,
                                   size_t *pdata_len);

       Feature availability macros:

       OSSL_DECODER_from_fp() is only available when OPENSSL_NO_STDIO is undefined.