BIO_s_core.3ossl - Man Page

OSSL_CORE_BIO functions


 #include <openssl/bio.h>

 const BIO_METHOD *BIO_s_core(void);

 BIO *BIO_new_from_core_bio(OSSL_LIB_CTX *libctx, OSSL_CORE_BIO *corebio);


BIO_s_core() returns the core BIO method function.

A core BIO is treated as source/sink BIO which communicates to some external BIO. This is primarily useful to provider authors. A number of calls from libcrypto into a provider supply an OSSL_CORE_BIO parameter. This represents a BIO within libcrypto, but cannot be used directly by a provider. Instead it should be wrapped using a BIO_s_core().

Once a BIO is constructed based on BIO_s_core(), the associated OSSL_CORE_BIO object should be set on it using BIO_set_data(3). Note that the BIO will only operate correctly if it is associated with a library context constructed using OSSL_LIB_CTX_new_from_dispatch(3). To associate the BIO with a library context construct it using BIO_new_ex(3).

BIO_new_from_core_bio() is a convenience function that constructs a new BIO based on BIO_s_core() and that is associated with the given library context. It then also sets the OSSL_CORE_BIO object on the BIO using BIO_set_data(3).

Return Values

BIO_s_core() return a core BIO BIO_METHOD structure.

BIO_new_from_core_bio() returns a BIO structure on success or NULL on failure. A failure will most commonly be because the library context was not constructed using OSSL_LIB_CTX_new_from_dispatch(3).


BIO_s_core() and BIO_new_from_core_bio() were added in OpenSSL 3.0.


Create a core BIO and write some data to it:

 int some_function(OSSL_LIB_CTX *libctx, OSSL_CORE_BIO *corebio) {
     BIO *cbio = BIO_new_from_core_bio(libctx, corebio);

     if (cbio == NULL)
         return 0;

     BIO_puts(cbio, "Hello World\n");

     return 1;

Referenced By

The man page BIO_new_from_core_bio.3ossl(3) is an alias of BIO_s_core.3ossl(3).

2024-04-04 3.2.1 OpenSSL