decode and encode an ASN.1 NULL
**val_out, const unsigned char **der_in,
unsigned char **der_out);
These functions decode and encode the ASN.1 value NULL of type NULL. For details about the semantics, examples, caveats, and bugs, see ASN1_item_d2i(3).
verifies that the BER-encoded value at *der_in is NULL
and of type NULL. It fails if length is less than 2 or
if the first two bytes of *der_in differ from 0x05 and
0x00. In case of success, *der_in is advanced by two
bytes and *val_out is set to a specific invalid
pointer representing the unique ASN1_NULL object.
ignores val_in and encodes the ASN.1 value NULL of
type NULL using DER. Specifically, it writes the identifier octet for the
type NULL, 0x05, followed by the length octet 0x00, and no content or
d2i_ASN1_NULL() returns a specific invalid
pointer representing the unique ASN1_NULL object or
NULL if an error occurs.
i2d_ASN1_NULL() returns 2 if successful or
0 if an error occurs.
ASN1_item_d2i(3), ASN1_item_new(3), ASN1_NULL_new(3), ASN1_TYPE_get(3)
ITU-T Recommendation X.690, also known as ISO/IEC 8825-1: Information technology - ASN.1 encoding rules: Specification of Basic Encoding Rules (BER), Canonical Encoding Rules (CER) and Distinguished Encoding Rules (DER), section 8.8: Encoding of null value
i2d_ASN1_NULL() first appeared in OpenSSL 0.9.5 and
have been available since OpenBSD 2.7.