EVP_PKEY_get_default_digest_nid.3ossl - Man Page

get default signature digest

Synopsis

 #include <openssl/evp.h>

 int EVP_PKEY_get_default_digest_name(EVP_PKEY *pkey,
                                      char *mdname, size_t mdname_sz);
 int EVP_PKEY_get_default_digest_nid(EVP_PKEY *pkey, int *pnid);

Description

EVP_PKEY_get_default_digest_name() fills in the default message digest name for the public key signature operations associated with key pkey into mdname, up to at most mdname_sz bytes including the ending NUL byte.  The name could be "UNDEF", signifying that no digest should be used.

EVP_PKEY_get_default_digest_nid() sets pnid to the default message digest NID for the public key signature operations associated with key pkey.  Note that some signature algorithms (i.e. Ed25519 and Ed448) do not use a digest during signing.  In this case pnid will be set to NID_undef.  This function is only reliable for legacy keys, which are keys with a EVP_PKEY_ASN1_METHOD; these keys have typically been loaded from engines, or created with EVP_PKEY_assign_RSA(3) or similar.

Notes

For all current standard OpenSSL public key algorithms SHA256 is returned.

Return Values

EVP_PKEY_get_default_digest_name() and EVP_PKEY_get_default_digest_nid() both return 1 if the message digest is advisory (that is other digests can be used) and 2 if it is mandatory (other digests can not be used). They return 0 or a negative value for failure.  In particular a return value of -2 indicates the operation is not supported by the public key algorithm.

See Also

EVP_PKEY_CTX_new(3), EVP_PKEY_sign(3), EVP_PKEY_digestsign_supports_digest(3), EVP_PKEY_verify(3), EVP_PKEY_verify_recover(3),

History

This function was added in OpenSSL 1.0.0.

Referenced By

EVP_PKEY_ASN1_METHOD.3ossl(3).

The man page EVP_PKEY_get_default_digest_name.3ossl(3) is an alias of EVP_PKEY_get_default_digest_nid.3ossl(3).

2021-09-09 3.0.0 OpenSSL