NAME

       es256_pk_new,    es256_pk_free,    es256_pk_from_EC_KEY,    es256_pk_from_EVP_PKEY,    es256_pk_from_ptr,
       es256_pk_to_EVP_PKEY — FIDO2 COSE ES256 API

SYNOPSIS

       #include <openssl/ec.h>
       #include <fido/es256.h>

       es256_pk_t *
       es256_pk_new(void);

       void
       es256_pk_free(es256_pk_t **pkp);

       int
       es256_pk_from_EC_KEY(es256_pk_t *pk, const EC_KEY *ec);

       int
       es256_pk_from_EVP_PKEY(es256_pk_t *pk, const EVP_PKEY *pkey);

       int
       es256_pk_from_ptr(es256_pk_t *pk, const void *ptr, size_t len);

       EVP_PKEY *
       es256_pk_to_EVP_PKEY(const es256_pk_t *pk);

DESCRIPTION

       ES256 is the name given in the CBOR Object Signing and Encryption (COSE) RFC to  ECDSA  over  P-256  with
       SHA-256.   The  COSE  ES256  API  of  libfido2  is  an auxiliary API with routines to convert between the
       different ECDSA public key types used in libfido2 and OpenSSL.

       In libfido2, ES256 public keys are abstracted by the es256_pk_t type.

       The es256_pk_new() function returns a pointer to a newly allocated, empty  es256_pk_t  type.   If  memory
       cannot be allocated, NULL is returned.

       The  es256_pk_free()  function  releases  the  memory  backing *pkp, where *pkp must have been previously
       allocated by es256_pk_new().  On return, *pkp is set to NULL.  Either pkp or *pkp may be NULL,  in  which
       case es256_pk_free() is a NOP.

       The es256_pk_from_EC_KEY() function fills pk with the contents of ec.  No references to ec are kept.

       The  es256_pk_from_EVP_PKEY()  function  fills  pk  with the contents of pkey.  No references to pkey are
       kept.

       The es256_pk_from_ptr() function fills pk with the contents of ptr, where ptr points to len  bytes.   The
       ptr  pointer  may point to an uncompressed point, or to the concatenation of the x and y coordinates.  No
       references to ptr are kept.

       The es256_pk_to_EVP_PKEY() function converts pk to a newly allocated EVP_PKEY type with a reference count
       of  1.   No  internal  references  to  the  returned   pointer   are   kept.    If   an   error   occurs,
       es256_pk_to_EVP_PKEY() returns NULL.

RETURN VALUES

       The es256_pk_from_EC_KEY(), es256_pk_from_EVP_PKEY(), and es256_pk_from_ptr() functions return FIDO_OK on
       success.  On error, a different error code defined in <fido/err.h> is returned.

SEE ALSO

       eddsa_pk_new(3), es384_pk_new(3), fido_assert_verify(3), fido_cred_pubkey_ptr(3), rs256_pk_new(3)

Debian                                            July 15, 2022                                  ES256_PK_NEW(3)