NAME

     eddsa_pk_new, eddsa_pk_free, eddsa_pk_from_EVP_PKEY, eddsa_pk_from_ptr, eddsa_pk_to_EVP_PKEY
     — FIDO2 COSE EDDSA API

SYNOPSIS

     #include <openssl/evp.h>
     #include <fido/eddsa.h>

     eddsa_pk_t *
     eddsa_pk_new(void);

     void
     eddsa_pk_free(eddsa_pk_t **pkp);

     int
     eddsa_pk_from_EVP_PKEY(eddsa_pk_t *pk, const EVP_PKEY *pkey);

     int
     eddsa_pk_from_ptr(eddsa_pk_t *pk, const void *ptr, size_t len);

     EVP_PKEY *
     eddsa_pk_to_EVP_PKEY(const eddsa_pk_t *pk);

DESCRIPTION

     EDDSA is the name given in the CBOR Object Signing and Encryption (COSE) RFC to EDDSA over
     Curve25519 with SHA-512.  The COSE EDDSA API of libfido2 is an auxiliary API with routines
     to convert between the different EDDSA public key types used in libfido2 and OpenSSL.

     In libfido2, EDDSA public keys are abstracted by the eddsa_pk_t type.

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

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

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

     The eddsa_pk_from_ptr() function fills pk with the contents of ptr, where ptr points to len
     bytes.  No references to ptr are kept.

     The eddsa_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, eddsa_pk_to_EVP_PKEY() returns NULL.

RETURN VALUES

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

SEE ALSO

     es256_pk_new(3), es384_pk_new(3), fido_assert_verify(3), fido_cred_pubkey_ptr(3),
     rs256_pk_new(3)