NAME

     rs256_pk_new, rs256_pk_free, rs256_pk_from_RSA, rs256_pk_from_EVP_PKEY, rs256_pk_from_ptr,
     rs256_pk_to_EVP_PKEY — FIDO2 COSE RS256 API

SYNOPSIS

     #include <openssl/rsa.h>
     #include <fido/rs256.h>

     rs256_pk_t *
     rs256_pk_new(void);

     void
     rs256_pk_free(rs256_pk_t **pkp);

     int
     rs256_pk_from_EVP_PKEY(rs256_pk_t *pk, const EVP_PKEY *pkey);

     int
     rs256_pk_from_RSA(rs256_pk_t *pk, const RSA *rsa);

     int
     rs256_pk_from_ptr(rs256_pk_t *pk, const void *ptr, size_t len);

     EVP_PKEY *
     rs256_pk_to_EVP_PKEY(const rs256_pk_t *pk);

DESCRIPTION

     RS256 is the name given in the CBOR Object Signing and Encryption (COSE) RFC to PKCS#1.5
     2048-bit RSA with SHA-256.  The COSE RS256 API of libfido2 is an auxiliary API with routines
     to convert between the different RSA public key types used in libfido2 and OpenSSL.

     In libfido2, RS256 public keys are abstracted by the rs256_pk_t type.

     The rs256_pk_new() function returns a pointer to a newly allocated, empty rs256_pk_t type.
     If memory cannot be allocated, NULL is returned.

     The rs256_pk_free() function releases the memory backing *pkp, where *pkp must have been
     previously allocated by rs256_pk_new().  On return, *pkp is set to NULL.  Either pkp or *pkp
     may be NULL, in which case rs256_pk_free() is a NOP.

     The rs256_pk_from_EVP_PKEY() function fills pk with the contents of pkey.  No references to
     pkey are kept.

     The rs256_pk_from_RSA() function fills pk with the contents of rsa.  No references to rsa
     are kept.

     The rs256_pk_from_ptr() function fills pk with the contents of ptr, where ptr points to len
     bytes.  No references to ptr are kept.

     The rs256_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, rs256_pk_to_EVP_PKEY() returns NULL.

RETURN VALUES

     The rs256_pk_from_EVP_PKEY(), rs256_pk_from_RSA(), and rs256_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), es256_pk_new(3), es384_pk_new(3), fido_assert_verify(3),
     fido_cred_pubkey_ptr(3)