1ES256_PK_NEW(3)          BSD Library Functions Manual          ES256_PK_NEW(3)
2

NAME

4     es256_pk_new, es256_pk_free, es256_pk_from_EC_KEY,
5     es256_pk_from_EVP_PKEY, es256_pk_from_ptr, es256_pk_to_EVP_PKEY — FIDO2
6     COSE ES256 API
7

SYNOPSIS

9     #include <openssl/ec.h>
10     #include <fido/es256.h>
11
12     es256_pk_t *
13     es256_pk_new(void);
14
15     void
16     es256_pk_free(es256_pk_t **pkp);
17
18     int
19     es256_pk_from_EC_KEY(es256_pk_t *pk, const EC_KEY *ec);
20
21     int
22     es256_pk_from_EVP_PKEY(es256_pk_t *pk, const EVP_PKEY *pkey);
23
24     int
25     es256_pk_from_ptr(es256_pk_t *pk, const void *ptr, size_t len);
26
27     EVP_PKEY *
28     es256_pk_to_EVP_PKEY(const es256_pk_t *pk);
29

DESCRIPTION

31     ES256 is the name given in the CBOR Object Signing and Encryption (COSE)
32     RFC to ECDSA over P-256 with SHA-256.  The COSE ES256 API of libfido2 is
33     an auxiliary API with routines to convert between the different ECDSA
34     public key types used in libfido2 and OpenSSL.
35
36     In libfido2, ES256 public keys are abstracted by the es256_pk_t type.
37
38     The es256_pk_new() function returns a pointer to a newly allocated, empty
39     es256_pk_t type.  If memory cannot be allocated, NULL is returned.
40
41     The es256_pk_free() function releases the memory backing *pkp, where *pkp
42     must have been previously allocated by es256_pk_new().  On return, *pkp
43     is set to NULL.  Either pkp or *pkp may be NULL, in which case
44     es256_pk_free() is a NOP.
45
46     The es256_pk_from_EC_KEY() function fills pk with the contents of ec.  No
47     references to ec are kept.
48
49     The es256_pk_from_EVP_PKEY() function fills pk with the contents of pkey.
50     No references to pkey are kept.
51
52     The es256_pk_from_ptr() function fills pk with the contents of ptr, where
53     ptr points to len bytes.  The ptr pointer may point to an uncompressed
54     point, or to the concatenation of the x and y coordinates.  No references
55     to ptr are kept.
56
57     The es256_pk_to_EVP_PKEY() function converts pk to a newly allocated
58     EVP_PKEY type with a reference count of 1.  No internal references to the
59     returned pointer are kept.  If an error occurs, es256_pk_to_EVP_PKEY()
60     returns NULL.
61

RETURN VALUES

63     The es256_pk_from_EC_KEY(), es256_pk_from_EVP_PKEY(), and
64     es256_pk_from_ptr() functions return FIDO_OK on success.  On error, a
65     different error code defined in <fido/err.h> is returned.
66

SEE ALSO

68     eddsa_pk_new(3), es384_pk_new(3), fido_assert_verify(3),
69     fido_cred_pubkey_ptr(3), rs256_pk_new(3)
70
71BSD                              July 15, 2022                             BSD
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