FIDO_LARGEBLOB_GET(3) | Library Functions Manual | FIDO_LARGEBLOB_GET(3) |
fido_dev_largeblob_get
,
fido_dev_largeblob_set
,
fido_dev_largeblob_remove
,
fido_dev_largeblob_get_array
,
fido_dev_largeblob_set_array
—
#include <fido.h>
int
fido_dev_largeblob_get
(fido_dev_t
*dev, const unsigned char
*key_ptr, size_t
key_len, unsigned char
**blob_ptr, size_t
*blob_len);
int
fido_dev_largeblob_set
(fido_dev_t
*dev, const unsigned char
*key_ptr, size_t
key_len, const unsigned
char *blob_ptr, size_t
blob_len, const char
*pin);
int
fido_dev_largeblob_remove
(fido_dev_t
*dev, const unsigned char
*key_ptr, size_t
key_len, const char
*pin);
int
fido_dev_largeblob_get_array
(fido_dev_t
*dev, unsigned char
**cbor_ptr, size_t
*cbor_len);
int
fido_dev_largeblob_set_array
(fido_dev_t
*dev, const unsigned char
*cbor_ptr, size_t
cbor_len, const char
*pin);
“largeBlobs” are stored as elements of a CBOR array. Confidentiality is ensured by encrypting each element with a distinct, credential-bound 256-bit AES-GCM key. The array is otherwise shared between different credentials and FIDO2 relying parties.
Retrieval of a credential's encryption key is possible during enrollment with fido_cred_set_extensions(3) and fido_cred_largeblob_key_ptr(3), during assertion with fido_assert_set_extensions(3) and fido_assert_largeblob_key_ptr(3), or, in the case of a resident credential, via libfido2's credential management API.
The “largeBlobs” CBOR array is opaque to the authenticator. Management of the array is left at the discretion of FIDO2 clients. For further details on CTAP 2.1's “largeBlobs” extension, please refer to the CTAP 2.1 spec.
The fido_dev_largeblob_get
() function
retrieves the authenticator's “largeBlobs” CBOR array and, on
success, returns the first blob (iterating from array index zero) that can
be decrypted by key_ptr, where
key_ptr points to key_len bytes.
On success, fido_dev_largeblob_get
() sets
blob_ptr to the body of the decrypted blob, and
blob_len to the length of the decrypted blob in bytes.
It is the caller's responsibility to free
blob_ptr.
The fido_dev_largeblob_set
() function uses
key_ptr to encrypt blob_ptr and
inserts the result in the authenticator's “largeBlobs” CBOR
array. Insertion happens at the end of the array if no existing element can
be decrypted by key_ptr, or at the position of the
first element (iterating from array index zero) that can be decrypted by
key_ptr. key_len holds the
length of key_ptr in bytes, and
blob_len the length of blob_ptr
in bytes. A pin or equivalent user-verification
gesture is required.
The fido_dev_largeblob_remove
() function
retrieves the authenticator's “largeBlobs” CBOR array and, on
success, drops the first blob (iterating from array index zero) that can be
decrypted by key_ptr, where
key_ptr points to key_len bytes.
A pin or equivalent user-verification gesture is
required.
The fido_dev_largeblob_get_array
()
function retrieves the authenticator's “largeBlobs” CBOR array
and, on success, sets cbor_ptr to the body of the CBOR
array, and cbor_len to its corresponding length in
bytes. It is the caller's responsibility to free
cbor_ptr.
Finally, the
fido_dev_largeblob_set_array
() function sets the
authenticator's “largeBlobs” CBOR array to the data pointed to
by cbor_ptr, where cbor_ptr
points to cbor_len bytes. A pin
or equivalent user-verification gesture is required.
fido_dev_largeblob_set
(),
fido_dev_largeblob_get
(),
fido_dev_largeblob_remove
(),
fido_dev_largeblob_get_array
(), and
fido_dev_largeblob_set_array
() return
FIDO_OK
on success. On error, an error code defined in
<fido/err.h>
is returned.
October 26, 2020 | Yubico AB |