Class AttestationObject

Namespace

Yubico.YubiKey.Fido2

Assembly

Yubico.YubiKey.dll

Represents a FIDO2 attestation object, which contains attestation format, authenticator data, and attestation statement.

public class AttestationObject : ICborEncode

Inheritance

object

AttestationObject

Implements

ICborEncode

Remarks

An attestation object is returned by the authenticator during credential creation (MakeCredential). It contains the attestation format identifier, authenticator data, and a typed attestation statement.

The CBOR structure is defined in CTAP 2.1 section 6.1.2 as:

map {
  1: fmt         (text string)  // Attestation statement format identifier
  2: authData    (byte string)  // Authenticator data
  3: attStmt     (map)          // Attestation statement (format-specific)
}

Constructors

AttestationObject(ReadOnlyMemory<byte>)

Constructs a new instance of AttestationObject from CBOR-encoded bytes.

public AttestationObject(ReadOnlyMemory<byte> cborEncoding)

Parameters

cborEncoding ReadOnlyMemory<byte>

The CBOR encoding of the attestation object.

Remarks

Use this overload when you do not need to know how many bytes were consumed. For sequential parsing of multiple CBOR objects from a shared buffer, use the overload with out int bytesRead.

Exceptions

Ctap2DataException

The cborEncoding is not a well-formed attestation object.

AttestationObject(ReadOnlyMemory<byte>, out int)

Constructs a new instance of AttestationObject from CBOR-encoded bytes.

public AttestationObject(ReadOnlyMemory<byte> cborEncoding, out int bytesRead)

Parameters

cborEncoding ReadOnlyMemory<byte>

The CBOR encoding of the attestation object.

bytesRead int

Returns the number of bytes read from the encoding.

Remarks

This constructor decodes an attestation object from CBOR encoding following the CTAP 2.1 specification (section 6.1.2).

The Statement property is populated with a format-specific statement type for statement formats parsed by this SDK. Unknown or malformed formats are represented by UnknownAttestationStatement, preserving the raw bytes via EncodedAttestationStatement.

Exceptions

Ctap2DataException

The cborEncoding is not a well-formed attestation object.

Properties

AuthenticatorData

The authenticator data, which includes the relying party ID hash, flags, signature counter, and optionally the attested credential data.

public AuthenticatorData AuthenticatorData { get; }

Property Value

AuthenticatorData

Encoded

The CBOR encoding of the entire attestation object.

public ReadOnlyMemory<byte> Encoded { get; }

Property Value

ReadOnlyMemory<byte>

Remarks

This includes the format identifier, authenticator data, and full attestation statement.

EncodedAttestationStatement

The raw CBOR encoding of the full attestation statement map (attStmt, key 3 in the attestation object).

public ReadOnlyMemory<byte> EncodedAttestationStatement { get; }

Property Value

ReadOnlyMemory<byte>

Format

The attestation statement format identifier (e.g., "packed", "tpm", "android-key"). See AttestationFormats for standard format identifiers.

public string Format { get; }

Property Value

string

Statement

The format-specific attestation statement.

public AttestationStatement Statement { get; }

Property Value

AttestationStatement

Methods

CborEncode()

Return a new byte array that is the object encoded following the FIDO2/CBOR standard.

public byte[] CborEncode()

Returns

byte[]

The encoded construct.

Exceptions

InvalidOperationException

The object contains no data.