CoseEcPublicKey Class
Namespace: Yubico.YubiKey.Fido2.Cose Assembly: Yubico.YubiKey.dllA representation of an Elliptic Curve public key in COSE form.
public class CoseEcPublicKey : CoseKeyRemarks
An ECC public key consists of a curve and public point. In FIDO2, the curve is represented by the CoseAlgorithmIdentifier and the public point is simply an x-coordinate and a y-coordinate.
The FIDO2 standard also specifies an encoding of the public key information. It uses the representation defined in RFC8152: CBOR Object Signing and Encryption (COSE) standard. Supplementary information can be found in section 6.5.6 of the CTAP2.1 specification (under the heading `getPublicKey()`).
This class has multiple constructors. One constructs an empty object and allows the caller to set the key parameters via the properties on this class. Another constructs a key based on the COSE form encoded in CBOR. Lastly, there is a constructor that takes in a .NET representation of an EC public key used for interoperating with the .NET cryptographic library.
The YubiKey's FIDO2 application currently only supports the NIST P-256 curve. Thus, the SDK - as of version 1.5.0 - will also only support this curve.
Constructors
| Name | Description |
|---|---|
| CoseEcPublicKey(ReadOnlyMemory<byte>) | Construct a CoseEcPublicKey based on the CBOR encoding
of a |
| CoseEcPublicKey(ECParameters) | Construct a CoseEcPublicKey based on .NET elliptic curve parameters. |
| CoseEcPublicKey(CoseEcCurve, ReadOnlyMemory<byte>, ReadOnlyMemory<byte>) | Construct a CoseEcPublicKey based on the curve and point. |
| CoseEcPublicKey(CoseEcCurve, CoseAlgorithmIdentifier, ReadOnlyMemory<byte>, ReadOnlyMemory<byte>) | Construct a CoseEcPublicKey based on the curve and x and y coordinates. |
Properties
| Name | Description |
|---|---|
| Curve | The Elliptic Curve that the key resides on. |
| XCoordinate | The X-coordinate of the public point. |
| YCoordinate | The Y-coordinate of the public point. |
Methods
| Name | Description |
|---|---|
| CreateFromEncodedKey(ReadOnlyMemory<byte>) | Creates a new instance of CoseEcPublicKey from the given encoded COSE key. |
| Encode() | Return a new byte array that is the key data encoded following the FIDO2/CBOR standard. |
| ToEcParameters() | Returns the COSE key as a new .NET |