CredentialDataResult

getDeviceMac

abstract fun getDeviceMac(): ByteArray?

Returns a message authentication code over the DeviceAuthenticationBytes CBOR specified in getDeviceNameSpaces(), to prove to the reader that the data is from a trusted credential.

The MAC proves to the reader that the data is from a trusted credential. This code is produced by using the key agreement and key derivation function from the ciphersuite with the authentication private key and the reader ephemeral public key to compute a shared message authentication code (MAC) key, then using the MAC function from the ciphersuite to compute a MAC of the authenticated data. See section 9.2.3.5 of ISO/IEC 18013-5 for details of this operation.

If the session transcript or reader ephemeral key wasn't set on the PresentationSession used to obtain this data no message authencation code will be produced and this method will return null.

getDeviceNameSpaces

abstract fun getDeviceNameSpaces(): ByteArray

Returns a CBOR structure containing the retrieved device-signed data.

This structure - along with the session transcript - may be cryptographically authenticated to prove to the reader that the data is from a trusted credential and getDeviceMac() can be used to get a MAC.

The CBOR structure which is cryptographically authenticated is the DeviceAuthenticationBytes structure according to the following CDDL schema:

DeviceAuthentication = [
      "DeviceAuthentication",
      SessionTranscript,
      DocType,
      DeviceNameSpacesBytes
    ]
 
    DocType = tstr
    SessionTranscript = any
    DeviceNameSpacesBytes = #6.24(bstr .cbor DeviceNameSpaces)
    DeviceAuthenticationBytes = #6.24(bstr .cbor DeviceAuthentication)
  

where

DeviceNameSpaces = {
      * NameSpace => DeviceSignedItems
    }
 
    DeviceSignedItems = {
      + DataItemName => DataItemValue
    }
 
    NameSpace = tstr
    DataItemName = tstr
    DataItemValue = any
  

The returned data is the binary encoding of the DeviceNameSpaces structure as defined above.

getDeviceSignature

open fun getDeviceSignature(): ByteArray?

Returns a signature over the DeviceAuthenticationBytes CBOR specified in getDeviceNameSpaces(), to prove to the reader that the data is from a trusted credential.

The signature is made using the authentication private key. See section 9.1.3.4 of ISO/IEC 18013-5:2021 for details of this operation.

If the session transcript or reader ephemeral key wasn't set on the PresentationSession used to obtain this data no signature will be produced and this method will return null.

This is only implemented in feature version 202301 or later. If not implemented, the call fails with UnsupportedOperationException. See android.content.pm.PackageManager#FEATURE_IDENTITY_CREDENTIAL_HARDWARE for known feature versions.

getDeviceSignedEntries

abstract fun getDeviceSignedEntries(): CredentialDataResult.Entries

Gets the device-signed entries that was returned.

getIssuerSignedEntries

abstract fun getIssuerSignedEntries(): CredentialDataResult.Entries

Gets the issuer-signed entries that was returned.

getStaticAuthenticationData

abstract fun getStaticAuthenticationData(): ByteArray

Returns the static authentication data associated with the dynamic authentication key used to MAC the data returned by getDeviceNameSpaces().