IdentityCredentialStore

abstract class IdentityCredentialStore

An interface to a secure store for user identity documents.

This interface is deliberately fairly general and abstract. To the extent possible, specification of the message formats and semantics of communication with credential verification devices and issuing authorities (IAs) is out of scope. It provides the interface with secure storage but a credential-specific Android application will be required to implement the presentation and verification protocols and processes appropriate for the specific credential type.

Multiple credentials can be created. Each credential comprises:

• A document type, which is a string.
• A set of namespaces, which serve to disambiguate value names. It is recommended that namespaces be structured as reverse domain names so that IANA effectively serves as the namespace registrar.
• For each namespace, a set of name/value pairs, each with an associated set of access control profile IDs. Names are strings and values are typed and can be any value supported by CBOR.
• A set of access control profiles (up to 32), each with a profile ID and a specification of the conditions which satisfy the profile's requirements.
• An asymmetric key pair which is used to authenticate the credential to the Issuing Authority, called the CredentialKey.
• A set of zero or more named reader authentication public keys, which are used to authenticate an authorized reader to the credential.
• A set of named signing keys, which are used to sign collections of values and session transcripts.

Implementing support for user identity documents in secure storage requires dedicated hardware-backed support and may not always be available.

Two different credential stores exist - the default store and the direct access store. Most often credentials will be accessed through the default store but that requires that the Android device be powered up and fully functional. It is desirable to allow identity credential usage when the Android device's battery is too low to boot the Android operating system, so direct access to the secure hardware via NFC may allow data retrieval, if the secure hardware chooses to implement it.

Credentials provisioned to the direct access store should always use reader authentication to protect data elements. The reason for this is user authentication or user approval of data release is not possible when the device is off.

The Identity Credential API is designed to be able to evolve and change over time but still provide 100% backwards compatibility. This is complicated by the fact that there may be a version skew between the API used by the application and the version implemented in secure hardware. To solve this problem, the API provides for a way for the application to query which feature version the hardware implements (if any at all) using android.content.pm#FEATURE_IDENTITY_CREDENTIAL_HARDWARE and android.content.pm#FEATURE_IDENTITY_CREDENTIAL_HARDWARE_DIRECT_ACCESS. Methods which only work on certain feature versions are clearly documented as such.

Summary

Constants

static val CIPHERSUITE_ECDHE_HKDF_ECDSA_WITH_AES_256_GCM_SHA256: Int

Value: 1

Public methods

abstract fun createCredential(
    credentialName: String, 
    docType: String
): WritableIdentityCredential

open fun createPresentationSession(cipherSuite: Int): PresentationSession

abstract fun deleteCredentialByName(credentialName: String): ByteArray?

ProofOfDeletion = [
           "ProofOfDeletion",            ; tstr
           tstr,                         ; DocType
           bool                          ; true if this is a test credential, should
                                         ; always be false.
       ]
  

abstract fun getCredentialByName(
    credentialName: String, 
    cipherSuite: Int
): IdentityCredential?

open static fun getDirectAccessInstance(context: Context): IdentityCredentialStore?

open static fun getInstance(context: Context): IdentityCredentialStore?

abstract fun getSupportedDocTypes(): Array<String!>