Added in API level 30

IdentityCredentialStore

abstract class IdentityCredentialStore
kotlin.Any
   ↳ android.security.identity.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 Int

Specifies that the cipher suite that will be used to secure communications between the reader and the prover is using the following primitives

  • ECKA-DH (Elliptic Curve Key Agreement Algorithm - Diffie-Hellman, see BSI TR-03111).
  • HKDF-SHA-256 (see RFC 5869).
  • AES-256-GCM (see NIST SP 800-38D).
  • HMAC-SHA-256 (see RFC 2104).
Public methods
abstract WritableIdentityCredential
createCredential(credentialName: String, docType: String)

Creates a new credential.
open PresentationSession

Creates a new presentation session.
abstract ByteArray?
deleteCredentialByName(credentialName: String)

Delete a named credential.
abstract IdentityCredential?
getCredentialByName(credentialName: String, cipherSuite: Int)

Retrieve a named credential.
open static IdentityCredentialStore?

Gets the IdentityCredentialStore for direct access.
open static IdentityCredentialStore?
getInstance(context: Context)

Gets the default IdentityCredentialStore.
abstract Array<String!>

Gets a list of supported document types.

Constants

CIPHERSUITE_ECDHE_HKDF_ECDSA_WITH_AES_256_GCM_SHA256

Added in API level 30
static val CIPHERSUITE_ECDHE_HKDF_ECDSA_WITH_AES_256_GCM_SHA256: Int

Specifies that the cipher suite that will be used to secure communications between the reader and the prover is using the following primitives

  • ECKA-DH (Elliptic Curve Key Agreement Algorithm - Diffie-Hellman, see BSI TR-03111).
  • HKDF-SHA-256 (see RFC 5869).
  • AES-256-GCM (see NIST SP 800-38D).
  • HMAC-SHA-256 (see RFC 2104).

The exact way these primitives are combined to derive the session key is specified in section 9.2.1.4 of ISO/IEC 18013-5 (see description of cipher suite '1').

At present this is the only supported cipher suite.

Value: 1

Public methods

createCredential

Added in API level 30
abstract fun createCredential(
    credentialName: String, 
    docType: String
): WritableIdentityCredential

Creates a new credential.

When a credential is created, a cryptographic key-pair - CredentialKey - is created which is used to authenticate the store to the Issuing Authority. The private part of this key-pair never leaves secure hardware and the public part can be obtained using WritableIdentityCredential#getCredentialKeyCertificateChain(byte[]) on the returned object.

In addition, all of the Credential data content is imported and a certificate for the CredentialKey and a signature produced with the CredentialKey are created. These latter values may be checked by an issuing authority to verify that the data was imported into secure hardware and that it was imported unmodified.

Parameters
credentialName String: The name used to identify the credential. This value cannot be null.
docType String: The document type for the credential. This value cannot be null.
Return
WritableIdentityCredential A WritableIdentityCredential that can be used to create a new credential. This value cannot be null.
Exceptions
android.security.identity.AlreadyPersonalizedException if a credential with the given name already exists.
android.security.identity.DocTypeNotSupportedException if the given document type isn't supported by the store.

createPresentationSession

Added in API level 33
open fun createPresentationSession(cipherSuite: Int): PresentationSession

Creates a new presentation session.

This method gets an object to be used for interaction with a remote verifier for presentation of one or more credentials.

This is only implemented in feature version 202201 or later. If not implemented, the call fails with UnsupportedOperationException. See android.content.pm.PackageManager#FEATURE_IDENTITY_CREDENTIAL_HARDWARE for known feature versions.

Parameters
cipherSuite Int: the cipher suite to use for communicating with the verifier. Value is android.security.identity.IdentityCredentialStore#CIPHERSUITE_ECDHE_HKDF_ECDSA_WITH_AES_256_GCM_SHA256
Return
PresentationSession The presentation session. This value cannot be null.

deleteCredentialByName

Added in API level 30
Deprecated in API level 31
abstract fun deleteCredentialByName(credentialName: String): ByteArray?

Deprecated: Use IdentityCredential#delete(byte[]) instead.

Delete a named credential.

This method returns a COSE_Sign1 data structure signed by the CredentialKey with payload set to ProofOfDeletion as defined below: 

ProofOfDeletion = [
           "ProofOfDeletion",            ; tstr
           tstr,                         ; DocType
           bool                          ; true if this is a test credential, should
                                         ; always be false.
       ]
Parameters
credentialName String: the name of the credential to delete. This value cannot be null.
Return
ByteArray? null if the credential was not found, the COSE_Sign1 data structure above if the credential was found and deleted.

getCredentialByName

Added in API level 30
abstract fun getCredentialByName(
    credentialName: String, 
    cipherSuite: Int
): IdentityCredential?

Retrieve a named credential.

The cipher suite used to communicate with the remote verifier must also be specified. Currently only a single cipher-suite is supported. Support for other cipher suites may be added in a future version of this API.

Parameters
credentialName String: the name of the credential to retrieve. This value cannot be null.
cipherSuite Int: the cipher suite to use for communicating with the verifier. Value is android.security.identity.IdentityCredentialStore#CIPHERSUITE_ECDHE_HKDF_ECDSA_WITH_AES_256_GCM_SHA256
Return
IdentityCredential? The named credential, or null if not found.

getDirectAccessInstance

Added in API level 30
open static fun getDirectAccessInstance(context: Context): IdentityCredentialStore?

Gets the IdentityCredentialStore for direct access.

Direct access requires specialized NFC hardware and may not be supported on all devices even if default store is available. Credentials provisioned to the direct access store should always use reader authentication to protect data elements.

Parameters
context Context: the application context. This value cannot be null.
Return
IdentityCredentialStore? the IdentityCredentialStore or null if direct access is not supported on this device.

getInstance

Added in API level 30
open static fun getInstance(context: Context): IdentityCredentialStore?

Gets the default IdentityCredentialStore.

Parameters
context Context: the application context. This value cannot be null.
Return
IdentityCredentialStore? the IdentityCredentialStore or null if the device doesn't have hardware-backed support for secure storage of user identity documents.

getSupportedDocTypes

Added in API level 30
abstract fun getSupportedDocTypes(): Array<String!>

Gets a list of supported document types.

Only the direct-access store may restrict the kind of document types that can be used for credentials. The default store always supports any document type.

Return
Array<String!> The supported document types or the empty array if any document type is supported. This value cannot be null.