KeyChain
class KeyChain
kotlin.Any | |
↳ | android.security.KeyChain |
The KeyChain
class provides access to private keys and their corresponding certificate chains in credential storage.
Applications accessing the KeyChain
normally go through these steps:
- Receive a callback from an
X509KeyManager
that a private key is requested. - Call #choosePrivateKeyAlias to allow the user to select from a list of currently available private keys and corresponding certificate chains. The chosen alias will be returned by the callback
KeyChainAliasCallback#alias
, or null if no private key is available or the user cancels the request. - Call
getPrivateKey
andgetCertificateChain
to retrieve the credentials to return to the corresponding callbacks.
An application may remember the value of a selected alias to avoid prompting the user with #choosePrivateKeyAlias on subsequent connections. If the alias is no longer valid, null will be returned on lookups using that value
An application can request the installation of private keys and certificates via the Intent
provided by createInstallIntent
. Private keys installed via this Intent
will be accessible via #choosePrivateKeyAlias while Certificate Authority (CA) certificates will be trusted by all applications through the default X509TrustManager
.
Summary
Constants | |
---|---|
static String |
Broadcast Action: Indicates the contents of the keychain has changed. |
static String |
Broadcast Action: Indicates that the access permissions for a private key have changed. |
static String |
Broadcast Action: Indicates the trusted storage has changed. |
static String |
Broadcast Action: Indicates the contents of the trusted certificate store has changed. |
static String |
Optional extra to specify an X. |
static String |
Used as a boolean extra field in |
static String |
Used as a String extra field in |
static String |
Optional extra to specify a |
static String |
Optional extra for use with the |
static String |
Used by DPC or delegated app in |
Public constructors | |
---|---|
KeyChain() |
Public methods | |
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static Unit |
choosePrivateKeyAlias(activity: Activity, response: KeyChainAliasCallback, keyTypes: Array<String!>?, issuers: Array<Principal!>?, host: String?, port: Int, alias: String?) Launches an |
static Unit |
choosePrivateKeyAlias(activity: Activity, response: KeyChainAliasCallback, keyTypes: Array<String!>?, issuers: Array<Principal!>?, uri: Uri?, alias: String?) Launches an |
static Intent |
Returns an |
static Intent |
Returns an |
static Array<X509Certificate!>? |
getCertificateChain(context: Context, alias: String) Returns the |
static AppUriAuthenticationPolicy |
getCredentialManagementAppPolicy(context: Context) Called by the credential management app to get the authentication policy |
static PrivateKey? |
getPrivateKey(context: Context, alias: String) Returns the |
static Boolean |
isBoundKeyAlgorithm(algorithm: String) Returns |
static Boolean |
isCredentialManagementApp(context: Context) Check whether the caller is the credential management app |
static Boolean |
isKeyAlgorithmSupported(algorithm: String) Returns |
static Boolean |
removeCredentialManagementApp(context: Context) Called by the credential management app |
Constants
ACTION_KEYCHAIN_CHANGED
static val ACTION_KEYCHAIN_CHANGED: String
Broadcast Action: Indicates the contents of the keychain has changed. Sent when a KeyChain entry is added, modified or removed.
Value: "android.security.action.KEYCHAIN_CHANGED"
ACTION_KEY_ACCESS_CHANGED
static val ACTION_KEY_ACCESS_CHANGED: String
Broadcast Action: Indicates that the access permissions for a private key have changed.
Value: "android.security.action.KEY_ACCESS_CHANGED"
ACTION_STORAGE_CHANGED
static valACTION_STORAGE_CHANGED: String
Deprecated: Use ACTION_KEYCHAIN_CHANGED
, ACTION_TRUST_STORE_CHANGED
or ACTION_KEY_ACCESS_CHANGED
. Apps that target a version higher than android.os.Build.VERSION_CODES#N_MR1
will only receive this broadcast if they register for it at runtime.
Broadcast Action: Indicates the trusted storage has changed. Sent when one of this happens:
- a new CA is added,
- an existing CA is removed or disabled,
- a disabled CA is enabled,
- trusted storage is reset (all user certs are cleared),
- when permission to access a private key is changed.
Value: "android.security.STORAGE_CHANGED"
ACTION_TRUST_STORE_CHANGED
static val ACTION_TRUST_STORE_CHANGED: String
Broadcast Action: Indicates the contents of the trusted certificate store has changed. Sent when one the following occurs:
- A pre-installed CA is disabled or re-enabled
- A CA is added or removed from the trust store
Value: "android.security.action.TRUST_STORE_CHANGED"
EXTRA_CERTIFICATE
static val EXTRA_CERTIFICATE: String
Optional extra to specify an X.509 certificate to install on the Intent
returned by createInstallIntent
. The extra value should be a PEM or ASN.1 DER encoded byte[]
. An X509Certificate
can be converted to DER encoded bytes with X509Certificate#getEncoded
.
EXTRA_NAME
may be used to provide a default alias name for the installed certificate.
Value: "CERT"
EXTRA_KEY_ACCESSIBLE
static val EXTRA_KEY_ACCESSIBLE: String
Used as a boolean extra field in ACTION_KEY_ACCESS_CHANGED
to supply if the key is accessible to the application.
Value: "android.security.extra.KEY_ACCESSIBLE"
EXTRA_KEY_ALIAS
static val EXTRA_KEY_ALIAS: String
Used as a String extra field in ACTION_KEY_ACCESS_CHANGED
to supply the alias of the key.
Value: "android.security.extra.KEY_ALIAS"
EXTRA_NAME
static val EXTRA_NAME: String
Optional extra to specify a String
credential name on the Intent
returned by createInstallIntent
.
Value: "name"
EXTRA_PKCS12
static val EXTRA_PKCS12: String
Optional extra for use with the Intent
returned by createInstallIntent
to specify a PKCS#12 key store to install. The extra value should be a byte[]
. The bytes may come from an external source or be generated with java.security.KeyStore#store on a "PKCS12" instance.
The user will be prompted for the password to load the key store.
The key store will be scanned for entries and both the private key and associated certificate chain will be installed.
EXTRA_NAME
may be used to provide a default alias name for the installed credentials.
Value: "PKCS12"
KEY_ALIAS_SELECTION_DENIED
static val KEY_ALIAS_SELECTION_DENIED: String
Used by DPC or delegated app in android.app.admin.DeviceAdminReceiver#onChoosePrivateKeyAlias
or android.app.admin.DelegatedAdminReceiver#onChoosePrivateKeyAlias
to identify that the requesting app is not granted access to any key, and nor will the user be able to grant access manually.
Value: "android:alias-selection-denied"
Public constructors
KeyChain
KeyChain()
Public methods
choosePrivateKeyAlias
static fun choosePrivateKeyAlias(
activity: Activity,
response: KeyChainAliasCallback,
keyTypes: Array<String!>?,
issuers: Array<Principal!>?,
host: String?,
port: Int,
alias: String?
): Unit
Launches an Activity
for the user to select the alias for a private key and certificate pair for authentication. The selected alias or null will be returned via the KeyChainAliasCallback callback.
A device policy controller (as a device or profile owner) can intercept the request before the activity is shown, to pick a specific private key alias by implementing onChoosePrivateKeyAlias
.
keyTypes
and issuers
may be used to narrow down suggested choices to the user. If either keyTypes
or issuers
is specified and non-empty, and there are no matching certificates in the KeyChain, then the certificate selection prompt would be suppressed entirely.
host
and port
may be used to give the user more context about the server requesting the credentials.
alias
allows the caller to preselect an existing alias which will still be subject to user confirmation.
Parameters | |
---|---|
activity |
Activity: The Activity context to use for launching the new sub-Activity to prompt the user to select a private key; used only to call startActivity(); must not be null. |
response |
KeyChainAliasCallback: Callback to invoke when the request completes; must not be null. |
keyTypes |
Array<String!>?: The acceptable types of asymmetric keys such as "RSA", "EC" or null. Value is android.security.keystore.KeyProperties#KEY_ALGORITHM_RSA , android.security.keystore.KeyProperties#KEY_ALGORITHM_EC , android.security.keystore.KeyProperties.KEY_ALGORITHM_XDH, android.security.keystore.KeyProperties#KEY_ALGORITHM_AES , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA1 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA224 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA256 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA384 , or android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA512 |
issuers |
Array<Principal!>?: The acceptable certificate issuers for the certificate matching the private key, or null. |
host |
String?: The host name of the server requesting the certificate, or null if unavailable. |
port |
Int: The port number of the server requesting the certificate, or -1 if unavailable. |
alias |
String?: The alias to preselect if available, or null if unavailable. |
choosePrivateKeyAlias
static fun choosePrivateKeyAlias(
activity: Activity,
response: KeyChainAliasCallback,
keyTypes: Array<String!>?,
issuers: Array<Principal!>?,
uri: Uri?,
alias: String?
): Unit
Launches an Activity
for the user to select the alias for a private key and certificate pair for authentication. The selected alias or null will be returned via the KeyChainAliasCallback callback.
A device policy controller (as a device or profile owner) can intercept the request before the activity is shown, to pick a specific private key alias by implementing onChoosePrivateKeyAlias
.
keyTypes
and issuers
may be used to narrow down suggested choices to the user. If either keyTypes
or issuers
is specified and non-empty, and there are no matching certificates in the KeyChain, then the certificate selection prompt would be suppressed entirely.
uri
may be used to give the user more context about the server requesting the credentials.
alias
allows the caller to preselect an existing alias which will still be subject to user confirmation.
Parameters | |
---|---|
activity |
Activity: The Activity context to use for launching the new sub-Activity to prompt the user to select a private key; used only to call startActivity(); must not be null. |
response |
KeyChainAliasCallback: Callback to invoke when the request completes; must not be null. |
keyTypes |
Array<String!>?: The acceptable types of asymmetric keys such as "RSA", "EC" or null. Value is android.security.keystore.KeyProperties#KEY_ALGORITHM_RSA , android.security.keystore.KeyProperties#KEY_ALGORITHM_EC , android.security.keystore.KeyProperties.KEY_ALGORITHM_XDH, android.security.keystore.KeyProperties#KEY_ALGORITHM_AES , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA1 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA224 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA256 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA384 , or android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA512 |
issuers |
Array<Principal!>?: The acceptable certificate issuers for the certificate matching the private key, or null. |
uri |
Uri?: The full URI the server is requesting the certificate for, or null if unavailable. |
alias |
String?: The alias to preselect if available, or null if unavailable. |
Exceptions | |
---|---|
java.lang.IllegalArgumentException |
if the specified issuers are not of type X500Principal . |
createInstallIntent
static fun createInstallIntent(): Intent
Returns an Intent
that can be used for credential installation. The intent may be used without any extras, in which case the user will be able to install credentials from their own source.
Alternatively, EXTRA_CERTIFICATE
or EXTRA_PKCS12
maybe used to specify the bytes of an X.509 certificate or a PKCS#12 key store for installation. These extras may be combined with EXTRA_NAME
to provide a default alias name for credentials being installed.
When used with android.app.Activity#startActivityForResult, Activity#RESULT_OK
will be returned if a credential was successfully installed, otherwise android.app.Activity#RESULT_CANCELED
will be returned.
Starting from android.os.Build.VERSION_CODES#R
, the intent returned by this method cannot be used for installing CA certificates. Since CA certificates can only be installed via Settings, the app should provide the user with a file containing the CA certificate. One way to do this would be to use the android.provider.MediaStore
API to write the certificate to the android.provider.MediaStore.Downloads
collection.
Return | |
---|---|
Intent |
This value cannot be null . |
createManageCredentialsIntent
static fun createManageCredentialsIntent(policy: AppUriAuthenticationPolicy): Intent
Returns an Intent
that should be used by an app to request to manage the user's credentials. This is limited to unmanaged devices. The authentication policy must be provided to be able to make this request successfully.
This intent should be started using Activity#startActivityForResult(Intent, int)
to verify whether the request was successful and whether the user accepted or denied the request. If the user successfully receives and accepts the request, the result code will be Activity#RESULT_OK
, otherwise the result code will be Activity#RESULT_CANCELED
.
KeyChain#isCredentialManagementApp(Context)
should be used to determine whether an app is already the credential management app.
Parameters | |
---|---|
policy |
AppUriAuthenticationPolicy: The authentication policy determines which alias for a private key and certificate pair should be used for authentication. This value cannot be null . |
Return | |
---|---|
Intent |
This value cannot be null . |
getCertificateChain
static fun getCertificateChain(
context: Context,
alias: String
): Array<X509Certificate!>?
Returns the X509Certificate
chain for the requested alias, or null if the alias does not exist or the caller has no permission to access it (see note on exceptions in getPrivateKey
).
Note: If a certificate chain was explicitly specified when the alias was installed, this method will return that chain. If only the client certificate was specified at the installation time, this method will try to build a certificate chain using all available trust anchors (preinstalled and user-added).
This method may block while waiting for a connection to another process, and must never be called from the main thread.
As Activity
and Service
contexts are short-lived and can be destroyed at any time from the main thread, it is safer to rely on a long-lived context such as one returned from Context#getApplicationContext()
.
In case the caller specifies an alias for which it lacks a grant, it must call #choosePrivateKeyAlias again. See getPrivateKey
for more details on coping with this scenario.
This method may take several seconds to complete, so it should only be called from a worker thread.
Parameters | |
---|---|
alias |
String: The alias of the desired certificate chain, typically returned via KeyChainAliasCallback#alias . This value cannot be null . |
context |
Context: This value cannot be null . |
Exceptions | |
---|---|
android.security.KeyChainException |
if the alias was valid but there was some problem accessing it. |
java.lang.IllegalStateException |
if called from the main thread. |
getCredentialManagementAppPolicy
static fun getCredentialManagementAppPolicy(context: Context): AppUriAuthenticationPolicy
Called by the credential management app to get the authentication policy AppUriAuthenticationPolicy
.
This method may take several seconds to complete, so it should only be called from a worker thread.
Parameters | |
---|---|
context |
Context: This value cannot be null . |
Return | |
---|---|
AppUriAuthenticationPolicy |
the credential management app's authentication policy. This value cannot be null . |
Exceptions | |
---|---|
java.lang.SecurityException |
if the caller is not the credential management app. |
getPrivateKey
static fun getPrivateKey(
context: Context,
alias: String
): PrivateKey?
Returns the PrivateKey
for the requested alias, or null if the alias does not exist or the caller has no permission to access it (see note on exceptions below).
This method may block while waiting for a connection to another process, and must never be called from the main thread.
As Activity
and Service
contexts are short-lived and can be destroyed at any time from the main thread, it is safer to rely on a long-lived context such as one returned from Context#getApplicationContext()
.
If the caller provides a valid alias to which it was not granted access, then the caller must invoke #choosePrivateKeyAlias again to get another valid alias or a grant to access the same alias.
On Android versions prior to Q, when a key associated with the specified alias is unavailable, the method will throw a KeyChainException
rather than return null. If the exception's cause (as obtained by calling KeyChainException.getCause()
) is a throwable of type IllegalStateException
then the caller lacks a grant to access the key and certificates associated with this alias.
This method may take several seconds to complete, so it should only be called from a worker thread.
Parameters | |
---|---|
alias |
String: The alias of the desired private key, typically returned via KeyChainAliasCallback#alias . This value cannot be null . |
context |
Context: This value cannot be null . |
Exceptions | |
---|---|
android.security.KeyChainException |
if the alias was valid but there was some problem accessing it. |
java.lang.IllegalStateException |
if called from the main thread. |
isBoundKeyAlgorithm
static funisBoundKeyAlgorithm(algorithm: String): Boolean
Deprecated: Whether the key is bound to the secure hardware is known only once the key has been imported. To find out, use:
<code>PrivateKey key = ...; // private key from KeyChain
KeyFactory keyFactory =
KeyFactory.getInstance(key.getAlgorithm(), "AndroidKeyStore");
KeyInfo keyInfo = keyFactory.getKeySpec(key, KeyInfo.class);
if (keyInfo.isInsideSecureHardware()) {
// The key is bound to the secure hardware of this Android
}</code>
Returns true
if the current device's KeyChain
binds any PrivateKey
of the given algorithm
to the device once imported or generated. This can be used to tell if there is special hardware support that can be used to bind keys to the device in a way that makes it non-exportable.
Parameters | |
---|---|
algorithm |
String: This value cannot be null . Value is android.security.keystore.KeyProperties#KEY_ALGORITHM_RSA , android.security.keystore.KeyProperties#KEY_ALGORITHM_EC , android.security.keystore.KeyProperties.KEY_ALGORITHM_XDH, android.security.keystore.KeyProperties#KEY_ALGORITHM_AES , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA1 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA224 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA256 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA384 , or android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA512 |
isCredentialManagementApp
static fun isCredentialManagementApp(context: Context): Boolean
Check whether the caller is the credential management app CredentialManagementApp
. The credential management app has the ability to manage the user's KeyChain credentials on unmanaged devices.
KeyChain#createManageCredentialsIntent
should be used by an app to request to become the credential management app. The user must approve this request before the app can manage the user's credentials. There can only be one credential management on the device.
This method may take several seconds to complete, so it should only be called from a worker thread.
Parameters | |
---|---|
context |
Context: This value cannot be null . |
Return | |
---|---|
Boolean |
true if the caller is the credential management app. |
isKeyAlgorithmSupported
static fun isKeyAlgorithmSupported(algorithm: String): Boolean
Returns true
if the current device's KeyChain
supports a specific PrivateKey
type indicated by algorithm
(e.g., "RSA").
Parameters | |
---|---|
algorithm |
String: This value cannot be null . Value is android.security.keystore.KeyProperties#KEY_ALGORITHM_RSA , android.security.keystore.KeyProperties#KEY_ALGORITHM_EC , android.security.keystore.KeyProperties.KEY_ALGORITHM_XDH, android.security.keystore.KeyProperties#KEY_ALGORITHM_AES , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA1 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA224 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA256 , android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA384 , or android.security.keystore.KeyProperties#KEY_ALGORITHM_HMAC_SHA512 |
removeCredentialManagementApp
static fun removeCredentialManagementApp(context: Context): Boolean
Called by the credential management app CredentialManagementApp
to unregister as the credential management app and stop managing the user's credentials.
All credentials previously installed by the credential management app will be removed from the user's device.
An app holding MANAGE_CREDENTIAL_MANAGEMENT_APP
permission can also call this method to remove the current credential management app, even if it's not the current credential management app itself.
This method may take several seconds to complete, so it should only be called from a worker thread.
Parameters | |
---|---|
context |
Context: This value cannot be null . |
Return | |
---|---|
Boolean |
true if the credential management app was successfully removed. |