KeyStore

AI-generated Key Takeaways

• The KeyStore class in Java securely stores cryptographic keys and certificates, used for authentication and data protection.

• It manages various entry types, including PrivateKeyEntry, SecretKeyEntry, and TrustedCertificateEntry, each holding specific data.

• Keystores offer flexibility in persistence and protection mechanisms, allowing storage in files or smart cards, for example.

• Numerous methods are provided for managing entries, like retrieving data, checking types, and modifying the keystore content.

• Android supports diverse KeyStore types, including AndroidKeyStore and PKCS12, offering platform-specific security features.

public class KeyStore extends Object

This class represents a storage facility for cryptographic keys and certificates.

A KeyStore manages different types of entries. Each type of entry implements the KeyStore.Entry interface. Three basic KeyStore.Entry implementations are provided:

• KeyStore.PrivateKeyEntry

  This type of entry holds a cryptographic PrivateKey, which is optionally stored in a protected format to prevent unauthorized access. It is also accompanied by a certificate chain for the corresponding public key.

  Private keys and certificate chains are used by a given entity for self-authentication. Applications for this authentication include software distribution organizations which sign JAR files as part of releasing and/or licensing software.

• KeyStore.SecretKeyEntry

  This type of entry holds a cryptographic SecretKey, which is optionally stored in a protected format to prevent unauthorized access.

• KeyStore.TrustedCertificateEntry

  This type of entry contains a single public key Certificate belonging to another party. It is called a trusted certificate because the keystore owner trusts that the public key in the certificate indeed belongs to the identity identified by the subject (owner) of the certificate.

  This type of entry can be used to authenticate other parties.

Each entry in a keystore is identified by an "alias" string. In the case of private keys and their associated certificate chains, these strings distinguish among the different ways in which the entity may authenticate itself. For example, the entity may authenticate itself using different certificate authorities, or using different public key algorithms.

Whether aliases are case sensitive is implementation dependent. In order to avoid problems, it is recommended not to use aliases in a KeyStore that only differ in case.

Whether keystores are persistent, and the mechanisms used by the keystore if it is persistent, are not specified here. This allows use of a variety of techniques for protecting sensitive (e.g., private or secret) keys. Smart cards or other integrated cryptographic engines (SafeKeyper) are one option, and simpler mechanisms such as files may also be used (in a variety of formats).

Typical ways to request a KeyStore object include relying on the default type and providing a specific keystore type.

• To rely on the default type:

      KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());
   

  The system will return a keystore implementation for the default type.
• To provide a specific keystore type:

        KeyStore ks = KeyStore.getInstance("JKS");
   

  The system will return the most preferred implementation of the specified keystore type available in the environment.

Before a keystore can be accessed, it must be loaded.

    KeyStore ks = KeyStore.getInstance(KeyStore.getDefaultType());

    // get user password and file input stream
    char[] password = getPassword();

    try (FileInputStream fis = new FileInputStream("keyStoreName")) {
        ks.load(fis, password);
    }
 

To create an empty keystore using the above load method, pass null as the InputStream argument.

Once the keystore has been loaded, it is possible to read existing entries from the keystore, or to write new entries into the keystore:

    KeyStore.ProtectionParameter protParam =
        new KeyStore.PasswordProtection(password);

    // get my private key
    KeyStore.PrivateKeyEntry pkEntry = (KeyStore.PrivateKeyEntry)
        ks.getEntry("privateKeyAlias", protParam);
    PrivateKey myPrivateKey = pkEntry.getPrivateKey();

    // save my secret key
    javax.crypto.SecretKey mySecretKey;
    KeyStore.SecretKeyEntry skEntry =
        new KeyStore.SecretKeyEntry(mySecretKey);
    ks.setEntry("secretKeyAlias", skEntry, protParam);

    // store away the keystore
    try (FileOutputStream fos = new FileOutputStream("newKeyStoreName")) {
        ks.store(fos, password);
    }
 

Note that although the same password may be used to load the keystore, to protect the private key entry, to protect the secret key entry, and to store the keystore (as is shown in the sample code above), different passwords or other protection parameters may also be used.

Android provides the following KeyStore types:

Algorithm	Supported API Levels
AndroidCAStore	14+
AndroidKeyStore	18+
BCPKCS12	1-8
BKS	1+
BouncyCastle	1+
PKCS12	1+
PKCS12-DEF	1-8

These types are described in the KeyStore section of the Java Cryptography Architecture Standard Algorithm Name Documentation.

See Also

• PrivateKey
• SecretKey
• Certificate

Nested Class Summary

class	KeyStore.Builder		A description of a to-be-instantiated KeyStore object.
class	KeyStore.CallbackHandlerProtection		A ProtectionParameter encapsulating a CallbackHandler.
interface	KeyStore.Entry		A marker interface for KeyStore entry types.
interface	KeyStore.LoadStoreParameter		A marker interface for KeyStore load and store parameters.
class	KeyStore.PasswordProtection		A password-based implementation of ProtectionParameter.
class	KeyStore.PrivateKeyEntry		A KeyStore entry that holds a PrivateKey and corresponding certificate chain.
interface	KeyStore.ProtectionParameter		A marker interface for keystore protection parameters.
class	KeyStore.SecretKeyEntry		A KeyStore entry that holds a SecretKey.
class	KeyStore.TrustedCertificateEntry		A KeyStore entry that holds a trusted Certificate.

Protected Constructor Summary

KeyStore(KeyStoreSpi keyStoreSpi, Provider provider, String type) Creates a KeyStore object of the given type, and encapsulates the given provider implementation (SPI object) in it.

Public Method Summary

final Enumeration<String>	aliases() Lists all the alias names of this keystore.
final boolean	containsAlias(String alias) Checks if the given alias exists in this keystore.
final void	deleteEntry(String alias) Deletes the entry identified by the given alias from this keystore.
final boolean	entryInstanceOf(String alias, Class<? extends KeyStore.Entry> entryClass) Determines if the keystore Entry for the specified alias is an instance or subclass of the specified entryClass.
final Certificate	getCertificate(String alias) Returns the certificate associated with the given alias.
final String	getCertificateAlias(Certificate cert) Returns the (alias) name of the first keystore entry whose certificate matches the given certificate.
final Certificate[]	getCertificateChain(String alias) Returns the certificate chain associated with the given alias.
final Date	getCreationDate(String alias) Returns the creation date of the entry identified by the given alias.
final static String	getDefaultType() Returns the default keystore type as specified by the keystore.type security property, or the string "jks" (acronym for "Java keystore") if no such property exists.
final KeyStore.Entry	getEntry(String alias, KeyStore.ProtectionParameter protParam) Gets a keystore Entry for the specified alias with the specified protection parameter.
static KeyStore	getInstance(String type) Returns a keystore object of the specified type.
static KeyStore	getInstance(String type, String provider) Returns a keystore object of the specified type.
static KeyStore	getInstance(String type, Provider provider) Returns a keystore object of the specified type.
final Key	getKey(String alias, char[] password) Returns the key associated with the given alias, using the given password to recover it.
final Provider	getProvider() Returns the provider of this keystore.
final String	getType() Returns the type of this keystore.
final boolean	isCertificateEntry(String alias) Returns true if the entry identified by the given alias was created by a call to setCertificateEntry, or created by a call to setEntry with a TrustedCertificateEntry.
final boolean	isKeyEntry(String alias) Returns true if the entry identified by the given alias was created by a call to setKeyEntry, or created by a call to setEntry with a PrivateKeyEntry or a SecretKeyEntry.
final void	load(KeyStore.LoadStoreParameter param) Loads this keystore using the given LoadStoreParameter.
final void	load(InputStream stream, char[] password) Loads this KeyStore from the given input stream.
final void	setCertificateEntry(String alias, Certificate cert) Assigns the given trusted certificate to the given alias.
final void	setEntry(String alias, KeyStore.Entry entry, KeyStore.ProtectionParameter protParam) Saves a keystore Entry under the specified alias.
final void	setKeyEntry(String alias, Key key, char[] password, Certificate[] chain) Assigns the given key to the given alias, protecting it with the given password.
final void	setKeyEntry(String alias, byte[] key, Certificate[] chain) Assigns the given key (that has already been protected) to the given alias.
final int	size() Retrieves the number of entries in this keystore.
final void	store(OutputStream stream, char[] password) Stores this keystore to the given output stream, and protects its integrity with the given password.
final void	store(KeyStore.LoadStoreParameter param) Stores this keystore using the given LoadStoreParameter.

Inherited Method Summary

From class java.lang.Object

Object	clone() Creates and returns a copy of this Object.
boolean	equals(Object obj) Compares this instance with the specified object and indicates if they are equal.
void	finalize() Invoked when the garbage collector has detected that this instance is no longer reachable.
final Class<?>	getClass() Returns the unique instance of Class that represents this object's class.
int	hashCode() Returns an integer hash code for this object.
final void	notify() Causes a thread which is waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
final void	notifyAll() Causes all threads which are waiting on this object's monitor (by means of calling one of the wait() methods) to be woken up.
String	toString() Returns a string containing a concise, human-readable description of this object.
final void	wait(long timeout, int nanos) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait(long timeout) Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object or until the specified timeout expires.
final void	wait() Causes the calling thread to wait until another thread calls the notify() or notifyAll() method of this object.

Protected Constructors

protected KeyStore (KeyStoreSpi keyStoreSpi, Provider provider, String type)

Creates a KeyStore object of the given type, and encapsulates the given provider implementation (SPI object) in it.

Parameters

keyStoreSpi	the provider implementation.
provider	the provider.
type	the keystore type.

Public Methods

public final Enumeration<String> aliases ()

Lists all the alias names of this keystore.

Returns

• enumeration of the alias names

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final boolean containsAlias (String alias)

Checks if the given alias exists in this keystore.

Parameters

alias	the alias name

Returns

• true if the alias exists, false otherwise

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final void deleteEntry (String alias)

Deletes the entry identified by the given alias from this keystore.

Parameters

alias	the alias name

Throws

KeyStoreException	if the keystore has not been initialized, or if the entry cannot be removed.

public final boolean entryInstanceOf (String alias, Class<? extends KeyStore.Entry> entryClass)

Determines if the keystore Entry for the specified alias is an instance or subclass of the specified entryClass.

Parameters

alias	the alias name
entryClass	the entry class

Returns

• true if the keystore Entry for the specified alias is an instance or subclass of the specified entryClass, false otherwise

Throws

NullPointerException	if alias or entryClass is null
KeyStoreException	if the keystore has not been initialized (loaded)

public final Certificate getCertificate (String alias)

Returns the certificate associated with the given alias.

If the given alias name identifies an entry created by a call to setCertificateEntry, or created by a call to setEntry with a TrustedCertificateEntry, then the trusted certificate contained in that entry is returned.

If the given alias name identifies an entry created by a call to setKeyEntry, or created by a call to setEntry with a PrivateKeyEntry, then the first element of the certificate chain in that entry is returned.

Parameters

alias	the alias name

Returns

• the certificate, or null if the given alias does not exist or does not contain a certificate.

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final String getCertificateAlias (Certificate cert)

Returns the (alias) name of the first keystore entry whose certificate matches the given certificate.

This method attempts to match the given certificate with each keystore entry. If the entry being considered was created by a call to setCertificateEntry, or created by a call to setEntry with a TrustedCertificateEntry, then the given certificate is compared to that entry's certificate.

If the entry being considered was created by a call to setKeyEntry, or created by a call to setEntry with a PrivateKeyEntry, then the given certificate is compared to the first element of that entry's certificate chain.

Parameters

cert	the certificate to match with.

Returns

• the alias name of the first entry with a matching certificate, or null if no such entry exists in this keystore.

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final Certificate[] getCertificateChain (String alias)

Returns the certificate chain associated with the given alias. The certificate chain must have been associated with the alias by a call to setKeyEntry, or by a call to setEntry with a PrivateKeyEntry.

Parameters

alias	the alias name

Returns

• the certificate chain (ordered with the user's certificate first followed by zero or more certificate authorities), or null if the given alias does not exist or does not contain a certificate chain

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final Date getCreationDate (String alias)

Returns the creation date of the entry identified by the given alias.

Parameters

alias	the alias name

Returns

• the creation date of this entry, or null if the given alias does not exist

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public static final String getDefaultType ()

Returns the default keystore type as specified by the keystore.type security property, or the string "jks" (acronym for "Java keystore") if no such property exists.

The default keystore type can be used by applications that do not want to use a hard-coded keystore type when calling one of the getInstance methods, and want to provide a default keystore type in case a user does not specify its own.

The default keystore type can be changed by setting the value of the keystore.type security property to the desired keystore type.

Returns

• the default keystore type as specified by the keystore.type security property, or the string "jks" if no such property exists.

See Also

• security properties

public final KeyStore.Entry getEntry (String alias, KeyStore.ProtectionParameter protParam)

Gets a keystore Entry for the specified alias with the specified protection parameter.

Parameters

alias	get the keystore Entry for this alias
protParam	the ProtectionParameter used to protect the Entry, which may be null

Returns

• the keystore Entry for the specified alias, or null if there is no such entry

Throws

NullPointerException	if alias is null
NoSuchAlgorithmException	if the algorithm for recovering the entry cannot be found
UnrecoverableEntryException	if the specified protParam were insufficient or invalid
UnrecoverableKeyException	if the entry is a PrivateKeyEntry or SecretKeyEntry and the specified protParam does not contain the information needed to recover the key (e.g. wrong password)
KeyStoreException	if the keystore has not been initialized (loaded).

See Also

• setEntry(String, KeyStore.Entry, KeyStore.ProtectionParameter)

public static KeyStore getInstance (String type)

Returns a keystore object of the specified type.

This method traverses the list of registered security Providers, starting with the most preferred Provider. A new KeyStore object encapsulating the KeyStoreSpi implementation from the first Provider that supports the specified type is returned.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Parameters

type	the type of keystore. See the KeyStore section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard keystore types.

Returns

• a keystore object of the specified type.

Throws

KeyStoreException	if no Provider supports a KeyStoreSpi implementation for the specified type.

See Also

• Provider

public static KeyStore getInstance (String type, String provider)

Returns a keystore object of the specified type.

A new KeyStore object encapsulating the KeyStoreSpi implementation from the specified provider is returned. The specified provider must be registered in the security provider list.

Note that the list of registered providers may be retrieved via the Security.getProviders() method.

Parameters

type	the type of keystore. See the KeyStore section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard keystore types.
provider	the name of the provider.

Returns

• a keystore object of the specified type.

Throws

KeyStoreException	if a KeyStoreSpi implementation for the specified type is not available from the specified provider.
NoSuchProviderException	if the specified provider is not registered in the security provider list.
IllegalArgumentException	if the provider name is null or empty.

See Also

• Provider

public static KeyStore getInstance (String type, Provider provider)

Returns a keystore object of the specified type.

A new KeyStore object encapsulating the KeyStoreSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.

Parameters

type	the type of keystore. See the KeyStore section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard keystore types.
provider	the provider.

Returns

• a keystore object of the specified type.

Throws

KeyStoreException	if KeyStoreSpi implementation for the specified type is not available from the specified Provider object.
IllegalArgumentException	if the specified provider is null.

See Also

• Provider

public final Key getKey (String alias, char[] password)

Returns the key associated with the given alias, using the given password to recover it. The key must have been associated with the alias by a call to setKeyEntry, or by a call to setEntry with a PrivateKeyEntry or SecretKeyEntry.

Parameters

alias	the alias name
password	the password for recovering the key

Returns

• the requested key, or null if the given alias does not exist or does not identify a key-related entry.

Throws

KeyStoreException	if the keystore has not been initialized (loaded).
NoSuchAlgorithmException	if the algorithm for recovering the key cannot be found
UnrecoverableKeyException	if the key cannot be recovered (e.g., the given password is wrong).

public final Provider getProvider ()

Returns the provider of this keystore.

Returns

• the provider of this keystore.

public final String getType ()

Returns the type of this keystore.

Returns

• the type of this keystore.

public final boolean isCertificateEntry (String alias)

Returns true if the entry identified by the given alias was created by a call to setCertificateEntry, or created by a call to setEntry with a TrustedCertificateEntry.

Parameters

alias	the alias for the keystore entry to be checked

Returns

• true if the entry identified by the given alias contains a trusted certificate, false otherwise.

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final boolean isKeyEntry (String alias)

Returns true if the entry identified by the given alias was created by a call to setKeyEntry, or created by a call to setEntry with a PrivateKeyEntry or a SecretKeyEntry.

Parameters

alias	the alias for the keystore entry to be checked

Returns

• true if the entry identified by the given alias is a key-related entry, false otherwise.

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final void load (KeyStore.LoadStoreParameter param)

Loads this keystore using the given LoadStoreParameter.

Note that if this KeyStore has already been loaded, it is reinitialized and loaded again from the given parameter.

Parameters

param	the LoadStoreParameter that specifies how to load the keystore, which may be null

Throws

IllegalArgumentException	if the given LoadStoreParameter input is not recognized
IOException	if there is an I/O or format problem with the keystore data. If the error is due to an incorrect ProtectionParameter (e.g. wrong password) the cause of the IOException should be an UnrecoverableKeyException
NoSuchAlgorithmException	if the algorithm used to check the integrity of the keystore cannot be found
CertificateException	if any of the certificates in the keystore could not be loaded

public final void load (InputStream stream, char[] password)

Loads this KeyStore from the given input stream.

A password may be given to unlock the keystore (e.g. the keystore resides on a hardware token device), or to check the integrity of the keystore data. If a password is not given for integrity checking, then integrity checking is not performed.

In order to create an empty keystore, or if the keystore cannot be initialized from a stream, pass null as the stream argument.

Note that if this keystore has already been loaded, it is reinitialized and loaded again from the given input stream.

Parameters

stream	the input stream from which the keystore is loaded, or null
password	the password used to check the integrity of the keystore, the password used to unlock the keystore, or null

Throws

IOException	if there is an I/O or format problem with the keystore data, if a password is required but not given, or if the given password was incorrect. If the error is due to a wrong password, the cause of the IOException should be an UnrecoverableKeyException
NoSuchAlgorithmException	if the algorithm used to check the integrity of the keystore cannot be found
CertificateException	if any of the certificates in the keystore could not be loaded

public final void setCertificateEntry (String alias, Certificate cert)

Assigns the given trusted certificate to the given alias.

If the given alias identifies an existing entry created by a call to setCertificateEntry, or created by a call to setEntry with a TrustedCertificateEntry, the trusted certificate in the existing entry is overridden by the given certificate.

Parameters

alias	the alias name
cert	the certificate

Throws

KeyStoreException	if the keystore has not been initialized, or the given alias already exists and does not identify an entry containing a trusted certificate, or this operation fails for some other reason.

public final void setEntry (String alias, KeyStore.Entry entry, KeyStore.ProtectionParameter protParam)

Saves a keystore Entry under the specified alias. The protection parameter is used to protect the Entry.

If an entry already exists for the specified alias, it is overridden.

Parameters

alias	save the keystore Entry under this alias
entry	the Entry to save
protParam	the ProtectionParameter used to protect the Entry, which may be null

Throws

NullPointerException	if alias or entry is null
KeyStoreException	if the keystore has not been initialized (loaded), or if this operation fails for some other reason

See Also

• getEntry(String, KeyStore.ProtectionParameter)

public final void setKeyEntry (String alias, Key key, char[] password, Certificate[] chain)

Assigns the given key to the given alias, protecting it with the given password.

If the given key is of type java.security.PrivateKey, it must be accompanied by a certificate chain certifying the corresponding public key.

If the given alias already exists, the keystore information associated with it is overridden by the given key (and possibly certificate chain).

Parameters

alias	the alias name
key	the key to be associated with the alias
password	the password to protect the key
chain	the certificate chain for the corresponding public key (only required if the given key is of type java.security.PrivateKey).

Throws

KeyStoreException	if the keystore has not been initialized (loaded), the given key cannot be protected, or this operation fails for some other reason

public final void setKeyEntry (String alias, byte[] key, Certificate[] chain)

Assigns the given key (that has already been protected) to the given alias.

If the protected key is of type java.security.PrivateKey, it must be accompanied by a certificate chain certifying the corresponding public key. If the underlying keystore implementation is of type jks, key must be encoded as an EncryptedPrivateKeyInfo as defined in the PKCS #8 standard.

If the given alias already exists, the keystore information associated with it is overridden by the given key (and possibly certificate chain).

Parameters

alias	the alias name
key	the key (in protected format) to be associated with the alias
chain	the certificate chain for the corresponding public key (only useful if the protected key is of type java.security.PrivateKey).

Throws

KeyStoreException	if the keystore has not been initialized (loaded), or if this operation fails for some other reason.

public final int size ()

Retrieves the number of entries in this keystore.

Returns

• the number of entries in this keystore

Throws

KeyStoreException	if the keystore has not been initialized (loaded).

public final void store (OutputStream stream, char[] password)

Stores this keystore to the given output stream, and protects its integrity with the given password.

Parameters

stream	the output stream to which this keystore is written.
password	the password to generate the keystore integrity check

Throws

KeyStoreException	if the keystore has not been initialized (loaded).
IOException	if there was an I/O problem with data
NoSuchAlgorithmException	if the appropriate data integrity algorithm could not be found
CertificateException	if any of the certificates included in the keystore data could not be stored

public final void store (KeyStore.LoadStoreParameter param)

Stores this keystore using the given LoadStoreParameter.

Parameters

param	the LoadStoreParameter that specifies how to store the keystore, which may be null

Throws

IllegalArgumentException	if the given LoadStoreParameter input is not recognized
KeyStoreException	if the keystore has not been initialized (loaded)
IOException	if there was an I/O problem with data
NoSuchAlgorithmException	if the appropriate data integrity algorithm could not be found
CertificateException	if any of the certificates included in the keystore data could not be stored