SecretKeyFactory

public class SecretKeyFactory extends Object

This class represents a factory for secret keys.

Key factories are used to convert keys (opaque cryptographic keys of type Key) into key specifications (transparent representations of the underlying key material), and vice versa. Secret key factories operate only on secret (symmetric) keys.

Key factories are bi-directional, i.e., they allow to build an opaque key object from a given key specification (key material), or to retrieve the underlying key material of a key object in a suitable format.

Application developers should refer to their provider's documentation to find out which key specifications are supported by the generateSecret and getKeySpec methods. For example, the DES secret-key factory supplied by the "SunJCE" provider supports DESKeySpec as a transparent representation of DES keys, and that provider's secret-key factory for Triple DES keys supports DESedeKeySpec as a transparent representation of Triple DES keys.

Android provides the following SecretKeyFactory algorithms:

Name Supported (API Levels)
AES 23+
DES 1+
DESede 1+
HmacSHA1 23+
HmacSHA224 23+
HmacSHA256 23+
HmacSHA384 23+
HmacSHA512 23+
PBEwithHmacSHA1 1+
PBEwithMD5and128BITAES-CBC-OPENSSL 1+
PBEwithMD5and192BITAES-CBC-OPENSSL 1+
PBEwithMD5and256BITAES-CBC-OPENSSL 1+
PBEwithMD5andDES 1+
PBEwithMD5andRC2 1+
PBEwithSHA1andDES 1+
PBEwithSHA1andRC2 1+
PBEwithSHA256and128BITAES-CBC-BC 1+
PBEwithSHA256and192BITAES-CBC-BC 1+
PBEwithSHA256and256BITAES-CBC-BC 1+
PBEwithSHAand128BITAES-CBC-BC 1+
PBEwithSHAand128BITRC2-CBC 10+
PBEwithSHAand128BITRC4 10+
PBEwithSHAand192BITAES-CBC-BC 1+
PBEwithSHAand2-KEYTRIPLEDES-CBC 1+
PBEwithSHAand256BITAES-CBC-BC 1+
PBEwithSHAand3-KEYTRIPLEDES-CBC 1+
PBEwithSHAand40BITRC2-CBC 1+
PBEwithSHAand40BITRC4 10+
PBEwithSHAandTWOFISH-CBC 10+
PBKDF2withHmacSHA1 10+
PBKDF2withHmacSHA1and8BIT 19+
These algorithms are described in the SecretKeyFactory section of the Java Cryptography Architecture Standard Algorithm Name Documentation.

Protected Constructor Summary

SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)
Creates a SecretKeyFactory object.

Public Method Summary

final SecretKey
generateSecret(KeySpec keySpec)
Generates a SecretKey object from the provided key specification (key material).
final String
getAlgorithm()
Returns the algorithm name of this SecretKeyFactory object.
final static SecretKeyFactory
getInstance(String algorithm)
Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
final static SecretKeyFactory
getInstance(String algorithm, String provider)
Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
final static SecretKeyFactory
getInstance(String algorithm, Provider provider)
Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.
final KeySpec
getKeySpec(SecretKey key, Class keySpec)
Returns a specification (key material) of the given key object in the requested format.
final Provider
getProvider()
Returns the provider of this SecretKeyFactory object.
final SecretKey
translateKey(SecretKey key)
Translates a key object, whose provider may be unknown or potentially untrusted, into a corresponding key object of this secret-key factory.

Inherited Method Summary

Protected Constructors

protected SecretKeyFactory (SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)

Creates a SecretKeyFactory object.

Parameters
keyFacSpi the delegate
provider the provider
algorithm the secret-key algorithm

Public Methods

public final SecretKey generateSecret (KeySpec keySpec)

Generates a SecretKey object from the provided key specification (key material).

Parameters
keySpec the specification (key material) of the secret key
Returns
  • the secret key
Throws
InvalidKeySpecException if the given key specification is inappropriate for this secret-key factory to produce a secret key.

public final String getAlgorithm ()

Returns the algorithm name of this SecretKeyFactory object.

This is the same name that was specified in one of the getInstance calls that created this SecretKeyFactory object.

Returns
  • the algorithm name of this SecretKeyFactory object.

public static final SecretKeyFactory getInstance (String algorithm)

Returns a SecretKeyFactory object that converts secret keys of the specified algorithm.

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

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

Parameters
algorithm the standard name of the requested secret-key algorithm. See the SecretKeyFactory section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names.
Returns
  • the new SecretKeyFactory object.
Throws
NullPointerException if the specified algorithm is null.