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SecretKeyFactory

public class SecretKeyFactory
extends Object

java.lang.Object
   ↳ javax.crypto.SecretKeyFactory


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.

See also:

Summary

Protected constructors

SecretKeyFactory(SecretKeyFactorySpi keyFacSpi, Provider provider, String algorithm)

Creates a SecretKeyFactory object.

Public methods

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.

static final SecretKeyFactory getInstance(String algorithm)

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

static final SecretKeyFactory getInstance(String algorithm, String provider)

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

static final 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 methods

From class java.lang.Object

Protected constructors

SecretKeyFactory

Added in API level 1
SecretKeyFactory (SecretKeyFactorySpi keyFacSpi, 
                Provider provider, 
                String algorithm)

Creates a SecretKeyFactory object.

Parameters
keyFacSpi SecretKeyFactorySpi: the delegate
provider Provider: the provider
algorithm String: the secret-key algorithm

Public methods

generateSecret

Added in API level 1
SecretKey generateSecret (KeySpec keySpec)

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

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

getAlgorithm

Added in API level 1
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
String the algorithm name of this SecretKeyFactory object.

getInstance

Added in API level 1
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 String: 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
SecretKeyFactory the new SecretKeyFactory object.
Throws
NullPointerException if the specified algorithm is null.
NoSuchAlgorithmException if no Provider supports a SecretKeyFactorySpi implementation for the specified algorithm.

See also:

getInstance

Added in API level 1
SecretKeyFactory getInstance (String algorithm, 
                String provider)

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

A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi 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
algorithm String: 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.
provider String: the name of the provider.
Returns
SecretKeyFactory the new SecretKeyFactory object.
Throws
NoSuchAlgorithmException if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified provider.
NullPointerException if the specified algorithm is null.
NoSuchProviderException if the specified provider is not registered in the security provider list.
IllegalArgumentException if the provider is null or empty.

See also:

getInstance

Added in API level 1
SecretKeyFactory getInstance (String algorithm, 
                Provider provider)

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

A new SecretKeyFactory object encapsulating the SecretKeyFactorySpi 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
algorithm String: 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.
provider Provider: the provider.
Returns
SecretKeyFactory the new SecretKeyFactory object.
Throws
NullPointerException if the specified algorithm is null.
NoSuchAlgorithmException if a SecretKeyFactorySpi implementation for the specified algorithm is not available from the specified Provider object.
IllegalArgumentException if the provider is null.

See also:

getKeySpec

Added in API level 1
KeySpec getKeySpec (SecretKey key, 
                Class keySpec)

Returns a specification (key material) of the given key object in the requested format.

Parameters
key SecretKey: the key
keySpec Class: the requested format in which the key material shall be returned
Returns
KeySpec the underlying key specification (key material) in the requested format
Throws
InvalidKeySpecException if the requested key specification is inappropriate for the given key (e.g., the algorithms associated with key and keySpec do not match, or key references a key on a cryptographic hardware device whereas keySpec is the specification of a software-based key), or the given key cannot be dealt with (e.g., the given key has an algorithm or format not supported by this secret-key factory).

getProvider

Added in API level 1
Provider getProvider ()

Returns the provider of this SecretKeyFactory object.

Returns
Provider the provider of this SecretKeyFactory object

translateKey

Added in API level 1
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.

Parameters
key SecretKey: the key whose provider is unknown or untrusted
Returns
SecretKey the translated key
Throws
InvalidKeyException if the given key cannot be processed by this secret-key factory.
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