This class is used as an opaque representation of cryptographic parameters.
An AlgorithmParameters
object for managing the parameters
for a particular algorithm can be obtained by
calling one of the getInstance
factory methods
(static methods that return instances of a given class).
Once an AlgorithmParameters
object is obtained, it must be
initialized via a call to init
, using an appropriate parameter
specification or parameter encoding.
A transparent parameter specification is obtained from an
AlgorithmParameters
object via a call to
getParameterSpec
, and a byte encoding of the parameters is
obtained via a call to getEncoded
.
Android provides the following AlgorithmParameters
algorithms:
Algorithm | Supported API Levels |
---|---|
AES | 1+ |
BLOWFISH | 10+ |
ChaCha20 | 28+ |
DES | 1+ |
DESede | 1+ |
DH | 1+ |
DSA | 1+ |
EC | 26+ |
GCM | 22+ |
IES | 1-8 |
OAEP | 1+ |
PBEwithHmacSHA1AndAES_128 | 26+ |
PBEwithHmacSHA1AndAES_256 | 26+ |
PBEwithHmacSHA224AndAES_128 | 26+ |
PBEwithHmacSHA224AndAES_256 | 26+ |
PBEwithHmacSHA256AndAES_128 | 26+ |
PBEwithHmacSHA256AndAES_256 | 26+ |
PBEwithHmacSHA384AndAES_128 | 26+ |
PBEwithHmacSHA384AndAES_256 | 26+ |
PBEwithHmacSHA512AndAES_128 | 26+ |
PBEwithHmacSHA512AndAES_256 | 26+ |
PKCS12PBE | 1+ |
PSS | 1-8,24+ |
Protected Constructor Summary
AlgorithmParameters(AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.
|
Public Method Summary
final String |
getAlgorithm()
Returns the name of the algorithm associated with this parameter object.
|
final byte[] | |
final byte[] |
getEncoded()
Returns the parameters in their primary encoding format.
|
static AlgorithmParameters | |
static AlgorithmParameters |
getInstance(String algorithm, String provider)
Returns a parameter object for the specified algorithm.
|
static AlgorithmParameters |
getInstance(String algorithm, Provider provider)
Returns a parameter object for the specified algorithm.
|
final <T extends AlgorithmParameterSpec> T |
getParameterSpec(Class<T> paramSpec)
Returns a (transparent) specification of this parameter object.
|
final Provider |
getProvider()
Returns the provider of this parameter object.
|
final void |
init(byte[] params)
Imports the specified parameters and decodes them according to the
primary decoding format for parameters.
|
final void |
init(AlgorithmParameterSpec paramSpec)
Initializes this parameter object using the parameters
specified in
paramSpec . |
final void | |
final String |
toString()
Returns a formatted string describing the parameters.
|
Inherited Method Summary
Protected Constructors
protected AlgorithmParameters (AlgorithmParametersSpi paramSpi, Provider provider, String algorithm)
Creates an AlgorithmParameters object.
Parameters
paramSpi | the delegate |
---|---|
provider | the provider |
algorithm | the algorithm |
Public Methods
public final String getAlgorithm ()
Returns the name of the algorithm associated with this parameter object.
Returns
- the algorithm name.
public final byte[] getEncoded (String format)
Returns the parameters encoded in the specified scheme.
If format
is null, the
primary encoding format for parameters is used. The primary encoding
format is ASN.1, if an ASN.1 specification for these parameters
exists.
Parameters
format | the name of the encoding format. |
---|
Returns
- the parameters encoded using the specified encoding scheme.
Throws
IOException | on encoding errors, or if this parameter object has not been initialized. |
---|
public final byte[] getEncoded ()
Returns the parameters in their primary encoding format. The primary encoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.
Returns
- the parameters encoded using their primary encoding format.
Throws
IOException | on encoding errors, or if this parameter object has not been initialized. |
---|
public static AlgorithmParameters getInstance (String algorithm)
Returns a parameter object for the specified algorithm.
This method traverses the list of registered security Providers, starting with the most preferred Provider. A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi 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.
The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or
parameter encoding.
Parameters
algorithm | the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names. |
---|
Returns
- the new parameter object.
Throws
NoSuchAlgorithmException | if no Provider supports an AlgorithmParametersSpi implementation for the specified algorithm. |
---|
See Also
public static AlgorithmParameters getInstance (String algorithm, String provider)
Returns a parameter object for the specified algorithm.
A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi 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.
The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or
parameter encoding.
Parameters
algorithm | the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names. |
---|---|
provider | the name of the provider. |
Returns
- the new parameter object.
Throws
NoSuchAlgorithmException | if an AlgorithmParametersSpi implementation for the specified algorithm 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
public static AlgorithmParameters getInstance (String algorithm, Provider provider)
Returns a parameter object for the specified algorithm.
A new AlgorithmParameters object encapsulating the AlgorithmParametersSpi implementation from the specified Provider object is returned. Note that the specified Provider object does not have to be registered in the provider list.
The returned parameter object must be initialized via a call to
init
, using an appropriate parameter specification or
parameter encoding.
Parameters
algorithm | the name of the algorithm requested. See the AlgorithmParameters section in the Java Cryptography Architecture Standard Algorithm Name Documentation for information about standard algorithm names. |
---|---|
provider | the name of the provider. |
Returns
- the new parameter object.
Throws
NoSuchAlgorithmException | if an AlgorithmParameterGeneratorSpi implementation for the specified algorithm is not available from the specified Provider object. |
---|---|
IllegalArgumentException | if the provider is null. |
See Also
public final T getParameterSpec (Class<T> paramSpec)
Returns a (transparent) specification of this parameter object.
paramSpec
identifies the specification class in which
the parameters should be returned. It could, for example, be
DSAParameterSpec.class
, to indicate that the
parameters should be returned in an instance of the
DSAParameterSpec
class.
Parameters
paramSpec | the specification class in which the parameters should be returned. |
---|
Returns
- the parameter specification.
Throws
InvalidParameterSpecException | if the requested parameter specification is inappropriate for this parameter object, or if this parameter object has not been initialized. |
---|
public final Provider getProvider ()
Returns the provider of this parameter object.
Returns
- the provider of this parameter object
public final void init (byte[] params)
Imports the specified parameters and decodes them according to the primary decoding format for parameters. The primary decoding format for parameters is ASN.1, if an ASN.1 specification for this type of parameters exists.
Parameters
params | the encoded parameters. |
---|
Throws
IOException | on decoding errors, or if this parameter object has already been initialized. |
---|
public final void init (AlgorithmParameterSpec paramSpec)
Initializes this parameter object using the parameters
specified in paramSpec
.
Parameters
paramSpec | the parameter specification. |
---|
Throws
InvalidParameterSpecException | if the given parameter specification is inappropriate for the initialization of this parameter object, or if this parameter object has already been initialized. |
---|
public final void init (byte[] params, String format)
Imports the parameters from params
and decodes them
according to the specified decoding scheme.
If format
is null, the
primary decoding format for parameters is used. The primary decoding
format is ASN.1, if an ASN.1 specification for these parameters
exists.
Parameters
params | the encoded parameters. |
---|---|
format | the name of the decoding scheme. |
Throws
IOException | on decoding errors, or if this parameter object has already been initialized. |
---|
public final String toString ()
Returns a formatted string describing the parameters.
Returns
- a formatted string describing the parameters, or null if this parameter object has not been initialized.