iaik.pkcs.pkcs1

Class MGF1Parameters

java.lang.Object

java.security.AlgorithmParametersSpi

iaik.pkcs.pkcs1.PKCS1AlgorithmParameters

iaik.pkcs.pkcs1.MGF1Parameters

public class MGF1Parameters
extends PKCS1AlgorithmParameters

Algorithm parameters for the PKCS#1v2.1 MGF1 mask generation function.

According to PKCS#1v2.1 the only parameter used by MGF1 is the algorithm id of the hash algorithm (default SHA-1) to be used:

 mgf1SHA1 MaskGenAlgorithm ::= {
   algorithm id-mgf1,
   parameters HashAlgorithm : sha1
 }
 

MGF1Parameters can be generated provider independently by calling one of the AlgorithmParameters.getInstance methods. Subsequently the new AlgorithmParameters object must be initialized with a proper MGF1 parameter specification or a DER encoded byte array, e.g.:

 MGF1ParameterSpec paramSpec = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("MGF1", "IAIK");
 params.init(paramSpec);
 

respectively:

 byte[] encodedParams = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("MGF1", "IAIK");
 params.init(encodedParams);
 

For obtaining MGF1 parameters in transparent representation from an opaque MGF1Parameters object, the getParameterSpec method can be used; for obtaining the parameters as DER encoded ASN.1 object, use getEncoded:

 MGF1ParameterSpec paramSpec = (MGF1ParameterSpec) params
     .getParameterSpec(MGF1ParameterSpec.class);
 

respectively

 byte[] encodedParams = params.getEncoded();
 

Version:

File Revision 8

See Also:

MGF1ParameterSpec, AlgorithmParameters

Constructor Summary

Constructors

Constructor and Description
MGF1Parameters() Default constructor.

Method Summary

Methods

Modifier and Type	Method and Description
void	decode(ASN1Object asn1Params) Initializes this MGF1Parameters object from the given ASN1Object.
protected byte[]	engineGetEncoded() Returns the parameters as DER byte array.
protected byte[]	engineGetEncoded(java.lang.String format) Returns the parameters as a DER byte array.
protected java.security.spec.AlgorithmParameterSpec	engineGetParameterSpec(java.lang.Class paramSpec) Returns the MGF1 parameters as transparent parameter specification of the given class type.
protected void	engineInit(java.security.spec.AlgorithmParameterSpec paramSpec) Initializes this MGF1Parameters from the given MGF1ParameterSpec.
protected void	engineInit(byte[] params) Initializes this MGF1Parameters object from the given DER encoded byte array.
protected void	engineInit(byte[] params, java.lang.String format) Inits the parameters from an DER encoded byte array.
protected java.lang.String	engineToString() Returns a String representation of this object.
ASN1Object	toASN1Object() Gets an ASN.1 representation of this MGF1 parameters.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

MGF1Parameters

public MGF1Parameters()

Default constructor. Only internally used for creating a MGF1Parameters object. Applications shall use one of the AlgorithmParameters.getInstance factory methods for obtaining MGF1Parameters.

Method Detail

engineGetEncoded

protected byte[] engineGetEncoded()
                           throws java.io.IOException

Returns the parameters as DER byte array.

Specified by:

engineGetEncoded in class java.security.AlgorithmParametersSpi

Returns:

the DER encoded hash algorithm id

Throws:

java.io.IOException - if an encoding error occurs

engineGetEncoded

protected byte[] engineGetEncoded(java.lang.String format)
                           throws java.io.IOException

Returns the parameters as a DER byte array.

Format is ignored. Only DER encoding is supported at this time. This method only calls engineGetEncoded(), regardless of what is specified in the format string.

Specified by:

engineGetEncoded in class java.security.AlgorithmParametersSpi

Parameters:

format - the encoding format; ignored

Returns:

the DER encoded hash algorithm id

Throws:

java.io.IOException - if an encoding error occurs

toASN1Object

public ASN1Object toASN1Object()

Gets an ASN.1 representation of this MGF1 parameters.

Returns:

the MGF1 parameter (hash algorithm id) as ASN1Object

engineGetParameterSpec

protected java.security.spec.AlgorithmParameterSpec engineGetParameterSpec(java.lang.Class paramSpec)
                                                                    throws java.security.spec.InvalidParameterSpecException

Returns the MGF1 parameters as transparent parameter specification of the given class type.

Specified by:

engineGetParameterSpec in class java.security.AlgorithmParametersSpi

Parameters:

paramSpec - the desired parameter specification class (MGF1ParameterSpec)

Returns:

the parameters as MGF1ParameterSpec

Throws:

java.security.spec.InvalidParameterSpecException - if the parameters cannot be converted to the desired parameter specification

engineInit

protected void engineInit(java.security.spec.AlgorithmParameterSpec paramSpec)
                   throws java.security.spec.InvalidParameterSpecException

Initializes this MGF1Parameters from the given MGF1ParameterSpec.

Overrides:

engineInit in class PKCS1AlgorithmParameters

Parameters:

paramSpec - the parameter specification, which has to be a MGF1ParameterSpec

Throws:

java.security.spec.InvalidParameterSpecException - if the given parameter specification is not a or is an invalid MGF1ParameterSpec

engineInit

protected void engineInit(byte[] params)
                   throws java.io.IOException

Initializes this MGF1Parameters object from the given DER encoded byte array.

Overrides:

engineInit in class PKCS1AlgorithmParameters

Parameters:

params - the DER encoded byte array

Throws:

java.io.IOException - if an error occurs when decoding the given byte array

decode

public void decode(ASN1Object asn1Params)
            throws CodingException

Initializes this MGF1Parameters object from the given ASN1Object.

Parameters:

asn1Params - the MGF1 parameters in ASN.1 representation

Throws:

CodingException - if an error occurs when parsing the parameters

engineInit

protected void engineInit(byte[] params,
              java.lang.String format)
                   throws java.io.IOException

Inits the parameters from an DER encoded byte array. Format is ignored. Only calls {engineInit(params) for initializing this MGF1Parameters object from the given DER encoded byte array, regardless of what is specified in the format string.

Specified by:

engineInit in class java.security.AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

format - the encoding format; ignored

Throws:

java.io.IOException - if an error occurs when decoding the given byte array

engineToString

protected java.lang.String engineToString()

Returns a String representation of this object.

Specified by:

engineToString in class java.security.AlgorithmParametersSpi

Returns:

a String representation this object