iaik.pkcs.pkcs1
Class RSAPssParameters

java.lang.Object
  |
  +--java.security.AlgorithmParametersSpi
        |
        +--iaik.pkcs.pkcs1.PKCS1AlgorithmParameters
              |
              +--iaik.pkcs.pkcs1.RSAPssParameters

public class RSAPssParameters

extends PKCS1AlgorithmParameters

Algorithm parameters for the PKCS#1 RSASSA-PSS signature scheme.

PKCS#1v2.1 defines the following parameters for the PSS signature scheme:

 RSASSA-PSS-params :: = SEQUENCE {
      hashAlgorithm            [0] HashAlgorithm     DEFAULT sha1,
      maskGenerationAlgorithm  [1] MaskGenAlgorithm  DEFAULT mgf1SHA1,
      saltLength               [2] INTEGER           DEFAULT 20,
      trailerField             [3] TrailerField      DEFAULT trailerFieldBC
 }

 HashAlgorithm ::= AlgorithmIdentifer { {OAEP-PSSDigestAlgorithms} }

 MaskGenAlgorithm ::= AlgorithmIdentifier { {PKCS1MGFAlgorithms} }

 TrailerField ::= INTEGER { trailerFieldBC(1) }
 

By default PSS uses SHA-1 as hash function, MGF1 (with SHA-1 as hash function parameter) as mask generation algorithm, 20 as salt length, and 1 as trailer field indicating a trailer value of 0xBC.

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

 RSAPssParameterSpec pssParamSpec = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("RSASSA-PSS", "IAIK");
 params.init(pssParamSpec);
 

repectively:

 byte[] encodedPssParams = ...;
 AlgorithmParameters params = AlgorithmParameters.getInstance("RSASSA-PSS", "IAIK");
 params.init(encodedPssParams);
 

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

 RSAPssParameterSpec pssParamSpec = (RSAPssParameterSpec)params.getParameterSpec(RSAPssParameterSpec.class);
 

repectively

 byte[] encodedPssParams = params.getEncoded();
 

Version:

File Revision 15

See Also:

RSAPssParameterSpec, AlgorithmParameters

Constructor Summary

RSAPssParameters()
The default constructor.

Method Summary

void	decode(ASN1Object asn1Params) Initializes this RSAPssParameters object from the given ASN1Object.
protected byte[]	engineGetEncoded() Returns the parameters as DER byte array.
protected byte[]	engineGetEncoded(String format) Returns the parameters as a DER byte array.
protected AlgorithmParameterSpec	engineGetParameterSpec(Class paramSpec) Returns the RSA-PSS parameters as transparent parameter specification of the given class type.
protected void	engineInit(AlgorithmParameterSpec paramSpec) Initializes this RSAPssParameters from the given RSAPssParameterSpec.
protected void	engineInit(byte[] params) Initializes this RSAPssParameters object from the given DER encoded byte array.
protected void	engineInit(byte[] params, String format) Inits the parameters from an DER encoded byte array.
protected String	engineToString() Returns a String representation of this object.
ASN1Object	toASN1Object() Gets an ASN.1 representation of this RSA PSS parameters.

Methods inherited from class java.lang.Object

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

Constructor Detail

RSAPssParameters

public RSAPssParameters()

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

Method Detail

engineGetEncoded

protected byte[] engineGetEncoded()
                           throws IOException

Returns the parameters as DER byte array.

Overrides:

engineGetEncoded in class AlgorithmParametersSpi

Returns:

the DER encoded parameters

Throws:

IOException - if an encoding error occurs

engineGetEncoded

protected byte[] engineGetEncoded(String format)
                           throws IOException

Returns the parameters as a DER byte array.

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

Overrides:

engineGetEncoded in class AlgorithmParametersSpi

Parameters:

format - the encoding format; ignored

Returns:

the DER encoded parameters

Throws:

IOException - if an encoding error occurs

toASN1Object

public ASN1Object toASN1Object()

Gets an ASN.1 representation of this RSA PSS parameters.

Returns:

this RSA PSS parameters as ASN1Objet

engineGetParameterSpec

protected AlgorithmParameterSpec engineGetParameterSpec(Class paramSpec)
                                                 throws InvalidParameterSpecException

Returns the RSA-PSS parameters as transparent parameter specification of the given class type.

Overrides:

engineGetParameterSpec in class AlgorithmParametersSpi

Parameters:

paramSpec - the desired parameter specification class (RSAPssParameterSpec)

Returns:

the parameters as RSAPssParameterSpec

Throws:

InvalidParameterSpecException - if the paramters cannot be converted to the desired parameter specification

engineInit

protected void engineInit(AlgorithmParameterSpec paramSpec)
                   throws InvalidParameterSpecException

Initializes this RSAPssParameters from the given RSAPssParameterSpec.

Overrides:

engineInit in class AlgorithmParametersSpi

Parameters:

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

Throws:

InvalidParameterSpecException - if the given parameter specification is not a or is an invalid RSAPssParameterSpec

engineInit

protected void engineInit(byte[] params)
                   throws IOException

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

Overrides:

engineInit in class AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

Throws:

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

decode

public void decode(ASN1Object asn1Params)
            throws CodingException

Initializes this RSAPssParameters object from the given ASN1Object.

Parameters:

params - the PSS parameters in ASN.1 representation

Throws:

CodingException - if an error occurs when parsing the parameters

engineInit

protected void engineInit(byte[] params,
                          String format)
                   throws IOException

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

Overrides:

engineInit in class AlgorithmParametersSpi

Parameters:

params - the DER encoded byte array

format - the encoding format; ignored

Throws:

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

engineToString

protected String engineToString()

Returns a String representation of this object.

Overrides:

engineToString in class AlgorithmParametersSpi

Returns:

a String representation this object