iaik.pkcs.pkcs1
Class RSAPssParameterSpec

java.lang.Object
  |
  +--iaik.pkcs.pkcs1.PKCS1AlgorithmParameterSpec
        |
        +--iaik.pkcs.pkcs1.RSAPssSaltParameterSpec
              |
              +--iaik.pkcs.pkcs1.RSAPssParameterSpec

All Implemented Interfaces:

AlgorithmParameterSpec, Cloneable

public class RSAPssParameterSpec

extends RSAPssSaltParameterSpec

implements Cloneable

Algorithm parameter specification 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.

Hash algorithm, mask generation function, and salt length value have to be supplied when creating a creating a RSAPssParameterSpec object. Trailer field, may be set later. Optionally also hash engine and MGF engine may be set by the application, e.g.:

 // hash and mgf algorithm ids
 AlgorithmID hashID = (AlgorithmID)AlgorithmID.sha1.clone();
 AlgorithmID mgfID = (AlgorithmID)AlgorithmID.mgf1.clone();
 mgfID.setParameter(hashID.toASN1Object());
 // hash and mgf engines
 MessageDigest hashEngine = hashID.getMessageDigestInstance();
 MaskGenerationAlgorithm mgfEngine = mfgID.getMaskGenerationAlgorithmInstance();
 MGF1ParameterSpec mgf1ParamSpec = new MGF1ParameterSpec(hashID);
 mgf1ParamSpec.setHashEngine(hashEngine);
 mgfEngine.setParameters(mgf1ParamSpec);
 // salt length
 int saltLength = 20;
 // create the RSAPssParameterSpec
 RSAPssParameterSpec pssParamSpec = new RSAPssParameterSpec(hashID, mgfID, saltLength);
 // set engines
 pssParamSpec.setHashEngine(hashEngine);
 pssParamSpec.setMGFEngine(mgfEngine);
 

Version:

File Revision 16

See Also:

RSAPssParameters, MaskGenerationAlgorithm, MGF1, MGF1ParameterSpec, AlgorithmID, RSAPssSignature

Field Summary

static AlgorithmID	DEFAULT_HASH_ALGORITHM Default hash algorithm (SHA-1).
static AlgorithmID	DEFAULT_MASK_GEN_ALGORITHM Default mask generation algorithm (MGF1 with SHA1 as hash algorithm)
static int	DEFAULT_TRAILER_FIELD Default trailer field number (1 indicating a trailer field byte of 0xBC).

Fields inherited from class iaik.pkcs.pkcs1.RSAPssSaltParameterSpec

DEFAULT_SALT_LENGTH, saltLength_

Constructor Summary

RSAPssParameterSpec()
Creates default RSASSA-PSS parameters.

RSAPssParameterSpec(AlgorithmID hashAlgorithm, AlgorithmID maskGenAlgorithm, int saltLength)
Creates a RSAPssParameterSpec for the given hash algorithm, mask generation function, salt length.

Method Summary

Object	clone() Returns a clone of this Object.
AlgorithmID	getHashAlgorithm() Returns the hash algorihtm.
MessageDigest	getHashEngine() Gets the JCA MessageDigest engine used for data hashing.
AlgorithmID	getMaskGenAlgorithm() Gets the mask generation algorithm.
MaskGenerationAlgorithm	getMGFEngine() Gets the MaskGenerationAlgorithm engine.
int	getTrailerField() Gets the trailer field.
void	setHashEngine(MessageDigest hashEngine) Sets the JCA MessageDigest engine to be used for data hashing.
void	setMGFEngine(MaskGenerationAlgorithm mgfEngine) Sets the MaskGenerationAlgorithm engine to be used.
void	setTrailerField(int trailerField) Sets the trailer field.
String	toString() Returns a string representation of this RSAPssParameterSpec.

Methods inherited from class iaik.pkcs.pkcs1.RSAPssSaltParameterSpec

getSaltLength

Methods inherited from class iaik.pkcs.pkcs1.PKCS1AlgorithmParameterSpec

getSecureRandom, setSecureRandom

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_HASH_ALGORITHM

public static final AlgorithmID DEFAULT_HASH_ALGORITHM

Default hash algorithm (SHA-1).

DEFAULT_MASK_GEN_ALGORITHM

public static final AlgorithmID DEFAULT_MASK_GEN_ALGORITHM

Default mask generation algorithm (MGF1 with SHA1 as hash algorithm)

DEFAULT_TRAILER_FIELD

public static final int DEFAULT_TRAILER_FIELD

Default trailer field number (1 indicating a trailer field byte of 0xBC).

Constructor Detail

RSAPssParameterSpec

public RSAPssParameterSpec()

Creates default RSASSA-PSS parameters.

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, see (see PKCS#1v2.1:

 rsaSSA-PSS-Default-Identifier    RSASSA-AlgorithmIdentifier ::= {
   algorithm   id-RSASSA-PSS,
   parameters  RSASSA-PSS-params : {
      hashAlgorithm            sha1,
      maskGenerationAlgorithm  mgf1SHA1,
      saltLength               20,
      trailerField             trailerFieldBC
   }
 }

 TrailerField ::= INTEGER { trailerFieldBC(1) }
 

RSAPssParameterSpec

public RSAPssParameterSpec(AlgorithmID hashAlgorithm,
                           AlgorithmID maskGenAlgorithm,
                           int saltLength)

Creates a RSAPssParameterSpec for the given hash algorithm, mask generation function, salt length.

Parameters:

hashAlgorithm - the hash algorithm to be used

Throws:

IllegalArgumentException - if saltLength < 0, or hashAlgorithm or maskGenAlgorithm are null

Method Detail

setTrailerField

public void setTrailerField(int trailerField)

Sets the trailer field.

Parameters:

trailerField - the trailer field number as used for the parameter encoding

getTrailerField

public int getTrailerField()

Gets the trailer field.

Returns:

the trailer field (as used for the parameter encoding)

getHashAlgorithm

public AlgorithmID getHashAlgorithm()

Returns the hash algorihtm.

Returns:

the hash algorithm

getMaskGenAlgorithm

public AlgorithmID getMaskGenAlgorithm()

Gets the mask generation algorithm.

Returns:

the mask generation algorithm

setHashEngine

public void setHashEngine(MessageDigest hashEngine)

Sets the JCA MessageDigest engine to be used for data hashing.

This method may be used to set a JCA MessageDigest engine to be used for doing the any required hashing operations. If not set by this method, getHashEngine will try to create a MessageDigest engine from the hash algorithm id.

Parameters:

hashEngine - the JCA MessageDigest engine to be used

getHashEngine

public MessageDigest getHashEngine()
                            throws NoSuchAlgorithmException

Gets the JCA MessageDigest engine used for data hashing.

If method setHashEngine has been used to set a MessageDigest engine, this engine is returned; otherwise it is tried to create a MessageDigest engine from the hash algorithm id.

Returns:

the MessageDigest engine to be used

setMGFEngine

public void setMGFEngine(MaskGenerationAlgorithm mgfEngine)

Sets the MaskGenerationAlgorithm engine to be used.

This method may be used to set a MaskGenerationAlgorithm engine. If not set by this method, getMGFEngine will try to create a MaskGenerationAlgorithm engine from the mask generation algorithm id.

Parameters:

mgfEngine - the MaskGenerationAlgorithm engine to be used

getMGFEngine

public MaskGenerationAlgorithm getMGFEngine()
                                     throws NoSuchAlgorithmException

Gets the MaskGenerationAlgorithm engine.

If method setMGFEngine has been used to set a MGF engine, this engine is returned; otherwise it is tried to create a MGF engine from the Mask generation algorithm id.

Returns:

the MGF engine to be used

clone

public Object clone()

Returns a clone of this Object.

Overrides:

clone in class Object

Returns:

a clone of this Object

toString

public String toString()

Returns a string representation of this RSAPssParameterSpec.

Overrides:

toString in class RSAPssSaltParameterSpec

Returns:

a string representation