Its ASN.1 definition in PKCS#1 standard is described below: *
* RSASSA-PSS-params ::= SEQUENCE {
* hashAlgorithm [0] OAEP-PSSDigestAlgorithms DEFAULT sha1,
* maskGenAlgorithm [1] PKCS1MGFAlgorithms DEFAULT mgf1SHA1,
* saltLength [2] INTEGER DEFAULT 20,
* trailerField [3] INTEGER DEFAULT 1
* }
*
* where
*
* OAEP-PSSDigestAlgorithms ALGORITHM-IDENTIFIER ::= {
* { OID id-sha1 PARAMETERS NULL }|
* { OID id-sha256 PARAMETERS NULL }|
* { OID id-sha384 PARAMETERS NULL }|
* { OID id-sha512 PARAMETERS NULL },
* ... -- Allows for future expansion --
* }
*
* PKCS1MGFAlgorithms ALGORITHM-IDENTIFIER ::= {
* { OID id-mgf1 PARAMETERS OAEP-PSSDigestAlgorithms },
* ... -- Allows for future expansion --
* }
*
* Note: the PSSParameterSpec.DEFAULT uses the following:
* message digest -- "SHA-1"
* mask generation function (mgf) -- "MGF1"
* parameters for mgf -- MGF1ParameterSpec.SHA1
* SaltLength -- 20
* TrailerField -- 1
*
* @see MGF1ParameterSpec
* @see AlgorithmParameterSpec
* @see java.security.Signature
*
* @author Valerie Peng
*
*
* @since 1.4
*/
public class PSSParameterSpec implements AlgorithmParameterSpec {
private String mdName = "SHA-1";
private String mgfName = "MGF1";
private AlgorithmParameterSpec mgfSpec = MGF1ParameterSpec.SHA1;
private int saltLen = 20;
private int trailerField = 1;
/**
* The PSS parameter set with all default values.
* @since 1.5
*/
public static final PSSParameterSpec DEFAULT = new PSSParameterSpec();
/**
* Constructs a new PSSParameterSpec as defined in
* the PKCS #1 standard using the default values.
*/
private PSSParameterSpec() {
}
/**
* Creates a new PSSParameterSpec as defined in
* the PKCS #1 standard using the specified message digest,
* mask generation function, parameters for mask generation
* function, salt length, and trailer field values.
*
* @param mdName the algorithm name of the hash function.
* @param mgfName the algorithm name of the mask generation
* function.
* @param mgfSpec the parameters for the mask generation
* function. If null is specified, null will be returned by
* getMGFParameters().
* @param saltLen the length of salt.
* @param trailerField the value of the trailer field.
* @exception NullPointerException if mdName,
* or mgfName is null.
* @exception IllegalArgumentException if saltLen
* or trailerField is less than 0.
* @since 1.5
*/
public PSSParameterSpec(String mdName, String mgfName,
AlgorithmParameterSpec mgfSpec,
int saltLen, int trailerField) {
if (mdName == null) {
throw new NullPointerException("digest algorithm is null");
}
if (mgfName == null) {
throw new NullPointerException("mask generation function " +
"algorithm is null");
}
if (saltLen < 0) {
throw new IllegalArgumentException("negative saltLen value: " +
saltLen);
}
if (trailerField < 0) {
throw new IllegalArgumentException("negative trailerField: " +
trailerField);
}
this.mdName = mdName;
this.mgfName = mgfName;
this.mgfSpec = mgfSpec;
this.saltLen = saltLen;
this.trailerField = trailerField;
}
/**
* Creates a new PSSParameterSpec
* using the specified salt length and other default values as
* defined in PKCS#1.
*
* @param saltLen the length of salt in bits to be used in PKCS#1
* PSS encoding.
* @exception IllegalArgumentException if saltLen is
* less than 0.
*/
public PSSParameterSpec(int saltLen) {
if (saltLen < 0) {
throw new IllegalArgumentException("negative saltLen value: " +
saltLen);
}
this.saltLen = saltLen;
}
/**
* Returns the message digest algorithm name.
*
* @return the message digest algorithm name.
* @since 1.5
*/
public String getDigestAlgorithm() {
return mdName;
}
/**
* Returns the mask generation function algorithm name.
*
* @return the mask generation function algorithm name.
*
* @since 1.5
*/
public String getMGFAlgorithm() {
return mgfName;
}
/**
* Returns the parameters for the mask generation function.
*
* @return the parameters for the mask generation function.
* @since 1.5
*/
public AlgorithmParameterSpec getMGFParameters() {
return mgfSpec;
}
/**
* Returns the salt length in bits.
*
* @return the salt length.
*/
public int getSaltLength() {
return saltLen;
}
/**
* Returns the value for the trailer field, i.e. bc in PKCS#1 v2.1.
*
* @return the value for the trailer field, i.e. bc in PKCS#1 v2.1.
* @since 1.5
*/
public int getTrailerField() {
return trailerField;
}
}