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package java.security.spec;

import java.util.Objects;

This class specifies a parameter spec for RSASSA-PSS signature scheme, as defined in the PKCS#1 v2.2 standard.

Its ASN.1 definition in PKCS#1 standard is described below:

RSASSA-PSS-params ::= SEQUENCE {
  hashAlgorithm      [0] HashAlgorithm      DEFAULT sha1,
  maskGenAlgorithm   [1] MaskGenAlgorithm   DEFAULT mgf1SHA1,
  saltLength         [2] INTEGER            DEFAULT 20,
  trailerField       [3] TrailerField       DEFAULT trailerFieldBC(1)
}
where
HashAlgorithm ::= AlgorithmIdentifier {
  {OAEP-PSSDigestAlgorithms}
}
MaskGenAlgorithm ::= AlgorithmIdentifier { {PKCS1MGFAlgorithms} }
TrailerField ::= INTEGER { trailerFieldBC(1) }
OAEP-PSSDigestAlgorithms    ALGORITHM-IDENTIFIER ::= {
  { OID id-sha1       PARAMETERS NULL }|
  { OID id-sha224     PARAMETERS NULL }|
  { OID id-sha256     PARAMETERS NULL }|
  { OID id-sha384     PARAMETERS NULL }|
  { OID id-sha512     PARAMETERS NULL }|
  { OID id-sha512-224 PARAMETERS NULL }|
  { OID id-sha512-256 PARAMETERS NULL },
  ...  -- Allows for future expansion --
}
PKCS1MGFAlgorithms    ALGORITHM-IDENTIFIER ::= {
  { OID id-mgf1 PARAMETERS HashAlgorithm },
  ...  -- 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

Author:Valerie Peng
See Also:
Since:1.4
/** * This class specifies a parameter spec for RSASSA-PSS signature scheme, * as defined in the * <a href="https://tools.ietf.org/rfc/rfc8017.txt">PKCS#1 v2.2</a> standard. * * <p>Its ASN.1 definition in PKCS#1 standard is described below: * <pre> * RSASSA-PSS-params ::= SEQUENCE { * hashAlgorithm [0] HashAlgorithm DEFAULT sha1, * maskGenAlgorithm [1] MaskGenAlgorithm DEFAULT mgf1SHA1, * saltLength [2] INTEGER DEFAULT 20, * trailerField [3] TrailerField DEFAULT trailerFieldBC(1) * } * </pre> * where * <pre> * HashAlgorithm ::= AlgorithmIdentifier { * {OAEP-PSSDigestAlgorithms} * } * MaskGenAlgorithm ::= AlgorithmIdentifier { {PKCS1MGFAlgorithms} } * TrailerField ::= INTEGER { trailerFieldBC(1) } * * OAEP-PSSDigestAlgorithms ALGORITHM-IDENTIFIER ::= { * { OID id-sha1 PARAMETERS NULL }| * { OID id-sha224 PARAMETERS NULL }| * { OID id-sha256 PARAMETERS NULL }| * { OID id-sha384 PARAMETERS NULL }| * { OID id-sha512 PARAMETERS NULL }| * { OID id-sha512-224 PARAMETERS NULL }| * { OID id-sha512-256 PARAMETERS NULL }, * ... -- Allows for future expansion -- * } * PKCS1MGFAlgorithms ALGORITHM-IDENTIFIER ::= { * { OID id-mgf1 PARAMETERS HashAlgorithm }, * ... -- Allows for future expansion -- * } * </pre> * <p>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 final String mdName; private final String mgfName; private final AlgorithmParameterSpec mgfSpec; private final int saltLen; private final int trailerField;
The TrailerFieldBC constant as defined in PKCS#1
Since:11
/** * The {@code TrailerFieldBC} constant as defined in PKCS#1 * * @since 11 */
public static final int TRAILER_FIELD_BC = 1;
The PSS parameter set with all default values
Since:1.5
/** * The PSS parameter set with all default values * * @since 1.5 */
public static final PSSParameterSpec DEFAULT = new PSSParameterSpec ("SHA-1", "MGF1", MGF1ParameterSpec.SHA1, 20, TRAILER_FIELD_BC); // disallowed private PSSParameterSpec() { throw new RuntimeException("default constructor not allowed"); }
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.
Params:
  • mdName – the algorithm name of the hash function
  • mgfName – the algorithm name of the mask generation function
  • mgfSpec – the parameters for the mask generation function. If null is specified, null will be returned by getMGFParameters().
  • saltLen – the length of salt
  • trailerField – the value of the trailer field
Throws:
Since:1.5
/** * Creates a new {@code 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 {@code mdName}, or {@code mgfName} * is null * @exception IllegalArgumentException if {@code saltLen} or * {@code trailerField} is less than 0 * @since 1.5 */
public PSSParameterSpec(String mdName, String mgfName, AlgorithmParameterSpec mgfSpec, int saltLen, int trailerField) { Objects.requireNonNull(mdName, "digest algorithm is null"); Objects.requireNonNull(mgfName, "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.
Params:
  • saltLen – the length of salt in bytes to be used in PKCS#1 PSS encoding
Throws:
/** * Creates a new {@code PSSParameterSpec} * using the specified salt length and other default values as * defined in PKCS#1. * * @param saltLen the length of salt in bytes to be used in PKCS#1 * PSS encoding * @exception IllegalArgumentException if {@code saltLen} is * less than 0 */
public PSSParameterSpec(int saltLen) { this("SHA-1", "MGF1", MGF1ParameterSpec.SHA1, saltLen, TRAILER_FIELD_BC); }
Returns the message digest algorithm name.
Returns:the message digest algorithm name
Since:1.5
/** * 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.
Returns:the mask generation function algorithm name
Since:1.5
/** * 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.
Returns:the parameters for the mask generation function
Since:1.5
/** * 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 bytes.
Returns:the salt length
/** * Returns the salt length in bytes. * * @return the salt length */
public int getSaltLength() { return saltLen; }
Returns the value for the trailer field.
Returns:the value for the trailer field
Since:1.5
/** * Returns the value for the trailer field. * * @return the value for the trailer field * @since 1.5 */
public int getTrailerField() { return trailerField; } @Override public String toString() { StringBuilder sb = new StringBuilder(); sb.append("MD: " + mdName + "\n") .append("MGF: " + mgfSpec + "\n") .append("SaltLength: " + saltLen + "\n") .append("TrailerField: " + trailerField + "\n"); return sb.toString(); } }