src/java.base/share/classes/sun/security/rsa/RSAPSSSignature.java - platform/libcore - Git at Google

 /*
  * Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
  * under the terms of the GNU General Public License version 2 only, as
  * published by the Free Software Foundation.  Oracle designates this
  * particular file as subject to the "Classpath" exception as provided
  * by Oracle in the LICENSE file that accompanied this code.
  *
  * This code is distributed in the hope that it will be useful, but WITHOUT
  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  * version 2 for more details (a copy is included in the LICENSE file that
  * accompanied this code).
  *
  * You should have received a copy of the GNU General Public License version
  * 2 along with this work; if not, write to the Free Software Foundation,
  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  *
  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  * or visit www.oracle.com if you need additional information or have any
  * questions.
  */

 package sun.security.rsa;

 import java.io.IOException;
 import java.nio.ByteBuffer;

 import java.security.*;
 import java.security.spec.AlgorithmParameterSpec;
 import java.security.spec.PSSParameterSpec;
 import java.security.spec.MGF1ParameterSpec;
 import java.security.interfaces.*;

 import java.util.Arrays;
 import java.util.Hashtable;

 import sun.security.util.*;
 import sun.security.jca.JCAUtil;


 /**
  * PKCS#1 v2.2 RSASSA-PSS signatures with various message digest algorithms.
  * RSASSA-PSS implementation takes the message digest algorithm, MGF algorithm,
  * and salt length values through the required signature PSS parameters.
  * We support SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and
  * SHA-512/256 message digest algorithms and MGF1 mask generation function.
  *
  * @since   11
  */
 public class RSAPSSSignature extends SignatureSpi {

     private static final boolean DEBUG = false;

     // utility method for comparing digest algorithms
     // NOTE that first argument is assumed to be standard digest name
     private boolean isDigestEqual(String stdAlg, String givenAlg) {
         if (stdAlg == null || givenAlg == null) return false;

         if (givenAlg.indexOf("-") != -1) {
             return stdAlg.equalsIgnoreCase(givenAlg);
         } else {
             if (stdAlg.equals("SHA-1")) {
                 return (givenAlg.equalsIgnoreCase("SHA")
                         || givenAlg.equalsIgnoreCase("SHA1"));
             } else {
                 StringBuilder sb = new StringBuilder(givenAlg);
                 // case-insensitive check
                 if (givenAlg.regionMatches(true, 0, "SHA", 0, 3)) {
                     givenAlg = sb.insert(3, "-").toString();
                     return stdAlg.equalsIgnoreCase(givenAlg);
                 } else {
                     throw new ProviderException("Unsupported digest algorithm "
                             + givenAlg);
                 }
             }
         }
     }

     private static final byte[] EIGHT_BYTES_OF_ZEROS = new byte[8];

     private static final Hashtable<String, Integer> DIGEST_LENGTHS =
         new Hashtable<String, Integer>();
     static {
         DIGEST_LENGTHS.put("SHA-1", 20);
         DIGEST_LENGTHS.put("SHA", 20);
         DIGEST_LENGTHS.put("SHA1", 20);
         DIGEST_LENGTHS.put("SHA-224", 28);
         DIGEST_LENGTHS.put("SHA224", 28);
         DIGEST_LENGTHS.put("SHA-256", 32);
         DIGEST_LENGTHS.put("SHA256", 32);
         DIGEST_LENGTHS.put("SHA-384", 48);
         DIGEST_LENGTHS.put("SHA384", 48);
         DIGEST_LENGTHS.put("SHA-512", 64);
         DIGEST_LENGTHS.put("SHA512", 64);
         DIGEST_LENGTHS.put("SHA-512/224", 28);
         DIGEST_LENGTHS.put("SHA512/224", 28);
         DIGEST_LENGTHS.put("SHA-512/256", 32);
         DIGEST_LENGTHS.put("SHA512/256", 32);
     }

     // message digest implementation we use for hashing the data
     private MessageDigest md;
     // flag indicating whether the digest is reset
     private boolean digestReset = true;

     // private key, if initialized for signing
     private RSAPrivateKey privKey = null;
     // public key, if initialized for verifying
     private RSAPublicKey pubKey = null;
     // PSS parameters from signatures and keys respectively
     private PSSParameterSpec sigParams = null; // required for PSS signatures

     // PRNG used to generate salt bytes if none given
     private SecureRandom random;

     /**
      * Construct a new RSAPSSSignatur with arbitrary digest algorithm
      */
     public RSAPSSSignature() {
         this.md = null;
     }

     // initialize for verification. See JCA doc
     @Override
     protected void engineInitVerify(PublicKey publicKey)
             throws InvalidKeyException {
         if (!(publicKey instanceof RSAPublicKey)) {
             throw new InvalidKeyException("key must be RSAPublicKey");
         }
         this.pubKey = (RSAPublicKey) isValid((RSAKey)publicKey);
         this.privKey = null;
         resetDigest();
     }

     // initialize for signing. See JCA doc
     @Override
     protected void engineInitSign(PrivateKey privateKey)
             throws InvalidKeyException {
         engineInitSign(privateKey, null);
     }

     // initialize for signing. See JCA doc
     @Override
     protected void engineInitSign(PrivateKey privateKey, SecureRandom random)
             throws InvalidKeyException {
         if (!(privateKey instanceof RSAPrivateKey)) {
             throw new InvalidKeyException("key must be RSAPrivateKey");
         }
         this.privKey = (RSAPrivateKey) isValid((RSAKey)privateKey);
         this.pubKey = null;
         this.random =
             (random == null? JCAUtil.getSecureRandom() : random);
         resetDigest();
     }

     /**
      * Utility method for checking the key PSS parameters against signature
      * PSS parameters.
      * Returns false if any of the digest/MGF algorithms and trailerField
      * values does not match or if the salt length in key parameters is
      * larger than the value in signature parameters.
      */
     private static boolean isCompatible(AlgorithmParameterSpec keyParams,
             PSSParameterSpec sigParams) {
         if (keyParams == null) {
             // key with null PSS parameters means no restriction
             return true;
         }
         if (!(keyParams instanceof PSSParameterSpec)) {
             return false;
         }
         // nothing to compare yet, defer the check to when sigParams is set
         if (sigParams == null) {
             return true;
         }
         PSSParameterSpec pssKeyParams = (PSSParameterSpec) keyParams;
         // first check the salt length requirement
         if (pssKeyParams.getSaltLength() > sigParams.getSaltLength()) {
             return false;
         }

         // compare equality of the rest of fields based on DER encoding
         PSSParameterSpec keyParams2 =
             new PSSParameterSpec(pssKeyParams.getDigestAlgorithm(),
                     pssKeyParams.getMGFAlgorithm(),
                     pssKeyParams.getMGFParameters(),
                     sigParams.getSaltLength(),
                     pssKeyParams.getTrailerField());
         PSSParameters ap = new PSSParameters();
         // skip the JCA overhead
         try {
             ap.engineInit(keyParams2);
             byte[] encoded = ap.engineGetEncoded();
             ap.engineInit(sigParams);
             byte[] encoded2 = ap.engineGetEncoded();
             return Arrays.equals(encoded, encoded2);
         } catch (Exception e) {
             if (DEBUG) {
                 e.printStackTrace();
             }
             return false;
         }
     }

     /**
      * Validate the specified RSAKey and its associated parameters against
      * internal signature parameters.
      */
     private RSAKey isValid(RSAKey rsaKey) throws InvalidKeyException {
         try {
             AlgorithmParameterSpec keyParams = rsaKey.getParams();
             // validate key parameters
             if (!isCompatible(rsaKey.getParams(), this.sigParams)) {
                 throw new InvalidKeyException
                     ("Key contains incompatible PSS parameter values");
             }
             // validate key length
             if (this.sigParams != null) {
                 Integer hLen =
                     DIGEST_LENGTHS.get(this.sigParams.getDigestAlgorithm());
                 if (hLen == null) {
                     throw new ProviderException("Unsupported digest algo: " +
                         this.sigParams.getDigestAlgorithm());
                 }
                 checkKeyLength(rsaKey, hLen, this.sigParams.getSaltLength());
             }
             return rsaKey;
         } catch (SignatureException e) {
             throw new InvalidKeyException(e);
         }
     }

     /**
      * Validate the specified Signature PSS parameters.
      */
     private PSSParameterSpec validateSigParams(AlgorithmParameterSpec p)
             throws InvalidAlgorithmParameterException {
         if (p == null) {
             throw new InvalidAlgorithmParameterException
                 ("Parameters cannot be null");
         }
         if (!(p instanceof PSSParameterSpec)) {
             throw new InvalidAlgorithmParameterException
                 ("parameters must be type PSSParameterSpec");
         }
         // no need to validate again if same as current signature parameters
         PSSParameterSpec params = (PSSParameterSpec) p;
         if (params == this.sigParams) return params;

         RSAKey key = (this.privKey == null? this.pubKey : this.privKey);
         // check against keyParams if set
         if (key != null) {
             if (!isCompatible(key.getParams(), params)) {
                 throw new InvalidAlgorithmParameterException
                     ("Signature parameters does not match key parameters");
             }
         }
         // now sanity check the parameter values
         if (!(params.getMGFAlgorithm().equalsIgnoreCase("MGF1"))) {
             throw new InvalidAlgorithmParameterException("Only supports MGF1");

         }
         if (params.getTrailerField() != PSSParameterSpec.TRAILER_FIELD_BC) {
             throw new InvalidAlgorithmParameterException
                 ("Only supports TrailerFieldBC(1)");

         }
         String digestAlgo = params.getDigestAlgorithm();
         // check key length again
         if (key != null) {
             try {
                 int hLen = DIGEST_LENGTHS.get(digestAlgo);
                 checkKeyLength(key, hLen, params.getSaltLength());
             } catch (SignatureException e) {
                 throw new InvalidAlgorithmParameterException(e);
             }
         }
         return params;
     }

     /**
      * Ensure the object is initialized with key and parameters and
      * reset digest
      */
     private void ensureInit() throws SignatureException {
         RSAKey key = (this.privKey == null? this.pubKey : this.privKey);
         if (key == null) {
             throw new SignatureException("Missing key");
         }
         if (this.sigParams == null) {
             // Parameters are required for signature verification
             throw new SignatureException
                 ("Parameters required for RSASSA-PSS signatures");
         }
     }

     /**
      * Utility method for checking key length against digest length and
      * salt length
      */
     private static void checkKeyLength(RSAKey key, int digestLen,
             int saltLen) throws SignatureException {
         if (key != null) {
             int keyLength = (getKeyLengthInBits(key) + 7) >> 3;
             int minLength = Math.addExact(Math.addExact(digestLen, saltLen), 2);
             if (keyLength < minLength) {
                 throw new SignatureException
                     ("Key is too short, need min " + minLength + " bytes");
             }
         }
     }

     /**
      * Reset the message digest if it is not already reset.
      */
     private void resetDigest() {
         if (digestReset == false) {
             this.md.reset();
             digestReset = true;
         }
     }

     /**
      * Return the message digest value.
      */
     private byte[] getDigestValue() {
         digestReset = true;
         return this.md.digest();
     }

     // update the signature with the plaintext data. See JCA doc
     @Override
     protected void engineUpdate(byte b) throws SignatureException {
         ensureInit();
         this.md.update(b);
         digestReset = false;
     }

     // update the signature with the plaintext data. See JCA doc
     @Override
     protected void engineUpdate(byte[] b, int off, int len)
             throws SignatureException {
         ensureInit();
         this.md.update(b, off, len);
         digestReset = false;
     }

     // update the signature with the plaintext data. See JCA doc
     @Override
     protected void engineUpdate(ByteBuffer b) {
         try {
             ensureInit();
         } catch (SignatureException se) {
             // hack for working around API bug
             throw new RuntimeException(se.getMessage());
         }
         this.md.update(b);
         digestReset = false;
     }

     // sign the data and return the signature. See JCA doc
     @Override
     protected byte[] engineSign() throws SignatureException {
         ensureInit();
         byte[] mHash = getDigestValue();
         try {
             byte[] encoded = encodeSignature(mHash);
             byte[] encrypted = RSACore.rsa(encoded, privKey, true);
             return encrypted;
         } catch (GeneralSecurityException e) {
             throw new SignatureException("Could not sign data", e);
         } catch (IOException e) {
             throw new SignatureException("Could not encode data", e);
         }
     }

     // verify the data and return the result. See JCA doc
     // should be reset to the state after engineInitVerify call.
     @Override
     protected boolean engineVerify(byte[] sigBytes) throws SignatureException {
         ensureInit();
         try {
             if (sigBytes.length != RSACore.getByteLength(this.pubKey)) {
                 throw new SignatureException
                     ("Signature length not correct: got "
                     + sigBytes.length + " but was expecting "
                     + RSACore.getByteLength(this.pubKey));
             }
             byte[] mHash = getDigestValue();
             byte[] decrypted = RSACore.rsa(sigBytes, this.pubKey);
             return decodeSignature(mHash, decrypted);
         } catch (javax.crypto.BadPaddingException e) {
             // occurs if the app has used the wrong RSA public key
             // or if sigBytes is invalid
             // return false rather than propagating the exception for
             // compatibility/ease of use
             return false;
         } catch (IOException e) {
             throw new SignatureException("Signature encoding error", e);
         } finally {
             resetDigest();
         }
     }

     // return the modulus length in bits
     private static int getKeyLengthInBits(RSAKey k) {
         if (k != null) {
             return k.getModulus().bitLength();
         }
         return -1;
     }

     /**
      * Encode the digest 'mHash', return the to-be-signed data.
      * Also used by the PKCS#11 provider.
      */
     private byte[] encodeSignature(byte[] mHash)
         throws IOException, DigestException {
         AlgorithmParameterSpec mgfParams = this.sigParams.getMGFParameters();
         String mgfDigestAlgo;
         if (mgfParams != null) {
             mgfDigestAlgo =
                 ((MGF1ParameterSpec) mgfParams).getDigestAlgorithm();
         } else {
             mgfDigestAlgo = this.md.getAlgorithm();
         }
         try {
             int emBits = getKeyLengthInBits(this.privKey) - 1;
             int emLen = (emBits + 7) >> 3;
             int hLen = this.md.getDigestLength();
             int dbLen = emLen - hLen - 1;
             int sLen = this.sigParams.getSaltLength();

             // maps DB into the corresponding region of EM and
             // stores its bytes directly into EM
             byte[] em = new byte[emLen];

             // step7 and some of step8
             em[dbLen - sLen - 1] = (byte) 1; // set DB's padding2 into EM
             em[em.length - 1] = (byte) 0xBC; // set trailer field of EM

             if (!digestReset) {
                 throw new ProviderException("Digest should be reset");
             }
             // step5: generates M' using padding1, mHash, and salt
             this.md.update(EIGHT_BYTES_OF_ZEROS);
             digestReset = false; // mark digest as it now has data
             this.md.update(mHash);
             if (sLen != 0) {
                 // step4: generate random salt
                 byte[] salt = new byte[sLen];
                 this.random.nextBytes(salt);
                 this.md.update(salt);

                 // step8: set DB's salt into EM
                 System.arraycopy(salt, 0, em, dbLen - sLen, sLen);
             }
             // step6: generate H using M'
             this.md.digest(em, dbLen, hLen); // set H field of EM
             digestReset = true;

             // step7 and 8 are already covered by the code which setting up
             // EM as above

             // step9 and 10: feed H into MGF and xor with DB in EM
             MGF1 mgf1 = new MGF1(mgfDigestAlgo);
             mgf1.generateAndXor(em, dbLen, hLen, dbLen, em, 0);

             // step11: set the leftmost (8emLen - emBits) bits of the leftmost
             // octet to 0
             int numZeroBits = (emLen << 3) - emBits;

             if (numZeroBits != 0) {
                 byte MASK = (byte) (0xff >>> numZeroBits);
                 em[0] = (byte) (em[0] & MASK);
             }

             // step12: em should now holds maskedDB || hash h || 0xBC
             return em;
         } catch (NoSuchAlgorithmException e) {
             throw new IOException(e.toString());
         }
     }

     /**
      * Decode the signature data as under RFC8017 sec9.1.2 EMSA-PSS-VERIFY
      */
     private boolean decodeSignature(byte[] mHash, byte[] em)
             throws IOException {
         int hLen = mHash.length;
         int sLen = this.sigParams.getSaltLength();
         int emBits = getKeyLengthInBits(this.pubKey) - 1;
         int emLen = (emBits + 7) >> 3;

         // When key length is 8N+1 bits (N+1 bytes), emBits = 8N,
         // emLen = N which is one byte shorter than em.length.
         // Otherwise, emLen should be same as em.length
         int emOfs = em.length - emLen;
         if ((emOfs == 1) && (em[0] != 0)) {
             return false;
         }

         // step3
         if (emLen < (hLen + sLen + 2)) {
             return false;
         }

         // step4
         if (em[emOfs + emLen - 1] != (byte) 0xBC) {
             return false;
         }

         // step6: check if the leftmost (8emLen - emBits) bits of the leftmost
         // octet are 0
         int numZeroBits = (emLen << 3) - emBits;

         if (numZeroBits != 0) {
             byte MASK = (byte) (0xff << (8 - numZeroBits));
             if ((em[emOfs] & MASK) != 0) {
                 return false;
             }
         }
         String mgfDigestAlgo;
         AlgorithmParameterSpec mgfParams = this.sigParams.getMGFParameters();
         if (mgfParams != null) {
             mgfDigestAlgo =
                 ((MGF1ParameterSpec) mgfParams).getDigestAlgorithm();
         } else {
             mgfDigestAlgo = this.md.getAlgorithm();
         }
         // step 7 and 8
         int dbLen = emLen - hLen - 1;
         try {
             MGF1 mgf1 = new MGF1(mgfDigestAlgo);
             mgf1.generateAndXor(em, emOfs + dbLen, hLen, dbLen,
                     em, emOfs);
         } catch (NoSuchAlgorithmException nsae) {
             throw new IOException(nsae.toString());
         }

         // step9: set the leftmost (8emLen - emBits) bits of the leftmost
         //  octet to 0
         if (numZeroBits != 0) {
             byte MASK = (byte) (0xff >>> numZeroBits);
             em[emOfs] = (byte) (em[emOfs] & MASK);
         }

         // step10
         int i = emOfs;
         for (; i < emOfs + (dbLen - sLen - 1); i++) {
             if (em[i] != 0) {
                 return false;
             }
         }
         if (em[i] != 0x01) {
             return false;
         }
         // step12 and 13
         this.md.update(EIGHT_BYTES_OF_ZEROS);
         digestReset = false;
         this.md.update(mHash);
         if (sLen > 0) {
             this.md.update(em, emOfs + (dbLen - sLen), sLen);
         }
         byte[] digest2 = this.md.digest();
         digestReset = true;

         // step14
         byte[] digestInEM = Arrays.copyOfRange(em, emOfs + dbLen,
                 emOfs + emLen - 1);
         return MessageDigest.isEqual(digest2, digestInEM);
     }

     // set parameter, not supported. See JCA doc
     @Deprecated
     @Override
     protected void engineSetParameter(String param, Object value)
             throws InvalidParameterException {
         throw new UnsupportedOperationException("setParameter() not supported");
     }

     @Override
     protected void engineSetParameter(AlgorithmParameterSpec params)
             throws InvalidAlgorithmParameterException {
         this.sigParams = validateSigParams(params);
         // disallow changing parameters when digest has been used
         if (!digestReset) {
             throw new ProviderException
                 ("Cannot set parameters during operations");
         }
         String newHashAlg = this.sigParams.getDigestAlgorithm();
         // re-allocate md if not yet assigned or algorithm changed
         if ((this.md == null) ||
             !(this.md.getAlgorithm().equalsIgnoreCase(newHashAlg))) {
             try {
                 this.md = MessageDigest.getInstance(newHashAlg);
             } catch (NoSuchAlgorithmException nsae) {
                 // should not happen as we pick default digest algorithm
                 throw new InvalidAlgorithmParameterException
                     ("Unsupported digest algorithm " +
                      newHashAlg, nsae);
             }
         }
     }

     // get parameter, not supported. See JCA doc
     @Deprecated
     @Override
     protected Object engineGetParameter(String param)
             throws InvalidParameterException {
         throw new UnsupportedOperationException("getParameter() not supported");
     }

     @Override
     protected AlgorithmParameters engineGetParameters() {
         AlgorithmParameters ap = null;
         if (this.sigParams != null) {
             try {
                 ap = AlgorithmParameters.getInstance("RSASSA-PSS");
                 ap.init(this.sigParams);
             } catch (GeneralSecurityException gse) {
                 throw new ProviderException(gse.getMessage());
             }
         }
         return ap;
     }
 }
	/*
	* Copyright (c) 2018, 2020, Oracle and/or its affiliates. All rights reserved.
	* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
	*
	* This code is free software; you can redistribute it and/or modify it
	* under the terms of the GNU General Public License version 2 only, as
	* published by the Free Software Foundation. Oracle designates this
	* particular file as subject to the "Classpath" exception as provided
	* by Oracle in the LICENSE file that accompanied this code.
	*
	* This code is distributed in the hope that it will be useful, but WITHOUT
	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	* version 2 for more details (a copy is included in the LICENSE file that
	* accompanied this code).
	*
	* You should have received a copy of the GNU General Public License version
	* 2 along with this work; if not, write to the Free Software Foundation,
	* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
	*
	* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
	* or visit www.oracle.com if you need additional information or have any
	* questions.
	*/

	package sun.security.rsa;

	import java.io.IOException;
	import java.nio.ByteBuffer;

	import java.security.*;
	import java.security.spec.AlgorithmParameterSpec;
	import java.security.spec.PSSParameterSpec;
	import java.security.spec.MGF1ParameterSpec;
	import java.security.interfaces.*;

	import java.util.Arrays;
	import java.util.Hashtable;

	import sun.security.util.*;
	import sun.security.jca.JCAUtil;


	/**
	* PKCS#1 v2.2 RSASSA-PSS signatures with various message digest algorithms.
	* RSASSA-PSS implementation takes the message digest algorithm, MGF algorithm,
	* and salt length values through the required signature PSS parameters.
	* We support SHA-1, SHA-224, SHA-256, SHA-384, SHA-512, SHA-512/224, and
	* SHA-512/256 message digest algorithms and MGF1 mask generation function.
	*
	* @since 11
	*/
	public class RSAPSSSignature extends SignatureSpi {

	private static final boolean DEBUG = false;

	// utility method for comparing digest algorithms
	// NOTE that first argument is assumed to be standard digest name
	private boolean isDigestEqual(String stdAlg, String givenAlg) {
	if (stdAlg == null \|\| givenAlg == null) return false;

	if (givenAlg.indexOf("-") != -1) {
	return stdAlg.equalsIgnoreCase(givenAlg);
	} else {
	if (stdAlg.equals("SHA-1")) {
	return (givenAlg.equalsIgnoreCase("SHA")
	\|\| givenAlg.equalsIgnoreCase("SHA1"));
	} else {
	StringBuilder sb = new StringBuilder(givenAlg);
	// case-insensitive check
	if (givenAlg.regionMatches(true, 0, "SHA", 0, 3)) {
	givenAlg = sb.insert(3, "-").toString();
	return stdAlg.equalsIgnoreCase(givenAlg);
	} else {
	throw new ProviderException("Unsupported digest algorithm "
	+ givenAlg);
	}
	}
	}
	}

	private static final byte[] EIGHT_BYTES_OF_ZEROS = new byte[8];

	private static final Hashtable<String, Integer> DIGEST_LENGTHS =
	new Hashtable<String, Integer>();
	static {
	DIGEST_LENGTHS.put("SHA-1", 20);
	DIGEST_LENGTHS.put("SHA", 20);
	DIGEST_LENGTHS.put("SHA1", 20);
	DIGEST_LENGTHS.put("SHA-224", 28);
	DIGEST_LENGTHS.put("SHA224", 28);
	DIGEST_LENGTHS.put("SHA-256", 32);
	DIGEST_LENGTHS.put("SHA256", 32);
	DIGEST_LENGTHS.put("SHA-384", 48);
	DIGEST_LENGTHS.put("SHA384", 48);
	DIGEST_LENGTHS.put("SHA-512", 64);
	DIGEST_LENGTHS.put("SHA512", 64);
	DIGEST_LENGTHS.put("SHA-512/224", 28);
	DIGEST_LENGTHS.put("SHA512/224", 28);
	DIGEST_LENGTHS.put("SHA-512/256", 32);
	DIGEST_LENGTHS.put("SHA512/256", 32);
	}

	// message digest implementation we use for hashing the data
	private MessageDigest md;
	// flag indicating whether the digest is reset
	private boolean digestReset = true;

	// private key, if initialized for signing
	private RSAPrivateKey privKey = null;
	// public key, if initialized for verifying
	private RSAPublicKey pubKey = null;
	// PSS parameters from signatures and keys respectively
	private PSSParameterSpec sigParams = null; // required for PSS signatures

	// PRNG used to generate salt bytes if none given
	private SecureRandom random;

	/**
	* Construct a new RSAPSSSignatur with arbitrary digest algorithm
	*/
	public RSAPSSSignature() {
	this.md = null;
	}

	// initialize for verification. See JCA doc
	@Override
	protected void engineInitVerify(PublicKey publicKey)
	throws InvalidKeyException {
	if (!(publicKey instanceof RSAPublicKey)) {
	throw new InvalidKeyException("key must be RSAPublicKey");
	}
	this.pubKey = (RSAPublicKey) isValid((RSAKey)publicKey);
	this.privKey = null;
	resetDigest();
	}

	// initialize for signing. See JCA doc
	@Override
	protected void engineInitSign(PrivateKey privateKey)
	throws InvalidKeyException {
	engineInitSign(privateKey, null);
	}

	// initialize for signing. See JCA doc
	@Override
	protected void engineInitSign(PrivateKey privateKey, SecureRandom random)
	throws InvalidKeyException {
	if (!(privateKey instanceof RSAPrivateKey)) {
	throw new InvalidKeyException("key must be RSAPrivateKey");
	}
	this.privKey = (RSAPrivateKey) isValid((RSAKey)privateKey);
	this.pubKey = null;
	this.random =
	(random == null? JCAUtil.getSecureRandom() : random);
	resetDigest();
	}

	/**
	* Utility method for checking the key PSS parameters against signature
	* PSS parameters.
	* Returns false if any of the digest/MGF algorithms and trailerField
	* values does not match or if the salt length in key parameters is
	* larger than the value in signature parameters.
	*/
	private static boolean isCompatible(AlgorithmParameterSpec keyParams,
	PSSParameterSpec sigParams) {
	if (keyParams == null) {
	// key with null PSS parameters means no restriction
	return true;
	}
	if (!(keyParams instanceof PSSParameterSpec)) {
	return false;
	}
	// nothing to compare yet, defer the check to when sigParams is set
	if (sigParams == null) {
	return true;
	}
	PSSParameterSpec pssKeyParams = (PSSParameterSpec) keyParams;
	// first check the salt length requirement
	if (pssKeyParams.getSaltLength() > sigParams.getSaltLength()) {
	return false;
	}

	// compare equality of the rest of fields based on DER encoding
	PSSParameterSpec keyParams2 =
	new PSSParameterSpec(pssKeyParams.getDigestAlgorithm(),
	pssKeyParams.getMGFAlgorithm(),
	pssKeyParams.getMGFParameters(),
	sigParams.getSaltLength(),
	pssKeyParams.getTrailerField());
	PSSParameters ap = new PSSParameters();
	// skip the JCA overhead
	try {
	ap.engineInit(keyParams2);
	byte[] encoded = ap.engineGetEncoded();
	ap.engineInit(sigParams);
	byte[] encoded2 = ap.engineGetEncoded();
	return Arrays.equals(encoded, encoded2);
	} catch (Exception e) {
	if (DEBUG) {
	e.printStackTrace();
	}
	return false;
	}
	}

	/**
	* Validate the specified RSAKey and its associated parameters against
	* internal signature parameters.
	*/
	private RSAKey isValid(RSAKey rsaKey) throws InvalidKeyException {
	try {
	AlgorithmParameterSpec keyParams = rsaKey.getParams();
	// validate key parameters
	if (!isCompatible(rsaKey.getParams(), this.sigParams)) {
	throw new InvalidKeyException
	("Key contains incompatible PSS parameter values");
	}
	// validate key length
	if (this.sigParams != null) {
	Integer hLen =
	DIGEST_LENGTHS.get(this.sigParams.getDigestAlgorithm());
	if (hLen == null) {
	throw new ProviderException("Unsupported digest algo: " +
	this.sigParams.getDigestAlgorithm());
	}
	checkKeyLength(rsaKey, hLen, this.sigParams.getSaltLength());
	}
	return rsaKey;
	} catch (SignatureException e) {
	throw new InvalidKeyException(e);
	}
	}

	/**
	* Validate the specified Signature PSS parameters.
	*/
	private PSSParameterSpec validateSigParams(AlgorithmParameterSpec p)
	throws InvalidAlgorithmParameterException {
	if (p == null) {
	throw new InvalidAlgorithmParameterException
	("Parameters cannot be null");
	}
	if (!(p instanceof PSSParameterSpec)) {
	throw new InvalidAlgorithmParameterException
	("parameters must be type PSSParameterSpec");
	}
	// no need to validate again if same as current signature parameters
	PSSParameterSpec params = (PSSParameterSpec) p;
	if (params == this.sigParams) return params;

	RSAKey key = (this.privKey == null? this.pubKey : this.privKey);
	// check against keyParams if set
	if (key != null) {
	if (!isCompatible(key.getParams(), params)) {
	throw new InvalidAlgorithmParameterException
	("Signature parameters does not match key parameters");
	}
	}
	// now sanity check the parameter values
	if (!(params.getMGFAlgorithm().equalsIgnoreCase("MGF1"))) {
	throw new InvalidAlgorithmParameterException("Only supports MGF1");

	}
	if (params.getTrailerField() != PSSParameterSpec.TRAILER_FIELD_BC) {
	throw new InvalidAlgorithmParameterException
	("Only supports TrailerFieldBC(1)");

	}
	String digestAlgo = params.getDigestAlgorithm();
	// check key length again
	if (key != null) {
	try {
	int hLen = DIGEST_LENGTHS.get(digestAlgo);
	checkKeyLength(key, hLen, params.getSaltLength());
	} catch (SignatureException e) {
	throw new InvalidAlgorithmParameterException(e);
	}
	}
	return params;
	}

	/**
	* Ensure the object is initialized with key and parameters and
	* reset digest
	*/
	private void ensureInit() throws SignatureException {
	RSAKey key = (this.privKey == null? this.pubKey : this.privKey);
	if (key == null) {
	throw new SignatureException("Missing key");
	}
	if (this.sigParams == null) {
	// Parameters are required for signature verification
	throw new SignatureException
	("Parameters required for RSASSA-PSS signatures");
	}
	}

	/**
	* Utility method for checking key length against digest length and
	* salt length
	*/
	private static void checkKeyLength(RSAKey key, int digestLen,
	int saltLen) throws SignatureException {
	if (key != null) {
	int keyLength = (getKeyLengthInBits(key) + 7) >> 3;
	int minLength = Math.addExact(Math.addExact(digestLen, saltLen), 2);
	if (keyLength < minLength) {
	throw new SignatureException
	("Key is too short, need min " + minLength + " bytes");
	}
	}
	}

	/**
	* Reset the message digest if it is not already reset.
	*/
	private void resetDigest() {
	if (digestReset == false) {
	this.md.reset();
	digestReset = true;
	}
	}

	/**
	* Return the message digest value.
	*/
	private byte[] getDigestValue() {
	digestReset = true;
	return this.md.digest();
	}

	// update the signature with the plaintext data. See JCA doc
	@Override
	protected void engineUpdate(byte b) throws SignatureException {
	ensureInit();
	this.md.update(b);
	digestReset = false;
	}

	// update the signature with the plaintext data. See JCA doc
	@Override
	protected void engineUpdate(byte[] b, int off, int len)
	throws SignatureException {
	ensureInit();
	this.md.update(b, off, len);
	digestReset = false;
	}

	// update the signature with the plaintext data. See JCA doc
	@Override
	protected void engineUpdate(ByteBuffer b) {
	try {
	ensureInit();
	} catch (SignatureException se) {
	// hack for working around API bug
	throw new RuntimeException(se.getMessage());
	}
	this.md.update(b);
	digestReset = false;
	}

	// sign the data and return the signature. See JCA doc
	@Override
	protected byte[] engineSign() throws SignatureException {
	ensureInit();
	byte[] mHash = getDigestValue();
	try {
	byte[] encoded = encodeSignature(mHash);
	byte[] encrypted = RSACore.rsa(encoded, privKey, true);
	return encrypted;
	} catch (GeneralSecurityException e) {
	throw new SignatureException("Could not sign data", e);
	} catch (IOException e) {
	throw new SignatureException("Could not encode data", e);
	}
	}

	// verify the data and return the result. See JCA doc
	// should be reset to the state after engineInitVerify call.
	@Override
	protected boolean engineVerify(byte[] sigBytes) throws SignatureException {
	ensureInit();
	try {
	if (sigBytes.length != RSACore.getByteLength(this.pubKey)) {
	throw new SignatureException
	("Signature length not correct: got "
	+ sigBytes.length + " but was expecting "
	+ RSACore.getByteLength(this.pubKey));
	}
	byte[] mHash = getDigestValue();
	byte[] decrypted = RSACore.rsa(sigBytes, this.pubKey);
	return decodeSignature(mHash, decrypted);
	} catch (javax.crypto.BadPaddingException e) {
	// occurs if the app has used the wrong RSA public key
	// or if sigBytes is invalid
	// return false rather than propagating the exception for
	// compatibility/ease of use
	return false;
	} catch (IOException e) {
	throw new SignatureException("Signature encoding error", e);
	} finally {
	resetDigest();
	}
	}

	// return the modulus length in bits
	private static int getKeyLengthInBits(RSAKey k) {
	if (k != null) {
	return k.getModulus().bitLength();
	}
	return -1;
	}

	/**
	* Encode the digest 'mHash', return the to-be-signed data.
	* Also used by the PKCS#11 provider.
	*/
	private byte[] encodeSignature(byte[] mHash)
	throws IOException, DigestException {
	AlgorithmParameterSpec mgfParams = this.sigParams.getMGFParameters();
	String mgfDigestAlgo;
	if (mgfParams != null) {
	mgfDigestAlgo =
	((MGF1ParameterSpec) mgfParams).getDigestAlgorithm();
	} else {
	mgfDigestAlgo = this.md.getAlgorithm();
	}
	try {
	int emBits = getKeyLengthInBits(this.privKey) - 1;
	int emLen = (emBits + 7) >> 3;
	int hLen = this.md.getDigestLength();
	int dbLen = emLen - hLen - 1;
	int sLen = this.sigParams.getSaltLength();

	// maps DB into the corresponding region of EM and
	// stores its bytes directly into EM
	byte[] em = new byte[emLen];

	// step7 and some of step8
	em[dbLen - sLen - 1] = (byte) 1; // set DB's padding2 into EM
	em[em.length - 1] = (byte) 0xBC; // set trailer field of EM

	if (!digestReset) {
	throw new ProviderException("Digest should be reset");
	}
	// step5: generates M' using padding1, mHash, and salt
	this.md.update(EIGHT_BYTES_OF_ZEROS);
	digestReset = false; // mark digest as it now has data
	this.md.update(mHash);
	if (sLen != 0) {
	// step4: generate random salt
	byte[] salt = new byte[sLen];
	this.random.nextBytes(salt);
	this.md.update(salt);

	// step8: set DB's salt into EM
	System.arraycopy(salt, 0, em, dbLen - sLen, sLen);
	}
	// step6: generate H using M'
	this.md.digest(em, dbLen, hLen); // set H field of EM
	digestReset = true;

	// step7 and 8 are already covered by the code which setting up
	// EM as above

	// step9 and 10: feed H into MGF and xor with DB in EM
	MGF1 mgf1 = new MGF1(mgfDigestAlgo);
	mgf1.generateAndXor(em, dbLen, hLen, dbLen, em, 0);

	// step11: set the leftmost (8emLen - emBits) bits of the leftmost
	// octet to 0
	int numZeroBits = (emLen << 3) - emBits;

	if (numZeroBits != 0) {
	byte MASK = (byte) (0xff >>> numZeroBits);
	em[0] = (byte) (em[0] & MASK);
	}

	// step12: em should now holds maskedDB \|\| hash h \|\| 0xBC
	return em;
	} catch (NoSuchAlgorithmException e) {
	throw new IOException(e.toString());
	}
	}

	/**
	* Decode the signature data as under RFC8017 sec9.1.2 EMSA-PSS-VERIFY
	*/
	private boolean decodeSignature(byte[] mHash, byte[] em)
	throws IOException {
	int hLen = mHash.length;
	int sLen = this.sigParams.getSaltLength();
	int emBits = getKeyLengthInBits(this.pubKey) - 1;
	int emLen = (emBits + 7) >> 3;

	// When key length is 8N+1 bits (N+1 bytes), emBits = 8N,
	// emLen = N which is one byte shorter than em.length.
	// Otherwise, emLen should be same as em.length
	int emOfs = em.length - emLen;
	if ((emOfs == 1) && (em[0] != 0)) {
	return false;
	}

	// step3
	if (emLen < (hLen + sLen + 2)) {
	return false;
	}

	// step4
	if (em[emOfs + emLen - 1] != (byte) 0xBC) {
	return false;
	}

	// step6: check if the leftmost (8emLen - emBits) bits of the leftmost
	// octet are 0
	int numZeroBits = (emLen << 3) - emBits;

	if (numZeroBits != 0) {
	byte MASK = (byte) (0xff << (8 - numZeroBits));
	if ((em[emOfs] & MASK) != 0) {
	return false;
	}
	}
	String mgfDigestAlgo;
	AlgorithmParameterSpec mgfParams = this.sigParams.getMGFParameters();
	if (mgfParams != null) {
	mgfDigestAlgo =
	((MGF1ParameterSpec) mgfParams).getDigestAlgorithm();
	} else {
	mgfDigestAlgo = this.md.getAlgorithm();
	}
	// step 7 and 8
	int dbLen = emLen - hLen - 1;
	try {
	MGF1 mgf1 = new MGF1(mgfDigestAlgo);
	mgf1.generateAndXor(em, emOfs + dbLen, hLen, dbLen,
	em, emOfs);
	} catch (NoSuchAlgorithmException nsae) {
	throw new IOException(nsae.toString());
	}

	// step9: set the leftmost (8emLen - emBits) bits of the leftmost
	// octet to 0
	if (numZeroBits != 0) {
	byte MASK = (byte) (0xff >>> numZeroBits);
	em[emOfs] = (byte) (em[emOfs] & MASK);
	}

	// step10
	int i = emOfs;
	for (; i < emOfs + (dbLen - sLen - 1); i++) {
	if (em[i] != 0) {
	return false;
	}
	}
	if (em[i] != 0x01) {
	return false;
	}
	// step12 and 13
	this.md.update(EIGHT_BYTES_OF_ZEROS);
	digestReset = false;
	this.md.update(mHash);
	if (sLen > 0) {
	this.md.update(em, emOfs + (dbLen - sLen), sLen);
	}
	byte[] digest2 = this.md.digest();
	digestReset = true;

	// step14
	byte[] digestInEM = Arrays.copyOfRange(em, emOfs + dbLen,
	emOfs + emLen - 1);
	return MessageDigest.isEqual(digest2, digestInEM);
	}

	// set parameter, not supported. See JCA doc
	@Deprecated
	@Override
	protected void engineSetParameter(String param, Object value)
	throws InvalidParameterException {
	throw new UnsupportedOperationException("setParameter() not supported");
	}

	@Override
	protected void engineSetParameter(AlgorithmParameterSpec params)
	throws InvalidAlgorithmParameterException {
	this.sigParams = validateSigParams(params);
	// disallow changing parameters when digest has been used
	if (!digestReset) {
	throw new ProviderException
	("Cannot set parameters during operations");
	}
	String newHashAlg = this.sigParams.getDigestAlgorithm();
	// re-allocate md if not yet assigned or algorithm changed
	if ((this.md == null) \|\|
	!(this.md.getAlgorithm().equalsIgnoreCase(newHashAlg))) {
	try {
	this.md = MessageDigest.getInstance(newHashAlg);
	} catch (NoSuchAlgorithmException nsae) {
	// should not happen as we pick default digest algorithm
	throw new InvalidAlgorithmParameterException
	("Unsupported digest algorithm " +
	newHashAlg, nsae);
	}
	}
	}

	// get parameter, not supported. See JCA doc
	@Deprecated
	@Override
	protected Object engineGetParameter(String param)
	throws InvalidParameterException {
	throw new UnsupportedOperationException("getParameter() not supported");
	}

	@Override
	protected AlgorithmParameters engineGetParameters() {
	AlgorithmParameters ap = null;
	if (this.sigParams != null) {
	try {
	ap = AlgorithmParameters.getInstance("RSASSA-PSS");
	ap.init(this.sigParams);
	} catch (GeneralSecurityException gse) {
	throw new ProviderException(gse.getMessage());
	}
	}
	return ap;
	}
	}