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Tweaked port of SunPKCS11 security provider
/*
* Copyright (c) 2003, 2021, 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 com.github.kwart.jsign.pkcs11;
import java.io.IOException;
import java.math.BigInteger;
import java.nio.ByteBuffer;
import java.security.*;
import java.security.interfaces.*;
import java.security.spec.AlgorithmParameterSpec;
import javax.security.auth.login.LoginException;
import sun.nio.ch.DirectBuffer;
import sun.security.util.*;
import sun.security.x509.AlgorithmId;
import sun.security.rsa.RSASignature;
import sun.security.rsa.RSAPadding;
import sun.security.pkcs11.wrapper.*;
import static sun.security.pkcs11.wrapper.PKCS11Constants.*;
import sun.security.util.KeyUtil;
/**
* Signature implementation class. This class currently supports the
* following algorithms:
*
* . DSA
* . NONEwithDSA (RawDSA)
* . SHA1withDSA
* . RSA:
* . MD2withRSA
* . MD5withRSA
* . SHA1withRSA
* . SHA224withRSA
* . SHA256withRSA
* . SHA384withRSA
* . SHA512withRSA
* . ECDSA
* . NONEwithECDSA
* . SHA1withECDSA
* . SHA224withECDSA
* . SHA256withECDSA
* . SHA384withECDSA
* . SHA512withECDSA
*
* Note that the underlying PKCS#11 token may support complete signature
* algorithm (e.g. CKM_DSA_SHA1, CKM_MD5_RSA_PKCS), or it may just
* implement the signature algorithm without hashing (e.g. CKM_DSA, CKM_PKCS),
* or it may only implement the raw public key operation (CKM_RSA_X_509).
* This class uses what is available and adds whatever extra processing
* is needed.
*
* @author Andreas Sterbenz
* @since 1.5
*/
final class P11Signature extends SignatureSpi {
// token instance
private final Token token;
// algorithm name
private final String algorithm;
// name of the key algorithm, currently either RSA or DSA
private final String keyAlgorithm;
// mechanism id
private final long mechanism;
// digest algorithm OID, if we encode RSA signature ourselves
private final ObjectIdentifier digestOID;
// type, one of T_* below
private final int type;
// key instance used, if init*() was called
private P11Key p11Key;
// message digest, if we do the digesting ourselves
private final MessageDigest md;
// associated session, if any
private Session session;
// mode, one of M_* below
private int mode;
// flag indicating whether an operation is initialized
private boolean initialized;
// buffer, for update(byte) or DSA
private final byte[] buffer;
// total number of bytes processed in current operation
private int bytesProcessed;
// constant for signing mode
private final static int M_SIGN = 1;
// constant for verification mode
private final static int M_VERIFY = 2;
// constant for type digesting, we do the hashing ourselves
private final static int T_DIGEST = 1;
// constant for type update, token does everything
private final static int T_UPDATE = 2;
// constant for type raw, used with RawDSA and NONEwithECDSA only
private final static int T_RAW = 3;
// XXX PKCS#11 v2.20 says "should not be longer than 1024 bits",
// but this is a little arbitrary
private final static int RAW_ECDSA_MAX = 128;
P11Signature(Token token, String algorithm, long mechanism)
throws NoSuchAlgorithmException, PKCS11Exception {
super();
this.token = token;
this.algorithm = algorithm;
this.mechanism = mechanism;
byte[] buffer = null;
ObjectIdentifier digestOID = null;
MessageDigest md = null;
switch ((int)mechanism) {
case (int)CKM_MD2_RSA_PKCS:
case (int)CKM_MD5_RSA_PKCS:
case (int)CKM_SHA1_RSA_PKCS:
case (int)CKM_SHA224_RSA_PKCS:
case (int)CKM_SHA256_RSA_PKCS:
case (int)CKM_SHA384_RSA_PKCS:
case (int)CKM_SHA512_RSA_PKCS:
keyAlgorithm = "RSA";
type = T_UPDATE;
buffer = new byte[1];
break;
case (int)CKM_DSA_SHA1:
keyAlgorithm = "DSA";
type = T_UPDATE;
buffer = new byte[1];
break;
case (int)CKM_ECDSA_SHA1:
keyAlgorithm = "EC";
type = T_UPDATE;
buffer = new byte[1];
break;
case (int)CKM_DSA:
keyAlgorithm = "DSA";
if (algorithm.equals("DSA")) {
type = T_DIGEST;
md = MessageDigest.getInstance("SHA-1");
} else if (algorithm.equals("RawDSA")) {
type = T_RAW;
buffer = new byte[20];
} else {
throw new ProviderException(algorithm);
}
break;
case (int)CKM_ECDSA:
keyAlgorithm = "EC";
if (algorithm.equals("NONEwithECDSA")) {
type = T_RAW;
buffer = new byte[RAW_ECDSA_MAX];
} else {
String digestAlg;
if (algorithm.equals("SHA1withECDSA")) {
digestAlg = "SHA-1";
} else if (algorithm.equals("SHA224withECDSA")) {
digestAlg = "SHA-224";
} else if (algorithm.equals("SHA256withECDSA")) {
digestAlg = "SHA-256";
} else if (algorithm.equals("SHA384withECDSA")) {
digestAlg = "SHA-384";
} else if (algorithm.equals("SHA512withECDSA")) {
digestAlg = "SHA-512";
} else {
throw new ProviderException(algorithm);
}
type = T_DIGEST;
md = MessageDigest.getInstance(digestAlg);
}
break;
case (int)CKM_RSA_PKCS:
case (int)CKM_RSA_X_509:
keyAlgorithm = "RSA";
type = T_DIGEST;
if (algorithm.equals("MD5withRSA")) {
md = MessageDigest.getInstance("MD5");
digestOID = AlgorithmId.MD5_oid;
} else if (algorithm.equals("SHA1withRSA")) {
md = MessageDigest.getInstance("SHA-1");
digestOID = AlgorithmId.SHA_oid;
} else if (algorithm.equals("MD2withRSA")) {
md = MessageDigest.getInstance("MD2");
digestOID = AlgorithmId.MD2_oid;
} else if (algorithm.equals("SHA224withRSA")) {
md = MessageDigest.getInstance("SHA-224");
digestOID = AlgorithmId.SHA224_oid;
} else if (algorithm.equals("SHA256withRSA")) {
md = MessageDigest.getInstance("SHA-256");
digestOID = AlgorithmId.SHA256_oid;
} else if (algorithm.equals("SHA384withRSA")) {
md = MessageDigest.getInstance("SHA-384");
digestOID = AlgorithmId.SHA384_oid;
} else if (algorithm.equals("SHA512withRSA")) {
md = MessageDigest.getInstance("SHA-512");
digestOID = AlgorithmId.SHA512_oid;
} else {
throw new ProviderException("Unknown signature: " + algorithm);
}
break;
default:
throw new ProviderException("Unknown mechanism: " + mechanism);
}
this.buffer = buffer;
this.digestOID = digestOID;
this.md = md;
}
// reset the states to the pre-initialized values
private void reset(boolean doCancel) {
if (!initialized) {
return;
}
initialized = false;
try {
if (session == null) {
return;
}
if (doCancel && token.explicitCancel) {
cancelOperation();
}
} finally {
p11Key.releaseKeyID();
session = token.releaseSession(session);
}
}
private void cancelOperation() {
token.ensureValid();
// cancel operation by finishing it; avoid killSession as some
// hardware vendors may require re-login
try {
if (mode == M_SIGN) {
if (type == T_UPDATE) {
token.p11.C_SignFinal(session.id(), 0);
} else {
byte[] digest;
if (type == T_DIGEST) {
digest = md.digest();
} else { // T_RAW
digest = buffer;
}
token.p11.C_Sign(session.id(), digest);
}
} else { // M_VERIFY
byte[] signature;
if (keyAlgorithm.equals("DSA")) {
signature = new byte[40];
} else {
signature = new byte[(p11Key.length() + 7) >> 3];
}
if (type == T_UPDATE) {
token.p11.C_VerifyFinal(session.id(), signature);
} else {
byte[] digest;
if (type == T_DIGEST) {
digest = md.digest();
} else { // T_RAW
digest = buffer;
}
token.p11.C_Verify(session.id(), digest, signature);
}
}
} catch (PKCS11Exception e) {
if (e.getErrorCode() == CKR_OPERATION_NOT_INITIALIZED) {
// Cancel Operation may be invoked after an error on a PKCS#11
// call. If the operation inside the token was already cancelled,
// do not fail here. This is part of a defensive mechanism for
// PKCS#11 libraries that do not strictly follow the standard.
return;
}
if (mode == M_VERIFY) {
long errorCode = e.getErrorCode();
if ((errorCode == CKR_SIGNATURE_INVALID) ||
(errorCode == CKR_SIGNATURE_LEN_RANGE)) {
// expected since signature is incorrect
return;
}
}
throw new ProviderException("cancel failed", e);
}
}
private void ensureInitialized() {
if (!initialized) {
initialize();
}
}
// assumes current state is initialized == false
private void initialize() {
if (p11Key == null) {
throw new ProviderException(
"Operation cannot be performed without " +
"calling engineInit first");
}
long keyID = p11Key.getKeyID();
try {
token.ensureValid();
if (session == null) {
session = token.getOpSession();
}
if (mode == M_SIGN) {
token.p11.C_SignInit(session.id(),
new CK_MECHANISM(mechanism), keyID);
} else {
token.p11.C_VerifyInit(session.id(),
new CK_MECHANISM(mechanism), keyID);
}
} catch (PKCS11Exception e) {
p11Key.releaseKeyID();
session = token.releaseSession(session);
throw new ProviderException("Initialization failed", e);
}
if (bytesProcessed != 0) {
bytesProcessed = 0;
if (md != null) {
md.reset();
}
}
initialized = true;
}
private void checkKeySize(String keyAlgo, Key key)
throws InvalidKeyException {
CK_MECHANISM_INFO mechInfo = null;
try {
mechInfo = token.getMechanismInfo(mechanism);
} catch (PKCS11Exception e) {
// should not happen, ignore for now.
}
if (mechInfo == null) {
// skip the check if no native info available
return;
}
int minKeySize = (int) mechInfo.ulMinKeySize;
int maxKeySize = (int) mechInfo.ulMaxKeySize;
// need to override the MAX keysize for SHA1withDSA
if (md != null && mechanism == CKM_DSA && maxKeySize > 1024) {
maxKeySize = 1024;
}
int keySize = 0;
if (key instanceof P11Key) {
keySize = ((P11Key) key).length();
} else {
try {
if (keyAlgo.equals("RSA")) {
keySize = ((RSAKey) key).getModulus().bitLength();
} else if (keyAlgo.equals("DSA")) {
keySize = ((DSAKey) key).getParams().getP().bitLength();
} else if (keyAlgo.equals("EC")) {
keySize = ((ECKey) key).getParams().getCurve().getField().getFieldSize();
} else {
throw new ProviderException("Error: unsupported algo " + keyAlgo);
}
} catch (ClassCastException cce) {
throw new InvalidKeyException(keyAlgo +
" key must be the right type", cce);
}
}
if ((minKeySize != -1) && (keySize < minKeySize)) {
throw new InvalidKeyException(keyAlgo +
" key must be at least " + minKeySize + " bits");
}
if ((maxKeySize != -1) && (keySize > maxKeySize)) {
throw new InvalidKeyException(keyAlgo +
" key must be at most " + maxKeySize + " bits");
}
if (keyAlgo.equals("RSA")) {
checkRSAKeyLength(keySize);
}
}
private void checkRSAKeyLength(int len) throws InvalidKeyException {
RSAPadding padding;
try {
padding = RSAPadding.getInstance
(RSAPadding.PAD_BLOCKTYPE_1, (len + 7) >> 3);
} catch (InvalidAlgorithmParameterException iape) {
throw new InvalidKeyException(iape.getMessage());
}
int maxDataSize = padding.getMaxDataSize();
int encodedLength;
if (algorithm.equals("MD5withRSA") ||
algorithm.equals("MD2withRSA")) {
encodedLength = 34;
} else if (algorithm.equals("SHA1withRSA")) {
encodedLength = 35;
} else if (algorithm.equals("SHA224withRSA")) {
encodedLength = 47;
} else if (algorithm.equals("SHA256withRSA")) {
encodedLength = 51;
} else if (algorithm.equals("SHA384withRSA")) {
encodedLength = 67;
} else if (algorithm.equals("SHA512withRSA")) {
encodedLength = 83;
} else {
throw new ProviderException("Unknown signature algo: " + algorithm);
}
if (encodedLength > maxDataSize) {
throw new InvalidKeyException
("Key is too short for this signature algorithm");
}
}
// see JCA spec
@Override
protected void engineInitVerify(PublicKey publicKey)
throws InvalidKeyException {
if (publicKey == null) {
throw new InvalidKeyException("Key must not be null");
}
// Need to check key length whenever a new key is set
if (publicKey != p11Key) {
checkKeySize(keyAlgorithm, publicKey);
}
reset(true);
mode = M_VERIFY;
p11Key = P11KeyFactory.convertKey(token, publicKey, keyAlgorithm);
initialize();
}
// see JCA spec
@Override
protected void engineInitSign(PrivateKey privateKey)
throws InvalidKeyException {
if (privateKey == null) {
throw new InvalidKeyException("Key must not be null");
}
// Need to check RSA key length whenever a new key is set
if (privateKey != p11Key) {
checkKeySize(keyAlgorithm, privateKey);
}
reset(true);
mode = M_SIGN;
p11Key = P11KeyFactory.convertKey(token, privateKey, keyAlgorithm);
initialize();
}
// see JCA spec
@Override
protected void engineUpdate(byte b) throws SignatureException {
ensureInitialized();
switch (type) {
case T_UPDATE:
buffer[0] = b;
engineUpdate(buffer, 0, 1);
break;
case T_DIGEST:
md.update(b);
bytesProcessed++;
break;
case T_RAW:
if (bytesProcessed >= buffer.length) {
bytesProcessed = buffer.length + 1;
return;
}
buffer[bytesProcessed++] = b;
break;
default:
throw new ProviderException("Internal error");
}
}
// see JCA spec
@Override
protected void engineUpdate(byte[] b, int ofs, int len)
throws SignatureException {
ensureInitialized();
if (len == 0) {
return;
}
// check for overflow
if (len + bytesProcessed < 0) {
throw new ProviderException("Processed bytes limits exceeded.");
}
switch (type) {
case T_UPDATE:
try {
if (mode == M_SIGN) {
token.p11.C_SignUpdate(session.id(), 0, b, ofs, len);
} else {
token.p11.C_VerifyUpdate(session.id(), 0, b, ofs, len);
}
bytesProcessed += len;
} catch (PKCS11Exception e) {
reset(false);
throw new ProviderException(e);
}
break;
case T_DIGEST:
md.update(b, ofs, len);
bytesProcessed += len;
break;
case T_RAW:
if (bytesProcessed + len > buffer.length) {
bytesProcessed = buffer.length + 1;
return;
}
System.arraycopy(b, ofs, buffer, bytesProcessed, len);
bytesProcessed += len;
break;
default:
throw new ProviderException("Internal error");
}
}
// see JCA spec
@Override
protected void engineUpdate(ByteBuffer byteBuffer) {
ensureInitialized();
int len = byteBuffer.remaining();
if (len <= 0) {
return;
}
switch (type) {
case T_UPDATE:
if (byteBuffer instanceof DirectBuffer == false) {
// cannot do better than default impl
super.engineUpdate(byteBuffer);
return;
}
long addr = ((DirectBuffer)byteBuffer).address();
int ofs = byteBuffer.position();
try {
if (mode == M_SIGN) {
token.p11.C_SignUpdate
(session.id(), addr + ofs, null, 0, len);
} else {
token.p11.C_VerifyUpdate
(session.id(), addr + ofs, null, 0, len);
}
bytesProcessed += len;
byteBuffer.position(ofs + len);
} catch (PKCS11Exception e) {
reset(false);
throw new ProviderException("Update failed", e);
}
break;
case T_DIGEST:
md.update(byteBuffer);
bytesProcessed += len;
break;
case T_RAW:
if (bytesProcessed + len > buffer.length) {
bytesProcessed = buffer.length + 1;
return;
}
byteBuffer.get(buffer, bytesProcessed, len);
bytesProcessed += len;
break;
default:
reset(false);
throw new ProviderException("Internal error");
}
}
// see JCA spec
@Override
protected byte[] engineSign() throws SignatureException {
ensureInitialized();
try {
token.provider.contextSpecificLogin(session.id());
} catch (LoginException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
boolean doCancel = true;
try {
byte[] signature;
if (type == T_UPDATE) {
int len = keyAlgorithm.equals("DSA") ? 40 : 0;
signature = token.p11.C_SignFinal(session.id(), len);
} else {
byte[] digest;
if (type == T_DIGEST) {
digest = md.digest();
} else { // T_RAW
if (mechanism == CKM_DSA) {
if (bytesProcessed != buffer.length) {
throw new SignatureException
("Data for RawDSA must be exactly 20 bytes long");
}
digest = buffer;
} else { // CKM_ECDSA
if (bytesProcessed > buffer.length) {
throw new SignatureException("Data for NONEwithECDSA"
+ " must be at most " + RAW_ECDSA_MAX + " bytes long");
}
digest = new byte[bytesProcessed];
System.arraycopy(buffer, 0, digest, 0, bytesProcessed);
}
}
if (keyAlgorithm.equals("RSA") == false) {
// DSA and ECDSA
signature = token.p11.C_Sign(session.id(), digest);
} else { // RSA
byte[] data = encodeSignature(digest);
if (mechanism == CKM_RSA_X_509) {
data = pkcs1Pad(data);
}
signature = token.p11.C_Sign(session.id(), data);
}
}
doCancel = false;
if (keyAlgorithm.equals("RSA") == false) {
return dsaToASN1(signature);
} else {
return signature;
}
} catch (PKCS11Exception e) {
// As per the PKCS#11 standard, C_Sign and C_SignFinal may only
// keep the operation active on CKR_BUFFER_TOO_SMALL errors or
// successful calls to determine the output length. However,
// these cases are handled at OpenJDK's libj2pkcs11 native
// library. Thus, doCancel can safely be 'false' here.
doCancel = false;
throw new ProviderException(e);
} finally {
reset(doCancel);
}
}
// see JCA spec
@Override
protected boolean engineVerify(byte[] signature) throws SignatureException {
ensureInitialized();
boolean doCancel = true;
try {
if (keyAlgorithm.equals("DSA")) {
signature = asn1ToDSA(signature);
} else if (keyAlgorithm.equals("EC")) {
signature = asn1ToECDSA(signature);
}
if (type == T_UPDATE) {
token.p11.C_VerifyFinal(session.id(), signature);
} else {
byte[] digest;
if (type == T_DIGEST) {
digest = md.digest();
} else { // T_RAW
if (mechanism == CKM_DSA) {
if (bytesProcessed != buffer.length) {
throw new SignatureException
("Data for RawDSA must be exactly 20 bytes long");
}
digest = buffer;
} else {
if (bytesProcessed > buffer.length) {
throw new SignatureException("Data for NONEwithECDSA"
+ " must be at most " + RAW_ECDSA_MAX + " bytes long");
}
digest = new byte[bytesProcessed];
System.arraycopy(buffer, 0, digest, 0, bytesProcessed);
}
}
if (keyAlgorithm.equals("RSA") == false) {
// DSA and ECDSA
token.p11.C_Verify(session.id(), digest, signature);
} else { // RSA
byte[] data = encodeSignature(digest);
if (mechanism == CKM_RSA_X_509) {
data = pkcs1Pad(data);
}
token.p11.C_Verify(session.id(), data, signature);
}
}
doCancel = false;
return true;
} catch (PKCS11Exception e) {
doCancel = false;
long errorCode = e.getErrorCode();
if (errorCode == CKR_SIGNATURE_INVALID) {
return false;
}
if (errorCode == CKR_SIGNATURE_LEN_RANGE) {
// return false rather than throwing an exception
return false;
}
// ECF bug?
if (errorCode == CKR_DATA_LEN_RANGE) {
return false;
}
throw new ProviderException(e);
} finally {
reset(doCancel);
}
}
private byte[] pkcs1Pad(byte[] data) {
try {
int len = (p11Key.length() + 7) >> 3;
RSAPadding padding = RSAPadding.getInstance
(RSAPadding.PAD_BLOCKTYPE_1, len);
byte[] padded = padding.pad(data);
return padded;
} catch (GeneralSecurityException e) {
throw new ProviderException(e);
}
}
private byte[] encodeSignature(byte[] digest) throws SignatureException {
try {
return RSASignature.encodeSignature(digestOID, digest);
} catch (IOException e) {
throw new SignatureException("Invalid encoding", e);
}
}
// private static byte[] decodeSignature(byte[] signature) throws IOException {
// return RSASignature.decodeSignature(digestOID, signature);
// }
// For DSA and ECDSA signatures, PKCS#11 represents them as a simple
// byte array that contains the concatenation of r and s.
// For DSA, r and s are always exactly 20 bytes long.
// For ECDSA, r and s are of variable length, but we know that each
// occupies half of the array.
private static byte[] dsaToASN1(byte[] signature) {
int n = signature.length >> 1;
BigInteger r = new BigInteger(1, P11Util.subarray(signature, 0, n));
BigInteger s = new BigInteger(1, P11Util.subarray(signature, n, n));
try {
DerOutputStream outseq = new DerOutputStream(100);
outseq.putInteger(r);
outseq.putInteger(s);
DerValue result = new DerValue(DerValue.tag_Sequence,
outseq.toByteArray());
return result.toByteArray();
} catch (java.io.IOException e) {
throw new RuntimeException("Internal error", e);
}
}
private static byte[] asn1ToDSA(byte[] sig) throws SignatureException {
try {
// Enforce strict DER checking for signatures
DerInputStream in = new DerInputStream(sig, 0, sig.length, false);
DerValue[] values = in.getSequence(2);
// check number of components in the read sequence
// and trailing data
if ((values.length != 2) || (in.available() != 0)) {
throw new IOException("Invalid encoding for signature");
}
BigInteger r = values[0].getPositiveBigInteger();
BigInteger s = values[1].getPositiveBigInteger();
byte[] br = toByteArray(r, 20);
byte[] bs = toByteArray(s, 20);
if ((br == null) || (bs == null)) {
throw new SignatureException("Out of range value for R or S");
}
return P11Util.concat(br, bs);
} catch (SignatureException e) {
throw e;
} catch (Exception e) {
throw new SignatureException("Invalid encoding for signature", e);
}
}
private byte[] asn1ToECDSA(byte[] sig) throws SignatureException {
try {
// Enforce strict DER checking for signatures
DerInputStream in = new DerInputStream(sig, 0, sig.length, false);
DerValue[] values = in.getSequence(2);
// check number of components in the read sequence
// and trailing data
if ((values.length != 2) || (in.available() != 0)) {
throw new IOException("Invalid encoding for signature");
}
BigInteger r = values[0].getPositiveBigInteger();
BigInteger s = values[1].getPositiveBigInteger();
// trim leading zeroes
byte[] br = KeyUtil.trimZeroes(r.toByteArray());
byte[] bs = KeyUtil.trimZeroes(s.toByteArray());
int k = Math.max(br.length, bs.length);
// r and s each occupy half the array
byte[] res = new byte[k << 1];
System.arraycopy(br, 0, res, k - br.length, br.length);
System.arraycopy(bs, 0, res, res.length - bs.length, bs.length);
return res;
} catch (Exception e) {
throw new SignatureException("Invalid encoding for signature", e);
}
}
private static byte[] toByteArray(BigInteger bi, int len) {
byte[] b = bi.toByteArray();
int n = b.length;
if (n == len) {
return b;
}
if ((n == len + 1) && (b[0] == 0)) {
byte[] t = new byte[len];
System.arraycopy(b, 1, t, 0, len);
return t;
}
if (n > len) {
return null;
}
// must be smaller
byte[] t = new byte[len];
System.arraycopy(b, 0, t, (len - n), n);
return t;
}
// see JCA spec
@Override
protected void engineSetParameter(String param, Object value)
throws InvalidParameterException {
throw new UnsupportedOperationException("setParameter() not supported");
}
// see JCA spec
@Override
protected void engineSetParameter(AlgorithmParameterSpec params)
throws InvalidAlgorithmParameterException {
if (params != null) {
throw new InvalidAlgorithmParameterException("No parameter accepted");
}
}
// see JCA spec
@Override
protected Object engineGetParameter(String param)
throws InvalidParameterException {
throw new UnsupportedOperationException("getParameter() not supported");
}
// see JCA spec
@Override
protected AlgorithmParameters engineGetParameters() {
return null;
}
}