| /* |
| * Copyright (c) 1996, 2013, 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.ssl; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.IOException; |
| import java.util.Hashtable; |
| |
| import java.security.*; |
| import javax.crypto.*; |
| import javax.crypto.spec.SecretKeySpec; |
| import javax.crypto.spec.IvParameterSpec; |
| |
| import java.nio.*; |
| |
| import sun.security.ssl.CipherSuite.*; |
| import static sun.security.ssl.CipherSuite.*; |
| |
| import sun.misc.HexDumpEncoder; |
| |
| |
| /** |
| * This class handles bulk data enciphering/deciphering for each SSLv3 |
| * message. This provides data confidentiality. Stream ciphers (such |
| * as RC4) don't need to do padding; block ciphers (e.g. DES) need it. |
| * |
| * Individual instances are obtained by calling the static method |
| * newCipherBox(), which should only be invoked by BulkCipher.newCipher(). |
| * |
| * In RFC 2246, with bock ciphers in CBC mode, the Initialization |
| * Vector (IV) for the first record is generated with the other keys |
| * and secrets when the security parameters are set. The IV for |
| * subsequent records is the last ciphertext block from the previous |
| * record. |
| * |
| * In RFC 4346, the implicit Initialization Vector (IV) is replaced |
| * with an explicit IV to protect against CBC attacks. RFC 4346 |
| * recommends two algorithms used to generated the per-record IV. |
| * The implementation uses the algorithm (2)(b), as described at |
| * section 6.2.3.2 of RFC 4346. |
| * |
| * The usage of IV in CBC block cipher can be illustrated in |
| * the following diagrams. |
| * |
| * (random) |
| * R P1 IV C1 |
| * | | | | |
| * SIV---+ |-----+ |-... |----- |------ |
| * | | | | | | | | |
| * +----+ | +----+ | +----+ | +----+ | |
| * | Ek | | + Ek + | | Dk | | | Dk | | |
| * +----+ | +----+ | +----+ | +----+ | |
| * | | | | | | | | |
| * |----| |----| SIV--+ |----| |-... |
| * | | | | |
| * IV C1 R P1 |
| * (discard) |
| * |
| * CBC Encryption CBC Decryption |
| * |
| * NOTE that any ciphering involved in key exchange (e.g. with RSA) is |
| * handled separately. |
| * |
| * @author David Brownell |
| * @author Andreas Sterbenz |
| */ |
| final class CipherBox { |
| |
| // A CipherBox that implements the identity operation |
| final static CipherBox NULL = new CipherBox(); |
| |
| /* Class and subclass dynamic debugging support */ |
| private static final Debug debug = Debug.getInstance("ssl"); |
| |
| // the protocol version this cipher conforms to |
| private final ProtocolVersion protocolVersion; |
| |
| // cipher object |
| private final Cipher cipher; |
| |
| /** |
| * Cipher blocksize, 0 for stream ciphers |
| */ |
| private int blockSize; |
| |
| /** |
| * secure random |
| */ |
| private SecureRandom random; |
| |
| /** |
| * Is the cipher of CBC mode? |
| */ |
| private final boolean isCBCMode; |
| |
| /** |
| * Fixed masks of various block size, as the initial decryption IVs |
| * for TLS 1.1 or later. |
| * |
| * For performance, we do not use random IVs. As the initial decryption |
| * IVs will be discarded by TLS decryption processes, so the fixed masks |
| * do not hurt cryptographic strength. |
| */ |
| private static Hashtable<Integer, IvParameterSpec> masks; |
| |
| /** |
| * NULL cipherbox. Identity operation, no encryption. |
| */ |
| private CipherBox() { |
| this.protocolVersion = ProtocolVersion.DEFAULT; |
| this.cipher = null; |
| this.isCBCMode = false; |
| } |
| |
| /** |
| * Construct a new CipherBox using the cipher transformation. |
| * |
| * @exception NoSuchAlgorithmException if no appropriate JCE Cipher |
| * implementation could be found. |
| */ |
| private CipherBox(ProtocolVersion protocolVersion, BulkCipher bulkCipher, |
| SecretKey key, IvParameterSpec iv, SecureRandom random, |
| boolean encrypt) throws NoSuchAlgorithmException { |
| try { |
| this.protocolVersion = protocolVersion; |
| this.cipher = JsseJce.getCipher(bulkCipher.transformation); |
| int mode = encrypt ? Cipher.ENCRYPT_MODE : Cipher.DECRYPT_MODE; |
| |
| if (random == null) { |
| random = JsseJce.getSecureRandom(); |
| } |
| this.random = random; |
| this.isCBCMode = bulkCipher.isCBCMode; |
| |
| /* |
| * RFC 4346 recommends two algorithms used to generated the |
| * per-record IV. The implementation uses the algorithm (2)(b), |
| * as described at section 6.2.3.2 of RFC 4346. |
| * |
| * As we don't care about the initial IV value for TLS 1.1 or |
| * later, so if the "iv" parameter is null, we use the default |
| * value generated by Cipher.init() for encryption, and a fixed |
| * mask for decryption. |
| */ |
| if (iv == null && bulkCipher.ivSize != 0 && |
| mode == Cipher.DECRYPT_MODE && |
| protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| iv = getFixedMask(bulkCipher.ivSize); |
| } |
| |
| cipher.init(mode, key, iv, random); |
| |
| // Do not call getBlockSize until after init() |
| // otherwise we would disrupt JCE delayed provider selection |
| blockSize = cipher.getBlockSize(); |
| // some providers implement getBlockSize() incorrectly |
| if (blockSize == 1) { |
| blockSize = 0; |
| } |
| } catch (NoSuchAlgorithmException e) { |
| throw e; |
| } catch (Exception e) { |
| throw new NoSuchAlgorithmException |
| ("Could not create cipher " + bulkCipher, e); |
| } catch (ExceptionInInitializerError e) { |
| throw new NoSuchAlgorithmException |
| ("Could not create cipher " + bulkCipher, e); |
| } |
| } |
| |
| /* |
| * Factory method to obtain a new CipherBox object. |
| */ |
| static CipherBox newCipherBox(ProtocolVersion version, BulkCipher cipher, |
| SecretKey key, IvParameterSpec iv, SecureRandom random, |
| boolean encrypt) throws NoSuchAlgorithmException { |
| if (cipher.allowed == false) { |
| throw new NoSuchAlgorithmException("Unsupported cipher " + cipher); |
| } |
| |
| if (cipher == B_NULL) { |
| return NULL; |
| } else { |
| return new CipherBox(version, cipher, key, iv, random, encrypt); |
| } |
| } |
| |
| /* |
| * Get a fixed mask, as the initial decryption IVs for TLS 1.1 or later. |
| */ |
| private static IvParameterSpec getFixedMask(int ivSize) { |
| if (masks == null) { |
| masks = new Hashtable<Integer, IvParameterSpec>(5); |
| } |
| |
| IvParameterSpec iv = masks.get(ivSize); |
| if (iv == null) { |
| iv = new IvParameterSpec(new byte[ivSize]); |
| masks.put(ivSize, iv); |
| } |
| |
| return iv; |
| } |
| |
| /* |
| * Encrypts a block of data, returning the size of the |
| * resulting block. |
| */ |
| int encrypt(byte[] buf, int offset, int len) { |
| if (cipher == null) { |
| return len; |
| } |
| |
| try { |
| if (blockSize != 0) { |
| // TLSv1.1 needs a IV block |
| if (protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| // generate a random number |
| byte[] prefix = new byte[blockSize]; |
| random.nextBytes(prefix); |
| |
| // move forward the plaintext |
| System.arraycopy(buf, offset, |
| buf, offset + prefix.length, len); |
| |
| // prefix the plaintext |
| System.arraycopy(prefix, 0, |
| buf, offset, prefix.length); |
| |
| len += prefix.length; |
| } |
| |
| len = addPadding(buf, offset, len, blockSize); |
| } |
| if (debug != null && Debug.isOn("plaintext")) { |
| try { |
| HexDumpEncoder hd = new HexDumpEncoder(); |
| |
| System.out.println( |
| "Padded plaintext before ENCRYPTION: len = " |
| + len); |
| hd.encodeBuffer( |
| new ByteArrayInputStream(buf, offset, len), |
| System.out); |
| } catch (IOException e) { } |
| } |
| int newLen = cipher.update(buf, offset, len, buf, offset); |
| if (newLen != len) { |
| // catch BouncyCastle buffering error |
| throw new RuntimeException("Cipher buffering error " + |
| "in JCE provider " + cipher.getProvider().getName()); |
| } |
| return newLen; |
| } catch (ShortBufferException e) { |
| throw new ArrayIndexOutOfBoundsException(e.toString()); |
| } |
| } |
| |
| /* |
| * Encrypts a ByteBuffer block of data, returning the size of the |
| * resulting block. |
| * |
| * The byte buffers position and limit initially define the amount |
| * to encrypt. On return, the position and limit are |
| * set to last position padded/encrypted. The limit may have changed |
| * because of the added padding bytes. |
| */ |
| int encrypt(ByteBuffer bb) { |
| |
| int len = bb.remaining(); |
| |
| if (cipher == null) { |
| bb.position(bb.limit()); |
| return len; |
| } |
| |
| try { |
| int pos = bb.position(); |
| |
| if (blockSize != 0) { |
| // TLSv1.1 needs a IV block |
| if (protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| // generate a random number |
| byte[] prefix = new byte[blockSize]; |
| random.nextBytes(prefix); |
| |
| // move forward the plaintext |
| byte[] buf = null; |
| int limit = bb.limit(); |
| if (bb.hasArray()) { |
| int arrayOffset = bb.arrayOffset(); |
| buf = bb.array(); |
| System.arraycopy(buf, arrayOffset + pos, |
| buf, arrayOffset + pos + prefix.length, |
| limit - pos); |
| bb.limit(limit + prefix.length); |
| } else { |
| buf = new byte[limit - pos]; |
| bb.get(buf, 0, limit - pos); |
| bb.position(pos + prefix.length); |
| bb.limit(limit + prefix.length); |
| bb.put(buf); |
| } |
| bb.position(pos); |
| |
| // prefix the plaintext |
| bb.put(prefix); |
| bb.position(pos); |
| } |
| |
| // addPadding adjusts pos/limit |
| len = addPadding(bb, blockSize); |
| bb.position(pos); |
| } |
| if (debug != null && Debug.isOn("plaintext")) { |
| try { |
| HexDumpEncoder hd = new HexDumpEncoder(); |
| |
| System.out.println( |
| "Padded plaintext before ENCRYPTION: len = " |
| + len); |
| hd.encodeBuffer(bb, System.out); |
| |
| } catch (IOException e) { } |
| /* |
| * reset back to beginning |
| */ |
| bb.position(pos); |
| } |
| |
| /* |
| * Encrypt "in-place". This does not add its own padding. |
| */ |
| ByteBuffer dup = bb.duplicate(); |
| int newLen = cipher.update(dup, bb); |
| |
| if (bb.position() != dup.position()) { |
| throw new RuntimeException("bytebuffer padding error"); |
| } |
| |
| if (newLen != len) { |
| // catch BouncyCastle buffering error |
| throw new RuntimeException("Cipher buffering error " + |
| "in JCE provider " + cipher.getProvider().getName()); |
| } |
| return newLen; |
| } catch (ShortBufferException e) { |
| RuntimeException exc = new RuntimeException(e.toString()); |
| exc.initCause(e); |
| throw exc; |
| } |
| } |
| |
| |
| /* |
| * Decrypts a block of data, returning the size of the |
| * resulting block if padding was required. |
| * |
| * For SSLv3 and TLSv1.0, with block ciphers in CBC mode the |
| * Initialization Vector (IV) for the first record is generated by |
| * the handshake protocol, the IV for subsequent records is the |
| * last ciphertext block from the previous record. |
| * |
| * From TLSv1.1, the implicit IV is replaced with an explicit IV to |
| * protect against CBC attacks. |
| * |
| * Differentiating between bad_record_mac and decryption_failed alerts |
| * may permit certain attacks against CBC mode. It is preferable to |
| * uniformly use the bad_record_mac alert to hide the specific type of |
| * the error. |
| */ |
| int decrypt(byte[] buf, int offset, int len, |
| int tagLen) throws BadPaddingException { |
| if (cipher == null) { |
| return len; |
| } |
| |
| try { |
| int newLen = cipher.update(buf, offset, len, buf, offset); |
| if (newLen != len) { |
| // catch BouncyCastle buffering error |
| throw new RuntimeException("Cipher buffering error " + |
| "in JCE provider " + cipher.getProvider().getName()); |
| } |
| if (debug != null && Debug.isOn("plaintext")) { |
| try { |
| HexDumpEncoder hd = new HexDumpEncoder(); |
| |
| System.out.println( |
| "Padded plaintext after DECRYPTION: len = " |
| + newLen); |
| hd.encodeBuffer( |
| new ByteArrayInputStream(buf, offset, newLen), |
| System.out); |
| } catch (IOException e) { } |
| } |
| |
| if (blockSize != 0) { |
| newLen = removePadding( |
| buf, offset, newLen, tagLen, blockSize, protocolVersion); |
| |
| if (protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| if (newLen < blockSize) { |
| throw new BadPaddingException("invalid explicit IV"); |
| } |
| |
| // discards the first cipher block, the IV component. |
| System.arraycopy(buf, offset + blockSize, |
| buf, offset, newLen - blockSize); |
| |
| newLen -= blockSize; |
| } |
| } |
| return newLen; |
| } catch (ShortBufferException e) { |
| throw new ArrayIndexOutOfBoundsException(e.toString()); |
| } |
| } |
| |
| |
| /* |
| * Decrypts a block of data, returning the size of the |
| * resulting block if padding was required. position and limit |
| * point to the end of the decrypted/depadded data. The initial |
| * limit and new limit may be different, given we may |
| * have stripped off some padding bytes. |
| * |
| * @see decrypt(byte[], int, int) |
| */ |
| int decrypt(ByteBuffer bb, int tagLen) throws BadPaddingException { |
| |
| int len = bb.remaining(); |
| |
| if (cipher == null) { |
| bb.position(bb.limit()); |
| return len; |
| } |
| |
| try { |
| /* |
| * Decrypt "in-place". |
| */ |
| int pos = bb.position(); |
| ByteBuffer dup = bb.duplicate(); |
| int newLen = cipher.update(dup, bb); |
| if (newLen != len) { |
| // catch BouncyCastle buffering error |
| throw new RuntimeException("Cipher buffering error " + |
| "in JCE provider " + cipher.getProvider().getName()); |
| } |
| |
| if (debug != null && Debug.isOn("plaintext")) { |
| try { |
| HexDumpEncoder hd = new HexDumpEncoder(); |
| |
| System.out.println( |
| "Padded plaintext after DECRYPTION: len = " |
| + newLen); |
| |
| hd.encodeBuffer( |
| (ByteBuffer)bb.duplicate().position(pos), System.out); |
| } catch (IOException e) { } |
| } |
| |
| /* |
| * Remove the block padding. |
| */ |
| if (blockSize != 0) { |
| bb.position(pos); |
| newLen = removePadding( |
| bb, tagLen, blockSize, protocolVersion); |
| |
| if (protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| if (newLen < blockSize) { |
| throw new BadPaddingException("invalid explicit IV"); |
| } |
| |
| // discards the first cipher block, the IV component. |
| byte[] buf = null; |
| int limit = bb.limit(); |
| if (bb.hasArray()) { |
| int arrayOffset = bb.arrayOffset(); |
| buf = bb.array(); |
| System.arraycopy(buf, arrayOffset + pos + blockSize, |
| buf, arrayOffset + pos, limit - pos - blockSize); |
| bb.limit(limit - blockSize); |
| } else { |
| buf = new byte[limit - pos - blockSize]; |
| bb.position(pos + blockSize); |
| bb.get(buf); |
| bb.position(pos); |
| bb.put(buf); |
| bb.limit(limit - blockSize); |
| } |
| |
| // reset the position to the end of the decrypted data |
| limit = bb.limit(); |
| bb.position(limit); |
| } |
| } |
| return newLen; |
| } catch (ShortBufferException e) { |
| RuntimeException exc = new RuntimeException(e.toString()); |
| exc.initCause(e); |
| throw exc; |
| } |
| } |
| |
| private static int addPadding(byte[] buf, int offset, int len, |
| int blockSize) { |
| int newlen = len + 1; |
| byte pad; |
| int i; |
| |
| if ((newlen % blockSize) != 0) { |
| newlen += blockSize - 1; |
| newlen -= newlen % blockSize; |
| } |
| pad = (byte) (newlen - len); |
| |
| if (buf.length < (newlen + offset)) { |
| throw new IllegalArgumentException("no space to pad buffer"); |
| } |
| |
| /* |
| * TLS version of the padding works for both SSLv3 and TLSv1 |
| */ |
| for (i = 0, offset += len; i < pad; i++) { |
| buf [offset++] = (byte) (pad - 1); |
| } |
| return newlen; |
| } |
| |
| /* |
| * Apply the padding to the buffer. |
| * |
| * Limit is advanced to the new buffer length. |
| * Position is equal to limit. |
| */ |
| private static int addPadding(ByteBuffer bb, int blockSize) { |
| |
| int len = bb.remaining(); |
| int offset = bb.position(); |
| |
| int newlen = len + 1; |
| byte pad; |
| int i; |
| |
| if ((newlen % blockSize) != 0) { |
| newlen += blockSize - 1; |
| newlen -= newlen % blockSize; |
| } |
| pad = (byte) (newlen - len); |
| |
| /* |
| * Update the limit to what will be padded. |
| */ |
| bb.limit(newlen + offset); |
| |
| /* |
| * TLS version of the padding works for both SSLv3 and TLSv1 |
| */ |
| for (i = 0, offset += len; i < pad; i++) { |
| bb.put(offset++, (byte) (pad - 1)); |
| } |
| |
| bb.position(offset); |
| bb.limit(offset); |
| |
| return newlen; |
| } |
| |
| /* |
| * A constant-time check of the padding. |
| * |
| * NOTE that we are checking both the padding and the padLen bytes here. |
| * |
| * The caller MUST ensure that the len parameter is a positive number. |
| */ |
| private static int[] checkPadding( |
| byte[] buf, int offset, int len, byte pad) { |
| |
| if (len <= 0) { |
| throw new RuntimeException("padding len must be positive"); |
| } |
| |
| // An array of hits is used to prevent Hotspot optimization for |
| // the purpose of a constant-time check. |
| int[] results = {0, 0}; // {missed #, matched #} |
| for (int i = 0; i <= 256;) { |
| for (int j = 0; j < len && i <= 256; j++, i++) { // j <= i |
| if (buf[offset + j] != pad) { |
| results[0]++; // mismatched padding data |
| } else { |
| results[1]++; // matched padding data |
| } |
| } |
| } |
| |
| return results; |
| } |
| |
| /* |
| * A constant-time check of the padding. |
| * |
| * NOTE that we are checking both the padding and the padLen bytes here. |
| * |
| * The caller MUST ensure that the bb parameter has remaining. |
| */ |
| private static int[] checkPadding(ByteBuffer bb, byte pad) { |
| |
| if (!bb.hasRemaining()) { |
| throw new RuntimeException("hasRemaining() must be positive"); |
| } |
| |
| // An array of hits is used to prevent Hotspot optimization for |
| // the purpose of a constant-time check. |
| int[] results = {0, 0}; // {missed #, matched #} |
| bb.mark(); |
| for (int i = 0; i <= 256; bb.reset()) { |
| for (; bb.hasRemaining() && i <= 256; i++) { |
| if (bb.get() != pad) { |
| results[0]++; // mismatched padding data |
| } else { |
| results[1]++; // matched padding data |
| } |
| } |
| } |
| |
| return results; |
| } |
| |
| /* |
| * Typical TLS padding format for a 64 bit block cipher is as follows: |
| * xx xx xx xx xx xx xx 00 |
| * xx xx xx xx xx xx 01 01 |
| * ... |
| * xx 06 06 06 06 06 06 06 |
| * 07 07 07 07 07 07 07 07 |
| * TLS also allows any amount of padding from 1 and 256 bytes as long |
| * as it makes the data a multiple of the block size |
| */ |
| private static int removePadding(byte[] buf, int offset, int len, |
| int tagLen, int blockSize, |
| ProtocolVersion protocolVersion) throws BadPaddingException { |
| |
| // last byte is length byte (i.e. actual padding length - 1) |
| int padOffset = offset + len - 1; |
| int padLen = buf[padOffset] & 0xFF; |
| |
| int newLen = len - (padLen + 1); |
| if ((newLen - tagLen) < 0) { |
| // If the buffer is not long enough to contain the padding plus |
| // a MAC tag, do a dummy constant-time padding check. |
| // |
| // Note that it is a dummy check, so we won't care about what is |
| // the actual padding data. |
| checkPadding(buf, offset, len, (byte)(padLen & 0xFF)); |
| |
| throw new BadPaddingException("Invalid Padding length: " + padLen); |
| } |
| |
| // The padding data should be filled with the padding length value. |
| int[] results = checkPadding(buf, offset + newLen, |
| padLen + 1, (byte)(padLen & 0xFF)); |
| if (protocolVersion.v >= ProtocolVersion.TLS10.v) { |
| if (results[0] != 0) { // padding data has invalid bytes |
| throw new BadPaddingException("Invalid TLS padding data"); |
| } |
| } else { // SSLv3 |
| // SSLv3 requires 0 <= length byte < block size |
| // some implementations do 1 <= length byte <= block size, |
| // so accept that as well |
| // v3 does not require any particular value for the other bytes |
| if (padLen > blockSize) { |
| throw new BadPaddingException("Invalid SSLv3 padding"); |
| } |
| } |
| return newLen; |
| } |
| |
| /* |
| * Position/limit is equal the removed padding. |
| */ |
| private static int removePadding(ByteBuffer bb, |
| int tagLen, int blockSize, |
| ProtocolVersion protocolVersion) throws BadPaddingException { |
| |
| int len = bb.remaining(); |
| int offset = bb.position(); |
| |
| // last byte is length byte (i.e. actual padding length - 1) |
| int padOffset = offset + len - 1; |
| int padLen = bb.get(padOffset) & 0xFF; |
| |
| int newLen = len - (padLen + 1); |
| if ((newLen - tagLen) < 0) { |
| // If the buffer is not long enough to contain the padding plus |
| // a MAC tag, do a dummy constant-time padding check. |
| // |
| // Note that it is a dummy check, so we won't care about what is |
| // the actual padding data. |
| checkPadding(bb.duplicate(), (byte)(padLen & 0xFF)); |
| |
| throw new BadPaddingException("Invalid Padding length: " + padLen); |
| } |
| |
| // The padding data should be filled with the padding length value. |
| int[] results = checkPadding( |
| (ByteBuffer)bb.duplicate().position(offset + newLen), |
| (byte)(padLen & 0xFF)); |
| if (protocolVersion.v >= ProtocolVersion.TLS10.v) { |
| if (results[0] != 0) { // padding data has invalid bytes |
| throw new BadPaddingException("Invalid TLS padding data"); |
| } |
| } else { // SSLv3 |
| // SSLv3 requires 0 <= length byte < block size |
| // some implementations do 1 <= length byte <= block size, |
| // so accept that as well |
| // v3 does not require any particular value for the other bytes |
| if (padLen > blockSize) { |
| throw new BadPaddingException("Invalid SSLv3 padding"); |
| } |
| } |
| |
| /* |
| * Reset buffer limit to remove padding. |
| */ |
| bb.position(offset + newLen); |
| bb.limit(offset + newLen); |
| |
| return newLen; |
| } |
| |
| /* |
| * Dispose of any intermediate state in the underlying cipher. |
| * For PKCS11 ciphers, this will release any attached sessions, and |
| * thus make finalization faster. |
| */ |
| void dispose() { |
| try { |
| if (cipher != null) { |
| // ignore return value. |
| cipher.doFinal(); |
| } |
| } catch (GeneralSecurityException e) { |
| // swallow for now. |
| } |
| } |
| |
| /* |
| * Does the cipher use CBC mode? |
| * |
| * @return true if the cipher use CBC mode, false otherwise. |
| */ |
| boolean isCBCMode() { |
| return isCBCMode; |
| } |
| |
| /** |
| * Is the cipher null? |
| * |
| * @return true if the cipher is null, false otherwise. |
| */ |
| boolean isNullCipher() { |
| return cipher == null; |
| } |
| |
| /** |
| * Sanity check the length of a fragment before decryption. |
| * |
| * In CBC mode, check that the fragment length is one or multiple times |
| * of the block size of the cipher suite, and is at least one (one is the |
| * smallest size of padding in CBC mode) bigger than the tag size of the |
| * MAC algorithm except the explicit IV size for TLS 1.1 or later. |
| * |
| * In non-CBC mode, check that the fragment length is not less than the |
| * tag size of the MAC algorithm. |
| * |
| * @return true if the length of a fragment matches above requirements |
| */ |
| boolean sanityCheck(int tagLen, int fragmentLen) { |
| if (!isCBCMode) { |
| return fragmentLen >= tagLen; |
| } |
| |
| if ((fragmentLen % blockSize) == 0) { |
| int minimal = tagLen + 1; |
| minimal = (minimal >= blockSize) ? minimal : blockSize; |
| if (protocolVersion.v >= ProtocolVersion.TLS11.v) { |
| minimal += blockSize; // plus the size of the explicit IV |
| } |
| |
| return (fragmentLen >= minimal); |
| } |
| |
| return false; |
| } |
| |
| } |
