예제 #1
0
  public byte[] decodeCiphertext(short type, byte[] ciphertext, int offset, int len)
      throws IOException {
    int blockSize = decryptCipher.getBlockSize();
    int macSize = readMac.getSize();

    /*
     *  TODO[TLS 1.1] Explicit IV implies minLen = blockSize + max(blockSize, macSize + 1),
     *  and will need further changes to offset and plen variables below.
     */

    int minLen = Math.max(blockSize, macSize + 1);
    if (len < minLen) {
      throw new TlsFatalAlert(AlertDescription.decode_error);
    }

    if (len % blockSize != 0) {
      throw new TlsFatalAlert(AlertDescription.decryption_failed);
    }

    for (int i = 0; i < len; i += blockSize) {
      decryptCipher.processBlock(ciphertext, offset + i, ciphertext, offset + i);
    }

    int plen = len;

    // If there's anything wrong with the padding, this will return zero
    int totalPad = checkPaddingConstantTime(ciphertext, offset, plen, blockSize, macSize);

    int macInputLen = plen - totalPad - macSize;

    byte[] decryptedMac =
        Arrays.copyOfRange(ciphertext, offset + macInputLen, offset + macInputLen + macSize);
    byte[] calculatedMac =
        readMac.calculateMacConstantTime(
            type, ciphertext, offset, macInputLen, plen - macSize, randomData);

    boolean badMac = !Arrays.constantTimeAreEqual(calculatedMac, decryptedMac);

    if (badMac || totalPad == 0) {
      throw new TlsFatalAlert(AlertDescription.bad_record_mac);
    }

    return Arrays.copyOfRange(ciphertext, offset, offset + macInputLen);
  }
예제 #2
0
  /** @deprecated */
  private boolean verifyDigest(byte[] digest, PublicKey key, byte[] signature, Provider sigProvider)
      throws NoSuchAlgorithmException, CMSException {
    String encName = CMSSignedHelper.INSTANCE.getEncryptionAlgName(this.getEncryptionAlgOID());

    try {
      if (encName.equals("RSA")) {
        Cipher c =
            CMSEnvelopedHelper.INSTANCE.createAsymmetricCipher("RSA/ECB/PKCS1Padding", sigProvider);

        c.init(Cipher.DECRYPT_MODE, key);

        DigestInfo digInfo = derDecode(c.doFinal(signature));

        if (!digInfo.getAlgorithmId().getObjectId().equals(digestAlgorithm.getObjectId())) {
          return false;
        }

        if (!isNull(digInfo.getAlgorithmId().getParameters())) {
          return false;
        }

        byte[] sigHash = digInfo.getDigest();

        return Arrays.constantTimeAreEqual(digest, sigHash);
      } else if (encName.equals("DSA")) {
        Signature sig = CMSSignedHelper.INSTANCE.getSignatureInstance("NONEwithDSA", sigProvider);

        sig.initVerify(key);

        sig.update(digest);

        return sig.verify(signature);
      } else {
        throw new CMSException("algorithm: " + encName + " not supported in base signatures.");
      }
    } catch (GeneralSecurityException e) {
      throw new CMSException("Exception processing signature: " + e, e);
    } catch (IOException e) {
      throw new CMSException("Exception decoding signature: " + e, e);
    }
  }
 /**
  * @param key
  * @param checksum
  * @return true if okay, false otherwise.
  * @see http://www.w3.org/TR/xmlenc-core/#sec-CMSKeyChecksum
  */
 private boolean checkCMSKeyChecksum(byte[] key, byte[] checksum) {
   return Arrays.constantTimeAreEqual(calculateCMSKeyChecksum(key), checksum);
 }
예제 #4
0
  /**
   * Process a packet of data for either CCM decryption or encryption.
   *
   * @param in data for processing.
   * @param inOff offset at which data starts in the input array.
   * @param inLen length of the data in the input array.
   * @param output output array.
   * @param outOff offset into output array to start putting processed bytes.
   * @return the number of bytes added to output.
   * @throws IllegalStateException if the cipher is not appropriately set up.
   * @throws InvalidCipherTextException if the input data is truncated or the mac check fails.
   * @throws DataLengthException if output buffer too short.
   */
  public int processPacket(byte[] in, int inOff, int inLen, byte[] output, int outOff)
      throws IllegalStateException, InvalidCipherTextException, DataLengthException {
    // TODO: handle null keyParam (e.g. via RepeatedKeySpec)
    // Need to keep the CTR and CBC Mac parts around and reset
    if (keyParam == null) {
      throw new IllegalStateException("CCM cipher unitialized.");
    }

    int n = nonce.length;
    int q = 15 - n;
    if (q < 4) {
      int limitLen = 1 << (8 * q);
      if (inLen >= limitLen) {
        throw new IllegalStateException("CCM packet too large for choice of q.");
      }
    }

    byte[] iv = new byte[blockSize];
    iv[0] = (byte) ((q - 1) & 0x7);
    System.arraycopy(nonce, 0, iv, 1, nonce.length);

    BlockCipher ctrCipher = new SICBlockCipher(cipher);
    ctrCipher.init(forEncryption, new ParametersWithIV(keyParam, iv));

    int outputLen;
    int inIndex = inOff;
    int outIndex = outOff;

    if (forEncryption) {
      outputLen = inLen + macSize;
      if (output.length < (outputLen + outOff)) {
        throw new DataLengthException("Output buffer too short.");
      }

      calculateMac(in, inOff, inLen, macBlock);

      ctrCipher.processBlock(macBlock, 0, macBlock, 0); // S0

      while (inIndex < (inOff + inLen - blockSize)) // S1...
      {
        ctrCipher.processBlock(in, inIndex, output, outIndex);
        outIndex += blockSize;
        inIndex += blockSize;
      }

      byte[] block = new byte[blockSize];

      System.arraycopy(in, inIndex, block, 0, inLen + inOff - inIndex);

      ctrCipher.processBlock(block, 0, block, 0);

      System.arraycopy(block, 0, output, outIndex, inLen + inOff - inIndex);

      System.arraycopy(macBlock, 0, output, outOff + inLen, macSize);
    } else {
      if (inLen < macSize) {
        throw new InvalidCipherTextException("data too short");
      }
      outputLen = inLen - macSize;
      if (output.length < (outputLen + outOff)) {
        throw new DataLengthException("Output buffer too short.");
      }

      System.arraycopy(in, inOff + outputLen, macBlock, 0, macSize);

      ctrCipher.processBlock(macBlock, 0, macBlock, 0);

      for (int i = macSize; i != macBlock.length; i++) {
        macBlock[i] = 0;
      }

      while (inIndex < (inOff + outputLen - blockSize)) {
        ctrCipher.processBlock(in, inIndex, output, outIndex);
        outIndex += blockSize;
        inIndex += blockSize;
      }

      byte[] block = new byte[blockSize];

      System.arraycopy(in, inIndex, block, 0, outputLen - (inIndex - inOff));

      ctrCipher.processBlock(block, 0, block, 0);

      System.arraycopy(block, 0, output, outIndex, outputLen - (inIndex - inOff));

      byte[] calculatedMacBlock = new byte[blockSize];

      calculateMac(output, outOff, outputLen, calculatedMacBlock);

      if (!Arrays.constantTimeAreEqual(macBlock, calculatedMacBlock)) {
        throw new InvalidCipherTextException("mac check in CCM failed");
      }
    }

    return outputLen;
  }
예제 #5
0
  protected void processClientHello(ServerHandshakeState state, byte[] body) throws IOException {
    ByteArrayInputStream buf = new ByteArrayInputStream(body);

    // TODO Read RFCs for guidance on the expected record layer version number
    ProtocolVersion client_version = TlsUtils.readVersion(buf);
    if (!client_version.isDTLS()) {
      throw new TlsFatalAlert(AlertDescription.illegal_parameter);
    }

    /*
     * Read the client random
     */
    byte[] client_random = TlsUtils.readFully(32, buf);

    byte[] sessionID = TlsUtils.readOpaque8(buf);
    if (sessionID.length > 32) {
      throw new TlsFatalAlert(AlertDescription.illegal_parameter);
    }

    // TODO RFC 4347 has the cookie length restricted to 32, but not in RFC 6347
    byte[] cookie = TlsUtils.readOpaque8(buf);

    int cipher_suites_length = TlsUtils.readUint16(buf);
    if (cipher_suites_length < 2 || (cipher_suites_length & 1) != 0) {
      throw new TlsFatalAlert(AlertDescription.decode_error);
    }

    /*
     * NOTE: "If the session_id field is not empty (implying a session resumption request) this
     * vector must include at least the cipher_suite from that session."
     */
    state.offeredCipherSuites = TlsUtils.readUint16Array(cipher_suites_length / 2, buf);

    int compression_methods_length = TlsUtils.readUint8(buf);
    if (compression_methods_length < 1) {
      throw new TlsFatalAlert(AlertDescription.illegal_parameter);
    }

    state.offeredCompressionMethods = TlsUtils.readUint8Array(compression_methods_length, buf);

    /*
     * TODO RFC 3546 2.3 If [...] the older session is resumed, then the server MUST ignore
     * extensions appearing in the client hello, and send a server hello containing no
     * extensions.
     */
    state.clientExtensions = TlsProtocol.readExtensions(buf);

    state.serverContext.setClientVersion(client_version);

    state.server.notifyClientVersion(client_version);

    state.serverContext.getSecurityParameters().clientRandom = client_random;

    state.server.notifyOfferedCipherSuites(state.offeredCipherSuites);
    state.server.notifyOfferedCompressionMethods(state.offeredCompressionMethods);

    /*
     * RFC 5746 3.6. Server Behavior: Initial Handshake
     */
    {
      /*
       * RFC 5746 3.4. The client MUST include either an empty "renegotiation_info" extension,
       * or the TLS_EMPTY_RENEGOTIATION_INFO_SCSV signaling cipher suite value in the
       * ClientHello. Including both is NOT RECOMMENDED.
       */

      /*
       * When a ClientHello is received, the server MUST check if it includes the
       * TLS_EMPTY_RENEGOTIATION_INFO_SCSV SCSV. If it does, set the secure_renegotiation flag
       * to TRUE.
       */
      if (Arrays.contains(
          state.offeredCipherSuites, CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV)) {
        state.secure_renegotiation = true;
      }

      /*
       * The server MUST check if the "renegotiation_info" extension is included in the
       * ClientHello.
       */
      byte[] renegExtData =
          TlsUtils.getExtensionData(state.clientExtensions, TlsProtocol.EXT_RenegotiationInfo);
      if (renegExtData != null) {
        /*
         * If the extension is present, set secure_renegotiation flag to TRUE. The
         * server MUST then verify that the length of the "renegotiated_connection"
         * field is zero, and if it is not, MUST abort the handshake.
         */
        state.secure_renegotiation = true;

        if (!Arrays.constantTimeAreEqual(
            renegExtData, TlsProtocol.createRenegotiationInfo(TlsUtils.EMPTY_BYTES))) {
          throw new TlsFatalAlert(AlertDescription.handshake_failure);
        }
      }
    }

    state.server.notifySecureRenegotiation(state.secure_renegotiation);

    if (state.clientExtensions != null) {
      state.server.processClientExtensions(state.clientExtensions);
    }
  }
예제 #6
0
  private boolean doVerify(SignerInformationVerifier verifier) throws CMSException {
    String digestName = CMSSignedHelper.INSTANCE.getDigestAlgName(this.getDigestAlgOID());
    String encName = CMSSignedHelper.INSTANCE.getEncryptionAlgName(this.getEncryptionAlgOID());
    String signatureName = digestName + "with" + encName;

    try {
      if (digestCalculator != null) {
        resultDigest = digestCalculator.getDigest();
      } else {
        DigestCalculator calc = verifier.getDigestCalculator(this.getDigestAlgorithmID());
        if (content != null) {
          OutputStream digOut = calc.getOutputStream();

          content.write(digOut);

          digOut.close();
        } else if (signedAttributeSet == null) {
          // TODO Get rid of this exception and just treat content==null as empty not missing?
          throw new CMSException("data not encapsulated in signature - use detached constructor.");
        }

        resultDigest = calc.getDigest();
      }
    } catch (IOException e) {
      throw new CMSException("can't process mime object to create signature.", e);
    } catch (NoSuchAlgorithmException e) {
      throw new CMSException("can't find algorithm: " + e.getMessage(), e);
    } catch (OperatorCreationException e) {
      throw new CMSException("can't create digest calculator: " + e.getMessage(), e);
    }

    // RFC 3852 11.1 Check the content-type attribute is correct
    {
      DERObject validContentType =
          getSingleValuedSignedAttribute(CMSAttributes.contentType, "content-type");
      if (validContentType == null) {
        if (!isCounterSignature && signedAttributeSet != null) {
          throw new CMSException(
              "The content-type attribute type MUST be present whenever signed attributes are present in signed-data");
        }
      } else {
        if (isCounterSignature) {
          throw new CMSException(
              "[For counter signatures,] the signedAttributes field MUST NOT contain a content-type attribute");
        }

        if (!(validContentType instanceof DERObjectIdentifier)) {
          throw new CMSException(
              "content-type attribute value not of ASN.1 type 'OBJECT IDENTIFIER'");
        }

        DERObjectIdentifier signedContentType = (DERObjectIdentifier) validContentType;

        if (!signedContentType.equals(contentType)) {
          throw new CMSException("content-type attribute value does not match eContentType");
        }
      }
    }

    // RFC 3852 11.2 Check the message-digest attribute is correct
    {
      DERObject validMessageDigest =
          getSingleValuedSignedAttribute(CMSAttributes.messageDigest, "message-digest");
      if (validMessageDigest == null) {
        if (signedAttributeSet != null) {
          throw new CMSException(
              "the message-digest signed attribute type MUST be present when there are any signed attributes present");
        }
      } else {
        if (!(validMessageDigest instanceof ASN1OctetString)) {
          throw new CMSException("message-digest attribute value not of ASN.1 type 'OCTET STRING'");
        }

        ASN1OctetString signedMessageDigest = (ASN1OctetString) validMessageDigest;

        if (!Arrays.constantTimeAreEqual(resultDigest, signedMessageDigest.getOctets())) {
          throw new CMSSignerDigestMismatchException(
              "message-digest attribute value does not match calculated value");
        }
      }
    }

    // RFC 3852 11.4 Validate countersignature attribute(s)
    {
      AttributeTable signedAttrTable = this.getSignedAttributes();
      if (signedAttrTable != null
          && signedAttrTable.getAll(CMSAttributes.counterSignature).size() > 0) {
        throw new CMSException("A countersignature attribute MUST NOT be a signed attribute");
      }

      AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
      if (unsignedAttrTable != null) {
        ASN1EncodableVector csAttrs = unsignedAttrTable.getAll(CMSAttributes.counterSignature);
        for (int i = 0; i < csAttrs.size(); ++i) {
          Attribute csAttr = (Attribute) csAttrs.get(i);
          if (csAttr.getAttrValues().size() < 1) {
            throw new CMSException(
                "A countersignature attribute MUST contain at least one AttributeValue");
          }

          // Note: We don't recursively validate the countersignature value
        }
      }
    }

    try {
      ContentVerifier contentVerifier =
          verifier.getContentVerifier(sigAlgFinder.find(signatureName));
      OutputStream sigOut = contentVerifier.getOutputStream();

      if (signedAttributeSet == null) {
        if (digestCalculator != null) {
          if (contentVerifier instanceof RawContentVerifier) {
            RawContentVerifier rawVerifier = (RawContentVerifier) contentVerifier;

            if (encName.equals("RSA")) {
              DigestInfo digInfo = new DigestInfo(digestAlgorithm, resultDigest);

              return rawVerifier.verify(digInfo.getDEREncoded(), this.getSignature());
            }

            return rawVerifier.verify(resultDigest, this.getSignature());
          }

          throw new CMSException("verifier unable to process raw signature");
        } else if (content != null) {
          // TODO Use raw signature of the hash value instead
          content.write(sigOut);
        }
      } else {
        sigOut.write(this.getEncodedSignedAttributes());
      }

      sigOut.close();

      return contentVerifier.verify(this.getSignature());
    } catch (IOException e) {
      throw new CMSException("can't process mime object to create signature.", e);
    } catch (OperatorCreationException e) {
      throw new CMSException("can't create content verifier: " + e.getMessage(), e);
    }
  }
예제 #7
0
  /** @deprecated */
  private boolean doVerify(PublicKey key, Provider sigProvider)
      throws CMSException, NoSuchAlgorithmException {
    String digestName = CMSSignedHelper.INSTANCE.getDigestAlgName(this.getDigestAlgOID());
    String encName = CMSSignedHelper.INSTANCE.getEncryptionAlgName(this.getEncryptionAlgOID());
    String signatureName = digestName + "with" + encName;
    Signature sig = CMSSignedHelper.INSTANCE.getSignatureInstance(signatureName, sigProvider);
    MessageDigest digest = CMSSignedHelper.INSTANCE.getDigestInstance(digestName, sigProvider);

    // TODO [BJA-109] Note: PSSParameterSpec requires JDK1.4+
    /*
            try
            {
                DERObjectIdentifier sigAlgOID = encryptionAlgorithm.getObjectId();
                DEREncodable sigParams = this.encryptionAlgorithm.getParameters();
                if (sigAlgOID.equals(PKCSObjectIdentifiers.id_RSASSA_PSS))
                {
                    // RFC 4056
                    // When the id-RSASSA-PSS algorithm identifier is used for a signature,
                    // the AlgorithmIdentifier parameters field MUST contain RSASSA-PSS-params.
                    if (sigParams == null)
                    {
                        throw new CMSException(
                            "RSASSA-PSS signature must specify algorithm parameters");
                    }

                    AlgorithmParameters params = AlgorithmParameters.getInstance(
                        sigAlgOID.getId(), sig.getProvider().getName());
                    params.init(sigParams.getDERObject().getEncoded(), "ASN.1");

                    PSSParameterSpec spec = (PSSParameterSpec)params.getParameterSpec(PSSParameterSpec.class);
                    sig.setParameter(spec);
                }
                else
                {
                    // TODO Are there other signature algorithms that provide parameters?
                    if (sigParams != null)
                    {
                        throw new CMSException("unrecognised signature parameters provided");
                    }
                }
            }
            catch (IOException e)
            {
                throw new CMSException("error encoding signature parameters.", e);
            }
            catch (InvalidAlgorithmParameterException e)
            {
                throw new CMSException("error setting signature parameters.", e);
            }
            catch (InvalidParameterSpecException e)
            {
                throw new CMSException("error processing signature parameters.", e);
            }
    */

    try {
      if (digestCalculator != null) {
        resultDigest = digestCalculator.getDigest();
      } else {
        if (content != null) {
          content.write(new DigOutputStream(digest));
        } else if (signedAttributeSet == null) {
          // TODO Get rid of this exception and just treat content==null as empty not missing?
          throw new CMSException("data not encapsulated in signature - use detached constructor.");
        }

        resultDigest = digest.digest();
      }
    } catch (IOException e) {
      throw new CMSException("can't process mime object to create signature.", e);
    }

    // RFC 3852 11.1 Check the content-type attribute is correct
    {
      DERObject validContentType =
          getSingleValuedSignedAttribute(CMSAttributes.contentType, "content-type");
      if (validContentType == null) {
        if (!isCounterSignature && signedAttributeSet != null) {
          throw new CMSException(
              "The content-type attribute type MUST be present whenever signed attributes are present in signed-data");
        }
      } else {
        if (isCounterSignature) {
          throw new CMSException(
              "[For counter signatures,] the signedAttributes field MUST NOT contain a content-type attribute");
        }

        if (!(validContentType instanceof DERObjectIdentifier)) {
          throw new CMSException(
              "content-type attribute value not of ASN.1 type 'OBJECT IDENTIFIER'");
        }

        DERObjectIdentifier signedContentType = (DERObjectIdentifier) validContentType;

        if (!signedContentType.equals(contentType)) {
          throw new CMSException("content-type attribute value does not match eContentType");
        }
      }
    }

    // RFC 3852 11.2 Check the message-digest attribute is correct
    {
      DERObject validMessageDigest =
          getSingleValuedSignedAttribute(CMSAttributes.messageDigest, "message-digest");
      if (validMessageDigest == null) {
        if (signedAttributeSet != null) {
          throw new CMSException(
              "the message-digest signed attribute type MUST be present when there are any signed attributes present");
        }
      } else {
        if (!(validMessageDigest instanceof ASN1OctetString)) {
          throw new CMSException("message-digest attribute value not of ASN.1 type 'OCTET STRING'");
        }

        ASN1OctetString signedMessageDigest = (ASN1OctetString) validMessageDigest;

        if (!Arrays.constantTimeAreEqual(resultDigest, signedMessageDigest.getOctets())) {
          throw new CMSSignerDigestMismatchException(
              "message-digest attribute value does not match calculated value");
        }
      }
    }

    // RFC 3852 11.4 Validate countersignature attribute(s)
    {
      AttributeTable signedAttrTable = this.getSignedAttributes();
      if (signedAttrTable != null
          && signedAttrTable.getAll(CMSAttributes.counterSignature).size() > 0) {
        throw new CMSException("A countersignature attribute MUST NOT be a signed attribute");
      }

      AttributeTable unsignedAttrTable = this.getUnsignedAttributes();
      if (unsignedAttrTable != null) {
        ASN1EncodableVector csAttrs = unsignedAttrTable.getAll(CMSAttributes.counterSignature);
        for (int i = 0; i < csAttrs.size(); ++i) {
          Attribute csAttr = (Attribute) csAttrs.get(i);
          if (csAttr.getAttrValues().size() < 1) {
            throw new CMSException(
                "A countersignature attribute MUST contain at least one AttributeValue");
          }

          // Note: We don't recursively validate the countersignature value
        }
      }
    }

    try {
      sig.initVerify(key);

      if (signedAttributeSet == null) {
        if (digestCalculator != null) {
          // need to decrypt signature and check message bytes
          return verifyDigest(resultDigest, key, this.getSignature(), sigProvider);
        } else if (content != null) {
          // TODO Use raw signature of the hash value instead
          content.write(new SigOutputStream(sig));
        }
      } else {
        sig.update(this.getEncodedSignedAttributes());
      }

      return sig.verify(this.getSignature());
    } catch (InvalidKeyException e) {
      throw new CMSException("key not appropriate to signature in message.", e);
    } catch (IOException e) {
      throw new CMSException("can't process mime object to create signature.", e);
    } catch (SignatureException e) {
      throw new CMSException("invalid signature format in message: " + e.getMessage(), e);
    }
  }
예제 #8
0
  private void processHandshakeMessage(short type, byte[] buf) throws IOException {
    ByteArrayInputStream is = new ByteArrayInputStream(buf);

    switch (type) {
      case HandshakeType.certificate:
        {
          switch (connection_state) {
            case CS_SERVER_HELLO_RECEIVED:
              {
                // Parse the Certificate message and send to cipher suite

                Certificate serverCertificate = Certificate.parse(is);

                assertEmpty(is);

                this.keyExchange.processServerCertificate(serverCertificate);

                this.authentication = tlsClient.getAuthentication();
                this.authentication.notifyServerCertificate(serverCertificate);

                break;
              }
            default:
              this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
          }

          connection_state = CS_SERVER_CERTIFICATE_RECEIVED;
          break;
        }
      case HandshakeType.finished:
        switch (connection_state) {
          case CS_SERVER_CHANGE_CIPHER_SPEC_RECEIVED:
            /*
             * Read the checksum from the finished message, it has always 12
             * bytes for TLS 1.0 and 36 for SSLv3.
             */
            boolean isTls =
                tlsClientContext.getServerVersion().getFullVersion()
                    >= ProtocolVersion.TLSv10.getFullVersion();

            int checksumLength = isTls ? 12 : 36;
            byte[] serverVerifyData = new byte[checksumLength];
            TlsUtils.readFully(serverVerifyData, is);

            assertEmpty(is);

            /*
             * Calculate our own checksum.
             */
            byte[] expectedServerVerifyData =
                TlsUtils.calculateVerifyData(
                    tlsClientContext, "server finished", rs.getCurrentHash(TlsUtils.SSL_SERVER));

            /*
             * Compare both checksums.
             */
            if (!Arrays.constantTimeAreEqual(expectedServerVerifyData, serverVerifyData)) {
              /*
               * Wrong checksum in the finished message.
               */
              this.failWithError(AlertLevel.fatal, AlertDescription.handshake_failure);
            }

            connection_state = CS_DONE;

            /*
             * We are now ready to receive application data.
             */
            this.appDataReady = true;
            break;
          default:
            this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
        }
        break;
      case HandshakeType.server_hello:
        switch (connection_state) {
          case CS_CLIENT_HELLO_SEND:
            /*
             * Read the server hello message
             */
            ProtocolVersion server_version = TlsUtils.readVersion(is);
            ProtocolVersion client_version = this.tlsClientContext.getClientVersion();
            if (server_version.getFullVersion() > client_version.getFullVersion()) {
              this.failWithError(AlertLevel.fatal, AlertDescription.illegal_parameter);
            }

            this.tlsClientContext.setServerVersion(server_version);
            this.tlsClient.notifyServerVersion(server_version);

            /*
             * Read the server random
             */
            securityParameters.serverRandom = new byte[32];
            TlsUtils.readFully(securityParameters.serverRandom, is);

            byte[] sessionID = TlsUtils.readOpaque8(is);
            if (sessionID.length > 32) {
              this.failWithError(AlertLevel.fatal, AlertDescription.illegal_parameter);
            }

            this.tlsClient.notifySessionID(sessionID);

            /*
             * Find out which CipherSuite the server has chosen and check that
             * it was one of the offered ones.
             */
            int selectedCipherSuite = TlsUtils.readUint16(is);
            if (!arrayContains(offeredCipherSuites, selectedCipherSuite)
                || selectedCipherSuite == CipherSuite.TLS_EMPTY_RENEGOTIATION_INFO_SCSV) {
              this.failWithError(AlertLevel.fatal, AlertDescription.illegal_parameter);
            }

            this.tlsClient.notifySelectedCipherSuite(selectedCipherSuite);

            /*
             * Find out which CompressionMethod the server has chosen and check that
             * it was one of the offered ones.
             */
            short selectedCompressionMethod = TlsUtils.readUint8(is);
            if (!arrayContains(offeredCompressionMethods, selectedCompressionMethod)) {
              this.failWithError(AlertLevel.fatal, AlertDescription.illegal_parameter);
            }

            this.tlsClient.notifySelectedCompressionMethod(selectedCompressionMethod);

            /*
             * RFC3546 2.2 The extended server hello message format MAY be
             * sent in place of the server hello message when the client has
             * requested extended functionality via the extended client hello
             * message specified in Section 2.1. ... Note that the extended
             * server hello message is only sent in response to an extended
             * client hello message. This prevents the possibility that the
             * extended server hello message could "break" existing TLS 1.0
             * clients.
             */

            /*
             * TODO RFC 3546 2.3 If [...] the older session is resumed, then
             * the server MUST ignore extensions appearing in the client
             * hello, and send a server hello containing no extensions.
             */

            // Integer -> byte[]
            Hashtable serverExtensions = new Hashtable();

            if (is.available() > 0) {
              // Process extensions from extended server hello
              byte[] extBytes = TlsUtils.readOpaque16(is);

              ByteArrayInputStream ext = new ByteArrayInputStream(extBytes);
              while (ext.available() > 0) {
                Integer extType = Integers.valueOf(TlsUtils.readUint16(ext));
                byte[] extValue = TlsUtils.readOpaque16(ext);

                /*
                 * RFC 5746 Note that sending a "renegotiation_info"
                 * extension in response to a ClientHello containing only
                 * the SCSV is an explicit exception to the prohibition in
                 * RFC 5246, Section 7.4.1.4, on the server sending
                 * unsolicited extensions and is only allowed because the
                 * client is signaling its willingness to receive the
                 * extension via the TLS_EMPTY_RENEGOTIATION_INFO_SCSV
                 * SCSV. TLS implementations MUST continue to comply with
                 * Section 7.4.1.4 for all other extensions.
                 */

                if (!extType.equals(EXT_RenegotiationInfo)
                    && clientExtensions.get(extType) == null) {
                  /*
                   * RFC 3546 2.3 Note that for all extension types
                   * (including those defined in future), the extension
                   * type MUST NOT appear in the extended server hello
                   * unless the same extension type appeared in the
                   * corresponding client hello. Thus clients MUST abort
                   * the handshake if they receive an extension type in
                   * the extended server hello that they did not request
                   * in the associated (extended) client hello.
                   */
                  this.failWithError(AlertLevel.fatal, AlertDescription.unsupported_extension);
                }

                if (serverExtensions.containsKey(extType)) {
                  /*
                   * RFC 3546 2.3 Also note that when multiple
                   * extensions of different types are present in the
                   * extended client hello or the extended server hello,
                   * the extensions may appear in any order. There MUST
                   * NOT be more than one extension of the same type.
                   */
                  this.failWithError(AlertLevel.fatal, AlertDescription.illegal_parameter);
                }

                serverExtensions.put(extType, extValue);
              }
            }

            assertEmpty(is);

            /*
             * RFC 5746 3.4. When a ServerHello is received, the client MUST
             * check if it includes the "renegotiation_info" extension:
             */
            {
              boolean secure_negotiation = serverExtensions.containsKey(EXT_RenegotiationInfo);

              /*
               * If the extension is present, set the secure_renegotiation
               * flag to TRUE. The client MUST then verify that the length
               * of the "renegotiated_connection" field is zero, and if it
               * is not, MUST abort the handshake (by sending a fatal
               * handshake_failure alert).
               */
              if (secure_negotiation) {
                byte[] renegExtValue = (byte[]) serverExtensions.get(EXT_RenegotiationInfo);

                if (!Arrays.constantTimeAreEqual(
                    renegExtValue, createRenegotiationInfo(emptybuf))) {
                  this.failWithError(AlertLevel.fatal, AlertDescription.handshake_failure);
                }
              }

              tlsClient.notifySecureRenegotiation(secure_negotiation);
            }

            if (clientExtensions != null) {
              tlsClient.processServerExtensions(serverExtensions);
            }

            this.keyExchange = tlsClient.getKeyExchange();

            connection_state = CS_SERVER_HELLO_RECEIVED;
            break;
          default:
            this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
        }
        break;
      case HandshakeType.server_hello_done:
        switch (connection_state) {
          case CS_SERVER_HELLO_RECEIVED:

            // There was no server certificate message; check it's OK
            this.keyExchange.skipServerCertificate();
            this.authentication = null;

            // NB: Fall through to next case label

          case CS_SERVER_CERTIFICATE_RECEIVED:

            // There was no server key exchange message; check it's OK
            this.keyExchange.skipServerKeyExchange();

            // NB: Fall through to next case label

          case CS_SERVER_KEY_EXCHANGE_RECEIVED:
          case CS_CERTIFICATE_REQUEST_RECEIVED:
            assertEmpty(is);

            connection_state = CS_SERVER_HELLO_DONE_RECEIVED;

            TlsCredentials clientCreds = null;
            if (certificateRequest == null) {
              this.keyExchange.skipClientCredentials();
            } else {
              clientCreds = this.authentication.getClientCredentials(certificateRequest);

              if (clientCreds == null) {
                this.keyExchange.skipClientCredentials();

                boolean isTls =
                    tlsClientContext.getServerVersion().getFullVersion()
                        >= ProtocolVersion.TLSv10.getFullVersion();

                if (isTls) {
                  sendClientCertificate(Certificate.EMPTY_CHAIN);
                } else {
                  sendAlert(AlertLevel.warning, AlertDescription.no_certificate);
                }
              } else {
                this.keyExchange.processClientCredentials(clientCreds);

                sendClientCertificate(clientCreds.getCertificate());
              }
            }

            /*
             * Send the client key exchange message, depending on the key
             * exchange we are using in our CipherSuite.
             */
            sendClientKeyExchange();

            connection_state = CS_CLIENT_KEY_EXCHANGE_SEND;

            /*
             * Calculate the master_secret
             */
            byte[] pms = this.keyExchange.generatePremasterSecret();

            securityParameters.masterSecret =
                TlsUtils.calculateMasterSecret(this.tlsClientContext, pms);

            // TODO Is there a way to ensure the data is really overwritten?
            /*
             * RFC 2246 8.1. The pre_master_secret should be deleted from
             * memory once the master_secret has been computed.
             */
            Arrays.fill(pms, (byte) 0);

            if (clientCreds != null && clientCreds instanceof TlsSignerCredentials) {
              TlsSignerCredentials signerCreds = (TlsSignerCredentials) clientCreds;
              byte[] md5andsha1 = rs.getCurrentHash(null);
              byte[] clientCertificateSignature =
                  signerCreds.generateCertificateSignature(md5andsha1);
              sendCertificateVerify(clientCertificateSignature);

              connection_state = CS_CERTIFICATE_VERIFY_SEND;
            }

            /*
             * Now, we send change cipher state
             */
            byte[] cmessage = new byte[1];
            cmessage[0] = 1;
            rs.writeMessage(ContentType.change_cipher_spec, cmessage, 0, cmessage.length);

            connection_state = CS_CLIENT_CHANGE_CIPHER_SPEC_SEND;

            /*
             * Initialize our cipher suite
             */
            rs.clientCipherSpecDecided(tlsClient.getCompression(), tlsClient.getCipher());

            /*
             * Send our finished message.
             */
            byte[] clientVerifyData =
                TlsUtils.calculateVerifyData(
                    tlsClientContext, "client finished", rs.getCurrentHash(TlsUtils.SSL_CLIENT));

            ByteArrayOutputStream bos = new ByteArrayOutputStream();
            TlsUtils.writeUint8(HandshakeType.finished, bos);
            TlsUtils.writeOpaque24(clientVerifyData, bos);
            byte[] message = bos.toByteArray();

            rs.writeMessage(ContentType.handshake, message, 0, message.length);

            this.connection_state = CS_CLIENT_FINISHED_SEND;
            break;
          default:
            this.failWithError(AlertLevel.fatal, AlertDescription.handshake_failure);
        }
        break;
      case HandshakeType.server_key_exchange:
        {
          switch (connection_state) {
            case CS_SERVER_HELLO_RECEIVED:

              // There was no server certificate message; check it's OK
              this.keyExchange.skipServerCertificate();
              this.authentication = null;

              // NB: Fall through to next case label

            case CS_SERVER_CERTIFICATE_RECEIVED:
              this.keyExchange.processServerKeyExchange(is);

              assertEmpty(is);
              break;

            default:
              this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
          }

          this.connection_state = CS_SERVER_KEY_EXCHANGE_RECEIVED;
          break;
        }
      case HandshakeType.certificate_request:
        {
          switch (connection_state) {
            case CS_SERVER_CERTIFICATE_RECEIVED:

              // There was no server key exchange message; check it's OK
              this.keyExchange.skipServerKeyExchange();

              // NB: Fall through to next case label

            case CS_SERVER_KEY_EXCHANGE_RECEIVED:
              {
                if (this.authentication == null) {
                  /*
                   * RFC 2246 7.4.4. It is a fatal handshake_failure alert
                   * for an anonymous server to request client identification.
                   */
                  this.failWithError(AlertLevel.fatal, AlertDescription.handshake_failure);
                }

                int numTypes = TlsUtils.readUint8(is);
                short[] certificateTypes = new short[numTypes];
                for (int i = 0; i < numTypes; ++i) {
                  certificateTypes[i] = TlsUtils.readUint8(is);
                }

                byte[] authorities = TlsUtils.readOpaque16(is);

                assertEmpty(is);

                Vector authorityDNs = new Vector();

                ByteArrayInputStream bis = new ByteArrayInputStream(authorities);
                while (bis.available() > 0) {
                  byte[] dnBytes = TlsUtils.readOpaque16(bis);
                  authorityDNs.addElement(
                      X500Name.getInstance(ASN1Primitive.fromByteArray(dnBytes)));
                }

                this.certificateRequest = new CertificateRequest(certificateTypes, authorityDNs);
                this.keyExchange.validateCertificateRequest(this.certificateRequest);

                break;
              }
            default:
              this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
          }

          this.connection_state = CS_CERTIFICATE_REQUEST_RECEIVED;
          break;
        }
      case HandshakeType.hello_request:
        /*
         * RFC 2246 7.4.1.1 Hello request This message will be ignored by the
         * client if the client is currently negotiating a session. This message
         * may be ignored by the client if it does not wish to renegotiate a
         * session, or the client may, if it wishes, respond with a
         * no_renegotiation alert.
         */
        if (connection_state == CS_DONE) {
          // Renegotiation not supported yet
          sendAlert(AlertLevel.warning, AlertDescription.no_renegotiation);
        }
        break;
      case HandshakeType.client_key_exchange:
      case HandshakeType.certificate_verify:
      case HandshakeType.client_hello:
      default:
        // We do not support this!
        this.failWithError(AlertLevel.fatal, AlertDescription.unexpected_message);
        break;
    }
  }