| /* |
| * Copyright (C) 2018 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.android.internal.net.ipsec.ike.message; |
| |
| import android.net.ipsec.ike.exceptions.IkeProtocolException; |
| |
| import com.android.internal.net.ipsec.ike.exceptions.InvalidSyntaxException; |
| import com.android.internal.net.ipsec.ike.utils.RandomnessFactory; |
| |
| import java.nio.ByteBuffer; |
| import java.security.SecureRandom; |
| |
| /** |
| * IkeNoncePayload represents a Nonce payload. |
| * |
| * <p>Length of nonce data must be at least half the key size of negotiated PRF. It must be between |
| * 16 and 256 octets. IKE library always generates nonce of GENERATED_NONCE_LEN octets which is long |
| * enough for all currently known PRFs. |
| * |
| * <p>Critical bit must be ignored when doing decoding and must not be set when doing encoding for |
| * this payload. |
| * |
| * @see <a href="https://tools.ietf.org/html/rfc7296">RFC 7296, Internet Key Exchange Protocol |
| * Version 2 (IKEv2). |
| */ |
| public final class IkeNoncePayload extends IkePayload { |
| // The longest key size of all currently known PRFs is 512 bits (64 bytes). Since we are |
| // required to generate nonce that is long enough for all proposed PRFs, it is simple that we |
| // always generate 32 bytes nonce, which is enough for all known PRFs. |
| private static final int GENERATED_NONCE_LEN = 32; |
| |
| private static final int MIN_NONCE_LEN = 16; |
| private static final int MAX_NONCE_LEN = 256; |
| |
| public final byte[] nonceData; |
| |
| /** |
| * Construct an instance of IkeNoncePayload in the context of {@link IkePayloadFactory}. |
| * |
| * @param critical indicates if it is a critical payload. |
| * @param payloadBody the nonce data |
| */ |
| IkeNoncePayload(boolean critical, byte[] payloadBody) throws IkeProtocolException { |
| super(PAYLOAD_TYPE_NONCE, critical); |
| if (payloadBody.length < MIN_NONCE_LEN || payloadBody.length > MAX_NONCE_LEN) { |
| throw new InvalidSyntaxException( |
| "Invalid nonce data with length of: " + payloadBody.length); |
| } |
| // Check that the length of payloadBody satisfies the "half the key size of negotiated PRF" |
| // condition when processing IKE Message in upper layer. Cannot do this check here for |
| // lacking PRF information. |
| nonceData = payloadBody; |
| } |
| |
| /** Generate Nonce data and construct an instance of IkeNoncePayload. */ |
| public IkeNoncePayload(RandomnessFactory randomnessFactory) { |
| super(PAYLOAD_TYPE_NONCE, false); |
| nonceData = new byte[GENERATED_NONCE_LEN]; |
| |
| SecureRandom random = randomnessFactory.getRandom(); |
| random = random == null ? new SecureRandom() : random; |
| random.nextBytes(nonceData); |
| } |
| |
| /** |
| * Encode Nonce payload to ByteBuffer. |
| * |
| * @param nextPayload type of payload that follows this payload. |
| * @param byteBuffer destination ByteBuffer that stores encoded payload. |
| */ |
| @Override |
| protected void encodeToByteBuffer(@PayloadType int nextPayload, ByteBuffer byteBuffer) { |
| int payloadLength = GENERIC_HEADER_LENGTH + nonceData.length; |
| |
| encodePayloadHeaderToByteBuffer(nextPayload, payloadLength, byteBuffer); |
| byteBuffer.put(nonceData); |
| } |
| |
| /** |
| * Get entire payload length. |
| * |
| * @return entire payload length. |
| */ |
| @Override |
| protected int getPayloadLength() { |
| return GENERIC_HEADER_LENGTH + nonceData.length; |
| } |
| |
| /** |
| * Return the payload type as a String. |
| * |
| * @return the payload type as a String. |
| */ |
| @Override |
| public String getTypeString() { |
| return "Nonce"; |
| } |
| } |