1 files changed, 108 insertions, 0 deletions
diff --git a/src/java/com/android/internal/net/ipsec/ike/message/IkeNoncePayload.java b/src/java/com/android/internal/net/ipsec/ike/message/IkeNoncePayload.java
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+++ b/src/java/com/android/internal/net/ipsec/ike/message/IkeNoncePayload.java
@@ -0,0 +1,108 @@
+/*
+ * 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 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() {
+        super(PAYLOAD_TYPE_NONCE, false);
+        nonceData = new byte[GENERATED_NONCE_LEN];
+        new SecureRandom().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";
+    }
+}