From 6ee27b4e16c9478762516bb90ac49e64317b6e57 Mon Sep 17 00:00:00 2001
From: Peter Palfrader <peter@palfrader.org>
Date: Mon, 27 Oct 2003 19:07:26 +0000
Subject: First go at SURBs.  Still needs testing.  Moo.

---
 src/org/noreply/fancydress/type3/SURB.java | 84 +++++++++++++++++++++++++++---
 1 file changed, 76 insertions(+), 8 deletions(-)

(limited to 'src/org/noreply/fancydress/type3/SURB.java')

diff --git a/src/org/noreply/fancydress/type3/SURB.java b/src/org/noreply/fancydress/type3/SURB.java
index 400db34..4ef8948 100644
--- a/src/org/noreply/fancydress/type3/SURB.java
+++ b/src/org/noreply/fancydress/type3/SURB.java
@@ -4,23 +4,91 @@ package org.noreply.fancydress.type3;
 import org.noreply.fancydress.type3.routing.*;
 import org.noreply.fancydress.status.*;
 import org.noreply.fancydress.crypto.*;
+import org.noreply.fancydress.misc.*;
 
 public class SURB extends SingleLeg {
+	public static final byte[] VERSION = {0, 1};
+	public static final String ARMOR_VERSION = "0.2";
+	private byte[] sharedSecret;
 
-	public SURB (Path path, RoutingDestination address) throws Mix3BadArgumentsChainTooLongException {
+	public SURB (HalfPath path, byte[] secret, RoutingDestination address) throws Mix3BadArgumentsChainTooLongException {
 		super();
+		byte[] seed;
+		byte[] validateHash;
+		byte[] validate = Util.toOctets("Validate");
 
-		byte[][] sharedKeys = {};
-		Hop[] hops = new Hop[0]; // path.getHops();
+		Hop[] hops = path.getHops();
 
-		/* FIXME */
+		do {
+			seed = CryptoPrimitives.rand(20);
+			seed[0] &= 0x7f;
+			validateHash = CryptoPrimitives.hash(seed, secret, validate);
+		} while (validateHash[validateHash.length-1] == 0);
 
-		makeLeg ( hops, sharedKeys, address);
+		byte[] key = Util.slice(CryptoPrimitives.hash(seed, secret, Util.toOctets("Generate")), 0,CryptoPrimitives.KEY_LEN);
+		byte[] stream = CryptoPrimitives.prng(key, CryptoPrimitives.KEY_LEN*(hops.length + 1));
 
+		sharedSecret = Util.slice(stream, CryptoPrimitives.KEY_LEN*hops.length, CryptoPrimitives.KEY_LEN);
+		byte[][] sharedKeys = new byte[hops.length][];
+		for (int i=0; i<hops.length; i++)
+			sharedKeys[i] = Util.slice(stream, (hops.length-i-1)*CryptoPrimitives.KEY_LEN, CryptoPrimitives.KEY_LEN);
+
+		makeLeg(hops, sharedKeys, address);
 	};
 
-	public byte[] getEncryptionKey() {
-		return new byte[16];
+    /*
+      Begin Marker: 4 octets
+      Version:      2 octets
+      Use-by-Date:  4 octets
+      SURB header:  2048 octets
+      Routing Size: 2 octets
+      Routing Type: 2 octets
+      Encryption key: 16 octets
+      Routing Info: (Routing Size) octets
+     */
+
+	public String export() {
+		byte[] beginMarker = Util.toOctets("SURB");
+		int useBy = 1068595200; //FIXME // Y2k36
+		byte[] routingInformation = getRoute().getRoutingInformation();
+		int routingSize = routingInformation.length;
+		int routingType = getRoute().getRoutingType();
+
+		byte[] result = new byte[4+2+4+SINGLE_HEADER_LEN+2+2+CryptoPrimitives.KEY_LEN+routingSize];
+
+		int pos = 0;
+		System.arraycopy(beginMarker, 0, result,  pos, beginMarker.length);
+		pos += beginMarker.length;
+		System.arraycopy(VERSION, 0, result,  pos, VERSION.length);
+		pos += VERSION.length;
+		result[pos] = (byte) ( (useBy >>24) & 0xff);
+		pos++;
+		result[pos] = (byte) ( (useBy >>16) & 0xff);
+		pos++;
+		result[pos] = (byte) ( (useBy >> 8) & 0xff);
+		pos++;
+		result[pos] = (byte) ( (useBy     ) & 0xff);
+		pos++;
+		System.arraycopy(super.asOctets(), 0, result,  pos, SINGLE_HEADER_LEN);
+		pos += SINGLE_HEADER_LEN;
+		result[pos] = (byte) ( (routingSize >> 8) & 0xff);
+		pos++;
+		result[pos] = (byte) (  routingSize       & 0xff);
+		pos++;
+		result[pos] = (byte) ( (routingType >> 8) & 0xff);
+		pos++;
+		result[pos] = (byte) (  routingType       & 0xff);
+		pos++;
+		System.arraycopy(sharedSecret, 0, result,  pos, CryptoPrimitives.KEY_LEN);
+		pos += CryptoPrimitives.KEY_LEN;
+		System.arraycopy(routingInformation, 0, result,  pos, routingSize);
+		pos += routingSize;
+
+		if (pos != result.length)
+			throw new Error("did not fill in expected number of bytes");
+
+		String[] headers = new String[1];
+		headers[0] = "Version: "+ARMOR_VERSION;
+		return Util.armor(result, "TYPE III REPLY BLOCK", headers);
 	}
 }
-
-- 
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