Added concierge service to clean up KeyTree

arch.md

@@ -46,3 +46,9 @@ if SUC:
 
 ## REP ##
 TODO
+
+# TODO #
+
+[ ] Admin communication
+[ ] Admin interface
+[ ] Adapt brainflyer

bfclient/hash/hash160.h

@@ -0,0 +1,14 @@
+/*  Copyright (c) 2015 Ryan Castellucci, All Rights Reserved */
+#ifndef __BRAINFLAYER_HASH160_H_
+#define __BRAINFLAYER_HASH160_H_
+
+#include <openssl/sha.h>
+#include <openssl/ripemd.h>
+
+typedef union hash160_u {
+  unsigned char uc[RIPEMD160_DIGEST_LENGTH];
+  uint32_t      ul[RIPEMD160_DIGEST_LENGTH>>2];
+} hash160_t;
+
+/*  vim: set ts=2 sw=2 et ai si: */
+#endif /* __BRAINFLAYER_HASH160_H_ */

bfclient/hash/ripemd160_256.c

@@ -0,0 +1,286 @@
+#define _RIPEMD160_C_ 1
+
+#include "ripemd160_256.h"
+
+// adapted by Pieter Wuille in 2012; all changes are in the public domain
+// modified by Ryan Castellucci in 2015; all changes are in the public domain
+
+/*
+ *
+ *  RIPEMD160.c : RIPEMD-160 implementation
+ *
+ * Written in 2008 by Dwayne C. Litzenberger <dlitz@dlitz.net>
+ *
+ * ===================================================================
+ * The contents of this file are dedicated to the public domain.  To
+ * the extent that dedication to the public domain is not available,
+ * everyone is granted a worldwide, perpetual, royalty-free,
+ * non-exclusive license to exercise all rights associated with the
+ * contents of this file for any purpose whatsoever.
+ * No rights are reserved.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ * ===================================================================
+ *
+ * Country of origin: Canada
+ *
+ * This implementation (written in C) is based on an implementation the author
+ * wrote in Python.
+ *
+ * This implementation was written with reference to the RIPEMD-160
+ * specification, which is available at:
+ * http://homes.esat.kuleuven.be/~cosicart/pdf/AB-9601/
+ *
+ * It is also documented in the _Handbook of Applied Cryptography_, as
+ * Algorithm 9.55.  It's on page 30 of the following PDF file:
+ * http://www.cacr.math.uwaterloo.ca/hac/about/chap9.pdf
+ *
+ * The RIPEMD-160 specification doesn't really tell us how to do padding, but
+ * since RIPEMD-160 is inspired by MD4, you can use the padding algorithm from
+ * RFC 1320.
+ *
+ * According to http://www.users.zetnet.co.uk/hopwood/crypto/scan/md.html:
+ *   "RIPEMD-160 is big-bit-endian, little-byte-endian, and left-justified."
+ */
+
+#include <stdint.h>
+
+#include <string.h>
+
+#define RIPEMD160_DIGEST_SIZE 20
+#define BLOCK_SIZE 64
+
+/* cyclic left-shift the 32-bit word n left by s bits */
+#define ROL(s, n) (((n) << (s)) | ((n) >> (32-(s))))
+
+/* Initial values for the chaining variables.
+ * This is just 0123456789ABCDEFFEDCBA9876543210F0E1D2C3 in little-endian. */
+static const uint32_t initial_h[5] = { 0x67452301u, 0xEFCDAB89u, 0x98BADCFEu, 0x10325476u, 0xC3D2E1F0u };
+
+/* Ordering of message words.  Based on the permutations rho(i) and pi(i), defined as follows:
+ *
+ *  rho(i) := { 7, 4, 13, 1, 10, 6, 15, 3, 12, 0, 9, 5, 2, 14, 11, 8 }[i]  0 <= i <= 15
+ *
+ *  pi(i) := 9*i + 5 (mod 16)
+ *
+ *  Line  |  Round 1  |  Round 2  |  Round 3  |  Round 4  |  Round 5
+ * -------+-----------+-----------+-----------+-----------+-----------
+ *  left  |    id     |    rho    |   rho^2   |   rho^3   |   rho^4
+ *  right |    pi     |   rho pi  |  rho^2 pi |  rho^3 pi |  rho^4 pi
+ */
+
+/* Left line */
+static const uint8_t RL[5][16] = {
+    { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15 },   /* Round 1: id */
+    { 7, 4, 13, 1, 10, 6, 15, 3, 12, 0, 9, 5, 2, 14, 11, 8 },   /* Round 2: rho */
+    { 3, 10, 14, 4, 9, 15, 8, 1, 2, 7, 0, 6, 13, 11, 5, 12 },   /* Round 3: rho^2 */
+    { 1, 9, 11, 10, 0, 8, 12, 4, 13, 3, 7, 15, 14, 5, 6, 2 },   /* Round 4: rho^3 */
+    { 4, 0, 5, 9, 7, 12, 2, 10, 14, 1, 3, 8, 11, 6, 15, 13 }    /* Round 5: rho^4 */
+};
+
+/* Right line */
+static const uint8_t RR[5][16] = {
+    { 5, 14, 7, 0, 9, 2, 11, 4, 13, 6, 15, 8, 1, 10, 3, 12 },   /* Round 1: pi */
+    { 6, 11, 3, 7, 0, 13, 5, 10, 14, 15, 8, 12, 4, 9, 1, 2 },   /* Round 2: rho pi */
+    { 15, 5, 1, 3, 7, 14, 6, 9, 11, 8, 12, 2, 10, 0, 4, 13 },   /* Round 3: rho^2 pi */
+    { 8, 6, 4, 1, 3, 11, 15, 0, 5, 12, 2, 13, 9, 7, 10, 14 },   /* Round 4: rho^3 pi */
+    { 12, 15, 10, 4, 1, 5, 8, 7, 6, 2, 13, 14, 0, 3, 9, 11 }    /* Round 5: rho^4 pi */
+};
+
+/*
+ * Shifts - Since we don't actually re-order the message words according to
+ * the permutations above (we could, but it would be slower), these tables
+ * come with the permutations pre-applied.
+ */
+
+/* Shifts, left line */
+static const uint8_t SL[5][16] = {
+    { 11, 14, 15, 12, 5, 8, 7, 9, 11, 13, 14, 15, 6, 7, 9, 8 }, /* Round 1 */
+    { 7, 6, 8, 13, 11, 9, 7, 15, 7, 12, 15, 9, 11, 7, 13, 12 }, /* Round 2 */
+    { 11, 13, 6, 7, 14, 9, 13, 15, 14, 8, 13, 6, 5, 12, 7, 5 }, /* Round 3 */
+    { 11, 12, 14, 15, 14, 15, 9, 8, 9, 14, 5, 6, 8, 6, 5, 12 }, /* Round 4 */
+    { 9, 15, 5, 11, 6, 8, 13, 12, 5, 12, 13, 14, 11, 8, 5, 6 }  /* Round 5 */
+};
+
+/* Shifts, right line */
+static const uint8_t SR[5][16] = {
+    { 8, 9, 9, 11, 13, 15, 15, 5, 7, 7, 8, 11, 14, 14, 12, 6 }, /* Round 1 */
+    { 9, 13, 15, 7, 12, 8, 9, 11, 7, 7, 12, 7, 6, 15, 13, 11 }, /* Round 2 */
+    { 9, 7, 15, 11, 8, 6, 6, 14, 12, 13, 5, 14, 13, 13, 7, 5 }, /* Round 3 */
+    { 15, 5, 8, 11, 14, 14, 6, 14, 6, 9, 12, 9, 12, 5, 15, 8 }, /* Round 4 */
+    { 8, 5, 12, 9, 12, 5, 14, 6, 8, 13, 6, 5, 15, 13, 11, 11 }  /* Round 5 */
+};
+
+/* static padding for 256 bit input */
+static const uint8_t pad256[32] = {
+    0x80, 0x00, 0x00, 0x00,   0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00,   0x00, 0x00, 0x00, 0x00,
+    0x00, 0x00, 0x00, 0x00,   0x00, 0x00, 0x00, 0x00,
+    /* length 256 bits, little endian uint64_t */
+    0x00, 0x01, 0x00, 0x00,   0x00, 0x00, 0x00, 0x00
+};
+
+/* Boolean functions */
+
+#define F1(x, y, z) ((x) ^ (y) ^ (z))
+#define F2(x, y, z) (((x) & (y)) | (~(x) & (z)))
+#define F3(x, y, z) (((x) | ~(y)) ^ (z))
+#define F4(x, y, z) (((x) & (z)) | ((y) & ~(z)))
+#define F5(x, y, z) ((x) ^ ((y) | ~(z)))
+
+/* Round constants, left line */
+static const uint32_t KL[5] = {
+    0x00000000u,    /* Round 1: 0 */
+    0x5A827999u,    /* Round 2: floor(2**30 * sqrt(2)) */
+    0x6ED9EBA1u,    /* Round 3: floor(2**30 * sqrt(3)) */
+    0x8F1BBCDCu,    /* Round 4: floor(2**30 * sqrt(5)) */
+    0xA953FD4Eu     /* Round 5: floor(2**30 * sqrt(7)) */
+};
+
+/* Round constants, right line */
+static const uint32_t KR[5] = {
+    0x50A28BE6u,    /* Round 1: floor(2**30 * cubert(2)) */
+    0x5C4DD124u,    /* Round 2: floor(2**30 * cubert(3)) */
+    0x6D703EF3u,    /* Round 3: floor(2**30 * cubert(5)) */
+    0x7A6D76E9u,    /* Round 4: floor(2**30 * cubert(7)) */
+    0x00000000u     /* Round 5: 0 */
+};
+
+static inline void byteswap32(uint32_t *v)
+{
+    union { uint32_t w; uint8_t b[4]; } x, y;
+
+    x.w = *v;
+    y.b[0] = x.b[3];
+    y.b[1] = x.b[2];
+    y.b[2] = x.b[1];
+    y.b[3] = x.b[0];
+    *v = y.w;
+
+    /* Wipe temporary variables */
+    x.w = y.w = 0;
+}
+
+static inline void byteswap_digest(uint32_t *p)
+{
+    unsigned int i;
+
+    for (i = 0; i < 4; i++) {
+        byteswap32(p++);
+        byteswap32(p++);
+        byteswap32(p++);
+        byteswap32(p++);
+    }
+}
+
+/* The RIPEMD160 compression function. */
+static inline void ripemd160_rawcompress(void *pbuf, void *ph)
+{
+    uint8_t w, round;
+    uint32_t T;
+    uint32_t AL, BL, CL, DL, EL;    /* left line */
+    uint32_t AR, BR, CR, DR, ER;    /* right line */
+
+    uint32_t *buf = pbuf;
+    uint32_t *h = ph;
+
+    /* Byte-swap the buffer if we're on a big-endian machine */
+#ifdef PCT_BIG_ENDIAN
+    byteswap_digest(buf);
+#endif
+
+    /* initialize state */
+    memcpy(h, initial_h, RIPEMD160_DIGEST_SIZE);
+
+    /* Load the left and right lines with the initial state */
+    AL = AR = h[0];
+    BL = BR = h[1];
+    CL = CR = h[2];
+    DL = DR = h[3];
+    EL = ER = h[4];
+
+    /* Round 1 */
+    round = 0;
+    for (w = 0; w < 16; w++) { /* left line */
+        T = ROL(SL[round][w], AL + F1(BL, CL, DL) + buf[RL[round][w]] + KL[round]) + EL;
+        AL = EL; EL = DL; DL = ROL(10, CL); CL = BL; BL = T;
+    }
+    for (w = 0; w < 16; w++) { /* right line */
+        T = ROL(SR[round][w], AR + F5(BR, CR, DR) + buf[RR[round][w]] + KR[round]) + ER;
+        AR = ER; ER = DR; DR = ROL(10, CR); CR = BR; BR = T;
+    }
+
+    /* Round 2 */
+    round++;
+    for (w = 0; w < 16; w++) { /* left line */
+        T = ROL(SL[round][w], AL + F2(BL, CL, DL) + buf[RL[round][w]] + KL[round]) + EL;
+        AL = EL; EL = DL; DL = ROL(10, CL); CL = BL; BL = T;
+    }
+    for (w = 0; w < 16; w++) { /* right line */
+        T = ROL(SR[round][w], AR + F4(BR, CR, DR) + buf[RR[round][w]] + KR[round]) + ER;
+        AR = ER; ER = DR; DR = ROL(10, CR); CR = BR; BR = T;
+    }
+
+    /* Round 3 */
+    round++;
+    for (w = 0; w < 16; w++) { /* left line */
+        T = ROL(SL[round][w], AL + F3(BL, CL, DL) + buf[RL[round][w]] + KL[round]) + EL;
+        AL = EL; EL = DL; DL = ROL(10, CL); CL = BL; BL = T;
+    }
+    for (w = 0; w < 16; w++) { /* right line */
+        T = ROL(SR[round][w], AR + F3(BR, CR, DR) + buf[RR[round][w]] + KR[round]) + ER;
+        AR = ER; ER = DR; DR = ROL(10, CR); CR = BR; BR = T;
+    }
+
+    /* Round 4 */
+    round++;
+    for (w = 0; w < 16; w++) { /* left line */
+        T = ROL(SL[round][w], AL + F4(BL, CL, DL) + buf[RL[round][w]] + KL[round]) + EL;
+        AL = EL; EL = DL; DL = ROL(10, CL); CL = BL; BL = T;
+    }
+    for (w = 0; w < 16; w++) { /* right line */
+        T = ROL(SR[round][w], AR + F2(BR, CR, DR) + buf[RR[round][w]] + KR[round]) + ER;
+        AR = ER; ER = DR; DR = ROL(10, CR); CR = BR; BR = T;
+    }
+
+    /* Round 5 */
+    round++;
+    for (w = 0; w < 16; w++) { /* left line */
+        T = ROL(SL[round][w], AL + F5(BL, CL, DL) + buf[RL[round][w]] + KL[round]) + EL;
+        AL = EL; EL = DL; DL = ROL(10, CL); CL = BL; BL = T;
+    }
+    for (w = 0; w < 16; w++) { /* right line */
+        T = ROL(SR[round][w], AR + F1(BR, CR, DR) + buf[RR[round][w]] + KR[round]) + ER;
+        AR = ER; ER = DR; DR = ROL(10, CR); CR = BR; BR = T;
+    }
+
+    /* Final mixing stage */
+    T = h[1] + CL + DR;
+    h[1] = h[2] + DL + ER;
+    h[2] = h[3] + EL + AR;
+    h[3] = h[4] + AL + BR;
+    h[4] = h[0] + BL + CR;
+    h[0] = T;
+
+    /* Byte-swap the output if we're on a big-endian machine */
+#ifdef PCT_BIG_ENDIAN
+    byteswap_digest(h);
+#endif
+}
+
+void ripemd160_256(const void *in, void *out) {
+  unsigned char buf[64];
+  /* copy input data */
+  memcpy(buf +  0, in,     32);
+  /* append fixed padding */
+  memcpy(buf + 32, pad256, 32);
+  /* compute and output hash */
+  ripemd160_rawcompress(buf, out);
+}

bfclient/hash/ripemd160_256.h

@@ -0,0 +1,8 @@
+#ifndef __RIPEMD160_256_H_
+#define __RIPEMD160_256_H_
+
+#include <stdint.h>
+
+void ripemd160_256(const void *in, void *out);
+
+#endif//__RIPEMD160_256_H_

client/src/client/ClientRunner.java

@@ -0,0 +1,54 @@
+package client;
+
+import java.io.BufferedReader;
+import java.io.InputStreamReader;
+import java.io.OutputStreamWriter;
+import java.io.PrintWriter;
+import java.net.Socket;
+
+public class ClientRunner implements Runnable {
+	long sleep;
+	private String host;
+	private Integer port;
+	private boolean skip;
+
+	public ClientRunner(String host, Integer port, long sleep, boolean skip) {
+		this.sleep = sleep;
+		this.host = host;
+		this.port = port;
+		this.skip = skip;
+	}
+
+	@Override
+	public void run() {
+		try {
+			Socket socket = new Socket(host, port);
+
+			BufferedReader in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+			PrintWriter out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
+
+			out.println("WRK");
+			String work = in.readLine();
+			System.out.println("Sleep: "+sleep+", skip: "+skip+", work: "+work);
+
+			socket.close();
+			if (!skip) {
+				Thread.sleep(sleep);
+
+				socket = new Socket(host, port);
+
+				in = new BufferedReader(new InputStreamReader(socket.getInputStream()));
+				out = new PrintWriter(new OutputStreamWriter(socket.getOutputStream()), true);
+
+				out.println("RES");
+				out.println(work);
+
+				socket.close();
+			}
+		} catch (Exception e) {
+			System.out.println(e);
+		}
+
+	}
+
+}

client/src/client/CommClient.java

@@ -0,0 +1,28 @@
+package client;
+
+public class CommClient {
+	private static final String HOST = "localhost";
+	private static final Integer PORT = 26765;
+
+	public static void main(String[] args) throws Exception {
+
+		for (int i = 0; i < 5; i++) {
+			new Thread(new ClientRunner(HOST, PORT, 5000, false)).start();
+			new Thread(new ClientRunner(HOST, PORT, 15000, false)).start();
+			new Thread(new ClientRunner(HOST, PORT, 0, true)).start();
+			new Thread(new ClientRunner(HOST, PORT, 5000, false)).start();
+		}
+		
+		Thread.sleep(20000);
+		System.out.println("******** BATCH 2 ********");
+
+		for (int i = 0; i < 5; i++) {
+			new Thread(new ClientRunner(HOST, PORT, 5000, false)).start();
+			new Thread(new ClientRunner(HOST, PORT, 5000, false)).start();
+
+			new Thread(new ClientRunner(HOST, PORT, 15000, false)).start();
+			new Thread(new ClientRunner(HOST, PORT, 0, true)).start();
+			new Thread(new ClientRunner(HOST, PORT, 5000, false)).start();
+		}
+	}
+}

cnc/src/main/java/org/btcollider/cnc/CnC.java

@@ -18,12 +18,14 @@ public class CnC {
 	public static final int MAX_BITS = 62;
 
 	public static void main(String[] args) {
-		KeyServer.init(55, 20);
+		KeyServer.init(10, 7, 10000);
 		CommServer server = new CommServer(PORT);
 		try {
 			server.listen();
 		} catch (CommException e) {
 			log.error("CommServer couldn't be started");
+		} finally {
+			server.stop();
 		}
 	}
 }

cnc/src/main/java/org/btcollider/cnc/comm/ClientWorker.java

@@ -27,7 +27,7 @@ public class ClientWorker implements Runnable {
 	public void run() {
 		try {
 			in = new BufferedReader(new InputStreamReader(clientSocket.getInputStream()));
-			out = new PrintWriter(new OutputStreamWriter(clientSocket.getOutputStream()));
+			out = new PrintWriter(new OutputStreamWriter(clientSocket.getOutputStream()), true);
 		} catch (IOException e) {
 			log.error("Couldn't open communication channel", e);
 			closeCommChannel();
@@ -53,6 +53,8 @@ public class ClientWorker implements Runnable {
 		default:
 			assert false;
 		}
+
+		shutDown();
 	}
 
 	private void closeCommChannel() {
@@ -71,12 +73,45 @@ public class ClientWorker implements Runnable {
 
 	private void sendWork() {
 		KeyServer ks = KeyServer.getInstance();
-		KeyRange kr = ks.getRange();
+		KeyRange kr;
-		out.println(kr.getStart() + " " + kr.getEnd() + " " + kr.getTotal());
+
-		out.flush();
+		synchronized (ks) {
+			kr = ks.getRange();
+			ks.setInWork(kr);
+		}
+
+		String work = Long.toHexString(kr.getStart()) + " " + Long.toHexString(kr.getEnd()) + " " + kr.getTotal();
+
+		out.println(work);
+
+		log.debug("Work <{}> sent to {}", work, clientSocket.getInetAddress());
 	}
 
 	private void retrieveResult() {
+		String[] result;
+		try {
+			result = in.readLine().split(" ");
+			KeyRange kr = new KeyRange(Long.parseLong(result[0], 16), Long.parseLong(result[1], 16));
 
+			synchronized (KeyServer.getInstance()) {
+				KeyServer.getInstance().setSearched(kr);
+			}
+
+			log.debug("Got result for {}", kr);
+
+		} catch (IOException e) {
+			log.error("Couldn't read result", e);
+		}
+	}
+
+	private void shutDown() {
+		closeCommChannel();
+		if (!clientSocket.isClosed()) {
+			try {
+				clientSocket.close();
+			} catch (IOException e) {
+				log.error("Couldn't close client socket", e);
+			}
+		}
 	}
 }

cnc/src/main/java/org/btcollider/cnc/comm/CommServer.java

@@ -47,7 +47,7 @@ public class CommServer {
 		log.debug("Opening socket on port {}", port);
 
 		try {
-			this.serverSocket = new ServerSocket();
+			this.serverSocket = new ServerSocket(port);
 		} catch (IOException e) {
 			log.error("Couldn't allocate server socket", e);
 

cnc/src/main/java/org/btcollider/cnc/dto/KeyRange.java

@@ -5,28 +5,38 @@ import java.util.BitSet;
 import org.btcollider.cnc.CnC;
 
 public class KeyRange {
-	private BitSet start;
+	private Long start;
-	private BitSet end;
+	private Long end;
 
 	public KeyRange(BitSet start, BitSet end) {
 		assert start.length() <= CnC.MAX_BITS && end.length() <= CnC.MAX_BITS;
 
+		this.start = start.toLongArray()[0];
+		this.end = end.toLongArray()[0];
+	}
+	
+	public KeyRange(Long start, Long end) {
 		this.start = start;
 		this.end = end;
 	}
 	
-	public BitSet getStart() {
+	public Long getStart() {
 		return start;
 	}
 
-	public BitSet getEnd() {
+	public Long getEnd() {
 		return end;
 	}
 
 	public Long getTotal() {
 		// asserted that <= MAX_BITS, first long contains all significant bits
-		Long total = getStart().toLongArray()[0] - getEnd().toLongArray()[0];
+		Long total = getEnd() - getStart() + 1; // +1 bc start is included too
 
 		return total;
 	}
+
+	@Override
+	public String toString() {
+		return "KeyRange [start=" + start + ", end=" + end + ", total=" + getTotal() +"]";
+	}
 }

cnc/src/main/java/org/btcollider/cnc/keysrv/KTConcierge.java

@@ -0,0 +1,45 @@
+package org.btcollider.cnc.keysrv;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+public class KTConcierge implements Runnable {
+	final Logger log = LoggerFactory.getLogger(KeyServer.class);
+	
+	private KeyTree keyTree;
+	private long maxWorkSpan;
+	
+	public KTConcierge(KeyTree keyTree, long maxWorkSpan) {
+		this.keyTree = keyTree;
+		this.maxWorkSpan = maxWorkSpan;
+	}
+	
+	@Override
+	public void run() {
+		recCheckInWork(keyTree);
+	}
+
+	private void recCheckInWork(KeyTree node) {
+		if (node == null) return;
+		
+		if (node.inWork()) {
+			long inWorkSpan = System.currentTimeMillis() - node.inWorkSince();
+			if (inWorkSpan >= maxWorkSpan) {
+				if (node.isLeaf()) {
+					StringBuilder key = new StringBuilder();
+					key.append(node.getValue() ? "1": "0");
+					KeyTree parent = node.getParent();
+					while (parent != null) {
+						key.insert(0, parent.getValue() ? "1": "0");
+						parent = parent.getParent();
+					}
+					log.debug("{}: Retracting Work for key {}, inWorkSince: {}", System.currentTimeMillis(), key, node.inWorkSince());
+				}
+				node.clearInWork();
+			}
+		}
+		
+		recCheckInWork(node.getLeft());
+		recCheckInWork(node.getRight());
+	}
+}

cnc/src/main/java/org/btcollider/cnc/keysrv/KeyServer.java

@@ -1,6 +1,12 @@
 package org.btcollider.cnc.keysrv;
 
 import java.util.BitSet;
+import java.util.LinkedList;
+import java.util.Queue;
+import java.util.Random;
+import java.util.concurrent.Executors;
+import java.util.concurrent.ScheduledExecutorService;
+import java.util.concurrent.TimeUnit;
 
 import org.btcollider.cnc.CnC;
 import org.btcollider.cnc.dto.KeyRange;
@@ -16,23 +22,29 @@ public class KeyServer {
 	private int index;
 	private int depth;
 
-	protected KeyServer(int index, int depth) {
+	protected KeyServer(int index, int depth, long maxWorkSpan) {
 		assert Math.pow(2, CnC.MAX_BITS) <= Long.MAX_VALUE;
 		assert index < CnC.MAX_BITS && depth <= CnC.MAX_BITS;
 
 		this.depth = depth;
 		this.index = index;
 		this.root = generateKeyTree(depth);
+		
+		log.info("Starting KeyTree concierge");
+		ScheduledExecutorService es = Executors.newSingleThreadScheduledExecutor();
+		es.scheduleWithFixedDelay(new KTConcierge(root, maxWorkSpan), 0, 30, TimeUnit.SECONDS);
 	}
 
-	public static void init(int index, int depth) {
+	public static void init(int index, int depth, long maxWorkSpan) {
-		instance = new KeyServer(index, depth);
+		if (instance == null)
+			instance = new KeyServer(index, depth, maxWorkSpan);
+		else
+			throw new IllegalAccessError("KeyServer already initialized");
 	}
 
 	public static KeyServer getInstance() {
 		if (instance == null)
 			throw new IllegalAccessError("KeyServer is not initialized");
-
 		return instance;
 	}
 
@@ -62,11 +74,49 @@ public class KeyServer {
 	}
 
 	public void setSearched(KeyRange keyRange) {
-		markSearched(keyRange.getStart());
+		markSearched(BitSet.valueOf(new long[] { keyRange.getStart() }));
 	}
 
 	public void setInWork(KeyRange keyRange) {
-		markInWork(keyRange.getStart());
+		markInWork(BitSet.valueOf(new long[] { keyRange.getStart() }));
+	}
+
+	public String printDot() {
+		StringBuffer buffer = new StringBuffer();
+		buffer.append("strict graph { \n");
+
+		Queue<KeyTree> frontier = new LinkedList<>();
+		frontier.add(root);
+
+		while (!frontier.isEmpty()) {
+			KeyTree node = frontier.poll();
+			buffer.append(dotNodeName(node) + ";\n");
+
+			if (node.getParent() != null) {
+				buffer.append(dotNodeName(node.getParent()) + " -- " + dotNodeName(node) + ";\n");
+			}
+
+			if (node.getLeft() != null)
+				frontier.add(node.getLeft());
+			if (node.getRight() != null)
+				frontier.add(node.getRight());
+		}
+
+		buffer.append("\n}");
+		return buffer.toString();
+	}
+
+	private String dotNodeName(KeyTree node) {
+		String nodeName = "\"" + node.hashCode() + "_" + node.getValue();
+
+		if (node.isSearched())
+			nodeName += "_s";
+		if (node.inWork())
+			nodeName += "_w";
+
+		nodeName += "\"";
+
+		return nodeName;
 	}
 
 	private void markInWork(BitSet key) {
@@ -103,10 +153,10 @@ public class KeyServer {
 			return;
 		}
 
-		// Mark parent searched too, check next level
+		// Mark parent inWork too, check next level
 		parent.setInWork(Long.max(parent.getLeft().inWorkSince(), parent.getRight().inWorkSince()));
 
-		recMarkSearchedParents(parent);
+		recMarkInWorkParents(parent);
 	}
 
 	private void markSearched(BitSet key) {
@@ -181,18 +231,40 @@ public class KeyServer {
 		KeyTree right = kt.getRight();
 
 		// Finish criteria
-		if (left.isLeaf() && !left.isSearched()) {
+		if (left.isLeaf() || right.isLeaf()) {
+			assert left.isLeaf() && right.isLeaf(); // fully balanced binary tree by construction
+
+			// No choice finish
+			if (!right.isFree())
 				keyStart.set(curIndex - 1, left.getValue());
-			return;
+			else if (!left.isFree())
-		} else if (right.isLeaf() && !right.isSearched()) {
 				keyStart.set(curIndex - 1, right.getValue());
+			else if (left.isLeaf() && right.isLeaf()) { // Randomized finish
+				Random r = new Random();
+				boolean leftFirst = r.nextBoolean();
+				if(leftFirst) keyStart.set(curIndex - 1, left.getValue());
+				else keyStart.set(curIndex - 1, right.getValue());
+			}
+		
 			return;
 		}
 
-		// Recursive depth-first traversal
+		// No choice depth-first traversal
-		if (!left.isSearched())
+		if (!left.isFree())
+			recCollectKey(right, keyStart, curIndex - 1);
+		else if (!right.isFree())
+			recCollectKey(left, keyStart, curIndex - 1);
+		else { // Randomized depth-first traversal
+			Random r = new Random();
+			boolean leftFirst = r.nextBoolean();
+			if (leftFirst)
 				recCollectKey(left, keyStart, curIndex - 1);
 			else
 				recCollectKey(right, keyStart, curIndex - 1);
 		}
+	}
+
+	protected KeyTree getKeyTree() {
+		return this.root;
+	}
 }

cnc/src/main/java/org/btcollider/cnc/keysrv/KeyTree.java

@@ -18,6 +18,10 @@ public class KeyTree {
 		this.inWorkSince = -1;
 	}
 	
+	public boolean isFree() {
+		return !isSearched() && !inWork();
+	}
+
 	public boolean isLeaf() {
 		return left == null && right == null;
 	}
@@ -34,6 +38,10 @@ public class KeyTree {
 		return left;
 	}
 
+	public boolean hasLeft() {
+		return left != null;
+	}
+
 	public void setLeft(KeyTree left) {
 		this.left = left;
 	}
@@ -42,6 +50,10 @@ public class KeyTree {
 		return right;
 	}
 	
+	public boolean hasRight() {
+		return right != null;
+	}
+
 	public void setRight(KeyTree right) {
 		this.right = right;
 	}
@@ -55,13 +67,17 @@ public class KeyTree {
 	}
 
 	public void setInWork(long since) {
-		this.inWorkSince = System.currentTimeMillis();
+		this.inWorkSince = since;
 	}
 
 	public void setInWork() {
 		this.inWorkSince = System.currentTimeMillis();
 	}
 	
+	public void clearInWork() {
+		this.inWorkSince = -1;
+	}
+
 	public boolean inWork() {
 		return inWorkSince != -1;
 	}

cnc/src/test/java/org/btcollider/cnc/keysrv/KeyServerTest.java

@@ -0,0 +1,14 @@
+package org.btcollider.cnc.keysrv;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+import org.junit.jupiter.api.Test;
+
+class KeyServerTest {
+
+	@Test
+	void testInitEmptyTree() {
+		assertThrows(AssertionError.class, () -> KeyServer.init(0, 0, 0));
+	}
+
+}