diff --git a/.kdev4/xmss_ref.kdev4 b/.kdev4/xmss_ref.kdev4
new file mode 100644
index 0000000..70b24e9
--- /dev/null
+++ b/.kdev4/xmss_ref.kdev4
@@ -0,0 +1,5 @@
+[Buildset]
+BuildItems=@Variant(\x00\x00\x00\t\x00\x00\x00\x00\x01\x00\x00\x00\x0b\x00\x00\x00\x00\x01\x00\x00\x00\x10\x00x\x00m\x00s\x00s\x00_\x00r\x00e\x00f)
+
+[Project]
+VersionControlSupport=kdevgit
diff --git a/Makefile b/Makefile
index b158e36..ac67a30 100644
--- a/Makefile
+++ b/Makefile
@@ -1,5 +1,18 @@
-CC=gcc
-CFLAGS="-Wall"
+CC = /usr/bin/gcc
+CFLAGS = -Wall -g -O3 
+
+all: test/test_chacha \
+test/test_wots \
+test/test_xmss
+
+test/test_chacha: chacha.c prg.c randombytes.c test/test_chacha.c chacha.h prg.h randombytes.h
+	$(CC) $(CFLAGS) chacha.c prg.c randombytes.c test/test_chacha.c -o $@ #-lcrypto -lm
+
+test/test_wots: chacha.c hash.c prg.c randombytes.c wots.c xmss_commons.c test/test_wots.c chacha.h hash.h prg.h randombytes.h wots.h xmss_commons.h 
+	$(CC) $(CFLAGS) chacha.c hash.c prg.c randombytes.c wots.c xmss_commons.c test/test_wots.c -o $@ -lcrypto -lm
+	
+test/test_xmss: chacha.c hash.c prg.c randombytes.c wots.c xmss.c xmss_commons.c test/test_xmss.c chacha.h hash.h prg.h randombytes.h wots.h xmss.h xmss_commons.h 
+	$(CC) $(CFLAGS) chacha.c hash.c prg.c randombytes.c wots.c xmss.c xmss_commons.c test/test_xmss.c -o $@ -lcrypto -lm
 
 debug:clean
 	$(CC) $(CFLAGS) -g -o xmss_ref main.c
diff --git a/chacha.c b/chacha.c
new file mode 100644
index 0000000..036fa15
--- /dev/null
+++ b/chacha.c
@@ -0,0 +1,208 @@
+/*
+ * This code is based on an OpenSSL implementation of chacha20. 
+ * Hence, the copyright below applies.
+ * 
+ */
+/* ====================================================================
+ * Copyright (c) 2011-2013 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ */
+
+/* Adapted from the public domain code by D. Bernstein from SUPERCOP. */
+
+#include <stdint.h>
+#include <string.h>
+#include "chacha.h"
+
+/* sigma contains the ChaCha constants, which happen to be an ASCII string. */
+static const char sigma[16] = "expand 32-byte k";
+
+#define ROTATE(v, n) (((v) << (n)) | ((v) >> (32 - (n))))
+#define XOR(v, w) ((v) ^ (w))
+#define PLUS(x, y) ((x) + (y))
+#define PLUSONE(v) (PLUS((v), 1))
+
+#define U32TO8_LITTLE(p, v) \
+	{ (p)[0] = (v >>  0) & 0xff; (p)[1] = (v >>  8) & 0xff; \
+	  (p)[2] = (v >> 16) & 0xff; (p)[3] = (v >> 24) & 0xff; }
+#define U8TO32_LITTLE(p)   \
+	(((uint32_t)((p)[0])      ) | ((uint32_t)((p)[1]) <<  8) | \
+	 ((uint32_t)((p)[2]) << 16) | ((uint32_t)((p)[3]) << 24)   )
+
+/* QUARTERROUND updates a, b, c, d with a ChaCha "quarter" round. */
+#define QUARTERROUND(a,b,c,d) \
+  x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]),16); \
+  x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]),12); \
+  x[a] = PLUS(x[a],x[b]); x[d] = ROTATE(XOR(x[d],x[a]), 8); \
+  x[c] = PLUS(x[c],x[d]); x[b] = ROTATE(XOR(x[b],x[c]), 7);
+
+/* chacha_core performs |num_rounds| rounds of ChaCha20 on the input words in
+ * |input| and writes the 64 output bytes to |output|. */
+static void chacha_core(unsigned char output[64], const uint32_t input[16],
+			int num_rounds)
+	{
+	uint32_t x[16];
+	int i;
+
+	memcpy(x, input, sizeof(uint32_t) * 16);
+	for (i = 20; i > 0; i -= 2)
+		{
+		QUARTERROUND( 0, 4, 8,12)
+		QUARTERROUND( 1, 5, 9,13)
+		QUARTERROUND( 2, 6,10,14)
+		QUARTERROUND( 3, 7,11,15)
+		QUARTERROUND( 0, 5,10,15)
+		QUARTERROUND( 1, 6,11,12)
+		QUARTERROUND( 2, 7, 8,13)
+		QUARTERROUND( 3, 4, 9,14)
+		}
+
+	for (i = 0; i < 16; ++i)
+		x[i] = PLUS(x[i], input[i]);
+	for (i = 0; i < 16; ++i)
+		U32TO8_LITTLE(output + 4 * i, x[i]);
+	}
+
+void CRYPTO_chacha_20(unsigned char *out,
+		      const unsigned char *in, size_t in_len,
+		      const unsigned char key[32],
+		      const unsigned char nonce[12],
+		      uint32_t counter)
+	{
+	uint32_t input[16];
+	unsigned char buf[64];
+	size_t todo, i;
+
+	input[0] = U8TO32_LITTLE(sigma + 0);
+	input[1] = U8TO32_LITTLE(sigma + 4);
+	input[2] = U8TO32_LITTLE(sigma + 8);
+	input[3] = U8TO32_LITTLE(sigma + 12);
+
+	input[4] = U8TO32_LITTLE(key + 0);
+	input[5] = U8TO32_LITTLE(key + 4);
+	input[6] = U8TO32_LITTLE(key + 8);
+	input[7] = U8TO32_LITTLE(key + 12);
+
+	input[8] = U8TO32_LITTLE(key + 16);
+	input[9] = U8TO32_LITTLE(key + 20);
+	input[10] = U8TO32_LITTLE(key + 24);
+	input[11] = U8TO32_LITTLE(key + 28);
+
+	input[12] = counter;
+	input[13] = U8TO32_LITTLE(nonce + 0);
+	input[14] = U8TO32_LITTLE(nonce + 4);
+	input[15] = U8TO32_LITTLE(nonce + 8);
+
+	while (in_len > 0)
+		{
+		todo = sizeof(buf);
+		if (in_len < todo)
+			todo = in_len;
+
+		chacha_core(buf, input, 20);
+		for (i = 0; i < todo; i++)
+			out[i] = in[i] ^ buf[i];
+
+		out += todo;
+		in += todo;
+		in_len -= todo;
+
+		input[12]++;
+		if (input[12] == 0)
+			input[13]++;
+		}
+	}
+	
+void CRYPTO_chacha_20_keystream(unsigned char *out,
+		      size_t out_len,
+		      const unsigned char key[32],
+		      const unsigned char nonce[12],
+		      uint32_t counter)
+	{
+	uint32_t input[16];
+	unsigned char buf[64];
+	size_t todo, i;
+
+	input[0] = U8TO32_LITTLE(sigma + 0);
+	input[1] = U8TO32_LITTLE(sigma + 4);
+	input[2] = U8TO32_LITTLE(sigma + 8);
+	input[3] = U8TO32_LITTLE(sigma + 12);
+
+	input[4] = U8TO32_LITTLE(key + 0);
+	input[5] = U8TO32_LITTLE(key + 4);
+	input[6] = U8TO32_LITTLE(key + 8);
+	input[7] = U8TO32_LITTLE(key + 12);
+
+	input[8] = U8TO32_LITTLE(key + 16);
+	input[9] = U8TO32_LITTLE(key + 20);
+	input[10] = U8TO32_LITTLE(key + 24);
+	input[11] = U8TO32_LITTLE(key + 28);
+
+	input[12] = counter;
+	input[13] = U8TO32_LITTLE(nonce + 0);
+	input[14] = U8TO32_LITTLE(nonce + 4);
+	input[15] = U8TO32_LITTLE(nonce + 8);
+
+	while (out_len > 0)
+		{
+		todo = sizeof(buf);
+		if (out_len < todo)
+			todo = out_len;
+
+		chacha_core(buf, input, 20);
+		for (i = 0; i < todo; i++)
+			out[i] = buf[i];
+
+		out += todo;
+		out_len -= todo;
+
+		input[12]++;
+		if (input[12] == 0)
+			input[13]++;
+		}
+	}
+  
\ No newline at end of file
diff --git a/chacha.h b/chacha.h
new file mode 100644
index 0000000..87a1d46
--- /dev/null
+++ b/chacha.h
@@ -0,0 +1,78 @@
+/*
+ * This code is based on an OpenSSL implementation of chacha20. 
+ * Hence, the copyright below applies.
+ * 
+ */
+/* ====================================================================
+ * Copyright (c) 2011-2013 The OpenSSL Project.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * 3. All advertising materials mentioning features or use of this
+ *    software must display the following acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
+ *
+ * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
+ *    endorse or promote products derived from this software without
+ *    prior written permission. For written permission, please contact
+ *    licensing@OpenSSL.org.
+ *
+ * 5. Products derived from this software may not be called "OpenSSL"
+ *    nor may "OpenSSL" appear in their names without prior written
+ *    permission of the OpenSSL Project.
+ *
+ * 6. Redistributions of any form whatsoever must retain the following
+ *    acknowledgment:
+ *    "This product includes software developed by the OpenSSL Project
+ *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
+ * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE OpenSSL PROJECT OR
+ * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ * ====================================================================
+ */
+#ifndef CHACHA_H
+#define CHACHA_H
+
+#include <stddef.h>
+
+typedef unsigned int uint32_t;
+/* CRYPTO_chacha_20 encrypts |in_len| bytes from |in| with the given key and
+ * nonce and writes the result to |out|, which may be equal to |in|. The
+ * initial block counter is specified by |counter|. */
+void CRYPTO_chacha_20(unsigned char *out,
+		      const unsigned char *in, size_t in_len,
+		      const unsigned char key[32],
+		      const unsigned char nonce[12],
+		      uint32_t counter);
+
+/* CRYPTO_chacha_20_keystream generates |out_len| bytes from the generated keystream with the given key and
+ * nonce and writes the result to |out|. The
+ * initial block counter is specified by |counter|. */
+void CRYPTO_chacha_20_keystream(unsigned char *out,
+		      size_t out_len,
+		      const unsigned char key[32],
+		      const unsigned char nonce[12],
+		      uint32_t counter);
+
+#endif
\ No newline at end of file
diff --git a/hash.c b/hash.c
new file mode 100644
index 0000000..4aeb87b
--- /dev/null
+++ b/hash.c
@@ -0,0 +1,143 @@
+#include "params.h"
+#include "prg.h"
+
+#include <stddef.h>
+#include "stdio.h"
+#include <openssl/sha.h>
+#include <openssl/hmac.h>
+#include <openssl/evp.h>
+
+
+#define SET_KEY_BIT(a,b) (a[15] = (a[15] & 253) | (b << 1))
+#define SET_BLOCK_BIT(a,b) (a[15] = (a[15] & 254) | b)
+
+#define WOTS_SELECT_KEY(a) (a[15] = (a[15] & 253) | 1)
+#define WOTS_SELECT_BLOCK(a) (a[15] = (a[15] & 254) | 0)
+
+/**
+ * Implements PRF_m
+ */
+int prf_m(unsigned char *out, const unsigned char *in, size_t inlen, const unsigned char *key, int keylen)
+{
+  unsigned int length;
+  if (keylen == 32){
+    HMAC(EVP_sha256(), key, keylen, in, inlen, out, &length);
+    if(length != 32)
+    {
+      fprintf(stderr, "HMAC outputs %d bytes... That should not happen...",length); 
+    }
+    return 0;
+  }
+  else
+  {
+    if(keylen == 64)
+    {
+      HMAC(EVP_sha512(), key, keylen, in, inlen, out, &length);
+      if(length != 64)
+      {
+	fprintf(stderr, "HMAC outputs %d bytes... That should not happen...",length); 
+      }
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/*
+ * Implemts H_m
+ */
+int hash_m(unsigned char *out,const unsigned char *in,unsigned long long inlen,const unsigned char *key, const int keylen, const int m)
+{
+  if(keylen != m){
+    fprintf(stderr, "H_m takes m-bit keys, we got m=%d but a keylength of %d.\n",m,keylen); 
+    return 1;
+  }
+  unsigned long long i;
+  unsigned char buf[inlen +keylen+m];
+  for(i=0;i<m;i++)
+  {
+    buf[i] = 0x00;
+  }
+  for(i=0;i <keylen;i++)
+  {
+    buf[m+i] = key[i];
+  }
+  for(i=0;i <inlen;i++)
+  {
+    buf[m+keylen+i] = in[i];
+  }
+  
+  if(m == 32)
+  {  
+    SHA256(buf,inlen +keylen+m,out);
+    return 0;
+  } 
+  else
+  {
+    if(m == 64)
+    {
+      SHA512(buf,inlen +keylen+m,out);
+      return 0;
+    }
+  }
+  return 1;
+}
+
+/**
+ * We assume the left half is in in[0]...in[n-1]
+ */
+int hash_2n_n(unsigned char *out,const unsigned char *in, const unsigned char *pub_seed, unsigned char addr[16], const int n)
+{
+  if(n != 32){ 
+    fprintf(stderr, "Hash.c:hash_2n_n: Current implementation does not support n != 32, yet.\n");
+    return -1;
+  }
+  unsigned char buf[4*n];
+  unsigned char key[n];
+  unsigned char bitmask[2*n];
+  int i;
+  
+  SET_KEY_BIT(addr,1);
+  SET_BLOCK_BIT(addr,0);
+  prg_with_counter(key, n, pub_seed, 32, addr);
+  SET_KEY_BIT(addr,0);
+  // Use MSB order
+  prg_with_counter(bitmask, n, pub_seed, 32, addr);
+  SET_BLOCK_BIT(addr,1);
+  prg_with_counter(bitmask+n, n, pub_seed, 32, addr);
+  for(i=0;i<n;i++)
+  {
+    buf[i] = 0x00;
+    buf[n+i] = key[i];
+    buf[2*n+i] = in[i] ^ bitmask[i];
+    buf[3*n+i] = in[n+i] ^ bitmask[n+i];
+  }
+  SHA256(buf,4*n,out);
+  return 0;
+}
+
+int hash_n_n(unsigned char *out,const unsigned char *in, const unsigned char *pub_seed, unsigned char addr[16], const int n)
+{
+  if(n != 32){ 
+    fprintf(stderr, "Hash.c:hash_n_n: Current implementation does not support n != 32, yet.\n");
+    return -1;
+  }
+  
+  unsigned char buf[3*n];
+  unsigned char key[n];
+  unsigned char bitmask[n];
+  int i;
+  
+  WOTS_SELECT_KEY(addr);
+  prg_with_counter(key, n, pub_seed, 32, addr);
+  WOTS_SELECT_BLOCK(addr);
+  prg_with_counter(bitmask, n, pub_seed, 32, addr);
+  for(i=0;i<n;i++)
+  {
+    buf[i] = 0x00;
+    buf[n+i] = key[i];
+    buf[2*n+i] = in[i] ^ bitmask[i];
+  }
+  SHA256(buf,3*n,out);
+  return 0;
+}
diff --git a/hash.h b/hash.h
new file mode 100644
index 0000000..1f6bfd6
--- /dev/null
+++ b/hash.h
@@ -0,0 +1,11 @@
+#ifndef HASH_H
+#define HASH_H
+
+#include "params.h"
+
+int prf_m(unsigned char *out, const unsigned char *in, size_t inlen, const unsigned char *key, int keylen);
+int hash_m(unsigned char *out,const unsigned char *in,unsigned long long inlen, const unsigned char *key, const int keylen, const int m);
+int hash_2n_n(unsigned char *out,const unsigned char *in, const unsigned char *pub_seed, unsigned char addr[16], const int n);
+int hash_n_n(unsigned char *out,const unsigned char *in, const unsigned char *pub_seed, unsigned char addr[16], const int n);
+
+#endif
diff --git a/main.c b/main.c
deleted file mode 100644
index 6211074..0000000
--- a/main.c
+++ /dev/null
@@ -1,7 +0,0 @@
-#include <stdio.h>
-#include <stdlib.h>
-
-int main(int argc, char **argv) {
-    printf("Hello World!");
-    return 0;
-}
diff --git a/params.h b/params.h
new file mode 100644
index 0000000..897e904
--- /dev/null
+++ b/params.h
@@ -0,0 +1,13 @@
+#define TREE_HEIGHT 10
+#define WOTS_LOGW 4 // -> w = 16
+
+#define SK_RAND_SEED_BYTES 32
+#define MESSAGE_HASH_SEED_BYTES 32
+
+#define WOTS_W (1 << WOTS_LOGW)
+#define WOTS_L1 ((256+WOTS_LOGW-1)/WOTS_LOGW)
+#define WOTS_L 67  // for WOTS_W == 16
+#define WOTS_LOG_L 7  // for WOTS_W == 16
+#define WOTS_SIGBYTES (WOTS_L*HASH_BYTES)
+
+#define HASH_BYTES 32 
diff --git a/prg.c b/prg.c
new file mode 100644
index 0000000..01bd7e3
--- /dev/null
+++ b/prg.c
@@ -0,0 +1,31 @@
+#include "chacha.h"
+//#include "params.h"
+#include "prg.h"
+
+const unsigned char zero_nonce[12] = {0};
+
+/**
+ * Generates rlen output bytes using ChaCha20 with a zero nonce and counter = 0
+ */
+void prg(unsigned char *r, unsigned long long rlen, const unsigned char *key, uint key_len)
+{  
+  CRYPTO_chacha_20_keystream(r, rlen, key, zero_nonce, 0);
+}
+
+/**
+ * Generates rlen output bytes using ChaCha20.
+ * Nonce and counter are set depending on the address addr.
+ */
+void prg_with_counter(unsigned char *r, unsigned long long rlen, const unsigned char *key, uint key_len, const unsigned char addr[16])
+{
+  int i;
+  unsigned char nonce[12];
+  for(i = 0; i < 12; i++)
+  {
+    nonce[i] = addr[i];
+  }
+  uint32_t counter;
+  counter = (addr[12] << 24)|(addr[13] << 16)|(addr[14] << 8)|addr[15];
+  // TODO: Check address handling. Endianess?
+  CRYPTO_chacha_20_keystream(r, rlen, key, nonce, counter);
+}
\ No newline at end of file
diff --git a/prg.h b/prg.h
new file mode 100644
index 0000000..ae5bd06
--- /dev/null
+++ b/prg.h
@@ -0,0 +1,16 @@
+#ifndef PRG_H
+#define PRG_H
+#include <stdlib.h>
+
+/**
+ * Generates rlen output bytes using key_len-byte key and places them in r.
+ * 
+ */
+void prg(unsigned char *r, unsigned long long rlen, const unsigned char *key, uint key_len);
+
+/**
+ * Generates rlen output bytes using key_len-byte key and hash address addr and places them in r.
+ * 
+ */
+void prg_with_counter(unsigned char *r, unsigned long long rlen, const unsigned char *key, uint key_len, const unsigned char addr[16]);
+#endif
diff --git a/randombytes.c b/randombytes.c
new file mode 100644
index 0000000..f3b8d41
--- /dev/null
+++ b/randombytes.c
@@ -0,0 +1,34 @@
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+/* it's really stupid that there isn't a syscall for this */
+
+static int fd = -1;
+
+void randombytes(unsigned char *x,unsigned long long xlen)
+{
+  int i;
+
+  if (fd == -1) {
+    for (;;) {
+      fd = open("/dev/urandom",O_RDONLY);
+      if (fd != -1) break;
+      sleep(1);
+    }
+  }
+
+  while (xlen > 0) {
+    if (xlen < 1048576) i = xlen; else i = 1048576;
+
+    i = read(fd,x,i);
+    if (i < 1) {
+      sleep(1);
+      continue;
+    }
+
+    x += i;
+    xlen -= i;
+  }
+}
diff --git a/randombytes.h b/randombytes.h
new file mode 100644
index 0000000..053d3f1
--- /dev/null
+++ b/randombytes.h
@@ -0,0 +1,6 @@
+#ifndef RANDOMBYTES_H
+#define RANDOMBYTES_H
+
+extern void randombytes(unsigned char * x,unsigned long long xlen);
+
+#endif
diff --git a/test/gen_testvectors.c b/test/gen_testvectors.c
new file mode 100644
index 0000000..3b59df7
--- /dev/null
+++ b/test/gen_testvectors.c
@@ -0,0 +1,92 @@
+#include <stdint.h>
+#include <stdio.h>
+#include "../crypto_sign.h"
+
+#define MAXMBYTES 2048
+
+typedef uint32_t uint32;
+
+static uint32 seed[32] = { 3,1,4,1,5,9,2,6,5,3,5,8,9,7,9,3,2,3,8,4,6,2,6,4,3,3,8,3,2,7,9,5 } ;
+static uint32 in[12];
+static uint32 out[8];
+static int outleft = 0;
+
+#define ROTATE(x,b) (((x) << (b)) | ((x) >> (32 - (b))))
+#define MUSH(i,b) x = t[i] += (((x ^ seed[i]) + sum) ^ ROTATE(x,b));
+
+static void surf(void)
+{
+  uint32 t[12]; uint32 x; uint32 sum = 0;
+  int r; int i; int loop;
+
+  for (i = 0;i < 12;++i) t[i] = in[i] ^ seed[12 + i];
+  for (i = 0;i < 8;++i) out[i] = seed[24 + i];
+  x = t[11];
+  for (loop = 0;loop < 2;++loop) {
+    for (r = 0;r < 16;++r) {
+      sum += 0x9e3779b9;
+      MUSH(0,5) MUSH(1,7) MUSH(2,9) MUSH(3,13)
+      MUSH(4,5) MUSH(5,7) MUSH(6,9) MUSH(7,13)
+      MUSH(8,5) MUSH(9,7) MUSH(10,9) MUSH(11,13)
+    }
+    for (i = 0;i < 8;++i) out[i] ^= t[i + 4];
+  }
+}
+
+void randombytes(unsigned char *x,unsigned long long xlen)
+{
+  while (xlen > 0) {
+    if (!outleft) {
+      if (!++in[0]) if (!++in[1]) if (!++in[2]) ++in[3];
+      surf();
+      outleft = 8;
+    }
+    *x = out[--outleft];
+    ++x;
+    --xlen;
+  }
+}
+
+
+unsigned char pk[CRYPTO_PUBLICKEYBYTES];
+unsigned char sk[CRYPTO_SECRETKEYBYTES];
+unsigned char m[MAXMBYTES];
+unsigned char sm[MAXMBYTES+CRYPTO_BYTES];
+//unsigned char mo[MAXMBYTES+CRYPTO_BYTES];
+unsigned long long smlen;
+unsigned long long mlen;
+
+int main(void)
+{
+  int n,i,r;
+  for(n=0;n<MAXMBYTES;n++)
+  {
+    crypto_sign_keypair(pk,sk);
+    randombytes(m,n);
+
+    crypto_sign(sm, &smlen, m, n, sk);
+    for(i=0;i<smlen;i++)
+      printf("%02x",sm[i]);
+    printf("\n");
+    r = crypto_sign_open(sm, &mlen, sm, smlen, pk);
+    if(r)
+    {
+      printf("signature verification fails\n");
+      return -1;
+    }
+    if(mlen != n)
+    {
+      printf("signature verification produces wrong message length\n");
+      return -1;
+    }
+    for(i=0;i<n;i++)
+    {
+      if(sm[i] != m[i])
+      {
+        printf("signature verification does not recover message\n");
+        return -1;
+      }
+    }
+  }
+  return 0;
+}
diff --git a/test/speed.c b/test/speed.c
new file mode 100644
index 0000000..705b405
--- /dev/null
+++ b/test/speed.c
@@ -0,0 +1,124 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "../crypto_sign.h"
+#include "../cpucycles.h"
+#include "../randombytes.h"
+#include "../horst.h"
+#include "../wots.h"
+#include "../hash.h"
+
+
+#define MLEN 59
+#define REP 1
+#define NRUNS 100
+
+static int ull_cmp(const void *a, const void *b) 
+{ 
+  const unsigned long long *ia = (const unsigned long long *)a; 
+  const unsigned long long *ib = (const unsigned long long *)b;
+  if (*ia > *ib) return 1;
+  if (*ia < *ib) return -1;
+  return 0;
+} 
+
+static const unsigned char seed[32] = {
+  0x22, 0x26, 0xb5, 0x64, 0xbb, 0x78, 0xcc, 0xab, 0x4a, 0x4c, 0x0a, 0x64, 0xc2, 0x0b, 0x5d, 0x68, 
+  0x38, 0x74, 0x1a, 0xc0, 0x03, 0x17, 0xff, 0xd8, 0xe3, 0x53, 0xc8, 0x59, 0xc6, 0x23, 0x5b, 0xaa};
+
+
+int main()
+{
+  unsigned long long t[NRUNS];
+  int i,j;
+
+  printf("\n=== Benchmarks of signatures ===\n\n");
+  unsigned char sk[CRYPTO_SECRETKEYBYTES];
+  unsigned char pk[CRYPTO_PUBLICKEYBYTES];
+
+  unsigned char m[MLEN+CRYPTO_BYTES];
+  unsigned char sm[MLEN+CRYPTO_BYTES];
+  unsigned long long mlen;
+  unsigned long long smlen;
+ 
+  unsigned char masks[2*HORST_LOGT*HASH_BYTES];
+  randombytes(masks,N_MASKS*HASH_BYTES);
+
+  unsigned char msg_seed[MSGHASH_BYTES];
+  randombytes(msg_seed, MSGHASH_BYTES);
+
+  //Benchmarking signature key generation
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      crypto_sign_keypair(pk, sk);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("keypair:           %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+
+  //Benchmarking signature generation
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      crypto_sign(sm, &smlen, m, MLEN, sk);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("sign:              %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+
+  //Benchmarking signature verification
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      crypto_sign_open(m, &mlen, sm, smlen, pk);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("sign_open:         %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+
+  //Benchmarking WOTS pkgen
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      wots_pkgen(sm, seed, masks);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("wots_pkgen:        %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+  printf("416*wots_pkgen:    %13.3lf\n", 416*(double)t[NRUNS/2-1]/REP);
+
+  //Benchmarking HORSt signing
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      horst_sign(sm, pk, &smlen, m, MLEN, seed, masks, msg_seed);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("horst_sign:        %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+
+  //Benchmarking hash_2n_n
+  for(i=0;i<NRUNS;i++)
+  {
+    t[i] = cpucycles();
+    for(j=0;j<REP;j++)
+      hash_2n_n(sm, sm);
+  }
+  for(i=0;i<NRUNS-1;i++)
+    t[i] = (t[i+1] - t[i]);
+  qsort(t, NRUNS-1, sizeof(unsigned long long), ull_cmp);
+  printf("hash_2n_n:         %13.3lf\n", (double)t[NRUNS/2-1]/REP);
+
+
+  return 0;
+}
diff --git a/test/test.sh b/test/test.sh
new file mode 100755
index 0000000..72770a8
--- /dev/null
+++ b/test/test.sh
@@ -0,0 +1,6 @@
+#!/bin/bash
+
+DIR=$(dirname $0)
+#for i in `ls $DIR/test* | grep -v \.c$ | grep -v \.sh$`;do ($i || echo 666) | bc | grep -v ^0$;done 
+for i in `ls $DIR/test* | grep -v \.c$ | grep -v \.sh$`;do ($i || echo 666) ;done 
+exit 0
diff --git a/test/test_chacha b/test/test_chacha
new file mode 100755
index 0000000..335b7d8
Binary files /dev/null and b/test/test_chacha differ
diff --git a/test/test_chacha.c b/test/test_chacha.c
new file mode 100644
index 0000000..606617f
--- /dev/null
+++ b/test/test_chacha.c
@@ -0,0 +1,33 @@
+#include <stdio.h>
+#include "../prg.h"
+
+static void hexdump(unsigned char *a, size_t len)
+{
+  size_t i;
+  for (i = 0; i < len; i++)
+    printf("%02x", a[i]);
+}
+
+
+int main()
+{
+  unsigned char seed[32] = {0};
+  unsigned char out[64];
+  unsigned char addr[16] = {2};
+
+  printf("Case 1: All 0\n");
+  prg(out, 64, seed, 32);
+
+  printf("\n");
+  hexdump(out, 64);
+  printf("\n");
+  
+  printf("Case 2: key = 1\n");
+  seed[31] = 1;
+  prg_with_counter(out, 64, seed, 32, addr);
+
+  printf("\n");
+  hexdump(out, 64);
+  printf("\n");
+  return 0;
+}
diff --git a/test/test_wots b/test/test_wots
new file mode 100755
index 0000000..8c743cc
Binary files /dev/null and b/test/test_wots differ
diff --git a/test/test_wots.c b/test/test_wots.c
new file mode 100644
index 0000000..aa496a3
--- /dev/null
+++ b/test/test_wots.c
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include "../wots.h"
+#include "../randombytes.h"
+#include "../params.h"
+
+static void hexdump(unsigned char *a, size_t len)
+{
+  size_t i;
+  for (i = 0; i < len; i++)
+    printf("%02x", a[i]);
+}
+
+int main()
+{
+unsigned char seed[32];
+unsigned char pub_seed[32];
+wots_params params;
+wots_set_params(&params, 32, 32, 16);
+
+int sig_len = params.len*params.n;
+
+unsigned char pk1[sig_len];
+unsigned char pk2[sig_len];
+unsigned char sig[sig_len];
+unsigned char addr[16] = {1,2,3,4};
+
+  unsigned char msg[32];
+  int i;
+
+  randombytes(seed, 32);
+  randombytes(pub_seed, 32);
+  randombytes(msg, 32);
+  //randombytes(addr, 16);
+
+  wots_pkgen(pk1, seed, &params, pub_seed, addr);
+  wots_sign(sig, msg, seed, &params, pub_seed, addr);
+  wots_pkFromSig(pk2, sig, msg, &params, pub_seed, addr);
+
+  for(i=0;i<sig_len;i++)
+    if(pk1[i] != pk2[i])
+    {
+      printf("fuck %d\n",i);
+      return -1;
+    }
+  printf("worked great!\npk1: ");
+  hexdump(pk1, sig_len);
+  printf("\npk2: ");
+  hexdump(pk2, sig_len);
+  printf("\nsig: ");
+  hexdump(sig, sig_len);
+  printf("\n");
+  
+  return 0;
+}
diff --git a/test/test_xmss b/test/test_xmss
new file mode 100755
index 0000000..a50c78a
Binary files /dev/null and b/test/test_xmss differ
diff --git a/test/test_xmss.c b/test/test_xmss.c
new file mode 100644
index 0000000..6473ccf
--- /dev/null
+++ b/test/test_xmss.c
@@ -0,0 +1,83 @@
+#include <stdio.h>
+#include <string.h>
+
+#include "../xmss.h"
+
+#define MLEN 3491
+
+
+
+unsigned char sk[100];
+unsigned char pk[64];
+unsigned char mi[MLEN];
+unsigned long long smlen;
+unsigned long long mlen;
+
+int main()
+{
+  int r;
+  unsigned long long i;
+  int m = 32;
+  int n = 32;
+  int h = 8;
+  int w = 16;
+  
+  xmss_params p;
+  xmss_params *params = &p;
+  xmss_set_params(params, m, n, h, w);
+  unsigned long long signature_length = 4+m+params->wots_par->keysize+h*n;
+  unsigned char mo[MLEN+signature_length];
+  unsigned char sm[MLEN+signature_length];
+
+  FILE *urandom = fopen("/dev/urandom", "r");
+  for(i=0;i<MLEN;i++) mi[i] = fgetc(urandom);
+
+  printf("keypair\n");
+  xmss_keypair(pk, sk, params);
+  // check pub_seed in SK
+  for(i=0;i<n;i++)
+  {
+    if(pk[n+i] != sk[4+m+n+i]) printf("fuck %llu",i);
+  }
+
+  // check index
+  unsigned long idx = (sk[0] << 24) | (sk[1] << 16) | (sk[2] << 8) || sk[3];
+  if(idx) printf("\nfuck %lu\n",idx);
+  
+  printf("sign\n");
+  xmss_sign(sk, sm, &smlen, mi, MLEN, params, pk);
+
+  r = memcmp(mi, sm+signature_length,MLEN);
+  printf("%d\n", r);
+  
+  /* Test valid signature */
+  printf("verify\n");
+  r = xmss_sign_open(mo, &mlen, sm, smlen, pk, params);
+  printf("%d\n", r);
+  r = memcmp(mi,mo,MLEN);
+  printf("%d\n", r);
+  printf("%llu\n", MLEN-mlen);
+
+  /* Test with modified message */
+  sm[52] ^= 1;
+  r = xmss_sign_open(mo, &mlen, sm, smlen, pk, params);
+  printf("%d\n", r+1);
+  r = memcmp(mi,mo,MLEN);
+  printf("%d\n", (r!=0) - 1);
+  printf("%llu\n", mlen+1);
+
+  /* Test with modified signature */
+  sm[260] ^= 1;
+  sm[52] ^= 1;
+  sm[2] ^= 1;
+  r = xmss_sign_open(mo, &mlen, sm, smlen, pk, params);
+  printf("%d\n", r+1);
+  r = memcmp(mi,mo,MLEN);
+  printf("%d\n", (r!=0) - 1);
+  printf("%llu\n", mlen+1);
+
+  fclose(urandom);
+  return 0;
+}
+
+
diff --git a/wots.c b/wots.c
new file mode 100644
index 0000000..04ee5cb
--- /dev/null
+++ b/wots.c
@@ -0,0 +1,200 @@
+/*
+wots.c version 2015xxxx
+Andreas Hülsing
+Public domain.
+*/
+
+#include "math.h"
+#include "stdio.h"
+#include "xmss_commons.h"
+//#include "params.h"
+#include "prg.h"
+#include "hash.h"
+#include "wots.h"
+
+/**
+ * Macros used to manipulate the respective fields
+ * in the 16byte hash address
+ */
+#define SET_HASH_ADDRESS(a, v) {\
+  a[15] = (a[15] & 1) | ((v << 1) & 255);\
+  a[14] = (a[14] & 254) | ((v >> 7) & 1);}
+  
+#define SET_CHAIN_ADDRESS(a, v) {\
+  a[14] = (a[14] & 1) | ((v << 1) & 255);\
+  a[13] = (v >> 7) & 255;\
+  a[12] = (a[12] & 254) | ((v >> 15) & 1);}
+
+
+void wots_set_params(wots_params *params, int m, int n, int w)
+{
+  params->m = m;
+  params->n = n;
+  params->w = w;
+  params->log_w = (int) log2(w);
+  params->len_1 = (int) ceil(((8*m) / params->log_w));
+  params->len_2 = (int) floor(log2(params->len_1*(w-1)) / params->log_w) + 1;
+  params->len = params->len_1 + params->len_2;
+  params->keysize = params->len*params->n;
+}
+
+/**
+ * Helper method for pseudorandom key generation
+ * Expands a 32 byte array into a len*n byte array 
+ * this is done using chacha20 with nonce 0 and counter 0
+ */
+static void expand_seed(unsigned char *outseeds, const unsigned char *inseed, wots_params *params)
+{
+  prg(outseeds, params->keysize, inseed, 32);
+}
+
+/**
+ * Computes the chaining function.
+ * out and in have to be n-byte arrays
+ * 
+ * interpretes in as start-th value of the chain
+ * addr has to contain the address of the chain
+ */
+static void gen_chain(unsigned char *out, const unsigned char *in, int start, int steps, const wots_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{
+  uint i,j;
+  for(j=0;j<params->n;j++) 
+    out[j] = in[j];
+
+  for(i=start;i<(start+steps) && i<params->w;i++){
+    SET_HASH_ADDRESS(addr,i);
+//     printf("Hash %d:",i);
+//     hexdump(addr,16);
+//     printf("\n");
+     hash_n_n(out,out, pub_seed, addr,params->n);
+  }
+}
+
+/**
+ * base_w algorithm as described in draft.
+ * 
+ * 
+ */
+static void base_w(int *output, const unsigned char *input, int in_len, wots_params *params)
+{
+  int in = 0;
+  int out = 0;
+  int total = 0;
+  int bits = 0;
+  int consumed = 0;
+  
+  for(consumed = 0; consumed < 8 * in_len; consumed += params->log_w)
+  {
+    if(bits == 0){
+      total = input[in_len - 1 - in];
+      in++;
+      bits += 8;
+    }
+    bits -= params->log_w;
+    output[out] = (total >> bits) & (params->w - 1);
+    out++;
+  }
+}
+
+/**
+ * Alternative base w algorithm for w = 16 to check...
+ */
+static void base_w_alternative(int *output, unsigned char *input, int in_len, wots_params *params)
+{
+  uint i = 0; 
+  for(i = 0; i < in_len; i += 2)
+  {
+    output[i] = input[in_len - 1 - (i / 2)] >> 4;
+    output[i+1] = input[in_len - 1 - (i / 2)] & 0xf;
+  }
+}
+
+void wots_pkgen(unsigned char *pk, const unsigned char *sk, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{
+  uint i;
+  expand_seed(pk, sk, params);
+  for(i=0;i<params->len;i++){
+    SET_CHAIN_ADDRESS(addr,i);
+//     printf("Chain: %d\n",i);
+//     hexdump(addr,16);
+//     printf("\n");
+     gen_chain(pk+i*params->n, pk+i*params->n, 0, params->w-1, params, pub_seed, addr);
+  }
+}
+
+
+void wots_sign(unsigned char *sig, const unsigned char *msg, const unsigned char *sk, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{
+  int basew[params->len];
+  int csum = 0;
+  uint i=0;
+
+  base_w(basew, msg, params->m, params);
+  
+  for(i=0;i<params->len_1;i++)
+  {
+    csum += params->w - 1 - basew[i];
+  }
+
+  csum = csum << ( 8 - ( ( params->len_2 * params->log_w ) % 8 ));
+  
+  int len_2_bytes = ((params->len_2 * params->log_w) + 7) / 8;
+  
+  unsigned char csum_bytes[len_2_bytes];
+  to_byte(csum_bytes, csum, len_2_bytes);
+  
+  int csum_basew[len_2_bytes / params->log_w];
+  base_w(csum_basew, csum_bytes, len_2_bytes, params);
+  
+  for(i = 0; i < params->len_2; i++)
+  {
+    basew[params->len_1 + i] = csum_basew[i];
+  }
+  
+  expand_seed(sig, sk, params);
+  
+  for(i=0;i<params->len;i++){
+    SET_CHAIN_ADDRESS(addr,i);
+//     printf("Chain: %d\n",i);
+//     hexdump(addr,16);
+//     printf("\n");
+     gen_chain(sig+i*params->n, sig+i*params->n, 0, basew[i], params, pub_seed, addr);
+  }
+}
+
+void wots_pkFromSig(unsigned char *pk, const unsigned char *sig, const unsigned char *msg, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{
+  int basew[params->len];
+  int csum = 0;
+  uint i=0;
+
+  base_w(basew, msg, params->m, params);
+  
+  for(i=0;i<params->len_1;i++)
+  {
+    csum += params->w - 1 - basew[i];
+  }
+
+  csum = csum << ( 8 - ( ( params->len_2 * params->log_w ) % 8 ));
+  
+  int len_2_bytes = ((params->len_2 * params->log_w) + 7) / 8;
+  
+  unsigned char csum_bytes[len_2_bytes];
+  to_byte(csum_bytes, csum, len_2_bytes);
+  
+  int csum_basew[len_2_bytes / params->log_w];
+  base_w(csum_basew, csum_bytes, len_2_bytes, params);
+  
+  for(i = 0; i < params->len_2; i++)
+  {
+    basew[params->len_1 + i] = csum_basew[i];
+  }
+  
+  for(i=0;i<params->len;i++){
+    SET_CHAIN_ADDRESS(addr,i);
+//     printf("Chain: %d\n",i);
+//     hexdump(addr,16);
+//     printf("\n");
+     gen_chain(pk+i*params->n, sig+i*params->n, basew[i], params->w-1-basew[i], params, pub_seed, addr);
+  }
+}
diff --git a/wots.h b/wots.h
new file mode 100644
index 0000000..3c03469
--- /dev/null
+++ b/wots.h
@@ -0,0 +1,52 @@
+#ifndef WOTS_H
+#define WOTS_H
+
+#include "params.h"
+/**
+ * WOTS parameter set
+ * 
+ * Meaning as defined in draft-irtf-cfrg-xmss-hash-based-signatures-02
+ */
+typedef struct{
+  int len_1;
+  int len_2;
+  int len;
+  int m;
+  int n;
+  int w;
+  int log_w;
+  int keysize;
+} wots_params;
+
+/**
+ * Set the WOTS parameters, 
+ * only m, n, w are required as inputs,
+ * len, len_1, and len_2 are computed from those.
+ *
+ * Assumes w is a power of 2
+ */
+void wots_set_params(wots_params *params, int m, int n, int w);
+
+/**
+ * WOTS key generation. Takes a 32byte seed for the secret key, expands it to a full WOTS secret key and computes the corresponding public key. 
+ * For this it takes the seed pub_seed which is used to generate bitmasks and hash keys and the address of this WOTS key pair addr
+ * 
+ * params, must have been initialized before using wots_set params for params ! This is not done in this function
+ * 
+ * Places the computed public key at address pk.
+ */
+void wots_pkgen(unsigned char *pk, const unsigned char *sk, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16]);
+
+/**
+ * Takes a m-byte message and the 32-byte seed for the secret key to compute a signature that is placed at "sig".
+ *  
+ */
+void wots_sign(unsigned char *sig, const unsigned char *msg, const unsigned char *sk, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16]);
+
+/**
+ * Takes a WOTS signature, a m-byte message and computes a WOTS public key that it places at pk.
+ * 
+ */
+void wots_pkFromSig(unsigned char *pk, const unsigned char *sig, const unsigned char *msg, wots_params *params, const unsigned char *pub_seed, unsigned char addr[16]);
+
+#endif
diff --git a/xmss.c b/xmss.c
new file mode 100644
index 0000000..3d05a5f
--- /dev/null
+++ b/xmss.c
@@ -0,0 +1,524 @@
+#include "xmss.h"
+#include <stdlib.h>
+#include <string.h>
+#include <stdint.h>
+#include <math.h>
+
+#include "randombytes.h"
+#include "wots.h"
+#include "hash.h"
+#include "prg.h"
+#include "xmss_commons.h"
+
+// For testing
+#include "stdio.h"
+
+/**
+ * Macros used to manipulate the respective fields
+ * in the 16byte hash address
+ */    
+#define SET_OTS_BIT(a, b) {\
+  a[9] = (a[9] & 253) | (b << 1);}
+
+#define SET_OTS_ADDRESS(a, v) {\
+  a[12] = (a[12] & 1) | ((v << 1) & 255);\
+  a[11] = (v >> 7) & 255;\
+  a[10] = (v >> 15) & 255;\
+  a[9] = (a[9] & 254) | ((v >> 23) & 1);}  
+  
+#define ZEROISE_OTS_ADDR(a) {\
+  a[12] = (a[12] & 254);\
+  a[13] = 0;\
+  a[14] = 0;\
+  a[15] = 0;}
+  
+#define SET_LTREE_BIT(a, b) {\
+  a[9] = (a[9] & 254) | b;}
+
+#define SET_LTREE_ADDRESS(a, v) {\
+  a[12] = v & 255;\
+  a[11] = (v >> 8) & 255;\
+  a[10] = (v >> 16) & 255;}
+
+#define SET_LTREE_TREE_HEIGHT(a, v) {\
+  a[13] = (a[13] & 3) | ((v << 2) & 255);}
+
+#define SET_LTREE_TREE_INDEX(a, v) {\
+  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[14] = (v >> 6) & 255;\
+  a[13] = (a[13] & 252) | ((v >> 14) & 3);}
+  
+#define SET_NODE_PADDING(a) {\
+  a[10] = 0;\
+  a[11] = a[11] & 3;}  
+
+#define SET_NODE_TREE_HEIGHT(a, v) {\
+  a[12] = (a[12] & 3) | ((v << 2) & 255);\
+  a[11] = (a[11] & 252) | ((v >> 6) & 3);}
+
+#define SET_NODE_TREE_INDEX(a, v) {\
+  a[15] = (a[15] & 3) | ((v << 2) & 255);\
+  a[14] = (v >> 6) & 255;\
+  a[13] = (v >> 14) & 255;\
+  a[12] = (a[12] & 252) | ((v >> 22) & 3);}
+
+
+  /**
+ * Used for pseudorandom keygeneration,
+ * generates the seed for the WOTS keypair at address addr
+ */
+static void get_seed(unsigned char seed[32], const unsigned char *sk_seed, unsigned char addr[16])
+{
+  // Make sure that chain addr, hash addr, and key bit are 0!
+  ZEROISE_OTS_ADDR(addr);
+  // Generate pseudorandom value
+  prg_with_counter(seed, 32, sk_seed, 32, addr);
+}
+
+/**
+ * Initialize xmss params struct
+ * parameter names are the same as in the draft
+ */
+void xmss_set_params(xmss_params *params, int m, int n, int h, int w)
+{
+  params->h = h;
+  params->m = m;
+  params->n = n;
+  wots_params wots_par;
+  wots_set_params(&wots_par, m, n, w);
+  params->wots_par = &wots_par;
+}
+
+/**
+ * Computes a leaf from a WOTS public key using an L-tree.
+ */
+static void l_tree(unsigned char *leaf, unsigned char *wots_pk, const xmss_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{ 
+  uint l = params->wots_par->len;
+  uint n = params->n;
+  unsigned long i = 0;
+  uint height = 0;
+  
+  //ADRS.setTreeHeight(0);
+  SET_LTREE_TREE_HEIGHT(addr,height);
+  unsigned long bound;
+  while ( l > 1 ) 
+  {
+     bound = l >> 1; //floor(l / 2); 
+     for ( i = 0; i < bound; i = i + 1 ) {
+       //ADRS.setTreeIndex(i);
+       SET_LTREE_TREE_INDEX(addr,i);
+       //wots_pk[i] = RAND_HASH(pk[2i], pk[2i + 1], SEED, ADRS);
+       hash_2n_n(wots_pk+i*n,wots_pk+i*2*n, pub_seed, addr, n);
+     }
+     //if ( l % 2 == 1 ) {
+     if(l&1)
+     {
+       //pk[floor(l / 2) + 1] = pk[l];
+       memcpy(wots_pk+(l>>1)*n,wots_pk+(l-1)*n, n);
+       //l = ceil(l / 2);
+       l=(l>>1)+1;
+     }
+     else
+     {
+       //l = ceil(l / 2);
+       l=(l>>1);
+     }     
+     //ADRS.setTreeHeight(ADRS.getTreeHeight() + 1);
+     height++;
+     SET_LTREE_TREE_HEIGHT(addr,height);
+   }
+   //return pk[0];
+   memcpy(leaf,wots_pk,n);
+}
+
+/**
+ * Computes the leaf at a given address. First generates the WOTS key pair, then computes leaf using l_tree. As this happens position independent, we only require that addr encodes the right ltree-address.
+ */
+static void gen_leaf_wots(unsigned char *leaf, const unsigned char *sk_seed, const xmss_params *params, const unsigned char *pub_seed, unsigned char ltree_addr[16], unsigned char ots_addr[16])
+{
+  unsigned char seed[32];
+  unsigned char pk[params->wots_par->keysize];
+
+  get_seed(seed, sk_seed, ots_addr);
+  wots_pkgen(pk, seed, params->wots_par, pub_seed, ots_addr);
+
+  l_tree(leaf, pk, params, pub_seed, ltree_addr); 
+}
+
+/**
+ * Merkle's TreeHash algorithm. The address only needs to initialize the first 78 bits of addr. Everything else will be set by treehash.
+ * Currently only used for key generation.
+ * 
+ */
+static void treehash(unsigned char *node, int height, int index, const unsigned char *sk_seed, const xmss_params *params, const unsigned char *pub_seed, const unsigned char addr[16])
+{
+
+  uint idx = index;
+  uint n = params->n;
+  // use three different addresses because at this point we use all three formats in parallel
+  unsigned char ots_addr[16];
+  unsigned char ltree_addr[16];
+  unsigned char node_addr[16];
+  memcpy(ots_addr, addr, 10);
+  SET_OTS_BIT(ots_addr, 1);
+  memcpy(ltree_addr, addr, 10);
+  SET_OTS_BIT(ltree_addr, 0);
+  SET_LTREE_BIT(ltree_addr, 1);
+  memcpy(node_addr, ltree_addr, 10);
+  SET_LTREE_BIT(node_addr, 0);
+  SET_NODE_PADDING(node_addr);
+  
+  int lastnode,i;
+  unsigned char stack[(height+1)*n];
+  unsigned int  stacklevels[height+1];
+  unsigned int  stackoffset=0;
+  
+  lastnode = idx+(1<<height);
+
+  for(;idx<lastnode;idx++) 
+  {
+    SET_LTREE_ADDRESS(ltree_addr,idx);
+    SET_OTS_ADDRESS(ots_addr,idx);
+    gen_leaf_wots(stack+stackoffset*n,sk_seed,params, pub_seed, ltree_addr, ots_addr);
+    stacklevels[stackoffset] = 0;
+    stackoffset++;
+    while(stackoffset>1 && stacklevels[stackoffset-1] == stacklevels[stackoffset-2])
+    {
+      SET_NODE_TREE_HEIGHT(node_addr,stacklevels[stackoffset-1]);
+      SET_NODE_TREE_INDEX(node_addr, (idx >> (stacklevels[stackoffset-1]+1)));
+      hash_2n_n(stack+(stackoffset-2)*n,stack+(stackoffset-2)*n, pub_seed,
+          node_addr, n);
+      stacklevels[stackoffset-2]++;
+      stackoffset--;
+    }
+  }
+  for(i=0;i<n;i++)
+    node[i] = stack[i];
+}
+
+/**
+ * Computes a root node given a leaf and an authapth
+ */
+static void validate_authpath(unsigned char *root, const unsigned char *leaf, unsigned long leafidx, const unsigned char *authpath, const xmss_params *params, const unsigned char *pub_seed, unsigned char addr[16])
+{
+  uint n = params->n;
+  
+  int i,j;
+  unsigned char buffer[2*n];
+
+  // If leafidx is odd (last bit = 1), current path element is a right child and authpath has to go to the left.
+  // Otherwise, it is the other way around
+  if(leafidx&1)
+  {
+    for(j=0;j<n;j++)
+      buffer[n+j] = leaf[j];
+    for(j=0;j<n;j++)
+      buffer[j] = authpath[j];
+  }
+  else
+  {
+    for(j=0;j<n;j++)
+      buffer[j] = leaf[j];
+    for(j=0;j<n;j++)
+      buffer[n+j] = authpath[j];
+  }
+  authpath += n;
+
+  for(i=0;i<params->h-1;i++)
+  {
+    SET_NODE_TREE_HEIGHT(addr,i);
+    leafidx >>= 1;
+    SET_NODE_TREE_INDEX(addr, leafidx);
+    if(leafidx&1)
+    {
+      hash_2n_n(buffer+n,buffer,pub_seed, addr, n);
+      for(j=0;j<n;j++)
+        buffer[j] = authpath[j];
+    }
+    else
+    {
+      hash_2n_n(buffer,buffer,pub_seed, addr, n);
+      for(j=0;j<n;j++)
+        buffer[j+n] = authpath[j];
+    }
+    authpath += n;
+  }
+  SET_NODE_TREE_HEIGHT(addr, (params->h-1));
+  leafidx >>= 1;
+  SET_NODE_TREE_INDEX(addr, leafidx);
+  hash_2n_n(root,buffer,pub_seed,addr,n);
+}
+
+/**
+ * Computes the authpath and the root. This method is using a lot of space as we build the whole tree and then select the authpath nodes.
+ * For more efficient algorithms see e.g. the chapter on hash-based signatures in Bernstein, Buchmann, Dahmen. "Post-quantum Cryptography", Springer 2009.
+ * It returns the authpath in "authpath" with the node on level 0 at index 0.  
+ */
+static void compute_authpath_wots(unsigned char *root, unsigned char *authpath, unsigned long leaf_idx, const unsigned char *sk_seed, const xmss_params *params, unsigned char *pub_seed, unsigned char addr[16])
+{
+  uint i, j, level;
+  int n = params->n;
+  int h = params->h;
+  
+  unsigned char tree[2*(1<<h)*n];
+
+  unsigned char ots_addr[16];
+  unsigned char ltree_addr[16];
+  unsigned char node_addr[16];
+  
+  memcpy(ots_addr, addr, 10);
+  SET_OTS_BIT(ots_addr, 1);
+  memcpy(ltree_addr, addr, 10);
+  SET_OTS_BIT(ltree_addr, 0);
+  SET_LTREE_BIT(ltree_addr, 1);
+  memcpy(node_addr, ltree_addr, 10);
+  SET_LTREE_BIT(node_addr, 0);
+  SET_NODE_PADDING(node_addr);
+
+  
+  // Compute all leaves
+  for(i = 0; i < (1<<h); i++)
+  {
+    SET_LTREE_ADDRESS(ltree_addr,i);
+    SET_OTS_ADDRESS(ots_addr,i);
+    gen_leaf_wots(tree+((1<<h)*n + i*n), sk_seed, params, pub_seed, ltree_addr, ots_addr);
+  }
+  
+  
+  level = 0;
+  // Compute tree:
+  // Outer loop: For each inner layer 
+  for (i = (1<<h); i > 0; i>>=1)
+  {
+    SET_NODE_TREE_HEIGHT(node_addr, level);
+    // Inner loop: for each pair of sibling nodes
+    for (j = 0; j < i; j+=2)
+    {
+      SET_NODE_TREE_INDEX(node_addr, j>>1);
+      hash_2n_n(tree + (i>>1)*n + (j>>1) * n, tree + i*n + j*n, pub_seed, node_addr, n);
+    }
+    level++;
+  }
+
+  // copy authpath
+  for(i=0;i<h;i++)
+    memcpy(authpath + i*n, tree + ((1<<h)>>i)*n + ((leaf_idx >> i) ^ 1) * n, n);
+  
+  // copy root
+  memcpy(root, tree+n, n);
+}
+
+
+/*
+ * Generates a XMSS key pair for a given parameter set.
+ * Format sk: [(32bit) idx || SK_SEED || SK_PRF || PUB_SEED]
+ * Format pk: [root || PUB_SEED] omitting algo oid.
+ */
+int xmss_keypair(unsigned char *pk, unsigned char *sk, xmss_params *params)
+{
+  uint n = params->n;
+  uint m = params->m;
+  // Set idx = 0
+  sk[0] = 0;
+  sk[1] = 0;
+  sk[2] = 0;
+  sk[3] = 0;
+  // Init SK_SEED (n byte), SK_PRF (m byte), and PUB_SEED (n byte)
+  randombytes(sk+4,2*n+m);
+  // Copy PUB_SEED to public key
+  memcpy(pk+n, sk+4+n+m,n);
+
+  unsigned char addr[16] = {0,0,0,0};
+  // Compute root
+  treehash(pk, params->h, 0, sk+4, params, sk+4+n+m, addr);
+  return 0;
+}
+
+/**
+ * Signs a message.
+ * Returns 
+ * 1. an array containing the signature followed by the message AND
+ * 2. an updated secret key!
+ * 
+ */
+int xmss_sign(unsigned char *sk, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg, unsigned long long msglen, const xmss_params *params, unsigned char* pk)
+{
+  uint n = params->n;
+  uint m = params->m;
+  
+  // Extract SK
+  unsigned long idx = (sk[0] << 24) | (sk[1] << 16) | (sk[2] << 8) || sk[3];
+  unsigned char sk_seed[n];
+  memcpy(sk_seed,sk+4,n);
+  unsigned char sk_prf[m];
+  memcpy(sk_prf,sk+4+n,m);
+  unsigned char pub_seed[n];
+  memcpy(pub_seed,sk+4+n+m,n);  
+  
+  // Update SK
+  sk[0] = ((idx + 1) >> 24) & 255;
+  sk[1] = ((idx + 1) >> 16) & 255;
+  sk[2] = ((idx + 1) >> 8) & 255;
+  sk[3] = (idx + 1) & 255;
+  // -- Secret key for this non-forward-secure version is now updated. 
+  // -- A productive implementation should use a file handle instead and write the updated secret key at this point! 
+  
+  // Init working params
+  unsigned long long i;
+  unsigned char R[m];
+  unsigned char msg_h[m];
+  unsigned char root[n];
+  unsigned char ots_seed[n];
+  unsigned char ots_addr[16] = {0,0,0,0};
+  
+  // ---------------------------------
+  // Message Hashing
+  // ---------------------------------
+  
+  // Message Hash: 
+  // First compute pseudorandom key
+  prf_m(R, msg, msglen, sk_prf, m); 
+  // Then use it for message digest
+  hash_m(msg_h, msg, msglen, R, m, m);
+  
+  // Start collecting signature
+  *sig_msg_len = 0;
+
+  // Copy index to signature
+  sig_msg[0] = (idx >> 24) & 255;
+  sig_msg[1] = (idx >> 16) & 255;
+  sig_msg[2] = (idx >> 8) & 255;
+  sig_msg[3] = idx & 255;
+  
+  sig_msg += 4;
+  *sig_msg_len += 4;
+  
+  // Copy R to signature
+  for(i=0; i<m; i++)
+    sig_msg[i] = R[i];
+
+  sig_msg += m;
+  *sig_msg_len += m;
+  
+  // ----------------------------------
+  // Now we start to "really sign" 
+  // ----------------------------------
+  
+  // Prepare Address
+  SET_OTS_BIT(ots_addr,1);
+  SET_OTS_ADDRESS(ots_addr,idx);
+  
+  // Compute seed for OTS key pair
+  get_seed(ots_seed, sk_seed, ots_addr);
+     
+  // Compute WOTS signature
+  wots_sign(sig_msg, msg_h, ots_seed, params->wots_par, pub_seed, ots_addr);
+  
+  sig_msg += params->wots_par->keysize;
+  *sig_msg_len += params->wots_par->keysize;
+
+  compute_authpath_wots(root, sig_msg, idx, sk_seed, params, pub_seed, ots_addr);
+  sig_msg += params->h*n;
+  *sig_msg_len += params->h*n;
+  
+  //DEBUG
+  for(i=0;i<n;i++)
+    if(root[i] != pk[i])
+      printf("Different PK's %llu",i);
+  
+  //Whipe secret elements?  
+  //zerobytes(tsk, CRYPTO_SECRETKEYBYTES);
+
+  memcpy(sig_msg,msg,msglen);
+  *sig_msg_len += msglen;
+
+  return 0;
+}
+
+/**
+ * Verifies a given message signature pair under a given public key.
+ */
+int xmss_sign_open(unsigned char *msg, unsigned long long *msglen, const unsigned char *sig_msg, unsigned long long sig_msg_len, const unsigned char *pk, const xmss_params *params)
+{
+  uint n = params->n;
+  uint m = params->m;
+    
+  unsigned long long i, m_len;
+  unsigned long idx=0;
+  unsigned char wots_pk[params->wots_par->keysize];
+  unsigned char pkhash[n];
+  unsigned char root[n];
+  unsigned char msg_h[m];
+  
+  unsigned char pub_seed[n];
+  memcpy(pub_seed,pk+n,n);  
+  
+  // Init addresses
+  unsigned char ots_addr[16] = {0,0,0,0};
+  unsigned char ltree_addr[16];
+  unsigned char node_addr[16];
+  
+  SET_OTS_BIT(ots_addr, 1);
+  
+  memcpy(ltree_addr, ots_addr, 10);
+  SET_OTS_BIT(ltree_addr, 0);
+  SET_LTREE_BIT(ltree_addr, 1);
+  
+  memcpy(node_addr, ltree_addr, 10);
+  SET_LTREE_BIT(node_addr, 0);
+  SET_NODE_PADDING(node_addr);  
+  
+  // Extract index
+  idx = (sig_msg[0] << 24) | (sig_msg[1] << 16) | (sig_msg[2] << 8) || sig_msg[3];
+  sig_msg += 4;
+  sig_msg_len -= 4;
+  
+  // hash message (recall, R is now on pole position at sig_msg
+  unsigned long long tmp_sig_len = m+params->wots_par->keysize+params->h*n;
+  m_len = sig_msg_len - tmp_sig_len;
+  hash_m(msg_h, sig_msg + tmp_sig_len, m_len, sig_msg, m, m);
+
+  sig_msg += m;
+  sig_msg_len -= m;
+  
+  //-----------------------
+  // Verify signature
+  //-----------------------
+  
+  // Prepare Address
+  SET_OTS_ADDRESS(ots_addr,idx);
+  // Check WOTS signature 
+  wots_pkFromSig(wots_pk, sig_msg, msg_h, params->wots_par, pub_seed, ots_addr);
+
+  sig_msg += params->wots_par->keysize;
+  sig_msg_len -= params->wots_par->keysize;
+  
+  // Compute Ltree
+  SET_LTREE_ADDRESS(ltree_addr, idx); 
+  l_tree(pkhash, wots_pk, params, pub_seed, ltree_addr);
+  
+  // Compute root
+  validate_authpath(root, pkhash, idx, sig_msg, params, pub_seed, node_addr);  
+
+  sig_msg += params->h*n;
+  sig_msg_len -= params->h*n;
+  
+  for(i=0;i<n;i++)
+    if(root[i] != pk[i])
+      goto fail;
+  
+  *msglen = sig_msg_len;
+  for(i=0;i<*msglen;i++)
+    msg[i] = sig_msg[i];
+
+  return 0;
+  
+  
+fail:
+  *msglen = sig_msg_len;
+  for(i=0;i<*msglen;i++)
+    msg[i] = 0;
+  *msglen = -1;
+  return -1;
+}
\ No newline at end of file
diff --git a/xmss.h b/xmss.h
new file mode 100644
index 0000000..e7ee288
--- /dev/null
+++ b/xmss.h
@@ -0,0 +1,45 @@
+#include "wots.h"
+
+#ifndef XMSS_H
+#define XMSS_H
+typedef struct{
+  int level;
+  unsigned long long subtree;
+  int subleaf;
+} leafaddr;
+
+typedef struct{
+  wots_params *wots_par;
+  int n;
+  int m;
+  int h;
+} xmss_params;
+
+/**
+ * Initializes parameter set.
+ * Needed, for any of the other methods.
+ */
+void xmss_set_params(xmss_params *params, int m, int n, int h, int w);
+/**
+ * Generates a XMSS key pair for a given parameter set.
+ * Format sk: [(32bit) idx || SK_SEED || SK_PRF || PUB_SEED]
+ * Format pk: [root || PUB_SEED] omitting algo oid.
+ */
+int xmss_keypair(unsigned char *pk, unsigned char *sk, xmss_params *params);
+/**
+ * Signs a message.
+ * Returns 
+ * 1. an array containing the signature followed by the message AND
+ * 2. an updated secret key!
+ * 
+ */
+int xmss_sign(unsigned char *sk, unsigned char *sig_msg, unsigned long long *sig_msg_len, const unsigned char *msg,unsigned long long msglen, const xmss_params *params, unsigned char* pk);
+/**
+ * Verifies a given message signature pair under a given public key.
+ * 
+ * Note: msg and msglen are pure outputs which carry the message in case verification succeeds. The (input) message is assumed to be within sig_msg which has the form (sig||msg). 
+ */
+int xmss_sign_open(unsigned char *msg,unsigned long long *msglen, const unsigned char *sig_msg,unsigned long long sig_msg_len, const unsigned char *pk, const xmss_params *params);
+
+#endif
+
diff --git a/xmss_commons.c b/xmss_commons.c
new file mode 100644
index 0000000..4457697
--- /dev/null
+++ b/xmss_commons.c
@@ -0,0 +1,19 @@
+#include "xmss_commons.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+void to_byte(unsigned char *out, uint in, int bytes)
+{
+  int i;
+  for(i = 0; i < bytes; i++){
+    out[i] = in & 0xff;
+    in = in >> 8;
+  }
+}
+
+void hexdump(const unsigned char *a, size_t len)
+{
+  size_t i;
+  for (i = 0; i < len; i++)
+    printf("%02x", a[i]);
+}
\ No newline at end of file
diff --git a/xmss_commons.h b/xmss_commons.h
new file mode 100644
index 0000000..be21195
--- /dev/null
+++ b/xmss_commons.h
@@ -0,0 +1,8 @@
+#ifndef XMSS_COMMONS_H
+#define XMSS_COMMONS_H
+
+#include <stdlib.h>
+
+void to_byte(unsigned char *output, uint in, int bytes);
+void hexdump(const unsigned char *a, size_t len);
+#endif
\ No newline at end of file
diff --git a/zerobytes.c b/zerobytes.c
new file mode 100644
index 0000000..bf04984
--- /dev/null
+++ b/zerobytes.c
@@ -0,0 +1,9 @@
+#include "zerobytes.h"
+
+unsigned char *zerobytes(unsigned char *r,unsigned long long n)
+{ 
+  volatile unsigned char *p=r; 
+  while (n--) 
+    *(p++) = 0; 
+  return r; 
+}
diff --git a/zerobytes.h b/zerobytes.h
new file mode 100644
index 0000000..18d0324
--- /dev/null
+++ b/zerobytes.h
@@ -0,0 +1,6 @@
+#ifndef ZEROBYTES_H
+#define ZEROBYTES_H
+
+unsigned char *zerobytes(unsigned char *r,unsigned long long n);
+
+#endif