diff --git a/src/Makefile.am b/src/Makefile.am
index 66a2c6e2..a9d3c79c 100644
--- a/src/Makefile.am
+++ b/src/Makefile.am
@@ -1,7 +1,7 @@
 ACLOCAL_AMFLAGS = -I m4
 
 lib_LTLIBRARIES = libckpool.la
-libckpool_la_SOURCES = libckpool.c libckpool.h
+libckpool_la_SOURCES = libckpool.c libckpool.h sha2.c sha2.h
 libckpool_la_LIBADD = @PTHREAD_LIBS@ @MATH_LIBS@ @RT_LIBS@ @JANSSON_LIBS@
 
 bin_PROGRAMS = ckpool
diff --git a/src/bitcoin.c b/src/bitcoin.c
index 7183221d..1bde6477 100644
--- a/src/bitcoin.c
+++ b/src/bitcoin.c
@@ -75,3 +75,155 @@ out:
 		json_decref(val);
 	return ret;
 }
+
+static bool gbt_merkle_bins(gbtbase_t *gbt, json_t *transaction_arr)
+{
+	char hashhex[68], *hashbin;
+	int i, j, binleft, binlen;
+	json_t *arr_val;
+
+	dealloc(gbt->txn_data);
+	gbt->transactions = 0;
+	gbt->merkles = 0;
+	gbt->transactions = json_array_size(transaction_arr);
+	binlen = gbt->transactions * 32 + 32;
+	hashbin = alloca(binlen + 32);
+	memset(hashbin, 0, 32);
+	binleft = binlen / 32;
+	if (gbt->transactions) {
+		int len = 1, ofs = 0;
+		const char *txn;
+
+		for (i = 0; i < gbt->transactions; i++) {
+			arr_val = json_array_get(transaction_arr, i);
+			txn = json_string_value(json_object_get(arr_val, "data"));
+			if (!txn) {
+				LOGWARNING("json_string_value fail - cannot find transaction data");
+				return false;
+			}
+			len += strlen(txn);
+		}
+
+		gbt->txn_data = ckalloc(len + 1);
+		gbt->txn_data[len] = '\0';
+
+		for (i = 0; i < gbt->transactions; i++) {
+			char binswap[32];
+			const char *hash;
+
+			arr_val = json_array_get(transaction_arr, i);
+			hash = json_string_value(json_object_get(arr_val, "hash"));
+			txn = json_string_value(json_object_get(arr_val, "data"));
+			len = strlen(txn);
+			memcpy(gbt->txn_data + ofs, txn, len);
+			ofs += len;
+#if 0
+			if (!hash) {
+				char *txn_bin;
+				int txn_len;
+
+				txn_len = len / 2;
+				txn_bin = ckalloc(txn_len);
+				hex2bin(txn_bin, txn, txn_len);
+				/* This is needed for pooled mining since only
+				 * transaction data and not hashes are sent */
+				gen_hash(txn_bin, hashbin + 32 + 32 * i, txn_len);
+				continue;
+			}
+#endif
+			if (!hex2bin(binswap, hash, 32)) {
+				LOGERR("Failed to hex2bin hash in gbt_merkle_bins");
+				return false;
+			}
+			bswap_256(hashbin + 32 + 32 * i, binswap);
+		}
+	}
+	if (binleft > 1) {
+		while (42) {
+			if (binleft == 1)
+				break;
+			memcpy(gbt->merklebin + (gbt->merkles * 32), hashbin + 32, 32);
+			gbt->merkles++;
+			if (binleft % 2) {
+				memcpy(hashbin + binlen, hashbin + binlen - 32, 32);
+				binlen += 32;
+				binleft++;
+			}
+			for (i = 32, j = 64; j < binlen; i += 32, j += 64)
+				gen_hash(hashbin + j, hashbin + i, 64);
+			binleft /= 2;
+			binlen = binleft * 32;
+		}
+	}
+	for (i = 0; i < gbt->merkles; i++) {
+		__bin2hex(hashhex, gbt->merklebin + i * 32, 32);
+		LOGDEBUG("MH%d %s",i, hashhex);
+	}
+	LOGINFO("Stored %d transactions", gbt->transactions);
+	return true;
+}
+
+static const char *gbt_req = "{\"method\": \"getblocktemplate\", \"params\": [{\"capabilities\": [\"coinbasetxn\", \"workid\", \"coinbase/append\"]}]}\n";
+
+bool gen_gbtbase(connsock_t *cs, gbtbase_t *gbt)
+{
+	json_t *transaction_arr, *coinbase_aux, *res_val, *val;
+	const char *previousblockhash;
+	uint64_t coinbasevalue;
+	char hash_swap[32];
+	const char *target;
+	const char *flags;
+	const char *bits;
+	int version;
+	int curtime;
+	int height;
+	bool ret = false;
+
+	val = json_rpc_call(cs, gbt_req);
+	if (!val) {
+		LOGWARNING("Failed to get valid json response to getblocktemplate");
+		return ret;
+	}
+	res_val = json_object_get(val, "result");
+	if (!res_val) {
+		LOGWARNING("Failed to get result in json response to getblocktemplate");
+		return ret;
+	}
+
+	previousblockhash = json_string_value(json_object_get(res_val, "previousblockhash"));
+	target = json_string_value(json_object_get(res_val, "target"));
+	transaction_arr = json_object_get(res_val, "transactions");
+	version = json_integer_value(json_object_get(res_val, "version"));
+	curtime = json_integer_value(json_object_get(res_val, "curtime"));
+	bits = json_string_value(json_object_get(res_val, "bits"));
+	height = json_integer_value(json_object_get(res_val, "height"));
+	coinbasevalue = json_integer_value(json_object_get(res_val, "coinbasevalue"));
+	coinbase_aux = json_object_get(res_val, "coinbaseaux");
+	flags = json_string_value(json_object_get(coinbase_aux, "flags"));
+
+	if (unlikely(!previousblockhash || !target || !version || !curtime || !bits || !coinbase_aux || !flags)) {
+		LOGERR("JSON failed to decode GBT %s %s %d %d %s %s", previousblockhash, target, version, curtime, bits, flags);
+		goto out;
+	}
+	hex2bin(hash_swap, previousblockhash, 32);
+	swap_256(gbt->previousblockhash, hash_swap);
+	__bin2hex(gbt->prev_hash, gbt->previousblockhash, 32);
+	hex2bin(hash_swap, target, 32);
+	bswap_256(gbt->target, hash_swap);
+	gbt->sdiff = diff_from_target(gbt->target);
+
+	gbt->version = htobe32(version);
+	gbt->curtime = htobe32(curtime);
+	snprintf(gbt->ntime, 9, "%08x", curtime);
+	snprintf(gbt->bbversion, 9, "%08x", version);
+	snprintf(gbt->nbit, 9, "%s", bits);
+	gbt->nValue = coinbasevalue;
+	hex2bin(&gbt->bits, bits, 4);
+	gbt_merkle_bins(gbt, transaction_arr);
+	gbt->height = height;
+
+out:
+	if (res_val)
+		json_decref(res_val);
+	return ret;
+}
diff --git a/src/bitcoin.h b/src/bitcoin.h
index ea1b743a..9148e566 100644
--- a/src/bitcoin.h
+++ b/src/bitcoin.h
@@ -11,5 +11,6 @@
 #define BITCOIN_H
 
 bool validate_address(connsock_t *cs, const char *address);
+bool gen_gbtbase(connsock_t *cs, gbtbase_t *gbt);
 
 #endif /* BITCOIN_H */
diff --git a/src/libckpool.c b/src/libckpool.c
index 20a36376..1301e26d 100644
--- a/src/libckpool.c
+++ b/src/libckpool.c
@@ -24,6 +24,7 @@
 
 #include "ckpool.h"
 #include "libckpool.h"
+#include "sha2.h"
 
 /* Place holders for when we add lock debugging */
 #define GETLOCK(_lock, _file, _func, _line)
@@ -552,7 +553,6 @@ json_t *json_rpc_call(connsock_t *cs, const char *rpc_req)
 			LOGWARNING("Failed to read http socket lines in json_rpc_call");
 			goto out;
 		}
-		val = json_loads(cs->buf, 0, &err_val);
 	} while (strncmp(cs->buf, "{", 1));
 
 	val = json_loads(cs->buf, 0, &err_val);
@@ -1163,3 +1163,11 @@ void target_from_diff(uchar *target, double diff)
 	data64 = (uint64_t *)(target);
 	*data64 = htole64(h64);
 }
+
+void gen_hash(uchar *data, uchar *hash, int len)
+{
+	uchar hash1[32];
+
+	sha256(data, len, hash1);
+	sha256(hash1, 32, hash);
+}
diff --git a/src/libckpool.h b/src/libckpool.h
index 147651d8..ea54f0a0 100644
--- a/src/libckpool.h
+++ b/src/libckpool.h
@@ -109,9 +109,10 @@ struct gbtbase {
 	double sdiff;
 	uint32_t version;
 	uint32_t curtime;
-	uchar ntime[12];
-	uchar bbversion[12];
-	uchar nbit[12];
+	uchar prev_hash[68];
+	char ntime[12];
+	char bbversion[12];
+	char nbit[12];
 	int nValue;
 	uint32_t bits;
 	int height;
@@ -235,4 +236,6 @@ double diff_from_target(uchar *target);
 double diff_from_header(uchar *header);
 void target_from_diff(uchar *target, double diff);
 
+void gen_hash(uchar *data, uchar *hash, int len);
+
 #endif /* LIBCKPOOL_H */
diff --git a/src/sha2.c b/src/sha2.c
new file mode 100644
index 00000000..b04d27fc
--- /dev/null
+++ b/src/sha2.c
@@ -0,0 +1,211 @@
+/*
+ * FIPS 180-2 SHA-224/256/384/512 implementation
+ * Last update: 02/02/2007
+ * Issue date:  04/30/2005
+ *
+ * Copyright (C) 2013, Con Kolivas <kernel@kolivas.org>
+ * Copyright (C) 2005, 2007 Olivier Gay <olivier.gay@a3.epfl.ch>
+ * 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. Neither the name of the project nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS 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 PROJECT OR 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.
+ */
+
+#include "config.h"
+
+#include <string.h>
+#include <stdint.h>
+
+#include "sha2.h"
+
+#define UNPACK32(x, str)                      \
+{                                             \
+    *((str) + 3) = (uint8_t) ((x)      );       \
+    *((str) + 2) = (uint8_t) ((x) >>  8);       \
+    *((str) + 1) = (uint8_t) ((x) >> 16);       \
+    *((str) + 0) = (uint8_t) ((x) >> 24);       \
+}
+
+#define PACK32(str, x)                        \
+{                                             \
+    *(x) =   ((uint32_t) *((str) + 3)      )    \
+           | ((uint32_t) *((str) + 2) <<  8)    \
+           | ((uint32_t) *((str) + 1) << 16)    \
+           | ((uint32_t) *((str) + 0) << 24);   \
+}
+
+#define SHA256_SCR(i)                         \
+{                                             \
+    w[i] =  SHA256_F4(w[i -  2]) + w[i -  7]  \
+          + SHA256_F3(w[i - 15]) + w[i - 16]; \
+}
+
+uint32_t sha256_h0[8] =
+            {0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
+             0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19};
+
+uint32_t sha256_k[64] =
+            {0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5,
+             0x3956c25b, 0x59f111f1, 0x923f82a4, 0xab1c5ed5,
+             0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+             0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174,
+             0xe49b69c1, 0xefbe4786, 0x0fc19dc6, 0x240ca1cc,
+             0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+             0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7,
+             0xc6e00bf3, 0xd5a79147, 0x06ca6351, 0x14292967,
+             0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+             0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85,
+             0xa2bfe8a1, 0xa81a664b, 0xc24b8b70, 0xc76c51a3,
+             0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+             0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5,
+             0x391c0cb3, 0x4ed8aa4a, 0x5b9cca4f, 0x682e6ff3,
+             0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+             0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2};
+
+/* SHA-256 functions */
+
+void sha256_transf(sha256_ctx *ctx, const unsigned char *message,
+                   unsigned int block_nb)
+{
+    uint32_t w[64];
+    uint32_t wv[8];
+    uint32_t t1, t2;
+    const unsigned char *sub_block;
+    int i;
+
+    int j;
+
+    for (i = 0; i < (int) block_nb; i++) {
+        sub_block = message + (i << 6);
+
+        for (j = 0; j < 16; j++) {
+            PACK32(&sub_block[j << 2], &w[j]);
+        }
+
+        for (j = 16; j < 64; j++) {
+            SHA256_SCR(j);
+        }
+
+        for (j = 0; j < 8; j++) {
+            wv[j] = ctx->h[j];
+        }
+
+        for (j = 0; j < 64; j++) {
+            t1 = wv[7] + SHA256_F2(wv[4]) + CH(wv[4], wv[5], wv[6])
+                + sha256_k[j] + w[j];
+            t2 = SHA256_F1(wv[0]) + MAJ(wv[0], wv[1], wv[2]);
+            wv[7] = wv[6];
+            wv[6] = wv[5];
+            wv[5] = wv[4];
+            wv[4] = wv[3] + t1;
+            wv[3] = wv[2];
+            wv[2] = wv[1];
+            wv[1] = wv[0];
+            wv[0] = t1 + t2;
+        }
+
+        for (j = 0; j < 8; j++) {
+            ctx->h[j] += wv[j];
+        }
+    }
+}
+
+void sha256(const unsigned char *message, unsigned int len, unsigned char *digest)
+{
+    sha256_ctx ctx;
+
+    sha256_init(&ctx);
+    sha256_update(&ctx, message, len);
+    sha256_final(&ctx, digest);
+}
+
+void sha256_init(sha256_ctx *ctx)
+{
+    int i;
+    for (i = 0; i < 8; i++) {
+        ctx->h[i] = sha256_h0[i];
+    }
+
+    ctx->len = 0;
+    ctx->tot_len = 0;
+}
+
+void sha256_update(sha256_ctx *ctx, const unsigned char *message,
+                   unsigned int len)
+{
+    unsigned int block_nb;
+    unsigned int new_len, rem_len, tmp_len;
+    const unsigned char *shifted_message;
+
+    tmp_len = SHA256_BLOCK_SIZE - ctx->len;
+    rem_len = len < tmp_len ? len : tmp_len;
+
+    memcpy(&ctx->block[ctx->len], message, rem_len);
+
+    if (ctx->len + len < SHA256_BLOCK_SIZE) {
+        ctx->len += len;
+        return;
+    }
+
+    new_len = len - rem_len;
+    block_nb = new_len / SHA256_BLOCK_SIZE;
+
+    shifted_message = message + rem_len;
+
+    sha256_transf(ctx, ctx->block, 1);
+    sha256_transf(ctx, shifted_message, block_nb);
+
+    rem_len = new_len % SHA256_BLOCK_SIZE;
+
+    memcpy(ctx->block, &shifted_message[block_nb << 6],
+           rem_len);
+
+    ctx->len = rem_len;
+    ctx->tot_len += (block_nb + 1) << 6;
+}
+
+void sha256_final(sha256_ctx *ctx, unsigned char *digest)
+{
+    unsigned int block_nb;
+    unsigned int pm_len;
+    unsigned int len_b;
+
+    int i;
+
+    block_nb = (1 + ((SHA256_BLOCK_SIZE - 9)
+                     < (ctx->len % SHA256_BLOCK_SIZE)));
+
+    len_b = (ctx->tot_len + ctx->len) << 3;
+    pm_len = block_nb << 6;
+
+    memset(ctx->block + ctx->len, 0, pm_len - ctx->len);
+    ctx->block[ctx->len] = 0x80;
+    UNPACK32(len_b, ctx->block + pm_len - 4);
+
+    sha256_transf(ctx, ctx->block, block_nb);
+
+    for (i = 0 ; i < 8; i++) {
+        UNPACK32(ctx->h[i], &digest[i << 2]);
+    }
+}
diff --git a/src/sha2.h b/src/sha2.h
new file mode 100644
index 00000000..8a6ecaba
--- /dev/null
+++ b/src/sha2.h
@@ -0,0 +1,69 @@
+/*
+ * FIPS 180-2 SHA-224/256/384/512 implementation
+ * Last update: 02/02/2007
+ * Issue date:  04/30/2005
+ *
+ * Copyright (C) 2013, Con Kolivas <kernel@kolivas.org>
+ * Copyright (C) 2005, 2007 Olivier Gay <olivier.gay@a3.epfl.ch>
+ * 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. Neither the name of the project nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS 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 PROJECT OR 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.
+ */
+
+#include "config.h"
+
+#ifndef SHA2_H
+#define SHA2_H
+
+#define SHA256_DIGEST_SIZE ( 256 / 8)
+#define SHA256_BLOCK_SIZE  ( 512 / 8)
+
+#define SHFR(x, n)    (x >> n)
+#define ROTR(x, n)   ((x >> n) | (x << ((sizeof(x) << 3) - n)))
+#define CH(x, y, z)  ((x & y) ^ (~x & z))
+#define MAJ(x, y, z) ((x & y) ^ (x & z) ^ (y & z))
+
+#define SHA256_F1(x) (ROTR(x,  2) ^ ROTR(x, 13) ^ ROTR(x, 22))
+#define SHA256_F2(x) (ROTR(x,  6) ^ ROTR(x, 11) ^ ROTR(x, 25))
+#define SHA256_F3(x) (ROTR(x,  7) ^ ROTR(x, 18) ^ SHFR(x,  3))
+#define SHA256_F4(x) (ROTR(x, 17) ^ ROTR(x, 19) ^ SHFR(x, 10))
+
+typedef struct {
+    unsigned int tot_len;
+    unsigned int len;
+    unsigned char block[2 * SHA256_BLOCK_SIZE];
+    uint32_t h[8];
+} sha256_ctx;
+
+uint32_t sha256_k[64];
+
+void sha256_init(sha256_ctx * ctx);
+void sha256_update(sha256_ctx *ctx, const unsigned char *message,
+                   unsigned int len);
+void sha256_final(sha256_ctx *ctx, unsigned char *digest);
+void sha256(const unsigned char *message, unsigned int len,
+            unsigned char *digest);
+
+#endif /* !SHA2_H */