diff -uNr a/bitcoin/src/init.cpp b/bitcoin/src/init.cpp
--- a/bitcoin/src/init.cpp 29fbb8792c3462ced61b4a0284360122f72c4fef7fb5fb84e5399967ab6474cd83ccf3a60eb3c425e183b1b95fb9ca71fc23bb791316d762034559df293f8bb0
+++ b/bitcoin/src/init.cpp 971b82be435c99a1af9d5cacc9c05af7616f4af7ee1466efacd46d41eddc1c4d7da2fdb4a302aab7c99933d33ad2d613f3bfbe76fec67a71c6d4d1fe14ac142d
@@ -177,6 +177,8 @@
 	    "  -verifyall       \t\t  " + _("Forbid the skipping of ECDSA signature verification between checkpoints.\n") +
 	    "  -setverstring    \t\t  " + _("Set a custom version string.\n") +
 	    "  -setvernum       \t\t  " + _("Set a custom version number.\n") +
+	    "  -highs           \t\t  " + _("Set all transactions to have DER 'S' Value set to 'high'.\n") +
+	    "  -lows            \t\t  " + _("Set all transactions to have DER 'S' Value set to 'low'.\n") +
             "  -logtimestamps   \t  "   + _("Prepend debug output with timestamp\n") +
             "  -printtoconsole  \t  "   + _("Send trace/debug info to console instead of debug.log file\n") +
             "  -rpcuser=<user>  \t  "   + _("Username for JSON-RPC connections\n") +
@@ -200,6 +202,14 @@
     fDaemon = GetBoolArg("-daemon");
     fCanEat = GetBoolArg("-caneat");
     fVerifyAll = GetBoolArg("-verifyall");
+    fHighS = GetBoolArg("-highs");
+    fLowS = GetBoolArg("-lows");
+
+    if (fHighS && fLowS)
+    {
+	printf("Error: '-highs' and '-lows' can not be set at the same time.\n");
+	return false;
+    }
 
     if (mapArgs.count("-setverstring"))
     {
diff -uNr a/bitcoin/src/key.h b/bitcoin/src/key.h
--- a/bitcoin/src/key.h 6b2389129dec411d013d754eaebc169a23f60b2169dc41cced21248a603ced46dfdc64e016c082a154af87784049333be75c91fb08265306a3bdc2bc0af2e6c5
+++ b/bitcoin/src/key.h afe71ade56fae65b970ff3dfb3f14edacee0af497ae57e2d2502c9a4b4f49f3336f9d3794b72a87d185b92fc01f1a5077e1ccd63a61ac4fa9c4464c6224fd1e4
@@ -291,12 +291,46 @@
     bool Sign(uint256 hash, std::vector<unsigned char>& vchSig)
     {
         vchSig.clear();
-        unsigned char pchSig[10000];
-        unsigned int nSize = 0;
-        if (!ECDSA_sign(0, (unsigned char*)&hash, sizeof(hash), pchSig, &nSize, pkey))
+        ECDSA_SIG *sig = ECDSA_do_sign((unsigned char *) &hash, sizeof(hash), pkey);
+
+        if (sig == NULL)
+        {
+            printf("ERROR, ECDSA_sign failed in key.h:Sign()\n");
             return false;
-        vchSig.resize(nSize);
-        memcpy(&vchSig[0], pchSig, nSize);
+        }
+
+        BN_CTX *ctx = BN_CTX_new();
+        BN_CTX_start(ctx);
+        const EC_GROUP *group = EC_KEY_get0_group(pkey);
+        BIGNUM *order = BN_CTX_get(ctx);
+        BIGNUM *halforder = BN_CTX_get(ctx);
+        EC_GROUP_get_order(group, order, ctx);
+        BN_rshift1(halforder, order);
+
+        if (fHighS && (BN_cmp(sig->s, halforder) < 0))
+        {
+            // enforce high S values
+            BN_sub(sig->s, order, sig->s);
+        }
+
+        if (fLowS && (BN_cmp(sig->s, halforder) > 0))
+        {
+            // enforce low S values
+            BN_sub(sig->s, order, sig->s);
+        }
+
+        BN_CTX_end(ctx);
+        BN_CTX_free(ctx);
+        unsigned int nSize = ECDSA_size(pkey);
+        vchSig.resize(nSize); // Make sure it is big enough
+        unsigned char *pos = &vchSig[0];
+        nSize = i2d_ECDSA_SIG(sig, &pos);
+        //printf("DEBUG DER R: 0x%s\n", BN_bn2hex(sig->r));
+        //printf("DEBUG DER R:   %s\n", BN_bn2dec(sig->r));
+        //printf("DEBUG DER S: 0x%s\n", BN_bn2hex(sig->s));
+        //printf("DEBUG DER S:   %s\n", BN_bn2dec(sig->s));
+        ECDSA_SIG_free(sig);
+        vchSig.resize(nSize); // Shrink to fit actual size
         return true;
     }
 
diff -uNr a/bitcoin/src/util.cpp b/bitcoin/src/util.cpp
--- a/bitcoin/src/util.cpp 72641fcb9bce1f705246cf52f08b3ece4b8df65e07ca10a32db860d4a120532a911fc62549960ccfdfc020fd1a5ef8baf0fcf181b861e0903c65b044899fc008
+++ b/bitcoin/src/util.cpp 66a8ac388136aceac7d24bd73c18b06445c2580849dd6c548d6684b5f1e9c19eafd3f71427476fd982383dcfd0425f34ce524eac1d8320fd990a28a1e4933288
@@ -32,6 +32,8 @@
 string strMiscWarning;
 bool fNoListen = false;
 bool fLogTimestamps = false;
+bool fLowS = false;
+bool fHighS = false;
 
 std::string CLIENT_NAME(DEFAULT_CLIENT_NAME);
 
diff -uNr a/bitcoin/src/util.h b/bitcoin/src/util.h
--- a/bitcoin/src/util.h d7e407108638c11f75b5bed04dc455ac78a96debc0776cd0e71871001c5886fd1472ae060e7a2334fcf3e323b7ad0a1b4fb68757392cc45a1b09721eb67415d1
+++ b/bitcoin/src/util.h f0c21c349b56516feac63c9cf8018c82b26583ad290a4b3610965e5a5a703d116671b1ef270395b8289c170b603630b5b7e493725e420e187ba1fbd326061ff5
@@ -122,6 +122,8 @@
 extern bool fNoListen;
 extern bool fLogTimestamps;
 extern std::string CLIENT_NAME;
+extern bool fLowS;
+extern bool fHighS;
 
 void RandAddSeed();
 void RandAddSeedPerfmon();